Plastic waste is clogging the Niger River in Bamako, Mali. After it sediments, plastic will become part of the geological record of human impacts on the planet. Credit: Michele Cattani/AFP via Getty
After 15 years of discussion, geologists last week decided that the Anthropocene — generally understood to be the age of irreversible human impacts on the planet — will not become an official epoch in Earth’s geological timeline.
The rejected proposal would have codified the end of the current Holocene epoch, which has been in place since the end of the last ice age 11,700 years ago. It suggested that the Anthropocene started in 1952, when plutonium from hydrogen-bomb tests showed up in the sediment of Crawford Lake near Toronto, Canada.
The vote has drawn controversy over procedural details, and debate about its legitimacy continues. But whether or not it’s formally approved as a stratigraphic term, the idea of the Anthropocene is now firmly rooted in research. So, how are scientists using the term, and what does it mean to them and their fields?
‘It’s a term that belongs to everyone’
As head of the Leverhulme Centre for Anthropocene Biodiversity at the University of York, UK, Chris Thomas has perhaps more riding on the term than most. “When the news of this — what sounds like a slightly dodgy vote — happened, I sort of wondered, is it the end of us? But I think not,” he says.
For Thomas, the word Anthropocene neatly summarizes the sense that humans are part of Earth’s system and integral to its processes — what he calls indivisible connectedness. “That helps move us away from the notion that somehow humanity is apart from the rest of nature and natural systems,” he says. “It’s undoable — the change is everywhere.”
The concept of an era of human-driven change also provides convenient common ground for him to collaborate with researchers from other disciplines. “This is something that people in the arts and humanities and the social sciences have picked up as well,” he says. “It is a means of enabling communication about the extent to which we are living in a truly unprecedented and human-altered world.”
Seen through that lens, the fact that the Anthropocene has been formally rejected because scientists can’t agree on when it began seems immaterial. “Many people in the humanities who are using the phrase find the concept of the articulation of a particular year, based on a deposit in a particular lake, a ridiculous way of framing the concept of a human-altered planet.”
Jacquelyn Gill, a palaeoecologist at the University of Maine in Orono, agrees. “It’s a term that belongs to everyone. To people working in philosophy and literary criticism, in the arts, in the humanities, the sciences,” she says. “I think it’s far more meaningful in the way that it is currently being used, than in any attempts that stratigraphers could have made to restrict or define it in some narrow sense.”
She adds: “It serves humanity best as a loose concept that we can use to define something that we all widely understand, which is that we live in an era where humans are the dominant force on ecological and geological processes.”
Capturing human influences
The idea of the Anthropocene is especially helpful to make clear that humans have been shaping the planet for thousands of years, and that not all of those changes have been bad, Gill says. “We could do a better job of thinking about human–environment relationships in ways that are not inherently negative all the time,” she says. “People are not a monolith, and neither are our attitudes or relationships to nature.”
Some 80% of biodiversity is currently stewarded on Indigenous lands, Gill points out. “Which should tell you something, right? That it’s not the presence of people that’s the problem,” she says. “The solution to those problems is changing the way that many dominant cultures relate to the natural world.”
The concept of the Anthropocene is owned by many fields, Gill says. “This reiterates the importance of understanding that the role of people on our planet requires many different ways of knowing and many different disciplines.”
In a world in which the threat of climate change dominates environmental debates, the term Anthropocene can help to broaden the discussion, says Yadvinder Malhi, a biodiversity researcher at the University of Oxford, UK.
“I use it all the time. For me, it captures the time where human influence has a global planetary effect, and it’s multidimensional. It’s much more than just climate change,” he says. “It’s what we’re doing. The oceans, the resources we are extracting, habitats changing.”
He adds: “I need that term when I’m trying to capture this idea of humans affecting the planet in multiple ways because of the size of our activity.”
The looseness of the term is popular, but would a formal definition help in any way? Malhi thinks it would. “There’s no other term available that captures the global multidimensional impacts on the planet,” he says. “But there is a problem in not having a formal definition if people are using it in different terms, in different ways.”
Although the word ‘Anthropocene’ makes some researchers think of processes that began 10,000 years ago, others consider it to mean those of the past century. “I think a formal adoption, like a definition, would actually help to clarify that.”
A 1953 nuclear weapons test in Nevada was among the human activities that could have marked the Anthropocene. NNSA/NEVADA FIELD OFFICE/SCIENCE SOURCE
For now, we’re still in the Holocene.
Science has confirmed that a panel of two dozen geologists has voted down a proposal to end the Holocene—our current span of geologic time, which began 11,700 years ago at the end of the last ice age—and inaugurate a new epoch, the Anthropocene. Starting in the 1950s, it would have marked a time when humanity’s influence on the planet became overwhelming. The vote, first reported by The New York Times, is a stunning—though not unexpected—rebuke for the proposal, which has been working its way through a formal approval process for more than a decade.
“The decision is definitive,” says Philip Gibbard, a geologist at the University of Cambridge who is on the panel and serves as secretary-general of the International Commission on Stratigraphy (ICS), the body that governs the geologic timescale. “There are no outstanding issues to be resolved. Case closed.”
The leaders of the Anthropocene Working Group (AWG), which developed the proposal for consideration by ICS’s Subcommission on Quaternary Stratigraphy, are not yet ready to admit defeat. They note that the online tally, in which 12 out of 18 subcommission members voted against the proposal, was leaked to the press without approval of the panel’s chair. “There remain several issues that need to be resolved about the validity of the vote and the circumstances surrounding it,” says Colin Waters, a geologist at the University of Leicester who chaired AWG.
Few opponents of the Anthropocene proposal doubted the enormous impact that human influence, including climate change, is having on the planet. But some felt the proposed marker of the epoch—some 10 centimeters of mud from Canada’s Crawford Lake that captures the global surge in fossil fuel burning, fertilizer use, and atomic bomb fallout that began in the 1950s—isn’t definitive enough.
Others questioned whether it’s even possible to affix one date to the start of humanity’s broad planetary influence: Why not the rise of agriculture? Why not the vast changes that followed European encroachment on the New World? “The Anthropocene epoch was never deep enough to understand human transformation of this planet,” says Erle Ellis, a geographer at the University of Maryland, Baltimore County who resigned last year in protest from AWG.
Opponents also felt AWG made too many announcements to the press over the years while being slow to submit a proposal to the subcommission. “The Anthropocene epoch was pushed through the media from the beginning—a publicity drive,” says Stanley Finney, a stratigrapher at California State University Long Beach and head of the International Union of Geological Sciences, which would have had final approval of the proposal.
Finney also complains that from the start, AWG was determined to secure an “epoch” categorization, and ignored or countered proposals for a less formal Anthropocene designation. If they had only made their formal proposal sooner, they could have avoided much lost time, Finney adds. “It would have been rejected 10 years earlier if they had not avoided presenting it to the stratigraphic community for careful consideration.”
The Anthropocene backers will now have to wait for a decade before their proposal can be considered again. ICS has long instituted this mandatory cooling-off period, given how furious debates can turn, for example, over the boundary between the Pliocene and Pleistocene, and whether the Quaternary—our current geologic period, a category above epochs—should exist at all.
Even if it is not formally recognized by geologists, the Anthropocene is here to stay. It is used in art exhibits, journal titles, and endless books. And Gibbard, Ellis, and others have advanced the view that it can remain an informal geologic term, calling it the “Anthropocene event.” Like the Great Oxygenation Event, in which cyanobacteria flushed the atmosphere with oxygen billions of years ago, the Anthropocene marks a huge transition, but one without an exact date. “Let us work together to ensure the creation of a far deeper and more inclusive Anthropocene event,” Ellis says.
Waters and his colleagues will continue to press that the Anthropocene is worthy of recognition in the geologic timescale, even if that advocacy has to continue in an informal capacity, he says. Although small in size, Anthropocene strata such as the 10 centimeters of lake mud are distinct and can be traced using more than 100 durable geochemical signals, he says. And there is no going back to where the planet was 100 years ago, he says. “The Earth system changes that mark the Anthropocene are collectively irreversible.”
A panel of experts voted down a proposal to officially declare the start of a new interval of geologic time, one defined by humanity’s changes to the planet.
In weighing their decision, scientists considered the effect on the world of nuclear activity. A 1946 test blast over Bikini atoll. Credit: Jack Rice/Associated Press
Not yet, scientists have decided, after a debate that has spanned nearly 15 years. Or the blink of an eye, depending on how you look at it.
A committee of roughly two dozen scholars has, by a large majority, voted down a proposal to declare the start of the Anthropocene, a newly created epoch of geologic time, according to an internal announcement of the voting results seen by The New York Times.
By geologists’ current timeline of Earth’s 4.6-billion-year history, our world right now is in the Holocene, which began 11,700 years ago with the most recent retreat of the great glaciers. Amending the chronology to say we had moved on to the Anthropocene would represent an acknowledgment that recent, human-induced changes to geological conditions had been profound enough to bring the Holocene to a close.
The declaration would shape terminology in textbooks, research articles and museums worldwide. It would guide scientists in their understanding of our still-unfolding present for generations, perhaps even millenniums, to come.
In the end, though, the members of the committee that voted on the Anthropocene over the past month were not only weighing how consequential this period had been for the planet. They also had to consider when, precisely, it began.
By the definition that an earlier panel of experts spent nearly a decade and a half debating and crafting, the Anthropocene started in the mid-20th century, when nuclear bomb tests scattered radioactive fallout across our world. To several members of the scientific committee that considered the panel’s proposal in recent weeks, this definition was too limited, too awkwardly recent, to be a fitting signpost of Homo sapiens’s reshaping of planet Earth.
“It constrains, it confines, it narrows down the whole importance of the Anthropocene,” said Jan A. Piotrowski, a committee member and geologist at Aarhus University in Denmark. “What was going on during the onset of agriculture? How about the Industrial Revolution? How about the colonizing of the Americas, of Australia?”
“Human impact goes much deeper into geological time,” said another committee member, Mike Walker, an earth scientist and professor emeritus at the University of Wales Trinity Saint David. “If we ignore that, we are ignoring the true impact, the real impact, that humans have on our planet.”
Hours after the voting results were circulated within the committee early Tuesday, some members said they were surprised at the margin of votes against the Anthropocene proposal compared with those in favor: 12 to four, with two abstentions. (Another three committee members neither voted nor formally abstained.)
Even so, it was unclear on Tuesday whether the results stood as a conclusive rejection or whether they might still be challenged or appealed. In an email to The Times, the committee’s chair, Jan A. Zalasiewicz, said there were “some procedural issues to consider” but declined to discuss them further. Dr. Zalasiewicz, a geologist at the University of Leicester, has expressed support for canonizing the Anthropocene.
This question of how to situate our time in the narrative arc of Earth history has thrust the rarefied world of geological timekeepers into an unfamiliar limelight.
The grandly named chapters of our planet’s history are governed by a body of scientists, the International Union of Geological Sciences. The organization uses rigorous criteria to decide when each chapter started and which characteristics defined it. The aim is to uphold common global standards for expressing the planet’s history.
Polyethylene being extruded and fed into a cooling bath during plastics manufacture, circa 1950. Credit: Hulton Archive, via Getty Images
Geoscientists don’t deny our era stands out within that long history. Radionuclides from nuclear tests. Plastics and industrial ash. Concrete and metal pollutants. Rapid greenhouse warming. Sharply increased species extinctions. These and other products of modern civilization are leaving unmistakable remnants in the mineral record, particularly since the mid-20th century.
Still, to qualify for its own entry on the geologic time scale, the Anthropocene would have to be defined in a very particular way, one that would meet the needs of geologists and not necessarily those of the anthropologists, artists and others who are already using the term.
That’s why several experts who have voiced skepticism about enshrining the Anthropocene emphasized that the vote against it shouldn’t be read as a referendum among scientists on the broad state of the Earth. “This was a narrow, technical matter for geologists, for the most part,” said one of those skeptics, Erle C. Ellis, an environmental scientist at the University of Maryland, Baltimore County. “This has nothing to do with the evidence that people are changing the planet,” Dr. Ellis said. “The evidence just keeps growing.”
Francine M.G. McCarthy, a micropaleontologist at Brock University in St. Catharines, Ontario, is the opposite of a skeptic: She helped lead some of the research to support ratifying the new epoch.
“We are in the Anthropocene, irrespective of a line on the time scale,” Dr. McCarthy said. “And behaving accordingly is our only path forward.”
The Anthropocene proposal got its start in 2009, when a working group was convened to investigate whether recent planetary changes merited a place on the geologic timeline. After years of deliberation, the group, which came to include Dr. McCarthy, Dr. Ellis and some three dozen others, decided that they did. The group also decided that the best start date for the new period was around 1950.
The group then had to choose a physical site that would most clearly show a definitive break between the Holocene and the Anthropocene. They settled on Crawford Lake, in Ontario, where the deep waters have preserved detailed records of geochemical change within the sediments at the bottom.
Last fall, the working group submitted its Anthropocene proposal to the first of three governing committees under the International Union of Geological Sciences. Sixty percent of each committee has to approve the proposal for it to advance to the next.
The members of the first one, the Subcommission on Quaternary Stratigraphy, submitted their votes starting in early February. (Stratigraphy is the branch of geology concerned with rock layers and how they relate in time. The Quaternary is the ongoing geologic period that began 2.6 million years ago.)
Under the rules of stratigraphy, each interval of Earth time needs a clear, objective starting point, one that applies worldwide. The Anthropocene working group proposed the mid-20th century because it bracketed the postwar explosion of economic growth, globalization, urbanization and energy use. But several members of the subcommission said humankind’s upending of Earth was a far more sprawling story, one that might not even have a single start date across every part of the planet.
The world’s first full-scale atomic power station in Britain in 1956. Credit: Hulton Archive, via Getty Images
This is why Dr. Walker, Dr. Piotrowski and others prefer to describe the Anthropocene as an “event,” not an “epoch.” In the language of geology, events are a looser term. They don’t appear on the official timeline, and no committees need to approve their start dates.
Yet many of the planet’s most significant happenings are called events, including mass extinctions, rapid expansions of biodiversity and the filling of Earth’s skies with oxygen 2.1 to 2.4 billion years ago.
Even if the subcommission’s vote is upheld and the Anthropocene proposal is rebuffed, the new epoch could still be added to the timeline at some later point. It would, however, have to go through the whole process of discussion and voting all over again.
Time will march on. Evidence of our civilization’s effects on Earth will continue accumulating in the rocks. The task of interpreting what it all means, and how it fits into the grand sweep of history, might fall to the future inheritors of our world.
“Our impact is here to stay and to be recognizable in the future in the geological record — there is absolutely no question about this,” Dr. Piotrowski said. “It will be up to the people that will be coming after us to decide how to rank it.”
