Arquivo da tag: Inundação

Deslizamentos e enchentes: culpar as chuvas mais uma vez? (JC)

JC 5373, 14 de março de 2016

Artigo de Álvaro Rodrigues dos Santos, geólogo e consultor em Geologia de Engenharia, Geotecnia e Meio Ambiente

A cada novo período chuvoso voltam às manchetes as mortes e sinistros associados a deslizamentos de encostas e enchentes. Tragédias insistentemente anunciadas, mas anualmente recorrentes dado ao descompromisso com que a administração pública em seus três níveis tem lidado com a questão.

Todos estão fartos de saber que esses fenômenos decorrem diretamente das formas equivocadas com que se expandem nossas cidades, impermeabilizando seus territórios, canalizando e retificando seus rios, ocupando terrenos, como encostas de alta declividade e margens de córrego, que não poderiam nunca ser ocupados dada sua já altíssima suscetibilidade natural a riscos, mas também ocupando terrenos de média declividade, onde a ocupação urbana seria aceitável, com a utilização de técnicas construtivas e urbanísticas totalmente inadequadas, que acabam transformando mesmo essas áreas em um verdadeiro canteiro de situações de risco.

E com toda essa realidade, escancarada anualmente pelo meio técnico e repercutida pelos meios de comunicação, a pungente verdade é que nossas autoridades sequer tomaram a providência mínima e cristalina de parar de errar, ou seja, parar de cometer os erros que estão na exata origem causal dessas tragédias de cunho geológico, geotécnico e hidrológico. Por consequência, o que se vê é, ao invés da redução do número de áreas de risco, a sua contínua multiplicação.

Como resultado, uma perspectiva de futuro assustadora: as tragédias em áreas de risco tendem a crescer em frequência e letalidade, na exata proporção do crescimento de nossas cidades.

Dentro desse panorama é preciso que se compreenda que do ponto de vista técnico não há lacuna alguma nos conhecimentos básicos de geologia, geotecnia e hidrologia, necessários para a boa solução desses problemas. Os fenômenos de enchentes e deslizamentos nos mais variados contextos geológicos do País são já bastante estudados e conhecidos. Os instrumentos que permitirão um correto planejamento do uso e ocupação do solo urbano são dominados, como a essencial Carta Geotécnica, um mapa municipal que informa sobre os locais que não poderão nunca ser ocupados e as áreas que poderão ser ocupadas caso sejam utilizadas as técnicas adequadas para tanto. Por paradoxal que possa parecer, o Brasil é liderança internacional nesse campo tecnológico.

Vale registrar apenas que não possuímos no País uma cultura técnica arquitetônica e urbanística especialmente adequada à ocupação de terrenos com maior declividade. Isso se verifica tanto nas formas espontâneas utilizadas pela própria população de baixa renda na autoconstrução de suas moradias, como também em projetos privados ou públicos  de maior porte que contam com o suporte técnico de arquitetos e urbanistas e têm, apesar do erro básico e grave de concepção, sua implantação autorizada pelos órgãos municipais responsáveis para tanto.

Em ambos os casos, ou seja, no empirismo popular e nos projetos mais elaborados, prevalece infelizmente a cultura técnica da área plana. Isto é, através de cortes e aterros obtidos por operações de terraplenagem nas encostas obsessivamente se procura produzir platôs planos sobre os quais irá ser edificado o empreendimento. Um fatal erro técnico de concepção. Esse tem sido o cacoete técnico que está invariavelmente presente na maciça produção de áreas de risco nas cidades brasileiras que, de alguma forma, crescem sobre relevos mais acidentados.

Vale insistir, no entanto, a maior dificuldade para a boa solução desses problemas continua a residir na falta de vontade e no descompromisso das administrações públicas em finalmente decidir ordenar corretamente a expansão urbana de suas cidades. Nesse mister é fundamental perceber que as populações mais pobres somente deixarão de optar por áreas de risco para instalar suas moradias quando o poder público, através de ousados Programas Habitacionais, lhes oferecer alternativas dignas e seguras de moradia na mesma faixa de custos que ela hoje só encontra na ocupação das áreas de risco. Essa é a verdade nua e crua da questão. Ou essa equação básica é resolvida, ou a instalação de novas situações de risco sempre superarão, em muito, o esforço em desarmar as já instaladas.

Em resumo, é preciso que as autoridades públicas deixem de irresponsavelmente ver a questão das áreas de risco como um problema de Defesa Civil e Corpo de Bombeiros, por mais heroicas que sejam essas corporações, e passem a entendê-la como um elemento próprio do campo das Políticas Habitacionais e de Planejamento Urbano. Somente sob essa ótica a administração pública passará ao comando ativo da situação, deixando de agir apenas a reboque das tragédias, situação em que lhes sobra apenas a descompostura esperta de, como sempre, culpar as chuvas pelos infortúnios.

Álvaro Rodrigues dos Santos (santosalvaro@uol.com.br)

  • Ex-Diretor de Planejamento e Gestão do IPT – Instituto de Pesquisas Tecnológicas
  • Autor dos livros “Geologia de Engenharia: Conceitos, Método e Prática”, “A Grande Barreira da Serra do Mar”, “Diálogos Geológicos”, “Cubatão”, “Enchentes e Deslizamentos: Causas e Soluções”, “Manual Básico para elaboração e uso da Carta Geotécnica”.
  • Consultor em Geologia de Engenharia e Geotecnia 

* Esse artigo expressa apenas a opinião do autor.

