Tag Archives: La Niña

In Brazil’s Amazon, rivers rise to record levels (Associated Press)

apnews.com

By FERNANDO CRISPIM and DIANE JEANTET

June 1st, 2021


MANAUS, Brazil (AP) — Rivers around the biggest city in Brazil’s Amazon rainforest have swelled to levels unseen in over a century of record-keeping, according to data published Tuesday by Manaus’ port authorities, straining a society that has grown weary of increasingly frequent flooding.

The Rio Negro was at its highest level since records began in 1902, with a depth of 29.98 meters (98 feet) at the port’s measuring station. The nearby Solimoes and Amazon rivers were also nearing all-time highs, flooding streets and houses in dozens of municipalities and affecting some 450,000 people in the region.

Higher-than-usual precipitation is associated with the La Nina phenomenon, when currents in the central and eastern Pacific Ocean affect global climate patterns. Environmental experts and organizations including the U.S. Environmental Protection Agency and the National Oceanic and Atmospheric Administration say there is strong evidence that human activity and global warming are altering the frequency and intensity of extreme weather events, including La Nina.

Seven of the 10 biggest floods in the Amazon basin have occurred in the past 13 years, data from Brazil’s state-owned Geological Survey shows.

“If we continue to destroy the Amazon the way we do, the climatic anomalies will become more and more accentuated,” said Virgílio Viana, director of the Sustainable Amazon Foundation, a nonprofit. ” Greater floods on the one hand, greater droughts on the other.”

Large swaths of Brazil are currently drying up in a severe drought, with a possible shortfall in power generation from the nation’s hydroelectric plants and increased electricity prices, government authorities have warned.

But in Manaus, 66-year-old Julia Simas has water ankle-deep in her home. Simas has lived in the working-class neighborhood of Sao Jorge since 1974 and is used to seeing the river rise and fall with the seasons. Simas likes her neighborhood because it is safe and clean. But the quickening pace of the floods in the last decade has her worried.

“From 1974 until recently, many years passed and we wouldn’t see any water. It was a normal place,” she said.

Aerial view of streets flooded by the Negro River, in downtown Manaus, Amazonas state, Brazil, Tuesday, June 1, 2021. Rivers around Brazil's biggest city in the Amazon rain forest have swelled to levels unseen in over a century of record-keeping, according to data published Tuesday by Manaus' port authorities. (AP Photos/Nelson Antoine)
Aerial view of streets flooded by the Negro River in downtown Manaus. (AP Photos/Nelson Antoine)
A man pushes a shopping cart loaded with bananas on a street flooded by the Negro River, in downtown Manaus, Amazonas state, Brazil, Tuesday, June 1, 2021. Rivers around Brazil's biggest city in the Amazon rain forest have swelled to levels unseen in over a century of record-keeping, according to data published Tuesday by Manaus' port authorities. (AP Photo/Edmar Barros)
A man pushes a shopping cart loaded with bananas on a street flooded by the Negro River, in downtown Manaus. (AP Photo/Edmar Barros)

When the river does overflow its banks and flood her street, she and other residents use boards and beams to build rudimentary scaffolding within their homes to raise their floors above the water.

“I think human beings have contributed a lot (to this situation,” she said. “Nature doesn’t forgive. She comes and doesn’t want to know whether you’re ready to face her or not.”

Flooding also has a significant impact on local industries such as farming and cattle ranching. Many family-run operations have seen their production vanish under water. Others have been unable to reach their shops, offices and market stalls or clients.

“With these floods, we’re out of work,” said Elias Gomes, a 38-year-old electrician in Cacau Pirera, on the other side of the Rio Negro, though noted he’s been able to earn a bit by transporting neighbors in his small wooden boat.

Gomes is now looking to move to a more densely populated area where floods won’t threaten his livelihood.

A man rides his motorcycle through a street flooded by the Negro River, in downtown Manaus, Amazonas state, Brazil, Tuesday, June 1, 2021. Rivers around Brazil's biggest city in the Amazon rain forest have swelled to levels unseen in over a century of record-keeping, according to data published Tuesday by Manaus' port authorities. (AP Photo/Edmar Barros)
A man rides his motorcycle through a street in downtown Manaus. (AP Photo/Edmar Barros)

Limited access to banking in remote parts of the Amazon can make things worse for residents, who are often unable to get loans or financial compensation for lost production, said Viana, of the Sustainable Amazon Foundation. “This is a clear case of climate injustice: Those who least contributed to global warming and climate change are the most affected.”

Meteorologists say Amazon water levels could continue to rise slightly until late June or July, when floods usually peak.

People walk on a wooden footbridge set up over a street flooded by the Negro River, in downtown Manaus, Amazonas state, Brazil, Tuesday, June 1, 2021. Rivers around Brazil's biggest city in the Amazon rain forest have swelled to levels unseen in over a century of record-keeping, according to data published Tuesday by Manaus' port authorities. (AP Photo/Edmar Barros)
People walk on a wooden footbridge set up over a street in downtown Manaus. (AP Photo/Edmar Barros)

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Diana Jeantet reported from Rio de Janeiro.