Raymond Zhong reports on climate and environmental issues for The Times.
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Un comité de expertos ha tumbado la propuesta de declarar un nuevo momento geológico, pero el propio presidente denuncia irregularidades en la votación
Manuel Ansede
Madrid –
Extracción de un testigo de sedimentos del fondo del lago Crawford, a las afueras de Toronto (Canadá). TIM PATTERSON / UNIVERSIDAD DE CARLETON
La idea del Antropoceno —que la humanidad vive desde 1950 en una nueva época geológica caracterizada por la contaminación humana— se ha hecho tan popular en los últimos años que hasta la Real Academia Española adoptó el término en el Diccionario de la Lengua en 2021. Los académicos se dieron esta vez demasiada prisa. El concepto sigue en el aire, en medio de una vehemente polémica entre especialistas. Miembros del comité de expertos que debe tomar la decisión en la Unión Internacional de Ciencias Geológicas (UICG) —la Subcomisión de Estratigrafía del Cuaternario— han filtrado este martes al diario The New York Times que han votado mayoritariamente en contra de reconocer la existencia del Antropoceno. Sin embargo, el presidente de la Subcomisión, el geólogo Jan Zalasiewicz, explica a EL PAÍS que el resultado preliminar de la votación se ha anunciado sin su autorización y que todavía quedan “algunos asuntos pendientes con los votos que hay que resolver”. La humanidad todavía no sabe en qué época geológica vive.
El químico holandés Paul Crutzen, ganador del Nobel de Química por iluminar el agujero de la capa de ozono, planteó en el año 2000 que el planeta había entrado en una nueva época, provocada por el impacto brutal de los seres humanos. Un equipo internacional de especialistas, el Grupo de Trabajo del Antropoceno, ha analizado los hechos científicos desde 2009 y el año pasado presentó una propuesta para proclamar oficialmente esta nueva época geológica, marcada por la radiactividad de las bombas atómicas y los contaminantes procedentes de la quema de carbón y petróleo. El diminuto lago Crawford, a las afueras de Toronto (Canadá), era el lugar indicado para ejemplificar el inicio del Antropoceno, gracias a los sedimentos de su fondo, imperturbados desde hace siglos.
La mayoría de los miembros de la Subcomisión de Estratigrafía del Cuaternario de la UICG ha votado en contra de la propuesta, según el periódico estadounidense. El geólogo británico Colin Waters, líder del Grupo de Trabajo del Antropoceno, explica a EL PAÍS que se ha enterado por la prensa. “Todavía no hemos recibido una confirmación oficial directamente del secretario de la Subcomisión de Estratigrafía del Cuaternario. Parece que The New York Times recibe los resultados antes que nosotros, es muy decepcionante”, lamenta Waters.
El geólogo reconoce que el dictamen, si se confirma, sería el fin de su propuesta actual, pero no se rinde. “Tenemos muchos investigadores eminentes que desean continuar como grupo, de manera informal, defendiendo las evidencias de que el Antropoceno debería ser formalizado como una época”, afirma. A su juicio, los estratos geológicos actuales —contaminados por isótopos radiactivos, microplásticos, cenizas y pesticidas— han cambiado de manera irreversible respecto a los del Holoceno, la época geológica iniciada hace más de 10.000 años, tras la última glaciación. “Dadas las pruebas existentes, que siguen aumentando, no me sorprendería un futuro llamamiento a reconsiderar nuestra propuesta”, opina Waters, de la Universidad de Leicester.
El jefe del Grupo de Trabajo del Antropoceno sostiene que hay “algunas cuestiones de procedimiento” que ponen en duda la validez de la votación. La geóloga italiana Silvia Peppoloni, jefa de la Comisión de Geoética de la UICG, confirma que su equipo ha realizado un informe sobre esta pelea entre la Subcomisión de Estratigrafía del Cuaternario y el Grupo de Trabajo del Antropoceno. El documento está sobre la mesa del presidente de la UICG, el británico John Ludden.
La geóloga canadiense Francine McCarthy estaba convencida de que el lago Crawford convencería a los escépticos. Desde fuera parece pequeño, con apenas 250 metros de largo, pero su profundidad roza los 25 metros. Sus aguas superficiales no se mezclan con las de su lecho, por lo que el suelo del fondo se puede analizar como una lasaña, en la que cada capa acumula sedimentos procedentes de la atmósfera. Ese calendario subacuático del lago Crawford revela la denominada Gran Aceleración, el momento alrededor de 1950 en el que la humanidad empezó a dejar una huella cada vez más evidente, con el lanzamiento de bombas atómicas, la quema masiva de petróleo y carbón y la extinción de especies.
“Ignorar el enorme impacto de los humanos en nuestro planeta desde mediados del siglo XX tiene potencialmente consecuencias dañinas, al minimizar la importancia de los datos científicos para hacer frente al evidente cambio en el sistema de la Tierra, como ya señaló Paul Crutzen hace casi 25 años”, advierte McCarthy.
Grupo rejeitou que mudanças sejam profundas o bastante para encerrar o Holoceno
Raymond Zhong
5 de março de 2024
O Triássico foi o amanhecer dos dinossauros. O Paleogeno viu a ascensão dos mamíferos. O Pleistoceno incluiu as últimas eras glaciais.
Está na hora de marcar a transformação da humanidade no planeta com seu próprio capítulo na história da Terra, o “Antropoceno”, ou a época humana?
Ainda não, decidiram os cientistas, após um debate que durou quase 15 anos. Ou um piscar de olhos, dependendo do ângulo pelo qual você olha.
Um comitê de cerca de duas dezenas de estudiosos votou, em grande maioria, contra uma proposta de declarar o início do Antropoceno, uma época recém-criada do tempo geológico, de acordo com um anúncio interno dos resultados da votação visto pelo The New York Times.
Pela linha do tempo atual dos geólogos da história de 4,6 bilhões de anos da Terra, nosso mundo agora está no Holoceno, que começou há 11,7 mil anos com o recuo mais recente dos grandes glaciares.
Alterar a cronologia para dizer que avançamos para o Antropoceno representaria um reconhecimento de que as mudanças recentes induzidas pelo homem nas condições geológicas foram profundas o suficiente para encerrar o Holoceno.
A declaração moldaria a terminologia em livros didáticos, artigos de pesquisa e museus em todo o mundo. Orientaria os cientistas em sua compreensão do nosso presente ainda em desenvolvimento por gerações, talvez até por milênios.
No fim das contas, porém, os membros do comitê que votaram sobre o Antropoceno nas últimas semanas não estavam apenas considerando o quão determinante esse período havia sido para o planeta. Eles também tiveram que considerar quando, precisamente, ele começou.
Pela definição que um painel anterior de especialistas passou quase uma década e meia debatendo e elaborando, o Antropoceno começou na metade do século 20, quando testes de bombas nucleares espalharam material radioativo por todo o nosso mundo.
Para vários membros do comitê científico que avaliaram a proposta do painel nas últimas semanas, essa definição era muito limitada, muito recente e inadequada para ser um marco adequado da remodelação do Homo sapiens no planeta Terra.
“Isso restringe, confina, estreita toda a importância do Antropoceno”, disse Jan A. Piotrowski, membro do comitê e geólogo da Universidade de Aarhus, na Dinamarca. “O que estava acontecendo durante o início da agricultura? E a Revolução Industrial? E a colonização das Américas, da Austrália?”
“O impacto humano vai muito mais fundo no tempo geológico”, disse outro membro do comitê, Mike Walker, cientista da Terra e professor emérito da Universidade de Gales Trinity Saint David. “Se ignorarmos isso, estamos ignorando o verdadeiro impacto que os humanos têm em nosso planeta.”
Horas após a circulação dos resultados da votação dentro do comitê nesta terça-feira (5) de manhã, alguns membros disseram que ficaram surpresos com a margem de votos contra a proposta do Antropoceno em comparação com os a favor: 12 a 4, com 2 abstenções.
Mesmo assim, nesta terça de manhã não ficou claro se os resultados representavam uma rejeição conclusiva ou se ainda poderiam ser contestados ou apelados. Em um e-mail para o Times, o presidente do comitê, Jan A. Zalasiewicz, disse que havia “algumas questões procedimentais a considerar”, mas se recusou a discuti-las mais a fundo.
Zalasiewicz, geólogo da Universidade de Leicester, expressou apoio à canonização do Antropoceno.
Essa questão de como situar nosso tempo na narrativa da história da Terra colocou o mundo dos guardiões do tempo geológico sob uma luz desconhecida.
Os capítulos grandiosamente nomeados da história de nosso planeta são governados por um grupo de cientistas, a União Internacional de Ciências Geológicas. A organização usa critérios rigorosos para decidir quando cada capítulo começou e quais características o definiram. O objetivo é manter padrões globais comuns para expressar a história do planeta.
Os geocientistas não negam que nossa era se destaca dentro dessa longa história. Radionuclídeos de testes nucleares. Plásticos e cinzas industriais. Poluentes de concreto e metal. Aquecimento global rápido. Aumento acentuado de extinções de espécies. Esses e outros produtos da civilização moderna estão deixando vestígios inconfundíveis no registro mineral, especialmente desde meados do século 20.
Ainda assim, para se qualificar para a entrada na escala de tempo geológico, o Antropoceno teria que ser definido de uma maneira muito específica, que atendesse às necessidades dos geólogos e não necessariamente dos antropólogos, artistas e outros que já estão usando o termo.
Por isso, vários especialistas que expressaram ceticismo quanto à consagração do Antropoceno enfatizaram que o voto contra não deve ser interpretado como um referendo entre cientistas sobre o amplo estado da Terra.
“Este é um assunto específico e técnico para os geólogos, em sua maioria”, disse um desses céticos, Erle C. Ellis, um cientista ambiental da Universidade de Maryland. “Isso não tem nada a ver com a evidência de que as pessoas estão mudando o planeta”, afirmou Ellis. “A evidência continua crescendo.”
Francine M.G. McCarthy, micropaleontóloga da Universidade Brock em St. Catharines, Ontário (Canadá), é tem visão oposta: ela ajudou a liderar algumas das pesquisas para apoiar a ratificação da nova época.
“Estamos no Antropoceno, independentemente de uma linha na escala de tempo”, disse McCarthy. “E agir de acordo é o nosso único caminho a seguir.”
A proposta do Antropoceno teve início em 2009, quando um grupo de trabalho foi convocado para investigar se as recentes mudanças planetárias mereciam um lugar na linha do tempo geológica.
Após anos de deliberação, o grupo, que passou a incluir McCarthy, Ellis e cerca de três dezenas de outros, decidiu que sim. O grupo também decidiu que a melhor data de início para o novo período era por volta de 1950.
O grupo então teve que escolher um local físico que mostrasse de forma mais clara uma quebra definitiva entre o Holoceno e o Antropoceno. Eles escolheram o Lago Crawford, em Ontário, no Canadá, onde as águas profundas preservaram registros detalhados de mudanças geoquímicas nos sedimentos do fundo.
No outono passado, o grupo de trabalho enviou sua proposta do Antropoceno para o primeiro dos três comitês governantes da União Internacional de Ciências Geológicas —60% de cada comitê precisam aprovar a proposta para que ela avance para o próximo.
Os membros do primeiro comitê, a Subcomissão de Estratigrafia do Quaternário, enviaram seus votos a partir do início de fevereiro. (Estratigrafia é o ramo da geologia que se dedica ao estudo das camadas de rocha e como elas se relacionam no tempo. O Quaternário é o período geológico em curso que começou há 2,6 milhões de anos.)
De acordo com as regras da estratigrafia, cada intervalo de tempo da Terra precisa de um ponto de partida claro e objetivo, que se aplique em todo o mundo. O grupo de trabalho do Antropoceno propôs meados do século 20 porque isso abrangia a explosão do crescimento econômico pós-guerra, a globalização, a urbanização e o uso de energia.
Mas vários membros da subcomissão disseram que a transformação da humanidade na Terra era uma história muito mais abrangente, que talvez nem tenha uma única data de início em todas as partes do planeta.
Por isso, Walker, Piotrowski e outros preferem descrever o Antropoceno como um “evento”, não como uma “época”. Na linguagem da geologia, eventos são um termo mais amplo. Eles não aparecem na linha do tempo oficial, e nenhum comitê precisa aprovar suas datas de início.
No entanto, muitos dos acontecimentos mais significativos do planeta são chamados de eventos, incluindo extinções em massa, expansões rápidas da biodiversidade e o preenchimento dos céus da Terra com oxigênio há 2,1 bilhões a 2,4 bilhões de anos.
Mesmo que o voto da subcomissão seja mantido e a proposta do Antropoceno seja rejeitada, a nova época ainda poderá ser adicionada à linha do tempo em algum momento posterior. No entanto, terá que passar por todo o processo de discussão e votação novamente.
“O mundo está mudando: sinto-o na água, sinto-o na terra e farejo-o no ar.” Quem só assistiu aos filmes da série “O Senhor dos Anéis” se acostumou a ouvir essa frase na voz augusta de Cate Blanchett (a elfa Galadriel); nos livros, quem a pronuncia é o ent (gigante arvoresco) Barbárvore. Trata-se, no fundo, de um resumo da conclusão do romance de fantasia de J.R.R. Tolkien: o fim de uma era e o começo de outra, caracterizada pelo Domínio dos Homens. E se fosse possível detectar diretamente algo muito parecido com isso no nosso mundo do século 21? Algo que prove, para além de qualquer dúvida, que a nossa espécie passou a moldar a Terra de forma irreversível?
A resposta a essa pergunta pode ser encontrada em muitos lugares, mas tudo indica que a versão mais contundente e consolidada dela, a que entrará para os livros de geologia e de história, vem do lago Crawford, no Canadá. Os cientistas encarregados de definir formalmente o início do chamado Antropoceno –a época geológica caracterizada pela intervenção humana maciça em diversos aspectos do funcionamento do planeta– estão usando o lago como o exemplo por excelência desse fenômeno.
É por isso que convido o leitor para um mergulho naquelas águas alcalinas. Entender os detalhes que fazem do lugar um exemplo tão útil para entender o Antropoceno é, ao mesmo tempo, uma pequena aula de método científico e um retrato do poderio –frequentemente destrutivo– que desenvolvemos como espécie.
Uma das análises mais completas da lagoa canadense foi publicado na revista científica The Anthropocene Review por uma equipe da Universidade Brock, no Canadá. A primeira coisa a se ter em mente é que o lago Crawford parece um grande funil: relativamente pequeno (2,4 hectares de área) e fundo (24 m entre a superfície e o leito). Isso faz com que as camadas d’água, embora bem oxigenadas, misturem-se pouco. Por causa da salinidade e alcalinidade elevadas, há pouca vida animal no fundo.