Climate Seer James Hansen Issues His Direst Forecast Yet (The Daily Beast) + other sources, and repercussions

A polar bear walks in the snow near the Hudson Bay waiting for the bay to freeze, 13 November 2007, outside Churchill, Mantioba, Canada. Polar bears return to Churchill, the polar bear capital of the world, to hunt for seals on the icepack every year at this time and remain on the icepack feeding on seals until the spring thaw.   AFP PHOTO/Paul J. Richards (Photo credit should read PAUL J. RICHARDS/AFP/Getty Images)

Paul J Richards/AFP/Getty

Mark Hertsgaard 

07.20.151:00 AM ET

James Hansen’s new study explodes conventional goals of climate diplomacy and warns of 10 feet of sea level rise before 2100. The good news is, we can fix it.

James Hansen, the former NASA scientist whose congressional testimony put global warming on the world’s agenda a quarter-century ago, is now warning that humanity could confront “sea level rise of several meters” before the end of the century unless greenhouse gas emissions are slashed much faster than currently contemplated.This roughly 10 feet of sea level rise—well beyond previous estimates—would render coastal cities such as New York, London, and Shanghai uninhabitable.  “Parts of [our coastal cities] would still be sticking above the water,” Hansen says, “but you couldn’t live there.”

James Hanson

Columbia University

This apocalyptic scenario illustrates why the goal of limiting temperature rise to 2 degrees Celsius is not the safe “guardrail” most politicians and media coverage imply it is, argue Hansen and 16 colleagues in a blockbuster study they are publishing this week in the peer-reviewed journal Atmospheric Chemistry and Physics. On the contrary, a 2 C future would be “highly dangerous.”

If Hansen is right—and he has been right, sooner, about the big issues in climate science longer than anyone—the implications are vast and profound.

Physically, Hansen’s findings mean that Earth’s ice is melting and its seas are rising much faster than expected. Other scientists have offered less extreme findings; the United Nations Intergovernmental Panel on Climate Change (IPCC) has projected closer to 3 feet of sea level rise by the end of the century, an amount experts say will be difficult enough to cope with. (Three feet of sea level rise would put runways of all three New York City-area airports underwater unless protective barriers were erected. The same holds for airports in the San Francisco Bay Area.)

Worldwide, approximately $3 trillion worth infrastructure vital to civilization such as water treatment plants, power stations, and highways are located at or below 3 feet of sea level, according to the Stern Review, a comprehensive analysis published by the British government.

Hansen’s track record commands respect. From the time the soft-spoken Iowan told the U.S. Senate in 1988 that man-made global warming was no longer a theory but had in fact begun and threatened unparalleled disaster, he has consistently been ahead of the scientific curve.

Hansen has long suspected that computer models underestimated how sensitive Earth’s ice sheets were to rising temperatures. Indeed, the IPCC excluded ice sheet melt altogether from its calculations of sea level rise. For their study, Hansen and his colleagues combined ancient paleo-climate data with new satellite readings and an improved model of the climate system to demonstrate that ice sheets can melt at a “non-linear” rate: rather than an incremental melting as Earth’s poles inexorably warm, ice sheets might melt at exponential rates, shedding dangerous amounts of mass in a matter of decades, not millennia. In fact, current observations indicate that some ice sheets already are melting this rapidly.

“Prior to this paper I suspected that to be the case,” Hansen told The Daily Beast. “Now we have evidence to make that statement based on much more than suspicion.”

The Nature Climate Change study and Hansen’s new paper give credence to the many developing nations and climate justice advocates who have called for more ambitious action.

Politically, Hansen’s new projections amount to a huge headache for diplomats, activists, and anyone else hoping that a much-anticipated global climate summit the United Nations is convening in Paris in December will put the world on a safe path. President Barack Obama and other world leaders must now reckon with the possibility that the 2 degrees goal they affirmed at the Copenhagen summit in 2009 is actually a recipe for catastrophe. In effect, Hansen’s study explodes what has long been the goal of conventional climate diplomacy.

More troubling, honoring even the conventional 2 degrees C target has so far proven extremely challenging on political and economic grounds. Current emission trajectories put the world on track towards a staggering 4 degrees of warming before the end of the century, an amount almost certainly beyond civilization’s coping capacity. In preparation for the Paris summit, governments have begun announcing commitments to reduce emissions, but to date these commitments are falling well short of satisfying the 2 degrees goal. Now, factor in the possibility that even 2 degrees is too much and many negotiators may be tempted to throw up their hands in despair.

They shouldn’t. New climate science brings good news as well as bad.  Humanity can limit temperature rise to 1.5 degrees C if it so chooses, according to a little-noticed study by experts at the Potsdam Institute for Climate Impacts (now perhaps the world’s foremost climate research center) and the International Institute for Applied Systems Analysis published in Nature Climate Change in May.

“Actions for returning global warming to below 1.5 degrees Celsius by 2100 are in many ways similar to those limiting warming to below 2 degrees Celsius,” said Joeri Rogelj, a lead author of the study. “However … emission reductions need to scale up swiftly in the next decades.” And there’s a significant catch: Even this relatively optimistic study concludes that it’s too late to prevent global temperature rising by 2 degrees C. But this overshoot of the 2 C target can be made temporary, the study argues; the total increase can be brought back down to 1.5 C later in the century.

Besides the faster emissions reductions Rogelj referenced, two additional tools are essential, the study outlines. Energy efficiency—shifting to less wasteful lighting, appliances, vehicles, building materials and the like—is already the cheapest, fastest way to reduce emissions. Improved efficiency has made great progress in recent years but will have to accelerate, especially in emerging economies such as China and India.

Also necessary will be breakthroughs in so-called “carbon negative” technologies. Call it the photosynthesis option: because plants inhale carbon dioxide and store it in their roots, stems, and leaves, one can remove carbon from the atmosphere by growing trees, planting cover crops, burying charred plant materials underground, and other kindred methods. In effect, carbon negative technologies can turn back the clock on global warming, making the aforementioned descent from the 2 C overshoot to the 1.5 C goal later in this century theoretically possible. Carbon-negative technologies thus far remain unproven at the scale needed, however; more research and deployment is required, according to the study.