New study ties solar variability to the onset of decadal La Nina events (Science Daily)

[Linking solar activity to the onset of droughts in places like Northeast Brazil has historically been treated as something that did not deserve attention by mainstream meteorology. The El Niño Southern Oscillation – of which La Niña is part – was always presented as the main causal factor for droughts. This new study connects solar activity with the La Niña. The interesting thing here is that many local farmers seen as knowledgeable about rains and drought in NE Brazil mention a 10 years period for the repetition of climate events. -RT]

Date: April 5, 2021

Source: National Center for Atmospheric Research/University Corporation for Atmospheric Research

Summary: A new study shows a correlation between the end of solar cycles and a switch from El Nino to La Nina conditions in the Pacific Ocean, suggesting that solar variability can drive seasonal weather variability on Earth.


A new study shows a correlation between the end of solar cycles and a switch from El Nino to La Nina conditions in the Pacific Ocean, suggesting that solar variability can drive seasonal weather variability on Earth.

If the connection outlined in the journal Earth and Space Science holds up, it could significantly improve the predictability of the largest El Nino and La Nina events, which have a number of seasonal climate effects over land. For example, the southern United States tends to be warmer and drier during a La Nina, while the northern U.S. tends to be colder and wetter.

“Energy from the Sun is the major driver of our entire Earth system and makes life on Earth possible,” said Scott McIntosh, a scientist at the National Center for Atmospheric Research (NCAR) and co-author of the paper. “Even so, the scientific community has been unclear on the role that solar variability plays in influencing weather and climate events here on Earth. This study shows there’s reason to believe it absolutely does and why the connection may have been missed in the past.”

The study was led by Robert Leamon at the University of Maryland-Baltimore County, and it is also co-authored by Daniel Marsh at NCAR. The research was funded by the National Science Foundation, which is NCAR’s sponsor, and the NASA Living With a Star program.

Applying a new solar clock

The appearance (and disappearance) of spots on the Sun — the outwardly visible signs of solar variability — have been observed by humans for hundreds of years. The waxing and waning of the number of sunspots takes place over approximately 11-year cycles, but these cycles do not have distinct beginnings and endings. This fuzziness in the length of any particular cycle has made it challenging for scientists to match up the 11-year cycle with changes happening on Earth.

In the new study, the researchers rely on a more precise 22-year “clock” for solar activity derived from the Sun’s magnetic polarity cycle, which they outlined as a more regular alternative to the 11-year solar cycle in several companion studies published recently in peer-reviewed journals.

The 22-year cycle begins when oppositely charged magnetic bands that wrap the Sun appear near the star’s polar latitudes, according to their recent studies. Over the cycle, these bands migrate toward the equator — causing sunspots to appear as they travel across the mid-latitudes. The cycle ends when the bands meet in the middle, mutually annihilating one another in what the research team calls a terminator event. These terminators provide precise guideposts for the end of one cycle and the beginning of the next.

The researchers imposed these terminator events over sea surface temperatures in the tropical Pacific stretching back to 1960. They found that the five terminator events that occurred between that time and 2010-11 all coincided with a flip from an El Nino (when sea surface temperatures are warmer than average) to a La Nina (when the sea surface temperatures are cooler than average). The end of the most recent solar cycle — which is unfolding now — is also coinciding with the beginning of a La Nina event.

“We are not the first scientists to study how solar variability may drive changes to the Earth system,” Leamon said. “But we are the first to apply the 22-year solar clock. The result — five consecutive terminators lining up with a switch in the El Nino oscillation — is not likely to be a coincidence.”

In fact, the researchers did a number of statistical analyses to determine the likelihood that the correlation was just a fluke. They found there was only a 1 in 5,000 chance or less (depending on the statistical test) that all five terminator events included in the study would randomly coincide with the flip in ocean temperatures. Now that a sixth terminator event — and the corresponding start of a new solar cycle in 2020 — has also coincided with an La Nina event, the chance of a random occurrence is even more remote, the authors said.

The paper does not delve into what physical connection between the Sun and Earth could be responsible for the correlation, but the authors note that there are several possibilities that warrant further study, including the influence of the Sun’s magnetic field on the amount of cosmic rays that escape into the solar system and ultimately bombard Earth. However, a robust physical link between cosmic rays variations and climate has yet to be determined.

“If further research can establish that there is a physical connection and that changes on the Sun are truly causing variability in the oceans, then we may be able to improve our ability to predict El Nino and La Nina events,” McIntosh said.


Story Source:

Materials provided by National Center for Atmospheric Research/University Corporation for Atmospheric Research. Original written by Laura Snider. Note: Content may be edited for style and length.


Journal Reference:

  1. Robert J. Leamon, Scott W. McIntosh, Daniel R. Marsh. Termination of Solar Cycles and Correlated Tropospheric Variability. Earth and Space Science, 2021; 8 (4) DOI: 10.1029/2020EA001223