E esse é o primeiro grande pulo do gato: tais características fazem com que camadas muito estáveis de sedimento possam se depositar anualmente no leito do lago Crawford. Todo ano é a mesma história: durante o outono, uma lâmina mais escura de matéria orgânica desce ao fundo (como estamos no Canadá, muitas árvores perdem as folhas nessa época); no verão, essa camada é recoberta por outra, mais clara, de minerais ricos em cálcio. Essa regularidade nunca é bagunçada pela chamada bioturbação (invertebrados aquáticos cavando o leito, por exemplo).
Ou seja, o fundo do lago é um reloginho, ou melhor, um calendário. Cilindros de sedimento tirados de seu fundo podem ser datados ano a ano com pouquíssima incerteza.
Isso significa que dá para identificar com precisão o aparecimento do elemento químico plutônio –resultado direto do uso de armas nucleares, principalmente em testes militares– a partir de 1948, com um pico em 1967 e uma queda nos anos 1980. Dada a natureza dos elementos radioativos, essa assinatura estará lá rigorosamente “para sempre” (ao menos do ponto de vista humano).
Algo muito parecido vale para as chamadas SCPs (partículas esferoidais carbonáceas, na sigla inglesa). Elas são produzidas pela queima industrial, em altas temperaturas, de carvão mineral e derivados do petróleo. Começam a aparecer nos sedimentos da segunda metade do século 19, mas sua presença só dispara mesmo, de novo, no começo dos anos 1950. Nada que não seja a ação humana poderia produzir esse fenômeno.
É por isso que os cientistas estão propondo o ano de 1950 como o início do Antropoceno. Ainda que a proposta não “pegue” nesse formato exato, o peso de evidências como as camadas do lago Crawford é dificílimo de contrariar. Está na água, na terra e no ar. E, para o bem ou para o mal, a responsabilidade é nossa.
A busca por energias mais limpas, um dos principais desafios para reduzir emissões de gases-estufa e enfrentar as mudanças climáticas, também vai custar recursos ao planeta. Oito bilhões de seres humanos detêm, juntos, um poder de impacto que vai deixar as marcas dessa decisão —seja ela tomada ou não.
É o que afirma o geólogo Colin Waters, secretário do AWG, sigla em inglês para Grupo de Trabalho do Antropoceno. Formado por 40 cientistas, o coletivo se prepara para apresentar, em junho, uma proposta para o “golden spike”, ponto em algum lugar da Terra que servirá de base para a definição do Antropoceno, a chamada “época dos humanos”.
Para os cientistas do AWG, a nova época geológica da Terra é marcada pela atividade humana, com a expansão da produção industrial e a elevação do consumo em cadeia global. Seu ponto de início é debatido desde 2009 pelos pesquisadores do grupo.
Waters, professor na Universidade de Leicester, no Reino Unido, tem sido o porta-voz do AWG para traduzir as implicações de uma nova época no planeta e por que isso é importante. Nesta semana, ele visita o Brasil pela primeira vez, para participar da reunião magna de 2023 da Academia Brasileira de Ciências, no Rio de Janeiro.
“Nosso pequeno grupo de trabalho sabe que há evidência científica [do Antropoceno]. Tudo que podemos fazer é usar isso para guiar nossas decisões. Como isso vai ser usado pelas pessoas é papel de políticos”, afirma Waters, em entrevista exclusiva à Folha. “Mas você começa a se perguntar: como lidamos com esse planeta que está mudando?”
A década de 1950 se firmou nas discussões como o ponto de início do Antropoceno em razão do aumento generalizado da queima de combustíveis fósseis, da realização de testes nucleares feitos a céu aberto, espalhando quantidades de plutônio pelo mundo, além das detonações de bombas de hidrogênio.
A ideia inicial de Crutzen sobre o começo do Antropoceno apontava para a revolução industrial, na Inglaterra, no século 18. Mas, naquela etapa, diz Waters, a revolução acontecia na Europa, e para se espalhar levaria boa parte de um século.
“Quanto mais investigamos, mais perto chegamos da década de 1950. Todos passavam por grandes mudanças na economia e no grau de industrialização. Temos a China decolando entre os anos 1950 e 1960”, explica. “E mesmo a Amazônia estaria ao alcance da contaminação atmosférica por partículas da queima de combustíveis fósseis.”
E por que não em 1949? “Porque há uma gradação”, diz o geólogo. “As evidências apontam para uma mudança drástica no meio do século 20.”
Além de pesquisar o marco temporal, é preciso achar um lugar no planeta —o chamado “golden spike”— que possa ser comparado a outros locais para identificar os sedimentos de poluição deixados pela atividade humana.
A proposta para a definição desse marcador, que deve ser feita em junho, vai escolher um entre 12 locais, que incluem lagos, gelo no Ártico ou corais. Os últimos, segundo o pesquisador, são bons candidatos porque permitem a visualização anual da mudança de partículas.
Após a decisão do grupo, o tema será votado em outras três instâncias. A última, que vai ratificar a decisão, é a União Internacional de Ciências Geológicas.
O desafio atual consiste no fato de que definir uma época geológica sempre foi uma tarefa de olhar para o passado —e continua sendo, já que geólogos analisam sedimentos e fósseis—, mas agora há uma outra escala temporal em questão.
“Uma das boas coisas é que a ciência de hoje permite monitorar esses efeitos quase em tempo real”, diz Waters.
E esses efeitos dizem respeito a como o planeta se calibra após eventos geológicos como um degelo em larga escala. “Erupções vulcânicas massivas, por exemplo, lançam uma quantidade enorme de gases estufa na atmosfera, com alta rápida, num tempo geológico, de temperatura.”
A partir daí, o planeta passa por um período de adaptação, com o equilíbrio de temperatura e do nível de oceanos. “Esses níveis se recuperam, mas a biologia, não. As espécies, nessa mudança dramática, se perdem, enquanto o planeta pode voltar a se parecer com o que era 100 mil anos antes”, destaca.
Para exemplificar os riscos que vivemos hoje, Waters relembra que a mudança desde a última glaciação, que definiu a passagem do Pleistoceno (iniciado há cerca de 1,8 milhão de anos), era gradual até que se tornou intensa a ponto de extinguir espécies e redesenhar o mundo.
No entanto, na visão do geólogo, a humanidade tem hoje capacidades tecnológicas que podem ser usadas para reduzir a emissão de gases que levam às mudanças climáticas.
Esse ponto será usado para comparar as diferenças entre os sedimentos e, no caso do Antropoceno, concentrações distintas de poluentes produzidos pela atividade humana.
Como o plutônio não ocorre naturalmente nessas quantidades, identificar sua presença no fundo de lagos, por exemplo, é visto como um bom referencial para estudos.
Esse marco temporal é proposto para retratar a passagem do Holoceno —até agora tido como a nossa época geológica atual, iniciada período da última glaciação, há 11,7 mil anos— para o Antropoceno.
As muitas localidades possíveis para o “golden spike” foram sendo gradativamente reduzidas, até sobrarem nove, que incluem lagos, gelo no Ártico ou corais. Os últimos, por exemplo, seriam bons candidatos porque seu crescimento é anual, e permitiriam a visualização também anual da mudança de partículas.
Definir uma época parte de evidências científicas, mas há também uma dimensão simbólica nessa decisão. Segundo especialistas, ela pode ajudar a promover reflexão sobre como queremos lidar com um planeta que está sofrendo efeitos de mudanças climáticas e um aquecimento generalizado, por exemplo.
Outro ponto de atenção é como a nossa “pegada” sempre vai se manifestar no planeta. Mudar as matrizes de energia para reduzir o uso de combustíveis fósseis também terá um impacto relevante no planeta.
O processo não termina nesta terça. Após a apresentação da proposta, a sugestão do AWG (sigla em inglês para o Grupo de Trabalho do Antropoceno) precisa ser validada pela Comissão Internacional de Estratigrafia, antes de ser votada na União Internacional de Ciências Geológicas.
Para a nova época ser aprovada, é necessário haver ao menos 60% de aprovação em cada instância.
Uma revolução fervilha, em fogo baixo, no mundo da geologia. E um anúncio dessa terça-feira, 11 de julho, acaba de aumentar a intensidade da chama: pesquisadores do Grupo de Trabalho do Antropoceno (AWG, na sigla em inglês) elegeram um ponto de referência geológica para demonstrar o advento da “época dos humanos”, ou Antropoceno.
Na prática, é um avanço na decisão sobre se o Antropoceno deve entrar ou não na escala de tempo geológico que demarca oficialmente eras, períodos, épocas e outros intervalos da idade da Terra como conhecemos.
Ilustração: Clarice Wenzel, Instituto Serrapilheira
De uma lista de 12 sítios geológicos que poderiam comprovar o surgimento da nova época, pesquisadores do AWG escolheram o lago Crawford — situado numa reserva natural ao sul de Ontário, no Canadá — como representante físico da mudança.
Com base em amostras coletadas em 2019 e 2022, um grupo de pesquisadores fez uma importante descoberta: as águas no fundo daquele lago continham oxigênio. Segundo a paleoclimatóloga Francine McCarthy — pesquisadora da Brock University, no Canadá, e coordenadora dos estudos no local —, encontrar oxigênio lá foi importante porque, assim, as camadas de rocha no leito do lago “conseguiram gravar, muito claramente, traços de plutônio liberado na detonação de bombas nucleares no início dos anos 1950” — marco temporal proposto como ponto de partida para o Antropoceno.
Para cravar um marco novo na cronologia geológica, os cientistas devem, antes de mais nada, recolher diversas amostras de rocha — e elas precisam espelhar uma grande mudança que tenha acontecido simultaneamente em escala global. No caso do Antropoceno, a explosão de bombas de hidrogênio poderia ser esse grande evento, já que nenhum continente escapou da radioatividade dessas explosões.
Uma vez eleita a amostra mais significativa, a discussão muda de patamar e é encaminhada para instâncias superiores. Agora a proposta do AWG precisa ser aprovada pela União Internacional de Ciências Geológicas, quando então a nomenclatura se tornará oficial. “A exigência de passar por três níveis de votação obriga a proposta a ser muito sólida. É um processo muito conservador, e há uma razão para tanto: não se pode formalizar uma unidade [estratigráfica] sem o apoio de evidências robustas,” diz o geólogo Colin Waters, coordenador do AWG.
Popularizado em 2000 pelo biólogo Eugene Stoermer e pelo Nobel de Química Paul Crutzen, o termo Antropoceno deriva do grego — combinação de anthropos (humano) e ceno (novo) — e batiza uma nova divisão geológica, na qual as atividades humanas tiveram um impacto decisivo na mudança ambiental. Assim a Terra deixa para trás o Holoceno, iniciado no fim da última glaciação, há cerca de 11.700 anos.
Foi no Holoceno que a humanidade conseguiu seus maiores avanços, da criação de sistemas de agricultura a progressos no âmbito da política e da economia, passando pelo surgimento da escrita e da ciência. “Como o clima no Holoceno se manteve extraordinariamente estável, a Europa, sobretudo no Renascimento, se deu o luxo de criar uma filosofia que não levava a natureza em conta, como se apenas a relação entre humanos fosse decisiva,” diz Renzo Taddei, professor de antropologia da Universidade Federal de São Paulo (Unifesp).
Por isso Taddei, que vem se debruçando sobre o tema há quase duas décadas, considera o Antropoceno uma “virada de chave” dramática, já que confere protagonismo à natureza na esfera do pensamento humano. “O Antropoceno nos mostra que o otimismo renascentista com relação à técnica, ao domínio da natureza e posteriormente ao capitalismo industrial era uma ilusão”, ele acrescenta.
Para o físico e historiador da ciência Jürgen Renn, diretor do Instituto Max Planck para a História da Ciência, em Berlim, um dos grandes desafios que a possível nova época propõe é fazer “uma geologia do presente”: abrir um novo capítulo no livro geológico enquanto testemunhamos a escrita dessa nova página — ou camada estratigráfica. Além disso, pelas perguntas filosóficas e questionamentos que suscita, a nova época “cria uma ponte entre as ciências naturais e as humanidades”.
Taddei observa que, enquanto a geologia decide se oficializa o termo ou não, disciplinas como a filosofia e a própria antropologia adotaram-no imediatamente. O conceito não é perfeito, ele diz, “mas consegue encapsular nossa relação disfuncional com o planeta em múltiplas dimensões”. Não porque tomamos consciência de que a reflexão era necessária, mas porque a natureza a impôs, com seu equilíbrio alterado e eventos extremos cada vez mais frequentes e intensos.
“O Antropoceno nos pegou desavisados. Vejo essa época como um imenso ‘tapa na cara’ da arrogância ocidental moderna, que efetivamente julgava estar resolvendo todos os problemas históricos,” conclui o antropólogo.
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Meghie Rodrigues é jornalista de ciência.
O blog Ciência Fundamental é editado pelo Serrapilheira, um instituto privado, sem fins lucrativos, que promove a ciência no Brasil.Inscreva-se na newsletter do Serrapilheira para acompanhar as novidades do instituto e do blog.
Ingestão de plástico por humanos e animais modifica células, dizem cientistas
Clive Cookson
9 de março de 2023
Novas evidências alarmantes estão surgindo sobre os danos potenciais causados pela poluição generalizada por plástico, com níveis significativos de partículas microscópicas da substância descobertas em muitos órgãos humanos e uma nova doença identificada em aves marinhas.
As pessoas consomem hoje, em média, cerca de cinco gramas de microplásticos por semana, ingeridos em alimentos e bebidas e inalados ao respirar ar poluído, disse o professor Philip Demokritou, da Universidade Rutgers, na reunião anual da Associação Americana para o Progresso da Ciência, em Washington.
“O que é realmente alarmante é que os microplásticos entram nas células e interferem nos núcleos, o que levanta preocupações sobre possíveis danos ao DNA”, disse ele. “Outro exemplo alarmante é que eles podem interferir na digestão e absorção de nutrientes importantes.”
Separadamente, no último dia 3, cientistas do Museu de História Natural de Londres anunciaram a descoberta de uma nova doença em aves marinhas causada exclusivamente pela ingestão de plástico. Eles chamaram a condição de plasticose —uma doença fibrótica causada por pequenos pedaços de plástico que inflamam o trato digestivo. A inflamação persistente danifica os tecidos, que ficam marcados por cicatrizes e deformados.
Estudando cagarras na ilha de Lord Howe, na Austrália, eles descobriram que o proventrículo —a primeira parte do estômago das aves— tinha cicatrizes generalizadas. As aves que ingeriram mais plástico tinham mais cicatrizes.
“Embora esses pássaros possam parecer saudáveis por fora, eles não estão bem por dentro”, disse Alex Bond, curador do museu encarregado dos pássaros. “Este estudo é a primeira vez que o tecido do estômago é investigado dessa maneira e mostra que o consumo de plástico pode causar sérios danos ao sistema digestivo dessas aves.”