Together, the Nature Climate Change study and Hansen’s new paper give credence to the many developing nations and climate justice advocates who have called for more ambitious action. The authors of the Nature Climate Changestudy point out that the 1.5 degrees goal “is supported by more than 100 countries worldwide, including those most vulnerable to climate change.” In May, the governments of 20 of those countries, including the Philippines, Costa Rica, Kenya, and Bangladesh, declared the 2 degrees target “inadequate” and called for governments to “reconsider” it in Paris.

Hansen too is confident that the world “could actually come in well under 2 degrees, if we make the price of fossil fuels honest.”

That means making the market price of gasoline and other products derived from fossil fuels reflect the enormous costs that burning those fuels currently externalizes onto society as a whole. Economists from left to right have advocated achieving this by putting a rising fee or tax on fossil fuels. This would give businesses, governments, and other consumers an incentive to shift to non-carbon fuels such as solar, wind, nuclear, and, best of all, increased energy efficiency. (The cheapest and cleanest fuel is the fuel you don’t burn in the first place.)

But putting a fee on fossil fuels will raise their price to consumers, threatening individual budgets and broader economic prospects, as opponents will surely point out. Nevertheless, higher prices for carbon-based fuels need not have injurious economic effects if the fees driving those higher prices are returned to the public to spend as it wishes. It’s been done that way for years with great success in Alaska, where all residents receive an annual check in compensation for the impact the Alaskan oil pipeline has on the state.

“Tax Pollution, Pay People” is the bumper sticker summary coined by activists at the Citizens Climate Lobby. Legislation to this effect has been introduced in both houses of the U.S. Congress.

Meanwhile, there are also a host of other reasons to believe it’s not too late to preserve a livable climate for young people and future generations.

The transition away from fossil fuels has begun and is gaining speed and legitimacy. In 2014, global greenhouse gas emissions remained flat even as the world economy grew—a first. There has been a spectacular boom in wind and solar energy, including in developing countries, as their prices plummet. These technologies now qualify as a “disruptive” economic force that promises further breakthroughs, said Achim Steiner, executive director of the UN Environment Programme.

Coal, the most carbon-intensive conventional fossil fuel, is in a death spiral, partly thanks to another piece of encouraging news: the historic climate agreement the U.S. and China reached last November, which envisions both nations slashing coal consumption (as China is already doing). Hammering another nail into coal’s coffin, the leaders of Great Britain’s three main political parties pledged to phase out coal, no matter who won the general elections last May.

“If you look at the long-term [for coal], it’s not getting any better,” said Standard & Poor’s Aneesh Prabhu when S&P downgraded coal company bonds to junk status. “It’s a secular decline,” not a mere cyclical downturn.

Last but not least, a vibrant mass movement has arisen to fight climate change, most visibly manifested when hundreds of thousands of people thronged the streets of New York City last September, demanding action from global leaders gathered at the UN. The rally was impressive enough that it led oil and gas giant ExxonMobil to increase its internal estimate of how likely the U.S. government is to take strong action. “That many people marching is clearly going to put pressure on government to do something,” an ExxonMobil spokesman told Bloomberg Businessweek.

The climate challenge has long amounted to a race between the imperatives of science and the contingencies of politics. With Hansen’s paper, the science has gotten harsher, even as the Nature Climate Change study affirms that humanity can still choose life, if it will. The question now is how the politics will respond—now, at Paris in December, and beyond.

Mark Hertsgaard has reported on politics, culture, and the environment from more than 20 countries and written six books, including “HOT: Living Through the Next Fifty Years on Earth.”

*   *   *

Experts make dire prediction about sea levels (CBS)

VIDEO

In the future, there could be major flooding along every coast. So says a new study that warns the world’s seas are rising.

Ever-warming oceans that are melting polar ice could raise sea levels 15 feet in the next 50 to 100 years, NASA’s former climate chief now says. That’s five times higher than previous predictions.

“This is the biggest threat the planet faces,” said James Hansen, the co-author of the new journal article raising that alarm scenario.

“If we get sea level rise of several meters, all coastal cities become dysfunctional,” he said. “The implications of this are just incalculable.”

If ocean levels rise just 10 feet, areas like Miami, Boston, Seattle and New York City would face flooding.

The melting ice would cool ocean surfaces at the poles even more. While the overall climate continues to warm. The temperature difference would fuel even more volatile weather.

“As the atmosphere gets warmer and there’s more water vapor, that’s going to drive stronger thunderstorms, stronger hurricanes, stronger tornadoes, because they all get their energy from the water vapor,” said Hansen.

Nearly a decade ago, Hansen told “60 Minutes” we had 10 years to get global warming under control, or we would reach “tipping point.”

“It will be a situation that is out of our control,” he said. “We’re essentially at the edge of that. That’s why this year is a critical year.”

Critical because of a United Nations meeting in Paris that is designed to reach legally binding agreements on carbons emissions, those greenhouse gases that create global warming.

*   *   *

Sea Levels Could Rise Much Faster than Thought (Climate Denial Crock of the Week)

with Peter SinclairJuly 21, 2015

Washington Post:

James Hansen has often been out ahead of his scientific colleagues.

With his 1988 congressional testimony, the then-NASA scientist is credited with putting the global warming issue on the map by saying that a warming trend had already begun. “It is time to stop waffling so much and say that the evidence is pretty strong that the greenhouse effect is here,” Hansen famously testified.

Now Hansen — who retired in 2013 from his NASA post, and is currently an adjunct professor at Columbia University’s Earth Institute — is publishing what he says may be his most important paper. Along with 16 other researchers — including leading experts on the Greenland and Antarctic ice sheets — he has authored a lengthy study outlining an scenario of potentially rapid sea level rise combined with more intense storm systems.

It’s an alarming picture of where the planet could be headed — and hard to ignore, given its author. But it may also meet with considerable skepticism in the broader scientific community, given that its scenarios of sea level rise occur more rapidly than those ratified by the United Nations’ Intergovernmental Panel on Climate Change in its latest assessment of the state of climate science, published in 2013.

In the new study, Hansen and his colleagues suggest that the “doubling time” for ice loss from West Antarctica — the time period over which the amount of loss could double — could be as short as 10 years. In other words, a non-linear process could be at work, triggering major sea level rise in a time frame of 50 to 200 years. By contrast, Hansen and colleagues note, the IPCC assumed more of a linear process, suggesting only around 1 meter of sea level rise, at most, by 2100.

Here, a clip from our extended interview with Eric Rignot in December of 2014.  Rignot is one of the co-authors of the new study.

Slate:

The study—written by James Hansen, NASA’s former lead climate scientist, and 16 co-authors, many of whom are considered among the top in their fields—concludes that glaciers in Greenland and Antarctica will melt 10 times faster than previous consensus estimates, resulting in sea level rise of at least 10 feet in as little as 50 years. The study, which has not yet been peer reviewed, brings new importance to a feedback loop in the ocean near Antarctica that results in cooler freshwater from melting glaciers forcing warmer, saltier water underneath the ice sheets, speeding up the melting rate. Hansen, who is known for being alarmist and also right, acknowledges that his study implies change far beyond previous consensus estimates. In a conference call with reporters, he said he hoped the new findings would be “substantially more persuasive than anything previously published.” I certainly find them to be.

We conclude that continued high emissions will make multi-meter sea level rise practically unavoidable and likely to occur this century. Social disruption and economic consequences of such large sea level rise could be devastating. It is not difficult to imagine that conflicts arising from forced migrations and economic collapse might make the planet ungovernable, threatening the fabric of civilization.

The science of ice melt rates is advancing so fast, scientists have generally been reluctant to put a number to what is essentially an unpredictable, non-linear response of ice sheets to a steadily warming ocean. With Hansen’s new study, that changes in a dramatic way. One of the study’s co-authors is Eric Rignot, whose own study last year found that glacial melt from West Antarctica now appears to be “unstoppable.” Chris Mooney, writing for Mother Jonescalled that study a “holy shit” moment for the climate.

Daily Beast:

New climate science brings good news as well as bad.  Humanity can limit temperature rise to 1.5 degrees C if it so chooses, according to a little-noticed study by experts at the Potsdam Institute for Climate Impacts (now perhaps the world’s foremost climate research center) and the International Institute for Applied Systems Analysis published in Nature Climate Changein May.

shanghai500

“Actions for returning global warming to below 1.5 degrees Celsius by 2100 are in many ways similar to those limiting warming to below 2 degrees Celsius,” said Joeri Rogelj, a lead author of the study. “However … emission reductions need to scale up swiftly in the next decades.” And there’s a significant catch: Even this relatively optimistic study concludes that it’s too late to prevent global temperature rising by 2 degrees C. But this overshoot of the 2 C target can be made temporary, the study argues; the total increase can be brought back down to 1.5 C later in the century.

Besides the faster emissions reductions Rogelj referenced, two additional tools are essential, the study outlines. Energy efficiency—shifting to less wasteful lighting, appliances, vehicles, building materials and the like—is already the cheapest, fastest way to reduce emissions. Improved efficiency has made great progress in recent years but will have to accelerate, especially in emerging economies such as China and India.

Also necessary will be breakthroughs in so-called “carbon negative” technologies. Call it the photosynthesis option: because plants inhale carbon dioxide and store it in their roots, stems, and leaves, one can remove carbon from the atmosphere by growing trees, planting cover crops, burying charred plant materials underground, and other kindred methods. In effect, carbon negative technologies can turn back the clock on global warming, making the aforementioned descent from the 2 C overshoot to the 1.5 C goal later in this century theoretically possible. Carbon-negative technologies thus far remain unproven at the scale needed, however; more research and deployment is required, according to the study.

*   *   *

Earth’s Most Famous Climate Scientist Issues Bombshell Sea Level Warning (Slate)

495456719-single-family-homes-on-islands-and-condo-buildings-on

Monday’s new study greatly increases the potential for catastrophic near-term sea level rise. Here, Miami Beach, among the most vulnerable cities to sea level rise in the world. Photo by Joe Raedle/Getty Images

In what may prove to be a turning point for political action on climate change, a breathtaking new study casts extreme doubt about the near-term stability of global sea levels.

The study—written by James Hansen, NASA’s former lead climate scientist, and 16 co-authors, many of whom are considered among the top in their fields—concludes that glaciers in Greenland and Antarctica will melt 10 times faster than previous consensus estimates, resulting in sea level rise of at least 10 feet in as little as 50 years. The study, which has not yet been peer-reviewed, brings new importance to a feedback loop in the ocean near Antarctica that results in cooler freshwater from melting glaciers forcing warmer, saltier water underneath the ice sheets, speeding up the melting rate. Hansen, who is known for being alarmist and also right, acknowledges that his study implies change far beyond previous consensus estimates. In a conference call with reporters, he said he hoped the new findings would be “substantially more persuasive than anything previously published.” I certainly find them to be.

To come to their findings, the authors used a mixture of paleoclimate records, computer models, and observations of current rates of sea level rise, but “the real world is moving somewhat faster than the model,” Hansen says.

Hansen’s study does not attempt to predict the precise timing of the feedback loop, only that it is “likely” to occur this century. The implications are mindboggling: In the study’s likely scenario, New York City—and every other coastal city on the planet—may only have a few more decades of habitability left. That dire prediction, in Hansen’s view, requires “emergency cooperation among nations.”

We conclude that continued high emissions will make multi-meter sea level rise practically unavoidable and likely to occur this century. Social disruption and economic consequences of such large sea level rise could be devastating. It is not difficult to imagine that conflicts arising from forced migrations and economic collapse might make the planet ungovernable, threatening the fabric of civilization.