As aves afetadas tornam-se mais vulneráveis a infecções e parasitas, enquanto perdem parte da capacidade de digerir alimentos e absorver vitaminas.
Outro estudo identificou partículas de plástico “não apenas no tecido placentário, mas também no mecônio, as primeiras fezes do bebê, o que significa que as partículas podem atravessar a placenta e chegar ao feto”, disse Campagnolo.
“Um grande número de diferentes tipos de partículas de plástico foi identificado”, acrescentou. “O mais abundante é o PVC, mas basicamente todos os outros tipos de plástico que fazem parte dos produtos de consumo diário estavam presentes.”
Craig Bennett, executivo-chefe do grupo de conservação The Wildlife Trusts, do Reino Unido, disse que a pesquisa “ressalta meu medo de que estejamos testemunhando apenas o começo do problema do plástico. Nossos mares, rios e campos já estão inundados de poluição plástica. A pesquisa mostra como os humanos e a vida natural consomem microplásticos comendo, bebendo e respirando.”
Microplastics found washed up on a beach. About 11 percent of microplastics in the atmosphere over the western U.S. come from the ocean. Visual: Alistair Berg/DigitalVision via Getty Images
Airborne microplastics can absorb or reflect sunlight and seed clouds. How might that change the planet’s trajectory?
Plastic has become an obvious pollutant over recent decades, choking turtles and seabirds, clogging up our landfills and waterways. But in just the past few years, a less obvious problem has emerged. Researchers are starting to get concerned about how tiny bits of plastic in the air, lofted into the skies from seafoam bubbles or spinning tires on the highway, might potentially change our future climate.
“Here’s something that people just didn’t think about — another aspect of plastic pollution,” says environmental analytical chemist Denise Mitrano of ETH Zürich University, in Switzerland, who co-wrote an article last November highlighting what researchers know — and don’t yet know — about how plastics can change clouds, potentially altering temperature and rainfall patterns.
This story was originally published by the Yale Environment 360 and is reproduced here as part of the Climate Desk collaboration.
Clouds form when water or ice condenses on “seeds” in the air: usually tiny particles of dust, salt, sand, soot, or other material thrown up by burning fossil fuels, forest fires, cooking, or volcanoes. There are plenty of these fine particles, or aerosols, in the skies — a lot more since the Industrial Revolution — and they affect everything from the quality of the air we breathe, to the color of sunsets, to the number and type of clouds in our skies.
Until recently, when chemists thought of the gunk in our air, plastics did not leap to mind. Concentrations were low, they thought, and plastic is often designed to be water repellent for applications like bags or clothing, which presumably made them unlikely to seed cloud droplets. But in recent years, studies have confirmed not only that microscopic pieces of plastic can seed clouds — sometimes powerfully — but they also travel thousands of miles from their source. And there are a lot more particles in the air than scientists originally thought. All this has opened researchers’ eyes to their potential contribution to atmospheric murk — and, possibly, to future climate change.
“The people who invented plastics all those decades ago, who were very proud of inventions that transformed society in many ways — I doubt they envisaged that plastics were going to end up floating around in the atmosphere and potentially influencing the global climate system,” says Laura Revell, an atmospheric scientist at the University of Canterbury in New Zealand. “We are still learning what the impacts are for humans, ecosystems, and climate. But certainly, from what we know so far, it doesn’t look good.”
Global annual production of plastics has skyrocketed from 2 million tons in 1950 to more than 450 million tons today. And despite growing concerns about this waste accumulating in the environment, production is ramping up rather than slowing down — some oil companies are building up their plastic production capacity as the demand for fossil fuel declines. To date, more than 9 billion tons of plastic has been produced, and about half of it has gone to landfills or been otherwise discarded. Some project that by 2025, 11 billion tons of plastic will have accumulated in the environment.
Plastic has been found in soils, water, crops, and on the ocean floor. And in recent years, several studies have suggested that microplastics (pieces less than 5 millimeters in length) and nanoplastics (smaller than approximately 1,000 nanometers) were being transported long distances through the air. In 2019, for example, researchers found microplastics in the Pyrenees that had arrived via rain or snowfall. In 2020, Janice Brahney of Utah State University and four co-authors published a high-profile Science paper revealing high amounts of plastic in federally protected areas of the United States. Brahney had found the plastic by accident; she had been looking for phosphorus, but was surprised by all the colorful bits of gunk in her ground-based filters. Her study led to a slew of headlines warning, “It’s raining plastic.”
Brahney’s extensive U.S. dataset also opened the door for modelers to figure out where, exactly, all this plastic was coming from. “It’s a really beautiful data set,” says Cornell University’s Natalie Mahowald, who did the modeling work.
Mahowald took the plastic concentrations Brahney had cataloged and mapped them against atmospheric patterns and known sources of plastics, including roads, agricultural dust, and oceans. On roadways, tires and brakes hurl microplastics into the air. Plastic winds up in agricultural dust, notes Mahowald, in part from plastics used on farm fields and in part because people toss fleece clothing into washing machines: The wastewater flows to treatment plants that separate solids from liquids, and about half the resulting biosolids get sent to farms for use as fertilizer. As for the ocean, Mahowald says, big globs of plastic in places like the Pacific Gyre degrade into microscopic pieces, which then float to the surface and are whipped up into the air by chopping waters and bursting air bubbles.
Mahowald’s model concluded that over the western U.S., 84 percent of microplastics were coming from roads, 5 percent from agricultural dust, and 11 percent from the oceans. Plastic is so lightweight that even chunks tens of micrometers across — the width of a human hair — can be lofted and blown great distances. The model revealed that some of this plastic was found thousands of miles from its presumed source. The smaller the pieces, the longer they can stay aloft.
While individual bits of plastic may stay in the air for only hours, days, or weeks, there’s so much being kicked up so consistently that there’s always some in the air: enough that plastic bits are now also found in human lungs. “We’re definitely breathing them right now,” says Mahowald.
Working out exactly how much plastic is in our skies is extremely difficult. Most of these studies are done by painstakingly teasing bits of plastic out of filters and examining them under a microscope to get an estimate of shape and color, then using spectroscopic techniques to confirm their source material. The smaller the pieces, the harder they are to identify. Studies can also be plagued by contamination: Walking into a lab wearing a fleece sweater, for example, can skew results with shedding plastic microfibers.
Nearly a dozen studies have shown airborne microplastic concentrations ranging from between 0.01 particles per cubic meter over the western Pacific Ocean to several thousand particles per cubic meter in London and Beijing. The cities showing higher levels are probably genuinely more polluted, says Revell, but it’s also true that those studies used a more-sensitive technique that could identify smaller bits of plastic (under 10 micrometers in size). The other studies would have missed such smaller pieces, which made up about half the plastic found in the London and Beijing studies.
Plastic bits are now found in human lungs. “We’re definitely breathing them right now,” says Mahowald.
Concentrations of airborne nanoplastics are understood even less. The numbers floating around today, says atmospheric chemist Zamin Kanji, Mitrano’s colleague at ETH Zürich, are likely to be “significantly underestimated.”
For now, the proportion of plastics to total airborne aerosols is tiny, so plastics aren’t contributing much to aerosol climate impacts, says Mahowald. Even in London and Beijing, plastic may account for only a millionth of the total aerosols. But plastic production, and the accumulation of plastic in the environment, keeps going up. Says Mahowald, “It’s only going to get worse.”
That’s especially true in less polluted regions — like over the oceans of the Southern Hemisphere, Kanji says. Since plastic can likely travel farther than other, denser aerosols, it could become a dominant airborne pollutant in more pristine areas. Brahney and Mahowald’s paper concludes that plastic currently makes up less than 1 percent of anthropogenic aerosols landing on the ground but they could, “alarmingly,” make up more than 50 percent of the aerosols landing on some parts of the ocean downwind from plastic sources.
Exactly how aerosols affect climate has been a critical sticking point in climate models, and many of the details are still unknown. Different aerosols can change the climate by either reflecting or absorbing sunlight, which can depend, in part, on their color. Black soot, for example, tends to have a warming effect, while salt reflects and cools. Aerosols can land on the ground and change the albedo, or reflectivity, of ice and snow.
Aerosols also affect cloud formation: Different bits and pieces can seed more and smaller droplets of water or ice, making for different types of clouds at different elevations that last for different amounts of time. High-altitude, thin, icy clouds tend to warm the Earth’s surface like a blanket, while low-altitude, bright and fluffy clouds tend to reflect sunlight and cool the Earth.
Though tiny, aerosols have an oversized influence on climate. The murk of anthropogenic aerosols in the sky has, overall, had a dramatic cooling effect since the Industrial Revolution (without them, global warming would be 30 to 50 percent greater than it is today). And they have more sway on extreme weather than greenhouse gases do: A world warmed by removing aerosols would have more floods and droughts, for example, than a world warmed the same amount by CO2.
Revell and her colleagues took a stab at trying to model how microplastics might affect temperature by either reflecting or absorbing sunlight, a calculation of what’s known as “radiative forcing.” For simplicity’s sake, they assumed that plastic is always clear, even though that’s not true (and darker material tends to absorb more sunlight), and that the global concentration is uniformly one particle per cubic meter, which is on the order of 1,000 times lower than concentrations measured in, say, London.
With those assumptions, Revell found that plastic’s direct impact on radiative forcing is “so small as to be insignificant.” But, importantly, if concentrations reach 100 particles per cubic meter (which they already have in many spots), plastics could have about the same magnitude of radiative forcing as some aerosols already included in Intergovernmental Panel on Climate Change assessments. In other words, plastics become noteworthy. But whether they would warm, or cool, the Earth is unknown.
Though tiny, aerosols have an oversized influence on climate.
Aerosols often have a greater impact on the climate through their influence on clouds. Pristine plastic beads, Kanji notes, repel water and so are unlikely to affect clouds. But plastic can “age” in a matter of hours, says Kanji, during its transit to the sky: It can be abraded, or it can accumulate salt from the ocean and other chemicals from the atmosphere, all of which can make the particles more water-loving. Plastic pieces can also contain nooks and crannies, which aid in the formation of ice.
In the lab, Kanji’s student Omar Girlanda has run preliminary tests showing that under such battered conditions, plastic pieces can be potent cloudmakers. “Some of them are as good as mineral dust particles,” says Kanji, “which is the most well-known, effective ice nucleus out there.”
Kanji says skies heavily polluted with plastic will probably make both more high-altitude ice clouds, which tend to warm the Earth’s surface, and more low-altitude water clouds, which tend to cool the Earth. Which effect will dominate is unknown. “It doesn’t make sense to model it at the moment, given the poor estimates we have of [atmospheric] plastic,” says Kanji. Plastic could also affect precipitation patterns: In general, Kanji says, clouds that are more polluted tend to last longer before bursting into rain than do less polluted clouds, and then they rain more heavily.
Revell and her colleagues are now whittling down the assumptions in their paper, working out more detailed calculations for more realistic estimates of plastic concentrations, colors, and sizes. “All we know is that the problem is not going to go away anytime soon,” she says. “These plastics are incredibly long lived. They’re breaking down, and they’re going to be forming new microplastics for centuries. We just don’t know how big the problem is that we’ve committed ourselves to.”
Nicola Jones is a freelance journalist based in Pemberton, British Columbia. Her work can be found in Nature, Scientific American, Globe and Mail, and New Scientist.
It was late fall of 2022 when David Stallknecht heard that bodies were raining from the sky.
Stallknecht, a wildlife biologist at the University of Georgia, was already fearing the worst. For months, wood ducks had been washing up on shorelines; black vultures had been teetering out of tree tops. But now thousands of ghostly white snow-goose carcasses were strewn across agricultural fields in Louisiana, Missouri, and Arkansas. The birds had tried to take flight, only to plunge back to the ground. “People were saying they were literally dropping down dead,” Stallknecht told me. Even before he and his team began testing specimens in the lab, they suspected they knew what they would find: yet another crop of casualties from the deadly strain of avian influenza that had been tearing across North America for roughly a year.
Months later, the bird-flu outbreak continues to rage. An estimated 58.4 million domestic birds have died in the United States alone. Farms with known outbreaks have had to cull their chickens en masse, sending the cost of eggs soaring; zoos have herded their birds indoors to shield them from encounters with infected waterfowl. The virus has been steadily trickling into mammalian populations—foxes, bears, mink, whales, seals—on both land and sea, fueling fears that humans could be next. Scientists maintain that the risk of sustained spread among people is very low, but each additional detection of the virus in something warm-blooded and furry hints that the virus is improving its ability to infiltrate new hosts. “Every time that happens, it’s another chance for that virus to make the changes that it needs,” says Richard Webby, a virologist at St. Jude Children’s Research Hospital. “Right now, this virus is a kid in a candy store.”
A human epidemic, though, remains a gloomy forecast that may not come to pass. In the meantime, the outbreak has already been larger, faster-moving, and more devastating to North America’s wildlife than any other in recorded history, and has not yet shown signs of stopping. “I would use just one word to describe it: unprecedented,” says Shayan Sharif, an avian immunologist at Ontario Veterinary College. “We have never seen anything like this before.” This strain of bird flu is unlikely to be our next pandemic. But a flu pandemic has already begun for countless other creatures—and it could alter North America’s biodiversity for good.
Deadly strains of avian flu have been ferried onto North American shores multiple times before, and rapidly petered out. That was the case in 2014, when a highly virulent version of the virus crossed the Pacific from Asia and invaded U.S. poultry farms, forcing workers to exterminate millions of chickens and turkeys. The brutal interventions worked: “They did all the right things, and nipped it in the bud,” says Nicole Nemeth, a veterinary pathologist at the University of Georgia. Hardly any wild birds were affected; egg prices bumped up briefly, then settled back roughly to baseline. “It just kind of died down,” Nemeth told me. “And everyone breathed a sigh of relief.”
Some birds are likely to make it through the outbreak just fine. For as long as humans have been aware of this particular strain of avian influenza, scientifically classed as H5N1, the virus has been relatively gentle on certain types of waterfowl, especially mallards, pintails, and other so-called dabbling ducks. “Some populations have a prevalence as high as 40 percent, and they’re as normal as normal could be,” Stallknecht said. Those same species have also been some of avian flu’s best chauffeurs in the past, silently spreading the feces-borne infection across countries and continents during their seasonal migrations.
Others haven’t been so lucky. Some of the same respiratory issues that strike humans who have the flu—sneezing, coughing, pneumonia when the disease gets severe—can hit birds, too. But across a variety of susceptible species, necropsies show more extensive damage, with evidence of virus in various organs, including the liver, gut, and brain. The neurologic problems can be among the worst: Swans might swim in listless circles; geese might waddle shakily onto shores, their necks twisted and turned; eagles might flap defeatedly from their perches, unable to launch themselves into the air. Michelle Hawkins, a veterinarian at UC Davis, told me that several of the red-tailed hawks she’s treated in her clinic have arrived with their eyes shaking so vigorously from side to side that the spasms turn the animals’ head; others appear to gaze off into nothingness, unresponsive even when humans approach.