The science of ice melt rates is advancing so fast, scientists have generally been reluctant to put a number to what is essentially an unpredictable, nonlinear response of ice sheets to a steadily warming ocean. With Hansen’s new study, that changes in a dramatic way. One of the study’s co-authors is Eric Rignot, whose own study last year found that glacial melt from West Antarctica now appears to be “unstoppable.” Chris Mooney, writing for Mother Jonescalled that study a “holy shit” moment for the climate.

One necessary note of caution: Hansen’s study comes via a nontraditional publishing decision by its authors. The study will be published in Atmospheric Chemistry and Physics, an open-access “discussion” journal, and will not have formal peer review prior to its appearance online later this week. [Update, July 23: The paper is now available.] The complete discussion draft circulated to journalists was 66 pages long, and included more than 300 references. The peer review will take place in real time, with responses to the work by other scientists also published online. Hansen said this publishing timeline was necessary to make the work public as soon as possible before global negotiators meet in Paris later this year. Still, the lack of traditional peer review and the fact that this study’s results go far beyond what’s been previously published will likely bring increased scrutiny. On Twitter, Ruth Mottram, a climate scientist whose work focuses on Greenland and the Arctic, was skeptical of such enormous rates of near-term sea level rise, though she defended Hansen’s decision to publish in a nontraditional way.

In 2013, Hansen left his post at NASA to become a climate activist because, in his words, “as a government employee, you can’t testify against the government.” In a wide-ranging December 2013 study, conducted to support Our Children’s Trust, a group advancing legal challenges to lax greenhouse gas emissions policies on behalf of minors, Hansen called for a “human tipping point”—essentially, a social revolution—as one of the most effective ways of combating climate change, though he still favors a bilateral carbon tax agreed upon by the United States and China as the best near-term climate policy. In the new study, Hansen writes, “there is no morally defensible excuse to delay phase-out of fossil fuel emissions as rapidly as possible.”

Asked whether Hansen has plans to personally present the new research to world leaders, he said: “Yes, but I can’t talk about that today.” What’s still uncertain is whether, like with so many previous dire warnings, world leaders will be willing to listen.

*   *   *

Ice Melt, Sea Level Rise and Superstorms (Climate Sciences, Awareness and Solutions / Earth Institute, Columbia University)

23 July 2015

James Hansen

The paper “Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2°C global warming is highly dangerous” has been published in Atmospheric Chemistry and Physics Discussion and is freely available here.

The paper draws on a large body of work by the research community, as indicated by the 300 references. No doubt we missed some important relevant contributions, which we may be able to rectify in the final version of the paper. I thank all the researchers who provided data or information, many of whom I may have failed to include in the acknowledgments, as the work for the paper occurred over a several year period.

I am especially grateful to the Durst family for a generous grant that allowed me to work full time this year on finishing the paper, as well as the other supporters of our program Climate Science, Awareness and Solutions at the Columbia University Earth Institute.

In the conceivable event that you do not read the full paper plus supplement, I include the Acknowledgments here:

Acknowledgments. Completion of this study was made possible by a generous gift from The Durst Family to the Climate Science, Awareness and Solutions program at the Columbia University Earth Institute. That program was initiated in 2013 primarily via support from the Grantham Foundation for Protection of the Environment, Jim and Krisann Miller, and Gerry Lenfest and sustained via their continuing support. Other substantial support has been provided by the Flora Family Foundation, Dennis Pence, the Skoll Global Threats Fund, Alexander Totic and Hugh Perrine. We thank Anders Carlson, Elsa Cortijo, Nil Irvali, Kurt Lambeck, Scott Lehman, and Ulysses Ninnemann for their kind provision of data and related information. Support for climate simulations was provided by the NASA High-End Computing (HEC) Program through the NASA Center for Climate Simulation (NCCS) at Goddard Space Flight Center.

Floods as war weapons – Humans caused a third of floods in past 500 years in SW Netherlands (Hydrology.nl)

new study shows that, from 1500 until 2000, about a third of floods in southwestern Netherlands were deliberately caused by humans during wartimes. Some of these inundations resulted in significant changes to the landscape, being as damaging as floods caused by heavy rainfall or storm surges. The work, by Dutch researcher Adriaan de Kraker, is published in Hydrology and Earth System Sciences, a journal of the European Geosciences Union (EGU).

This photograph shows remnants of the former breach made here in February 1584, now a tidal channel. The marshland visible in the picture is former arable land.

During the Eighty Years’ War, as the Spanish army fought to recapture territory in what is now northern Belgium and southwestern Netherlands in the late sixteenth century, the Dutch rebels led by William of Orange decided to use the low-lying, flood-prone landscape to their advantage. In an attempt to liberate Bruges, Ghent and Antwerp from Spanish dominance and defend their territory, the rebels destroyed seawalls at strategic places from 1584 to 1586 to cause deliberate, large-scale floods.

»The plan got completely out of hand«, says De Kraker, an assistant professor at the VU University Amsterdam in the Netherlands. »It came at the expense of the countryside of northern Flanders, now Zeeland Flanders, some two thirds of which was flooded.«

Floods can result in loss of life and damage homes and businesses, and when the water remains inland for a long time, it can change the landscape through erosion and deposition, forming new tidal channels and creeks. The area flooded during the Eighty Years’ War became part of a strategic line of defence and remained inundated for more than 100 years in some places, with profound consequences for the landscape. After the waters receded, a thick layer of clay covered all remnants of buildings and roads in the area. As sea water was used, soil salinity increased, affecting agricultural yields.

»Strategic flooding is a highly risky tactic. It can only be successful if there’s a well-thought-out backup plan and a plan for fast repairs«, warns De Kraker. However, that was not the case here, he says: »I desperately looked for evidence of backup plans for the repair of the dykes and who was going to pay for the costs incurred. I could find hardly any records of such plans.«

Map showing the strategic flooding of the Philippine area, southwestern Netherlands, in 1747 at the time of a French military attack.

De Kraker has been studying historical floods – occurring from the year 1500 to 2000 – in southwestern Netherlands since the 1980s to find out their causes and outcomes. Mostly below sea level, and dominated by three river estuaries populated with islands and a system of dykes and dams that protect the fertile land from the sea, this region is particularly susceptible to floods.

In his research, De Kraker used documents relating to land ownership and land use, accounts of maintenance of sea defences, and correspondence between stakeholders, such as rebels, Spanish officials, and mayors of besieged towns. He also used aerial photographs of the area, historical maps and maps of soil and landscape changes.

As reported in the new Hydrology and Earth System Sciences article, he noticed the main floods in the area in the past 500 years could be grouped into those caused by storm surges (21 events) and those happening during wartimes (11 events). The former had natural causes and the latter were created by humans, but De Kraker says human action played a major role in both.

The most damaging flood occurred in the winter of 1953, when strong winds blew for two days causing a long-lasting storm surge, which resulted in extremely high water levels. Over 1800 people died, 100 000 were evacuated and damages reached the equivalent of 700 million euros. While the cause of this flood was natural, De Kraker says human factors contributed to the extent of the damage. He reports that officials were slow at responding to the event, failing to take mitigation measures such as raising the dykes fast enough. Weak building construction and inadequate rescue procedures contributed to the material damage and human toll.

The study also shows floods in the Netherlands were used as a weapon as recently as the 1940s. »Strategic flooding during the Second World War undertaken by the Germans remained purely defensive, while the Allied flooding of the former island of Walcheren in the southwest of the country sped up the Allied offensive«, says De Kraker.

Seca faz cidade submersa há 45 anos ressurgir em SP (OESP)

Em Igaratá Velha (SP)

31/01/201509h00 Atualizada 31/01/201512h58 

Carlos de Almeida, 50, morador de Igaratá (SP), exibe uma foto da antiga cidade, inundada desde março de 1969

Carlos de Almeida, 50, morador de Igaratá (SP), exibe uma foto da antiga cidade, inundada desde março de 1969. Tiago Queiroz/Estadão

A seca que atinge o rio Jaguari fez reaparecer as ruínas de uma cidade que estava submersa desde março de 1969, quando começou a construção dos reservatórios usados na geração de energia para a região do Vale do Paraíba e do Sistema Cantareira.

No fundo de uma represa, que está 30 metros abaixo do nível normal, entre Joanópolis e São José dos Campos, no interior paulista, a igreja matriz, a praça e a rua principal da Igaratá Velha ressurgiram e se transformaram em ponto turístico.

Os 2 mil moradores do antigo povoado de Igaratá Velha, formado em meados de 1865 em uma confluência dos Rios Jaguari e do Peixe, foram removidos para uma nova cidade homônima um século depois. Criada em dezembro de 1969 a 3 quilômetros da antiga cidade, a nova Igaratá nasceu em um terreno da antiga Centrais Elétricas de São Paulo (Cesp), doado aos moradores. Hoje, o município tem cerca de 9 mil habitantes.

O reaparecimento das ruínas da Igreja Nossa Senhora do Patrocínio emociona quem viveu no antigo povoado. Um grupo colocou uma nova cruz onde ficava a igreja. “O pessoal mais velho vem e passa o domingo rezando em volta da cruz. Não querem que a água cubra de volta a igreja”, diz o agricultor Edilson Cardoso, de 32 anos.

Com um quadro da Igaratá Velha debaixo dos braços, o pescador José Carlos de Almeida, de 50 anos, cobra R$ 5 para levar turistas de canoa até as ruínas do antigo grupo escolar, no meio da represa. “Se a represa baixar os 10 metros que faltam, vai reaparecer a cidade inteira.”

A prefeitura de Igaratá também fez melhorias na pista de terra que dá acesso às ruínas, para facilitar a visitação. “Uma pena não ter dinheiro para fazer a preservação das peças encontradas. Muita coisa as pessoas já levaram embora”, diz o secretário de Obras de Igaratá, Emerson Rodrigues, de 35 anos.

Enchentes

Na época da remoção promovida pela Cesp, a maior parte dos moradores concordava com a mudança. “Era muita enchente. No período das chuvas todo mundo tinha de sair de casa. Só os mais antigos não queriam mudar”, recorda José Rodrigues, de 72 anos.

Na nova Igaratá, a emoção pelo ressurgimento da antiga igreja parece ter anestesiado a preocupação com a seca. Mesmo entre os mais jovens a curiosidade é grande. Muitos querem descobrir onde ficava a casa da avó, da tia que morreu, do prefeito.

Telhas dos anos 1940, escadarias, tanques de lavar roupa e restos das cadeiras da praça podem ser observados sobre o solo seco. No meio da represa estão estacas das casas demolidas na época da inundação.

“Toda semana aparece uma coisa nova. Muito velhinho vem aqui e se emociona, chora mesmo”, conta Fabio Saltonato, de 28 anos. “Quero achar a casa que era do meu pai. Pelo que vi nas fotos, se baixar mais 2 metros ela vai aparecer. Quem sabe depois do carnaval.”

Mas a seca derrubou o turismo, principal atividade econômica de Igaratá. Na beira da represa, dezenas de chácaras e sítios de veraneio estão à venda. Pontos que funcionavam como marinas estão vazios. “Com essa transposição de água da represa, a cidade vai ‘morrer’ economicamente. Esse é nosso medo”, diz o secretário de Obras.