Death can come swiftly—sometimes within a day or two of the infection’s start. Birds simply keel over as if they’ve been shot, their bodies dropping like rocks. On poultry farms, outbreaks can wipe out entire flocks in just two or three days. In wilder settings, locals have spotted bald eagles plummeting out of their nests, leaving shrieking chicks behind. By the time infected birds reach Hawkins in her clinic, “they’re usually almost dead,” she told me. “And we can’t figure out how to help them except to put them out of their misery.” Hawkins estimated that in the past few months alone, her team’s euthanasia rate has gone up by about 50 percent.
Mammals so far haven’t fared much better. Last spring, the corpse of a dolphin infected with the virus was found wedged into a canal in Florida—around the same time that Wisconsin locals happened upon litters of ailing fox kits, drooling, twitching, and struggling to stand in the hours before they seized and died. In the fall, three young, flu-stricken grizzlies in Montana were euthanized after researchers noticed that the disoriented animals had begun to go blind. Wendy Puryear, a molecular virologist at Tufts University, told me that seals sick with the virus will sometimes convulse so badly that they can barely hold their bodies straight. Every seal she’s seen that tested positive has ended up dead within days. This month, researchers in Peru reported that they were picking up the virus in some of the sea lions that have died by the hundreds along the country’s coast; a similar situation may now be playing out among a number of Scotland’s seals.
It’s hard to say why this outbreak is so much worse than the ones that came before. Microbial evolution may be one culprit: Flu viruses are particularly inclined to tweak their RNA code; when two genetically distinct versions of the pathogens wind up in the same cell, they can also swap bits of their genomes. This iteration of H5N1 may be particularly adept at sparking lethal disease—something Justin Brown, a veterinary pathologist at Penn State, thinks is quite likely, given how many animals have died. It may also be more easily exiting birds’ bodies in feces, or more efficiently entering cells in the airway or gut. “This particular virus seems to be better adapted to wild birds. I think that’s the key thing,” Stallknecht told me. As climate change alters migration schedules, and pushes certain avian species into more frequent contact with one another’s contaminated scat, the risks of intermingling are only growing. The greater the number of infections, the more animals will die. “It becomes a numbers game,” Stallknecht said.
Flu viruses have never had much trouble spreading: They can be breathed out or defecated; they can persist on surfaces for hours, and in cool waters for days. But Webby suspects that the ballooning of this epidemic can be at least partly blamed on the severity of disease. “The easiest birds to catch are the ones that are sick,” he told me. Hawks, eagles, owls, and other predatory birds may be stumbling across dying ducks and eating them, unwittingly infecting themselves. Nemeth thinks that certain species, including black vultures, are now cutting out the middlebird and feasting on the carcasses of their own kin as they continue to die in droves. “They see dead tissue, they’re going to eat it,” she told me. It’s a morbid tragedy of abundance, as the virus climbs the food chain to reach species it hasn’t easily accessed before. “The biggest impact is on these atypical hosts,” Webby told me, which lack the prior exposures to the virus that might have helped protect them.
Predation or scavenging of sick or dead birds is probably how certain mammals—grizzlies, foxes, opossums, and the like—are catching the virus too. The seals and dolphins present a bit more of a puzzle, Puryear told me, though it’s possible to guess at what’s at play. At least some types of seals have been documented consuming birds; other marine mammals might simply be gulping feces-infested water. A recent avian-flu outbreak at a mink farm in Spain suggests a more troubling mode of transmission: mammals repeatedly conveying the virus to one another—a possible first for H5N1. “That is really disconcerting,” Sharif told me. “It tells me the virus is adapting to mammals.”
Animals vulnerable to the virus don’t have many good options for protection. Some avian-flu vaccines have been used on certain poultry farms, mostly abroad. But some of the same issues that plague human-flu vaccines are obstacles in the bird world too, Brown told me: The ingredients of the shots aren’t always good matches for the circulating virus, and the immunizations, which may be pretty good at staving off severe disease, don’t do much to block infection or transmission, making outbreaks tough to contain. Wild birds, which can’t be corralled and immunized en masse, are essentially out of luck. Nemeth told me that some of her colleagues in Florida have been trying to clear the ground of carcasses so that they won’t become sources of infection for yet another unlucky mammal or bird. “But they just can’t keep up with the number of deaths,” she said. Essentially all avian species are thought to be susceptible to infection—and there’s simply no way to reach every bird, says Becky Poulson, an avian-flu researcher at the University of Georgia. After hopscotching across the globe for decades, H5N1 now seems very likely to be in North America for good, “part of the new normal here,” Poulson told me.
Experts told me they’re hopeful that the outbreak will abate before long. But even if that happens, some species may not live to see it. North America’s birds already face a medley of threats—chemical pollution, window collisions, habitat destruction, roving colonies of feral cats—and some of them cannot sustain another blow. “This could be the last nail in the coffin for some species,” says Min Huang, who leads the migratory-bird program at Connecticut’s Department of Energy and Environmental Protection.
The current epidemic “may not be directly affecting us, in that almost none of us are getting sick,” says Kishana Taylor, a virologist at Rutgers University. But the extent of its reach into wildlife means that humans will still notice its many impacts. In a world with fewer birds, other animals—such as coyotes, snakes, and even humans—might go hungrier, while the fish, insects, and rats that birds eat could experience population booms. The treetops and shorelines, once alive with song, could go silent; far fewer seeds might be dispersed. The U.S.’s national bird—one of the country’s few conservation success stories—could once again find itself pushed to the brink. Some locals in the Southeast have already told Nemeth that they’re feeling the absence of vultures, as roadside deer carcasses begin to fester in the sun. The bird pandemic will have its survivors. But they are likely to be living in a world that is quieter, lonelier, and harsher than it was before.
Image credits: Alamy; David Guttenfelder for The New York Times; Getty Images; Ashley Gilbertson for The New York Times; Michael Probst/Associated Press; Getty Images; NASA
For Planet Earth, This Might Be the Start of a New Age
A panel of experts has spent more than a decade deliberating on how, and whether, to mark a momentous new epoch in geologic time: our own.
Raymond Zhong
Dec. 17, 2022
The official timeline of Earth’s history — from the oldest rocks to the dinosaurs to the rise of primates, from the Paleozoic to the Jurassic and all points before and since — could soon include the age of nuclear weapons, human-caused climate change and the proliferation of plastics, garbage and concrete across the planet.
In short, the present.
Ten thousand years after our species began forming primitive agrarian societies, a panel of scientists on Saturday took a big step toward declaring a new interval of geologic time: the Anthropocene, the age of humans.
Our current geologic epoch, the Holocene, began 11,700 years ago with the end of the last big ice age. The panel’s roughly three dozen scholars appear close to recommending that, actually, we have spent the past few decades in a brand-new time unit, one characterized by human-induced, planetary-scale changes that are unfinished but very much underway.
“If you were around in 1920, your attitude would have been, ‘Nature’s too big for humans to influence,’” said Colin N. Waters, a geologist and chair of the Anthropocene Working Group, the panel that has been deliberating on the issue since 2009. The past century has upended that thinking, Dr. Waters said. “It’s been a shock event, a bit like an asteroid hitting the planet.”
The working group’s members on Saturday completed the first in a series of internal votes on details including when exactly they believe the Anthropocene began. Once these votes are finished, which could be by spring, the panel will submit its final proposal to three other committees of geologists whose votes will either make the Anthropocene official or reject it.
Sixty percent of each committee will need to approve the group’s proposal for it to advance to the next. If it fails in any of them, the Anthropocene might not have another chance to be ratified for years.
If it makes it all the way, though, geology’s amended timeline would officially recognize that humankind’s effects on the planet had been so consequential as to bring the previous chapter of Earth’s history to a close. It would acknowledge that these effects will be discernible in the rocks for millenniums.
Source: Syvitski, et al. (2020) By Mira Rojanasakul/The New York Times
“I teach the history of science — you know, Copernicus, Kepler, Galileo,” said Francine McCarthy, an earth scientist at Brock University in Canada and member of the working group. “We’re actually doing it,” she said. “We’re living the history of science.”
Still, the knives are out for the Anthropocene, even though, or maybe because, we all have such firsthand familiarity with it.
Stanley C. Finney, the secretary general of the International Union of Geological Sciences, fears the Anthropocene has become a way for geologists to make a “political statement.”
Within the vast expanse of geologic time, he notes, the Anthropocene would be a blip of a blip of a blip. Other geologic time units are useful because they orient scientists in stretches of deep time that left no written records and sparse scientific observations. The Anthropocene, by contrast, would be a time in Earth’s history that humans have already been documenting extensively.
“For the human transformation, we don’t need those terminologies — we have exact years,” said Dr. Finney, whose committee would be the last to vote on the working group’s proposal if it gets that far.
Martin J. Head, a working group member and earth scientist at Brock University, argues declining to recognize the Anthropocene would have political reverberations, too.
“People would say, ‘Well, does that then mean the geological community is denying that we have changed the planet drastically?’” he said. “We would have to justify our decision either way.”
Philip L. Gibbard, a geologist at the University of Cambridge, is secretary general of another of the committees that will vote on the working group’s proposal. He has serious concerns about how the proposal is shaping up, concerns he believes the wider geological community shares.
“It won’t get an easy ride,” he said.
‘A Messy and Disputatious Business’
Nineteenth-century fossil hunters. The rock record is full of gaps, “a jigsaw puzzle with many of the parts missing,” one geologist said. Credit: Oxford Science Archive/Print Collector, via Getty Images
Like the zoologists who regulate the names of animal species or the astronomers who decide what counts as a planet, geology’s timekeepers work conservatively, by design. They set classifications that will be reflected in academic studies, museums and textbooks for generations to come.
“Everybody picks on the Anthropocene Working Group because they’ve taken so long,” said Lucy E. Edwards, a retired scientist with the United States Geological Survey. “In geologic time, this isn’t long.”
The geologic time scale divides Earth’s 4.6 billion-year story into grandly named chapters. Like nesting dolls, the chapters contain sub-chapters, which themselves contain sub-sub-chapters. From largest to smallest, the chapters are called eons, eras, periods, epochs and ages.
Right now, according to the current timeline, we are in — deep breath — the Meghalayan Age of the Holocene Epoch of the Quaternary Period of the Cenozoic Era of the Phanerozoic Eon, and have been for 4,200 years.
Drawing lines in Earth time has never been easy. The rock record is full of gaps, “a jigsaw puzzle with many of the parts missing,” as Dr. Gibbard puts it. And most global-scale changes happen gradually, making it tricky to pinpoint when one chapter ended and the next one began. There haven’t been many moments when the entire planet changed at once.
“If a meteor hits the Yucatán Peninsula, that’s a pretty good marker,” Dr. Edwards said. “But other than that, there’s practically nothing out there in the geologic world that’s the best line.”
The early Cambrian Period, around 540 million years ago, saw Earth explode with an astonishing diversity of animal life, but its precise starting point has been contested for decades. A long controversy led to the redrawing of our current geologic period, the Quaternary, in 2009.
“It’s a messy and disputatious business,” said Jan A. Zalasiewicz, a geologist at the University of Leicester. “And of course, the Anthropocene brings a whole new range of dimensions to the messiness and disputatiousness.”
Humanity’s Fingerprint
A nuclear test near the Marshall Islands in 1958. A working group proposed the mid-20th century as the beginning of the Anthropocene, in part because of the plutonium isotopes left by bombs. Credit: Corbis, via Getty Images
It took a decade of debate — in emails, academic articles and meetings in London, Berlin, Oslo and beyond — for the Anthropocene Working Group to nail down a key aspect of its proposal.
In a 29-to-4 vote in 2019, the group agreed to recommend that the Anthropocene began in the mid-20th century. That’s when human populations, economic activity and greenhouse gas emissions began skyrocketing worldwide, leaving indelible traces: plutonium isotopes from nuclear explosions, nitrogen from fertilizers, ash from power plants.
The Anthropocene, like nearly all other geologic time intervals, needs to be defined by a specific physical site, known as a “golden spike,” where the rock record clearly sets it off from the interval before it.
After a yearslong hunt, the working group on Saturday finished voting on nine candidate sites for the Anthropocene. They represent the range of environments into which human effects are etched: a peat bog in Poland, the ice of the Antarctic Peninsula, a bay in Japan, a coral reef off the Louisiana coast.
One site — Crawford Lake in Ontario, Canada — is small enough to walk around in 10 minutes. But it is so deep that the bottom layer of water rarely mixes with the upper layers. Whatever sinks to the floor remains undisturbed, gradually accumulating into a tree-ring-like record of geochemical change.
The working group’s members also voted this month on what rank the Anthropocene should have in the timeline: an epoch, an age of the Holocene, or something else.
The group isn’t disclosing the results of these or the other votes to be held in the coming months until they are all complete and it has finalized its proposal for the next level of timekeepers to ponder. It is then that a far more contentious debate about the Anthropocene could begin.
Many scholars still aren’t sure the mid-20th century cutoff makes sense. It is awkwardly recent, especially for archaeologists and anthropologists who would have to start referring to World War II artifacts as “pre-Anthropocene.”
Crawford Lake, near Milton, Ontario. Its depth makes it a prime site for scientific research. Credit: Conservation Halton
And using nuclear bombs to mark a geologic interval strikes some scientists as abhorrent, or at least beside the point. Radionuclides are a convenient global marker, but they say nothing about climate change or other human effects, said Erle C. Ellis, an ecologist at the University of Maryland, Baltimore County.
Using the Industrial Revolution might help. But that definition would still leave out millenniums of planet-warping changes from farming and deforestation.
Call to Attention
Canonizing the Anthropocene is a call to attention, said Naomi Oreskes, a member of the working group. For geology, but also the wider world.
“I was raised in a generation where we were taught that geology ended when people showed up,” said Dr. Oreskes, a historian of science at Harvard. The Anthropocene announces that “actually, the human impact is part of geology as a science,” she said. It demands we recognize that our influence on the planet is more than surface level.
But Dr. Gibbard of Cambridge fears that, by trying to add the Anthropocene to the geologic time scale, the working group might actually be diminishing the concept’s significance. The timeline’s strict rules force the group to impose a single starting point on a sprawling story, one that has unspooled over different times in different places.
He and others argue the Anthropocene deserves a looser geologic label: an event. Events don’t appear on the timeline; no bureaucracy of scientists regulates them. But they have been transformative for the planet.