Megafloods: What They Leave Behind (Science Daily)

Jan. 16, 2014 — South-central Idaho and the surface of Mars have an interesting geological feature in common: amphitheater-headed canyons. These U-shaped canyons with tall vertical headwalls are found near the Snake River in Idaho as well as on the surface of Mars, according to photographs taken by satellites. Various explanations for how these canyons formed have been offered — some for Mars, some for Idaho, some for both — but in a paper published the week of December 16 in the online issue ofProceedings of the National Academy of Sciences,Caltech professor of geology Michael P. Lamb, Benjamin Mackey, formerly a postdoctoral fellow at Caltech, and W. M. Keck Foundation Professor of Geochemistry Kenneth A. Farley offer a plausible account that all these canyons were created by enormous floods.

Stubby Canyon, Malad Gorge State Park, Idaho. (Credit: Michael Lamb)

Canyons in Malad Gorge State Park, Idaho, are carved into a relatively flat plain composed of a type of volcanic rock known as basalt. The basalt originated from a hotspot, located in what is now Yellowstone Park, which has been active for the last few million years. Two canyons in Malad Gorge, Woody’s Cove and Stubby Canyon, are characterized by tall vertical headwalls, roughly 150 feet high, that curve around to form an amphitheater. Other amphitheater-headed canyons can be found nearby, outside the Gorge — Box Canyon, Blue Lakes Canyon, and Devil’s Corral — and also elsewhere on Earth, such as in Iceland.

To figure out how they formed, Lamb and Mackey conducted field surveys and collected rock samples from Woody’s Cove, Stubby Canyon, and a third canyon in Malad Gorge, known as Pointed Canyon. As its name indicates, Pointed Canyon ends not in an amphitheater but in a point, as it progressively narrows in the upstream direction toward the plateau at an average 7 percent grade. Through Pointed Canyon flows the Wood River, a tributary of the larger Snake River, which in turn empties into the Columbia River on its way to the Pacific Ocean.

Geologists have a good understanding of how the rocks in Woody’s Cove and Stubby Canyon achieved their characteristic appearance. The lava flows that hardened into basalt were initially laid down in layers, some more than six feet thick. As the lava cooled, it contracted and cracked, just as mud does when it dries. This produced vertical cracks across the entire layer of lava-turned-basalt. As each additional sheet of lava covered the same land, it too cooled and cracked vertically, leaving a wall that, when exposed, looks like stacks of tall blocks, slightly offset from one another with each additional layer. This type of structure is called columnar basalt.

While the formation of columnar basalt is well understood, it is not clear how, at Woody’s Cove and Stubby Canyon, the vertical walls became exposed or how they took on their curved shapes. The conventional explanation is that the canyons were formed via a process called “groundwater sapping,” in which springs at the bottom of the canyon gradually carve tunnels at the base of the rock wall until this undercutting destabilizes the structure so much that blocks or columns of basalt fall off from above, creating the amphitheater below.

This explanation has not been corroborated by the Caltech team’s observations, for two reasons. First, there is no evidence of undercutting, even though there are existing springs at the base of Woody’s Cove and Stubby Canyon. Second, undercutting should leave large boulders in place at the foot of the canyon, at least until they are dissolved or carried away by groundwater. “These blocks are too big to move by spring flow, and there’s not enough time for the groundwater to have dissolved them away,” Lamb explains, “which means that large floods are needed to move them out. To make a canyon, you have to erode the canyon headwall, and you also have to evacuate the material that collapses in.”

That leaves waterfall erosion during a large flood event as the only remaining candidate for the canyon formation that occurred in Malad Gorge, the Caltech team concludes.

No water flows over the top of Woody’s Cove and Stubby Canyon today. But even a single incident of overland water flow occurring during an unusually large flood event could pluck away and topple boulders from the columnar basalt, taking advantage of the vertical fracturing already present in the volcanic rock. A flood of this magnitude could also carry boulders downstream, leaving behind the amphitheater canyons we see today without massive boulder piles at their bottoms and with no existing watercourses.

Additional evidence that at some point in the past water flowed over the plateaus near Woody’s Cove and Stubby Canyon are the presence of scour marks on surface rocks on the plateau above the canyons. These scour marks are evidence of the type of abrasion that occurs when a water discharge containing sediment moves overland.

Taken together, the evidence from Malad Gorge, Lamb says, suggests that “amphitheater shapes might be diagnostic of very large-scale floods, which would imply much larger water discharges and much shorter flow durations than predicted by the previous groundwater theory.” Lamb points out that although groundwater sapping “is often assumed to explain the origin of amphitheater-headed canyons, there is no place on Earth where it has been demonstrated to work in columnar basalt.”

Closing the case on the canyons at Malad Gorge required one further bit of information: the ages of the rock samples. This was accomplished at Caltech’s Noble Gas Lab, run by Kenneth A. Farley, W. M. Keck Foundation Professor of Geochemistry and chair of the Division of Geological and Planetary Sciences.

The key to dating surface rocks on Earth is cosmic rays — very high-energy particles from space that regularly strike Earth. “Cosmic rays interact with the atmosphere and eventually with rocks at the surface, producing alternate versions of noble gas elements, or isotopes, called cosmogenic nuclides,” Lamb explains. “If we know the cosmic-ray flux, and we measure the accumulation of nuclides in a certain mineral, then we can calculate the time that rock has been sitting at Earth’s surface.”

At the Noble Gas Lab, Farley and Mackey determined that rock samples from the heads of Woody’s Cove and Stubby Canyon had been exposed for the same length of time, approximately 46,000 years. If Lamb and his colleagues are correct, this is when the flood event occurred that plucked the boulders off the canyon walls, leaving the amphitheaters behind.

Further evidence supporting the team’s theory can be found in Pointed Canyon. Rock samples collected along the walls of the first kilometer of the canyon show progressively more exposure in the downstream direction, suggesting that the canyon is still being carved by Wood River. Using the dates of exposure revealed in the rock samples, Lamb reconstructed the probable location of Pointed Canyon at the time of the formation of Woody’s Cove and Stubby Canyon. At that location, where the rock has been exposed approximately 46,000 years, the surrounding canyon walls form the characteristic U-shape of an amphitheater-headed canyon and then abruptly narrow into the point that forms the remainder of Pointed Canyon. “The same megaflood event that created Woody’s Cove and Stubby Canyon seems to have created Pointed Canyon,” Lamb concludes. “The only difference is that the other canyons had no continuing river action, while Pointed Canyon was cut relatively slowly over the last 46,000 years by the Wood River, which is not powerful enough to topple and pluck basalt blocks from the surrounding plateau, resulting in a narrow channel rather than tall vertical headwalls.”

Solving the puzzle of how amphitheater-headed canyons are created has implications reaching far beyond south-central Idaho because similar features — though some much larger — are also present on the surface of Mars. “A very popular interpretation for the amphitheater-headed canyons on Mars is that groundwater seeps out of cracks at the base of the canyon headwalls and that no water ever went over the top,” Lamb says. Judging from the evidence in Idaho, however, it seems more likely that on Mars, as on Earth, amphitheater-headed canyons were created by enormous flood events, suggesting that Mars was once a very watery planet.

Journal Reference:

  1. M. P. Lamb, B. H. Mackey, K. A. Farley. Amphitheater-headed canyons formed by megaflooding at Malad Gorge, IdahoProceedings of the National Academy of Sciences, 2013; 111 (1): 57 DOI: 10.1073/pnas.1312251111

Go With the Flow in Flood Prediction (Science Daily)

Dec. 3, 2012 — Floods have once again wreaked havoc across the country and climate scientists and meteorologists suggest that the problem is only going to get worse with wetter winters and rivers bursting their banks becoming the norm. A team based at Newcastle University and their colleagues in China have developed a computer model that can work out how the flood flow will develop and where flooding will be worst based on an understanding of fluid dynamics and the underlying topology of a region.

Writing in the journal Progress in Computational Fluid Dynamics,Newcastle civil engineer Qiuhua Liang and colleagues and Chi Zhang of Dalian University of Technology and Junxian Yin, China Institute of Water Resources and Hydropower Research in Beijing, explain how they have developed an adaptive computer model that could provide accurate and efficient predictions about the flow of water as a flood occurs. Such a model might provide environmental agencies and authorities with a more precise early-warning system for residents and businesses in a region at risk of flood. It could also be used by insurance companies to determine the relative risk of different areas within a given region and so make their underwriting of the risk economically viable.

The model is based on a numerical solution to the hydrodynamic equations of fluid flow . This allows the researchers to plot the likely movement of water during a dam break or flash flood over different kinds of terrain and around obstacles even when flood waves are spreading rapidly. The researchers have successfully tested their model on real-world flood data.

The team points out that flood disasters have become a major threat to human lives and assets. “Flood management is therefore an important task for different levels of governments and authorities in many countries”, the researchers explain. “The availability of accurate and efficient flood modelling tools is vital to assist engineers and managers charged with flood risk assessment, prevention and alleviation.”

Journal Reference:

  1. Chi Zhang, Qiuhua Liang, Junxian Yin. A first-order adaptive solution to rapidly spreading flood waves.Progress in Computational Fluid Dynamics, An International Journal, 2013; 13 (1): 1 DOI: 10.1504/PCFD.2013.050645

Blame, Responsibility and Demand for Change Following Floods (Science Daily)

Nov. 25, 2012 — New research shows concerns about governmental failure to act effectively and fairly in the aftermath of extreme weather events can affect the degree to which residents are willing to protect themselves.

Published in the journal Nature Climate Change, the findings of a team led by scientists at the University could prove key to establishing how society should evolve to cope with more turbulent weather and more frequent mega storms.

The team examined attitudes in Cumbria in north west England and Galway in western Ireland, which were both hit by heavy flooding in November 2009. Record rainfall was recorded in both countries, resulting in a number of deaths, properties being severely damaged and economic disruption.

Professor Neil Adger of Geography at the University of Exeter, who led the research, said: “The flooding of 2009 was devastating to both communities. Our study is the first to track the impacts of floods across two countries and how communities and individuals demand change after such events. When people in both studies felt that government had fallen short of their expectations, we found that the resulting perception of helplessness leads to an unwillingness to take personal action to prevent flooding in future.”

Scientists at the University of Exeter worked with colleagues at the National University of Ireland Maynooth and the Tyndall Centre for Climate Change Research at the University of East Anglia, which also provided funding for the study.

Researchers surveyed 356 residents in both areas eight months after the flooding. They measured perceptions of governments’ performances in dealing with the aftermath, as well as perceptions of fairness in that response and the willingness of individuals to take action.

Dr Irene Lorenzoni of the Tyndall Centre comments: “Residents in Galway were significantly more likely to believe that their property would be flooded again than those in Cumbria. Yet it was Cumbrians who believed they had more personal responsibility to adapt to reduce future incidents.

“Whether people felt responses were fair also diverged. In our survey in Cumbria three quarters of respondents agreed that everyone in their community had received prompt help following the flooding, while in Galway it was less than half.”

Dr Conor Murphy of the National University of Ireland, Maynooth said: “The strong perception in Galway that authorities failed to deliver on the expectations of flooded communities in late 2009 is a wakeup call. Given the high exposure of development in flood prone areas it is clear that both England and Ireland need to make major investments in building flood resilience with changing rainfall patterns induced by climate change. Political demand for those investments will only grow.”

Professor Adger says: “Our research shows that climate change is likely to lead to a series of crises which will cause major disruption as instant short-term solutions are sought. We need to consider the implicit contract between citizens and government agencies when planning for floods, to enable fairer and smoother processes of adaptation.”

Journal Reference:

  1. W. Neil Adger, Tara Quinn, Irene Lorenzoni, Conor Murphy, John Sweeney. Changing social contracts in climate-change adaptationNature Climate Change, 2012; DOI:10.1038/nclimate1751