Late-Holocene human footprints, at least 2,000 years old, in volcanic ash and mud in Nicaragua. The Anthropocene could mark an official end to the 11,700-year-old Holocene Epoch. Credit: Carl Frank/Science Source
The filling of Earth’s skies with oxygen, roughly 2.1 to 2.4 billion years ago — geologists call that the Great Oxidation Event. Mass extinctions are events, as is the burst of diversity in marine life 460 to 485 million years ago.
The term Anthropocene is already in such wide use by researchers across scientific disciplines that geologists shouldn’t force it into too narrow a definition, said Emlyn Koster, a geologist and former director of the North Carolina Museum of Natural Sciences.
“I always saw it not as an internal geological undertaking,” he said of the Anthropocene panel’s work, “but rather one that could be greatly beneficial to the world at large.”
Raymond Zhong is a climate reporter. He joined The Times in 2017 and was part of the team that won the 2021 Pulitzer Prize in public service for coverage of the coronavirus pandemic. @zhonggg
A version of this article appears in print on Dec. 18, 2022, Section A, Page 1 of the New York edition with the headline: The Next Epoch Of Planet Earth Might Be Today. Order Reprints | Today’s Paper | Subscribe
Researchers have zeroed in on nine sites that could describe a new geological time, marked by pollution and other signs of human activity.
McKenzie Prillaman
13 December 2022
Geologists could soon decide which spot on Earth marks the first clear evidence of the Anthropocene — which many of them think is a new geological epoch that began when humans started altering the planet with various forms of industrial and radioactive materials in the 1950s. They have so far whittled their choices down to nine candidate sites worldwide (see ‘Defining the Anthropocene’), each being considered for how reliably its layers of mud, ice or other matter tell the story of people’s influence on a timeline that extends billions of years into the past.
If the nearly two dozen voting members of the Anthropocene Working Group (AWG), a committee of scientists formed by the International Commission on Stratigraphy (ICS), agree on a site, the decision could usher in the end of the roughly 12,000-year-old Holocene epoch. And it would officially acknowledge that humans have had a profound influence on Earth.
Geologists could soon decide which spot on Earth marks the first clear evidence of the Anthropocene — which many of them think is a new geological epoch that began when humans started altering the planet with various forms of industrial and radioactive materials in the 1950s. They have so far whittled their choices down to nine candidate sites worldwide (see ‘Defining the Anthropocene’), each being considered for how reliably its layers of mud, ice or other matter tell the story of people’s influence on a timeline that extends billions of years into the past.Humans versus Earth: the quest to define the Anthropocene
“We’re pointing to something in the rock record that shows we’ve changed the planet,” says Kristine DeLong, a palaeoclimatologist at Louisiana State University in Baton Rouge who studies the West Flower Garden Bank, a candidate site in the Gulf of Mexico.
The Anthropocene site will join 79 others that physically define stages of Earth’s geological timescale — that is, if it’s approved. Even if the AWG agrees on a final candidate, several other committees of geologists must vote on the selection before it is made official. And not all scientists agree that it should be.
Here, Nature examines what it will take to formally define the Anthropocene epoch.
Why do some geologists want an Anthropocene marker?
Scientists coined the term Anthropocene in 2000, and researchers from several fields now use it informally to refer to the current geological time interval, in which human activity is driving Earth’s conditions and processes. Formalizing the Anthropocene would unite efforts to study people’s influence on Earth’s systems, in fields including climatology and geology, researchers say. Transitioning to a new epoch might also coax policymakers to take into account the impact of humans on the environment during decision-making.
Coral grows on an oil rig in Flower Garden Banks National Marine Sanctuary, in the Gulf of Mexico.Credit: Flip Nicklin/Minden Pictures/Alamy
“It’s a label,” says Colin Waters, who chairs the AWG and is a geologist at the University of Leicester, UK. “It’s a great way of summarizing a lot of concepts into one word.”
Mentioning the Jurassic period, for instance, helps scientists to picture plants and animals that were alive during that time, he says. “The Anthropocene represents an umbrella for all of these different changes that humans have made to the planet,” he adds.
How do scientists usually choose sites that define the geological timeline?
Typically, researchers will agree that a specific change in Earth’s geology must be captured in the official timeline. The ICS will then determine which set of rock layers, called strata, best illustrates that change, and it will choose which layer marks its lower boundary. This is called the Global Stratotype Section and Point (GSSP), and it is defined by a signal, such as the first appearance of a fossil species, trapped in the rock, mud or other material. One location is chosen to represent the boundary, and researchers mark this site physically with a golden spike, to commemorate it.
But the Anthropocene has posed problems. Geologists want to capture it in the timeline, but its beginning isn’t obvious in Earth’s strata, and signs of human activity have never before been part of the defining process. The AWG was established in 2009 to explore whether the Anthropocene should enter the geological timescale and, if so, how to define its start.
“We were starting from scratch,” says Jan Zalasiewicz, a geologist at the University of Leicester who formerly chaired the AWG and remains a voting member. “We had a vague idea about what it might be, [but] we didn’t know what kind of hard evidence would go into it.”
Years of debate among the group’s multidisciplinary members led them to identify a host of signals — radioactive isotopes from nuclear-bomb tests, ash from fossil-fuel combustion, microplastics, pesticides — that would be trapped in the strata of an Anthropocene-defining site. These began to appear in the early 1950s, when a booming human population started consuming materials and creating new ones faster than ever.
This golden spike in the Flinders Ranges of South Australia was approved by geologists in 2004, to mark strata exemplifying the Ediacaran period.Credit: James St. John (CC BY 2.0)
During a review that took place a few months ago, the AWG narrowed its list from 12 to 9 candidate sites, tossing out certain locations because their layers weren’t ideal. Among the sites remaining is Crawford Lake in Ontario, Canada, which is described as a sinkhole by Francine McCarthy, a geologist at Brock University in St Catharines, Canada, who studies the location. “The lake itself isn’t very big in area, but it’s very, very deep,” she says. Particles that fall into the lake settle at the bottom and accumulate into undisturbed layers.
Another site on the shortlist is West Flower Garden Bank. Corals here could become a living golden spike because they constantly build new exoskeletons that capture chemicals and particles from the water, DeLong says. “The skeleton has layers in it, kind of like tree rings,” she adds.
Why do some geologists oppose the Anthropocene as a new epoch?
“It misrepresents what we do” in the ICS, says Stanley Finney, a stratigrapher at California State University, Long Beach, and secretary-general for the International Union of Geological Sciences (IUGS). The AWG is working backwards, Finney says: normally, geologists identify strata that should enter the geological timescale before considering a golden spike; in this case, they’re seeking out the lower boundary of an undefined set of geological layers.Involve social scientists in defining the Anthropocene
Lucy Edwards, a palaeontologist who retired in 2008 from the Florence Bascom Geoscience Center in Reston, Virginia, agrees. For her, the strata that might define the Anthropocene do not yet exist because the proposed epoch is so young. “There is no geologic record of tomorrow,” she says.
Edwards, Finney and other researchers have instead proposed calling the Anthropocene a geological ‘event’, a flexible term that can stretch in time, depending on human impact. “It’s all-encompassing,” Edwards says.
Zalasiewicz disagrees. “The word ‘event’ has been used and stretched to mean all kinds of things,” he says. “So simply calling something an event doesn’t give it any wider meaning.”
What happens next?
In a recent Perspective article in Science, Waters and AWG secretary Simon Turner at University College London wrote that the committee would vote to choose a single site by the end of this year1. But 60% of the group’s voting members must agree on a final candidate — and, with several sites under consideration, Waters isn’t sure that a consensus can be reached anytime soon. If no clear winner emerges this month, more voting will be needed to narrow the candidate list, delaying a decision possibly until May 2023.Anthropocene now: influential panel votes to recognize Earth’s new epoch
And that’s not the end of the process. After selecting a finalist, the AWG will present its findings to the ICS’s Subcommission on Quaternary Stratigraphy. Favourable votes from this group would move the proposal to another ICS committee, and subsequent approval would push it to the final stage: ratification by the IUGS.
But the motion could fail at any of those points. And if it does, the AWG will have to revamp its proposal before it can try again — and possibly nominate a new golden-spike site.
Regardless of the outcome, Zalasiewicz thinks that the AWG’s work to define the Anthropocene has been useful. What everybody wants to know is how humans are changing the planet’s geology, he says. “That is the underlying reality that we’re trying to describe.”
A newly discovered network of “lost” ancient cities in the Amazon could provide a pivotal new insight into how ancient civilisations combined the construction of vast urban landscapes while living alongside nature.
A team of international researchers, including Professor Jose Iriarte from the University of Exeter, has uncovered an array of intricate settlements in the Llanos de Mojos savannah-forest, Bolivia, that have laid hidden under the thick tree canopies for centuries.
The cities, built by the Casarabe communities between 500-1400 AD, feature an unprecedented array of elaborate and intricate structures unlike any previously discovered in the region – including 5m high terraces covering 22 hectares – the equivalent of 30 football pitches – and 21m tall conical pyramids.
Researchers also found a vast network of reservoirs, causeways and checkpoints, spanning several kilometres.
The discovery, the researchers say, challenges the view of Amazonia as a historically “pristine” landscape, but was instead home to an early urbanism created and managed by indigenous populations for thousands of years.
Crucially, researchers maintain that these cities were constructed and managed not at odds with nature, but alongside it – employing successful sustainable subsistence strategies that promoted conservationism and maintained the rich biodiversity of the surrounding landscape.
The research, by Heiko Prümers, from the Deutsches Archäologisches Institut, Carla Jaimes Betancourt from the University of Bonn, José Iriarteand Mark Robinson from the University of Exeter, and Martin Schaichfrom the ArcTron 3D is published in the journal Nature.
Professor Iriarte said: “We long suspected that the most complex pre-Columbian societies in the whole basin developed in this part of the Bolivian Amazon, but evidence is concealed under the forest canopy and is hard to visit in person. Our lidar system has revealed built terraces, straight causeways, enclosures with checkpoints, and water reservoirs. There are monumental structures are just a mile apart connected by 600 miles of canals long raised causeways connecting sites, reservoirs and lakes.
“Lidar technology combined with extensive archaeological research reveals that indigenous people not only managed forested landscapes but also created urban landscapes, which can significantly contribute to perspectives on the conservation of the Amazon.
“This region was one of the earliest occupied by humans in Amazonia, where people started to domesticate crops of global importance such as manioc and rice. But little is known about daily life and the early cities built during this period.”
The team of experts used lidar technology – dubbed “lasers in the sky” – to peer through the tropical forest canopy and examine the sites, found in the savannah-forest of South West Amazonia.
The research revealed key insights into the sheer magnitude and magnificence of the civic-ceremonial centres found buried in the forest.
It showed that the core, central spread over several hectares, on top of which lay civic-ceremonial U-shaped structures, platform mounds and 21-m tall conical pyramids.
The research team conservatively suggest that the scale of labour and planning to construct the settlements has no precedents in Amazonia and is instead comparable only with the Archaic states of the central Andes.
Crucially, the research team insist this new discovery gives a pivotal new insight into how this ancient urbanism was carried out sustainably and embracing conservationism.
At the same time the cities were built communities in the Llanos de Mojos transformed Amazonian seasonally flooded savannas, roughly the size of England, into productive agricultural and aquacultural landscapes.
The study shows that the indigenous people not only managed forested landscapes, but also created urban landscapes in tandem – providing evidence of successful, sustainable subsistence strategies but also a previously undiscovered cultural-ecological heritage.
Co-author, Dr Mark Robinson of the University of Exeter added: “These ancient cities were primary centres of a regional settlement network connected by still visible, straight causeways that radiate from these sites into the landscape for several kilometres. Access to the sites may have been restricted and controlled.
“Our results put to rest arguments that western Amazonia was sparsely populated in pre-Hispanic times. The architectural layout of Casarabe culture large settlement sites indicates that the inhabitants of this region created a new social and public landscape.
“The scale, monumentality and labour involved in the construction of the civic-ceremonial architecture, water management infrastructure, and spatial extent of settlement dispersal, compare favourably to Andean cultures and are to a scale far beyond the sophisticated, interconnected settlements of Southern Amazonia.”
The climate crisis resembles a huge planetary lockdown, trapping humanity within an ever-deteriorating environment
‘The shallow layer of earth in which we live … has been transformed into a habitable milieu by the aeons-long labour of evolution.’ Photograph: Jon Helgason/Alamy
Fri 24 Dec 2021 14.00 GMT
There is a moment when a never-ending crisis turns into a way of life. This seems to be the case with the pandemic. If so, it’s wise to explore the permanent condition in which it has left us. One obvious lesson is that societies have to learn once again to live with pathogens, just as they learned to when microbes were first made visible by the discoveries of Louis Pasteur and Robert Koch.
These discoveries were concerned with only one aspect of microbial life. When you also consider the various sciences of the earth system, another aspect of viruses and bacteria comes to the fore. During the long geochemical history of the earth, microbes, together with fungi and plants, have been essential, and are still essential, to the very composition of the environment in which we humans live. The pandemic has shown us that we will never escape the invasive presence of these living beings, entangled as we are with them. They react to our actions; if they mutate, we have to mutate as well.
This is why the many national lockdowns, imposed on citizens to help them survive the virus, are a powerful analogy for the situation in which humanity finds itself detained for good. Lockdown was painful enough, and yet many ways have been found, thanks in part to vaccination, to allow people to resume a semblance of normal life. But there is no possibility of such a resumption if you consider that all living forms are locked down for good inside the limits of the earth. And by “earth” I don’t mean the planet as it can be seen from space, but its very superficial pellicle, the shallow layer of earth in which we live, and which has been transformed into a habitable milieu by the aeons-long labour of evolution.
This thin matrix is what geochemists call the “critical zone”, the only layer of earth where terrestrial life can flourish. It’s in this finite space where everything we care for and everything we have ever encountered exists.There is no way of escaping our earth-bound existence; as young climate activists shout: “There is no planet B.” Here is the connection between the Covid lockdowns we have experienced in the past two years, and the much larger but definitive state of lockdown that we find ourselves in: we are trapped in an environment that we have already altered irreversibly.
If we have been made aware of the agency of viruses in shaping our social relations, we must now reckon with the fact that they will also be moulded for ever by the climate crisis and the quick reactions of ecosystems to our actions. The feeling that we live in a new space appears again at the local as well as the global level. Why would all nations convene in Glasgow to keep global temperature rises below some agreed upon limit, if they did not have the sensation that a huge lid had been put over their territory? When you look up at the blue sky, are you not aware that you are now under some sort of dome inside which you are locked?
Gone is the infinite space; now you are responsible for the safety of this overbearing dome as much as you are for your own health and wealth. It weighs on you, body and soul. To survive under these new conditions we have to undergo a sort of metamorphosis.
This is where politics enters. It is very difficult for most people used to the industrialised way of life, with its dream of infinite space and its insistence on emancipation and relentless growth and development, to suddenly sense that it is instead enveloped, confined, tucked inside a closed space where their concerns have to be shared with new entities: other people of course, but also viruses, soils, coal, oil, water, and, worst of all, this damned, constantly shifting climate.
This disorienting shift is unprecedented, even cosmological, and it is already a source of deep political divisions. Although the sentence “you and I don’t live on the same planet” used to be a joking expression of dissent, it has become true of our present reality. We do live on different planets, with rich people employing private fire fighters and scouting for climate bunkers, while their poorer counterparts are forced to migrate, suffer and die amid the worst consequences of the crisis.
This is why it is important not to misconstrue the political conundrum of our present age. It is of the same magnitude as when, from the 17th century onward, westerners had to shift from the closed cosmos of the past to the infinite space of the modern period. As the cosmos seemed to open, political institutions had to be invented to work through the new and utopian possibilities offered by the Enlightenment. Now, in reverse, the same task falls to present generations: what new political institutions could they invent to cope with people so divided that they belong to different planets?
It would be a mistake to believe that the pandemic is a crisis that will end, instead of the perfect warning for what is coming, what I call the new climatic regime. It appears that all the resources of science, humanities and the arts will have to be mobilised once again to shift attention to our shared terrestrial condition.
Bruno Latour is a philosopher and anthropologist, the author of After Lockdown: A Metamorphosis and the winner of the 2013 Holberg prize
Summary: Human behavior drives the evolution of biological organisms in ways that can profoundly adversely impact human welfare. Understanding people’s incentives when they do so is essential to identify policies and other strategies to improve evolutionary outcomes. In a new study, researchers bring the tools of economics and game theory to evolution management.
Human behavior drives the evolution of biological organisms in ways that can profoundly adversely impact human welfare. Understanding people’s incentives when they do so is essential to identify policies and other strategies to improve evolutionary outcomes. In a new study publishing November 16thin the open access journal, PLOS Biology, researchers led by Troy Day at Queens University and David McAdams at Duke University bring the tools of economics and game theory to evolution management.
From antibiotic-resistant bacteria that endanger our health to control-resistant crop pests that threaten to undermine global food production, we are now facing the harmful consequences of our failure to efficiently manage the evolution of the biological world. As Day explains, “By modelling the joint economic and evolutionary consequences of people’s actions we can determine how best to incentivize behavior that is evolutionarily desirable.”
The centerpiece of the new analysis is a simple mathematical formula that determines when physicians, farmers, and other “evolution managers” will have sufficient incentive to steward the biological resources that are under their control, trading off the short-term costs of stewardship against the long-term benefits of delaying adverse evolution.
For instance, when a patient arrives in an urgent-care facility, screening them to determine if they are colonized by a dangerous superbug is costly, but protects future patients by allowing superbug carriers to be isolated from others. Whether the facility itself gains from screening patients depends on how it weighs these costs and benefits.
The researchers take the mathematical model further by implementing game theory, which analyzes how individuals’ decisions are interconnected and can impact each other — such as physicians in the same facility whose patients can infect each other or corn farmers with neighboring fields. Their game-theoretic analysis identifies conditions under which outcomes can be improved through policies that change incentives or facilitate coordination.
“In the example of antibiotic-resistant bacteria, hospitals could go above and beyond to control the spread of superbugs through methods like community contact tracing,” McAdams says. “This would entail additional costs and, alone, a hospital would likely not have an incentive to do so. But if every hospital took this additional step, they might all collectively benefit from slowing the spread of these bacteria. Game theory gives you a systematic way to think through those possibilities and maximize overall welfare.”
“Evolutionary change in response to human interventions, such as the evolution of resistance in response to drug treatment or evolutionary change in response to harvesting, can have significant economic repercussions,” Day adds. “We determine the conditions under which it is economically beneficial to employ costly strategies that limit evolution and thereby preserve the value of biological resources for longer.”
Journal Reference:
Troy Day, David A. Kennedy, Andrew F. Read, David McAdams. The economics of managing evolution. PLOS Biology, 2021; 19 (11): e3001409 DOI: 10.1371/journal.pbio.3001409
“Humans have impacted the ocean in a more dramatic fashion than merely capturing fish,” explained marine ecologist Ryan Heneghan from the Queensland University of Technology.
“It seems that we have broken the size spectrum – one of the largest power law distributions known in nature.”
The power law can be used to describe many things in biology, from patterns of cascading neural activity to the foraging journeys of various species. It’s when two quantities, whatever their initial starting point be, change in proportion relative to each other.
In the case of a particular type of power law, first described in a paper led by Raymond W. Sheldon in 1972 and now known as the ‘Sheldon spectrum’, the two quantities are the body size of an organism, scaled in proportion to its abundance. So, the larger they get, there tend to be consistently fewer individuals within a set species size group.
For example, while krill are 12 orders of magnitudes (about a billion) times smaller than tuna, they’re also 12 orders of magnitudes more abundant than tuna. So hypothetically, all the tuna flesh in the world combined (tuna biomass) is roughly the same amount (to within the same order of magnitude at least) as all the krill biomass in the world.
Since it was first proposed in 1972, scientists had only tested for this natural scaling pattern within limited groups of species in aquatic environments, at relatively small scales. From marine plankton, to fish in freshwater this pattern held true – the biomass of larger less abundant species was roughly equivalent to the biomass of the smaller yet more abundant species.
Now, Max Planck Institute ecologist Ian Hatton and colleagues have looked to see if this law also reflects what’s happening on a global scale.
“One of the biggest challenges to comparing organisms spanning bacteria to whales is the enormous differences in scale,” says Hatton.
“The ratio of their masses is equivalent to that between a human being and the entire Earth. We estimated organisms at the small end of the scale from more than 200,000 water samples collected globally, but larger marine life required completely different methods.”
Using historical data, the team confirmed the Sheldon spectrum fit this relationship globally for pre-industrial oceanic conditions (before 1850). Across 12 groups of sea life, including bacteria, algae, zooplankton, fish and mammals, over 33,000 grid points of the global ocean, roughly equal amounts of biomass occurred in each size category of organism.
“We were amazed to see that each order of magnitude size class contains approximately 1 gigaton of biomass globally,” says McGill University geoscientist Eric Galbraith.
(Ian Hatton et al, Science Advances, 2021)
Hatton and team discussed possible explanations for this, including limitations set by factors such as predator-prey interactions, metabolism, growth rates, reproduction and mortality. Many of these factors also scale with an organism’s size. But they’re all speculation at this point.
“The fact that marine life is evenly distributed across sizes is remarkable,” said Galbraith. “We don’t understand why it would need to be this way – why couldn’t there be much more small things than large things? Or an ideal size that lies in the middle? In that sense, the results highlight how much we don’t understand about the ecosystem.”
There were two exceptions to the rule however, at both extremes of the size scale examined. Bacteria were more abundant than the law predicted, and whales far less. Again, why is a complete mystery.
The researchers then compared these findings to the same analysis applied to present day samples and data. While the power law still mostly applied, there was a stark disruption to its pattern evident with larger organisms.
“Human impacts appear to have significantly truncated the upper one-third of the spectrum,” the team wrote in their paper. “Humans have not merely replaced the ocean’s top predators but have instead, through the cumulative impact of the past two centuries, fundamentally altered the flow of energy through the ecosystem.”
(Ian Hatton et al, Science Advances, 2021)
While fishes compose less than 3 percent of annual human food consumption, the team found we’ve reduced fish and marine mammal biomass by 60 percent since the 1800s. It’s even worse for Earth’s most giant living animals – historical hunting has left us with a 90 percent reduction of whales.
This really highlights the inefficiency of industrial fishing, Galbraith notes. Our current strategies are wasting magnitudes more biomass and the energy it holds, than we actually consume. Nor have we replaced the role that biomass once played, despite now being one of the largest vertebrate species by biomass.
Around 2.7 gigatonnes have been lost from the largest species groups in the oceans, whereas humans make up around 0.4 gigatonnes. Further work is needed to understand how this massive loss in biomass affects the oceans, the team wrote.
“The good news is that we can reverse the imbalance we’ve created, by reducing the number of active fishing vessels around the world,” Galbraith says. “Reducing overfishing will also help make fisheries more profitable and sustainable – it’s a potential win-win, if we can get our act together.”
If modernity is the Anthropocene and if secularization is a defining feature of modernity’s birth, then it is natural to ask: did secularization engender climate change?
Why is secularization never connected to climate change? And why is climate change not connected to secularization? If modernity is the Anthropocene and if secularization is a defining feature of modernity’s birth, then it is natural to ask: did secularization engender climate change?
I aim to open a new space in the study of both secularism and the Anthropocene, of religion and climate change. Further, I aim to create a philosophical bridge between influential currents in anthropology and the humanities. I build this bridge through the critique of Orientalism and the anthropology of secularism and Islam, respectively founded by Edward Said and Talal Asad, on one hand, and the literature on the Anthropocene influenced by scholars such as Donna Haraway and Bruno Latour, on the other.
I argue that secularization should be re-conceptualized not only as an imperial and racial but also as an ecological set of processes.
My perspective stems from a philosophical engagement with both the project and the concept of secularization. It therefore presupposes a critical understanding of what has been called ‘the secular’ as a name given to the result of the destruction of nature: the transformation of the earth itself by industrial and colonial powers. I propose an alternative definition of secularization, secularism, and secularity. As I argue fully in my first book, Des empires sous la terre, the Anthropocene is an outcome of secularization understood as a set of processes engendered by the imperial relations of power between Europe and the rest of the world.
Thinking Through the Secularocene
What is secularization? Neither a supposed decline of religion nor a simple continuation of Christianity by other means, secularization should be seen as a transformation of the earth itself by virtue of its connection with fossil empires and capitalism.
This perspective differs from scholars who have been engaged in criticizing the idea of secularization as a mythology of progress and privatization – a mythology to which 9/11 proved false. I argue that the concept of secularization should be redefined instead of being dissolved. It is only if one presupposes that secularization is reducible to the privatization of religion that the existence of political religion can be construed as testifying against the reality of secularization. When one opposes the permanence of religion or of Christianity to the reality of secularization, one is in fact reactivating the secularization thesis in its primitive, Hegelian version (developed by Marcel Gauchet) – that modernity is the secular realization of Christianity on earth – and, therefore, of all religions in the world.
In other words, before it can be seen as a process, secularization should be approached as an order which articulates philosophy and politics, discourse and practices throughout the 19th century in Western Europe. Secularization is the order which claims that the other-worldliness of religion and the divine must be abolished by virtue of its realization in this world. The first instance of this demand is Hegel’s absolute knowledge and his interpretation of the French Revolution as the realization of heaven on earth. The so-called ‘end of history’ is indeed the accomplishment of a secularizing process by which the divine becomes the institution of freedom through the modern state.
The first way in which secularization manifests its reality is discursive. As a discourse, it asserts that the modern West must be and therefore is Christianity itself, Christianity as the secular. Before it can become an analytical concept, the concept of secularization formulates a demand: Christianity and religions realize heaven and all forms of transcendence in this world.
Is the reality of secularization solely discursive? No. The reality of the secular is the earth itself as it is transformed by industrial capitalism. This redefinition of the secular and of secularization allows us to think alternatively about this ‘global’ event called climate change. I argue that the Anthropocene should be seen as an effect of secularization, and that one might use the word Secularocene to describe this dimension of ‘colonial modernity.’
How did secularization lead to climate change, one might ask? By authorizing the extraction of coal through expropriating lands that belonged to the Church, and dismissing the reality of demons in the underground as superstitious, secularization allowed fossil industrialism to transform the planet. For this reason, secularization should be seen as a crucial aspect of what Marx calls the primitive accumulation of capital: an extra-economic process of expropriation structured by state violence deploying itself through racial, gender, class, and religious hierarchies.
The critique of secularism is more than the critique of a political doctrine demanding the privatization of religion. It is the critique of how the earth itself has been transformed. As such, philosophical secularism refers to an ontology that posits this world as the sole reality. It defines immanence, or earth, as the reality which must be opposed to transcendence, or “heaven”. The critique of heaven is not the condition of all critique, as Marx famously puts it. It is part of how capitalism operates. Hence, the critique of heaven has transformed the earth itself through the secularization of both empire and capital.
While genealogy authorizes us to think about the categories of religion and secularity critically, it should be integrated within a larger perspective if we are to rethink secularization by constructing an alternative narrative of its deployment beyond the tropes of religion’s decline. A post-genealogical philosophy of history is a theory, not of progress, but of how the earth has been transformed through imperial and capitalist processes of globalization. The very existence of climate change invites us to think past Foucault’s legacies in postcolonial thought. Beyond genealogy, the hypothesis of the Anthropocene – or of the Secularocene for that matter – might require that we integrate genealogical inquiries into a radically new form of philosophical history. After the genealogy of religion and the secular, a philosophy of global history might help us understand imperial secularization as the birth of the Anthropocene.
Mohamad Amer Meziane holds a PhD from the University of Paris 1 Panthéon-Sorbonne. He is currently a Postdoctoral Research Fellow and Lecturer at Columbia University. He is affiliated to the Institute of Religion Culture and Public Life, the Institute of African Studies and the Department of Religion.
IMAGE: The Positive NAO index phase shows a stronger than usual subtropical high pressure center and a deeper than normal Icelandic low. The increased pressure difference results in more and stronger… view more Credit: Columbia University Lamont-Doherty Earth Observatory.
MIAMI–A new study led by scientists at the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science provides evidence that humans are influencing wind and weather patterns across the eastern United States and western Europe by releasing CO2 and other pollutants into Earth’s atmosphere.
In the new paper, published in the journal npj Climate and Atmospheric Science, the research team found that changes in the last 50 years to an important weather phenomenon in the North Atlantic–known as the North Atlantic Oscillation–can be traced back to human activities that impact the climate system.
“Scientists have long understood that human actions are warming the planet,” said the study’s lead author Jeremy Klavans, a UM Rosenstiel School alumnus. “However, this human-induced signal on weather patterns is much harder to identify.”
“In this study, we show that humans are influencing patterns of weather and climate over the Atlantic and that we may be able to use this information predict changes in weather and climate up to a decade in advance,” said Klavans.
The North Atlantic Oscillation, the result of fluctuations in air pressure across the Atlantic, affects weather by influencing the intensity and location of the jet stream. This oscillation has a strong effect on winter weather in Europe, Greenland, the northeastern U.S. and North Africa and the quality of crop yields and productivity of fisheries in the North Atlantic.
The researchers used multiple large climate model ensembles, compiled by researchers at the National Center for Atmospheric Research, to predict the North Atlantic Oscillation. The analysis consisted of 269 model runs, which is over 14,000 simulated model years.
The study, titled “NAO Predictability from External Forcing in the Late Twentieth Century,” was published on March 25 in the journal npj Climate and Atmospheric Science. The study’s authors include: Klavans, Amy Clement and Lisa Murphy from the UM Rosenstiel School, and Mark Cane from Columbia University’s Lamont-Doherty Earth Observatory.
The study was supported by the National Science Foundation (NSF) Climate and Large-Scale Dynamics program (grant # AGS 1735245 and AGS 1650209), NSF Paleo Perspectives on Climate Change program (grant # AGS 1703076) and NOAA’s Climate Variability and Predictability Program.
In the last two decades, the Anthropocene has become an informal buzzword to describe the numerous and unprecedented ways humans have come to modify the planet.
As the concept has become more widely adopted, however, definitions have begun to blur. Today, the very meaning of the Anthropocene and its timeline differs considerably depending on who is doing the talking.
To geologists and Earth system scientists, the Industrial Revolution is often considered the dawn of the Anthropocene – when human influence on Earth’s systems became predominant worldwide.
Many anthropologists, historians, and archaeologists, however, consider the 18th century as more of a sunrise, when the era of humans truly began to heat up in some regions. Before that, there were already glimmers of human domination.
Since the Late Pleistocene, right through to the Holocene (our current epoch), humans have been producing “distinct, detectable and unprecedented transformations of Earth’s environments,” states a new paper on the subject.
And while these changes might not be enough to be technically defined as a new geological epoch, we need terms to describe this earlier influence, too. Because right now, people from various disciplines are using the term with subtly different meanings.
“Dissecting the many interpretations of the Anthropocene suggests that a range of quite distinct, but variably overlapping, concepts are in play,” says geologist Colin Waters from the University of Leicester in the UK.
Thousands of years before the boom of industrialization, globalization, nuclear bombs, and modern climate change, humans were already in the first stages of becoming a dominant planetary force.
The rise of crop domestication and hunting, the spread of livestock and mining, and the move to urbanization, for instance, have all caused great changes to Earth’s soil signature and its fossil record, setting us on a course to the modern day.
As far back as 3400 BCE, for instance, people in China were already smelting copper, and 3,000 years ago, most of the planet was already transformed by hunter-gatherers and farmers.
While these smaller and slower regional changes did not destabilize Earth’s entire system as more modern actions have, some researchers think we are underestimating the climate effects of these earlier land-use changes.
As such, some have considered using the terms “pre-Anthropocene” or “proto‐Anthropocene” to describe significant human impacts before the mid‐twentieth century.
Others argue a capitalized “Anthropocene” should represent the tightly defined geological concept of an epoch, while the uncapitalized version should be used for broader interpretations.
Even after the Industrial Revolution, when human influence is clear to see, some argue we need to define further advances of the Anthropocene.
The “Great Acceleration” of the mid-twentieth century, for instance, has been proposed as a “second stage” to the Anthropocene, when human enterprise and influence began growing exponentially.
This second stage not only encompasses rapid geological changes, but it also refers to socioeconomic factors and modern biophysical processes that humans have also begun to alter with our actions.
“This shows an exemplar of ways in which ideas and terms move between disciplines, as is true for the Anthropocene,” researchers write.
It’s unclear what the next stage of the Anthropocene will look like, but many of the changes we have made are currently irreversible and may continue long after our species is gone.
Still, the authors argue, one thing is clear. The exceptionally rapid transformations humans have made to our planet since the Great Acceleration “vastly outweigh” earlier climactic events of the Holocene.
“Given both the rate and scale of change marking the onset of the chronostratigraphic Anthropocene, it would be difficult to justify a rank lower than series/epoch,” the authors conclude.
A 3D portrait of methane concentrations and a slightly wobblier Earth.
Of all the things attributable to climate change, the rotational poles moving differently is definitely one of the weirder ones. But a new study shows that’s exactly what’s happening. It builds on previous findings to show that disappearing ice is playing a major role, and shows that groundwater depletion is responsible for contributing to wobbles as well.
The findings, published last month in Geophysical Research Letters, uses satellites that track gravity to track what researchers call “polar drift.” While we think of gravity as a constant, it’s actually a moving target based on the shape of the planet. While earthquakes and other geophysical activities can certainly play a role by pushing land around, it’s water that is responsible for the biggest shifts. The satellites used for the study, known as GRACE and GRACE-FO, were calibrated to measure Earth’s shifting mass.
Polar drift is something that happens naturally. The Earth’s axis is slowly shifting, but there’s been a marked acceleration in recent decades. The poles are now moving at nearly 17 times the rate they were in 1981, a fairly remarkable speed-up. What’s even more remarkable, though, is that poles actually began moving in a new direction quite suddenly in 2000, at a rapid clip.
Previous research used the same satellite data to observe the speed-up and change of gear and attributed it to ice loss in Greenland and West Antarctica as well as groundwater pumping. The new study extends the record back to the 1990s and explores some of the year-to-year wobbles in more detail. The findings point to changes in groundwater use in specific regions as the source of some of those differences.
“Using the GRACE data (for the period 2002-2015) we showed that such interannual signals (as these authors pointed out: kinks at 2005 and 2012) can be explained by the terrestrial water storage,” Surendra Adhikari, a scientist at NASA Jet Propulsion Laboratory who led the 2016 research, said in an email. “The new paper reinforces the statement by also showing that another kink in the polar motion data (at 1995) is also explained by total water storage variability, especially by the on-set of accelerated Greenland ice mass loss and depletion of water storage in the Middle East and the Indian subcontinent.
“In general, the paper (along with our previous works) reveals the strong connection between the climate variability and how the Earth wobbles,” he added, noting the new study was a “nicely done paper.”
In the scheme of things, climate change triggering polar movement isn’t too worrisome, given the other clear and present dangers like intense heat waves, ocean acidification, and the sixth mass extinction. Ditto for the role of groundwater depletion, which has the potential to impact billions of lives. But it’s a powerful reminder of just how much humans have reshaped the planet and why we should probably cut it out sooner than later if we don’t want our world to turn upside down.
Correction, 4/23/21, 6:30 p.m.: This post has been updated to reflect that the rotational poles are the ones in question moving and being studied.
A new study by Simon Fraser University historical ecologists finds that Indigenous-managed forests—cared for as “forest gardens”—contain more biologically and functionally diverse species than surrounding conifer-dominated forests and create important habitat for animals and pollinators. The findings are published today in Ecology and Society.
According to researchers, ancient forests were once tended by Ts’msyen and Coast Salish peoples living along the north and south Pacific coast. These forest gardens continue to grow at remote archeological villages on Canada’s northwest coast and are composed of native fruit and nut trees and shrubs such as crabapple, hazelnut, cranberry, wild plum, and wild cherries. Important medicinal plants and root foods like wild ginger and wild rice root grow in the understory layers.
“These plants never grow together in the wild,” says Chelsey Geralda Armstrong, an SFU Indigenous Studies assistant professor and the study lead researcher. “It seemed obvious that people put them there to grow all in one spot—like a garden. Elders and knowledge holders talk about perennial management all the time.”
“It’s no surprise these forest gardens continue to grow at archeological village sites that haven’t yet been too severely disrupted by settler-colonial land-use.”
Ts’msyen and Coast Salish peoples’ management practices challenge the assumption that humans tend to overturn or exhaust the ecosystems they inhabit. This research highlights how Indigenous peoples not only improved the inhabited landscape, but were also keystone builders, facilitating the creation of habitat in some cases. The findings provide strong evidence that Indigenous management practices are tied to ecosystem health and resilience.
“Human activities are often considered detrimental to biodiversity, and indeed, industrial land management has had devastating consequences for biodiversity,” says Jesse Miller, study co-author, ecologist and lecturer at Stanford University. “Our research, however, shows that human activities can also have substantial benefits for biodiversity and ecosystem function. Our findings highlight that there continues to be an important role for human activities in restoring and managing ecosystems in the present and future.”
Forest gardens are a common management regime identified in Indigenous communities around the world, especially in tropical regions. Armstrong says the study is the first time forest gardens have been studied in North America—showing how important Indigenous peoples are in the maintenance and defense of some of the most functionally diverse ecosystems on the Northwest Coast.
“The forest gardens of Kitselas Canyon are a testament to the long-standing practice of Kitselas people shaping the landscape through stewardship and management,” says Chris Apps, director, Kitselas Lands & Resources Department. “Studies such as this reconnect the community with historic resources and support integration of traditional approaches with contemporary land-use management while promoting exciting initiatives for food sovereignty and cultural reflection.”
More information: Chelsey Geralda Armstrong et al, Historical Indigenous Land-Use Explains Plant Functional Trait Diversity, Ecology and Society (2021). DOI: 10.5751/ES-12322-260206
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Ancient Indigenous forest gardens promote a healthy ecosystem (Science Daily)
Date: April 22, 2021
Source: Simon Fraser University
Summary: A new study by historical ecologists finds that Indigenous-managed forests — cared for as ‘forest gardens’ — contain more biologically and functionally diverse species than surrounding conifer-dominated forests and create important habitat for animals and pollinators.
A new study by Simon Fraser University historical ecologists finds that Indigenous-managed forests — cared for as “forest gardens” — contain more biologically and functionally diverse species than surrounding conifer-dominated forests and create important habitat for animals and pollinators. The findings are published today in Ecology and Society.
According to researchers, ancient forests were once tended by Ts’msyen and Coast Salish peoples living along the north and south Pacific coast. These forest gardens continue to grow at remote archaeological villages on Canada’s northwest coast and are composed of native fruit and nut trees and shrubs such as crabapple, hazelnut, cranberry, wild plum, and wild cherries. Important medicinal plants and root foods like wild ginger and wild rice root grow in the understory layers.
“These plants never grow together in the wild,” says Chelsey Geralda Armstrong, an SFU Indigenous Studies assistant professor and the study lead researcher. “It seemed obvious that people put them there to grow all in one spot — like a garden. Elders and knowledge holders talk about perennial management all the time.”
“It’s no surprise these forest gardens continue to grow at archaeological village sites that haven’t yet been too severely disrupted by settler-colonial land-use.”
Ts’msyen and Coast Salish peoples’ management practices challenge the assumption that humans tend to overturn or exhaust the ecosystems they inhabit. This research highlights how Indigenous peoples not only improved the inhabited landscape, but were also keystone builders, facilitating the creation of habitat in some cases. The findings provide strong evidence that Indigenous management practices are tied to ecosystem health and resilience.
“Human activities are often considered detrimental to biodiversity, and indeed, industrial land management has had devastating consequences for biodiversity,” says Jesse Miller, study co-author, ecologist and lecturer at Stanford University. “Our research, however, shows that human activities can also have substantial benefits for biodiversity and ecosystem function. Our findings highlight that there continues to be an important role for human activities in restoring and managing ecosystems in the present and future.”
Forest gardens are a common management regime identified in Indigenous communities around the world, especially in tropical regions. Armstrong says the study is the first time forest gardens have been studied in North America — showing how important Indigenous peoples are in the maintenance and defence of some of the most functionally diverse ecosystems on the Northwest Coast.
“The forest gardens of Kitselas Canyon are a testament to the long-standing practice of Kitselas people shaping the landscape through stewardship and management,” says Chris Apps, director, Kitselas Lands & Resources Department. “Studies such as this reconnect the community with historic resources and support integration of traditional approaches with contemporary land-use management while promoting exciting initiatives for food sovereignty and cultural reflection.”
Journal Reference:
Chelsey Geralda Armstrong, Jesse E. D. Miller, Alex C. McAlvay, Patrick Morgan Ritchie, Dana Lepofsky. Historical Indigenous Land-Use Explains Plant Functional Trait Diversity. Ecology and Society, 2021; 26 (2) DOI: 10.5751/ES-12322-260206
Woodland in the UK has been influenced by human activity for millenniaSteve Speller/Alamy
As early as 12,000 years ago, nearly three-quarters of land on Earth was inhabited and shaped by human societies, suggesting global biodiversity loss in recent years may have been driven primarily by an intensification of land use rather than by the destruction of previously untouched nature.
“It’s not the process of using land itself [that causes biodiversity loss], it’s the way that land is used,” says Erle Ellis at the University of Maryland, Baltimore County. “You can have traditional land use and still have biodiversity.”
Ellis and his colleagues analysed the most recent reconstruction of global land use by humans over the past 12,000 years and compared this with contemporary global patterns of biodiversity and conservation. They found that most – 72.5 per cent – of Earth’s land has been shaped by human societies since as far back as 10,000 BC, including more than 95 per cent of temperate and 90 per cent of tropical woodlands.
“Our work confirms that untouched nature was almost as rare 12,000 years ago as it is today,” says Ellis. He and his team found that lands now considered natural, intact or wild generally exhibit long histories of use, as do protected areas and lands inhabited only by relatively small numbers of Indigenous peoples.
The extent of historical human land use may previously have been underestimated because prior analyses didn’t fully account for the influence that hunter-gatherer populations had on landscapes, says Ellis. “Even hunter-gatherer populations that are moving around are still interacting with the land, but maybe in what we would see as a more sustainable way,” he says.
The researchers also found that in regions now characterised as natural, current global patterns of vertebrate species richness and overall biodiversity are more strongly linked to past patterns of land use than they are with present ones. Ellis says this indicates the current biodiversity crisis can’t be explained by the loss of uninhabited wild lands alone. Instead, this points to a more significant role for recent appropriation, colonisation and intensification of land use, he says.
“The concept of wilderness as a place without people is a myth,” says Yadvinder Malhi at the University of Oxford. “Where we do find large biomes without people living in them and using them – as in North American national parks, Amazonian forests or African game parks – it is because of a history of people being removed from these lands through disease or by force.”
“[This study] shows that high biodiversity is compatible with, and in some cases a result of, people living in these landscapes,” says Malhi. “Working with local and traditional communities, and learning from them, is essential if we are to try to protect biodiversity.”
“With ambitious calls to expand global terrestrial protected areas to cover 30 per cent or even half of the Earth, this [study] brings into focus that protection necessarily cannot mean the exclusion of people and anthropogenic land uses,” says Jason Riggio at the University of California, Davis. The “30 by 30” pledge, being championed by a coalition of more than 50 countries, aims to expand protected areas to cover at least 30 per cent of land and sea by 2030.
Joice Ferreira at Embrapa Amazônia Oriental in Brazil says that there are important roles for both protected areas and sustainable land use in preserving biodiversity. “The combination of deforestation, degradation […] and climate change make protected areas paramount,” she says, adding: “if Indigenous custodianship was important in the past, it is much more so nowadays, in the face of new and more intense threats.”
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(Ian Hatton et al, Science Advances, 2021)
(Ian Hatton et al, Science Advances, 2021)
Uma (in)certa antropologia 
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