Suffering from an unprecedented drought, why is the Amazon rainforest so "thirsty" this year

【Today's Viewpoint】

◎ Reporter Liu Xia

In October, part of the Negro River in the Amazon rainforest near the city of Manaus in Brazil shrank to a depth of 10.12 meters, the lowest level measured in 7 years. And in Lake Tefe, about 120 kilometers west of the region, scientists found the carcasses of more than 500 dolphins, and the reason for the dolphin deaths was not the low water level, but probably because the temperature of the lake was close to 150 degrees Celsius.

These are the "symptoms" of the unprecedented drought that the Amazon rainforest has suffered this year. Climate change is certainly not at stake, but rainforest researchers say two other contributing factors, such as deforestation, are exacerbating the crisis. Moreover, the drought crisis has cut off food supplies to communities around the river, forcing indigenous people to use dirty, polluted water, causing gastrointestinal discomfort and other ailments.

The British journal Nature quoted Luciana Getty, a climate change researcher at Brazil's National Institute for Space Research (INPE), as saying that the causes of drought are threefold, starting with deforestation, "which is killing the resilience of the rainforest and making it drier and hotter".

Deforestation stifles rainforest resilience

Although deforestation in the Amazon fell by 1.7 percent between January and July this year compared to the same period last year, it has been at record highs for many years, according to INPE. Researchers point out that the culprit is agribusiness. MapBiomas is a consortium of academic, commercial, and non-governmental organizations that monitor land use in Brazil. A report by the alliance notes that over the past 42 years, ranchers and farmers have cut down trees, expanding Brazil's agricultural area by about 5 percent, much of it in the Amazon.

Getty noted that about 20 percent of the Amazon rainforest has been cut down and 40 percent is degraded, meaning that while the trees are still standing, their health has deteriorated and they are prone to fire and drought.

El Niño leads to a decrease in precipitation

The second factor contributing to the drought is the El Niño weather pattern that began to emerge this year.

El Niño occurs every 2-7 years. During the onset of El Niño, the winds that normally blow from east to west along the equator weaken or reverse, and warm ocean water rushes into the eastern tropical Pacific Ocean. El Niño has changed precipitation patterns in South America, resulting in dry air in the northern part where the rainforest is located, while humid air in the south. As a result, Uruguay has been hit by torrential rains, and in the past few months, floods have occurred in Paraguay, Argentina and southern Brazil, killing dozens of people and leaving thousands homeless.

Meanwhile, data from Brazil's National Center for Early Warning and Monitoring of Natural Disasters showed that eight states in Brazil's northern and northeastern regions experienced the lowest rainfall in 7 years between July and September this year. These months are the peak of the "fire season" in much of the Amazon.

In addition, Erica Berenger, an ecosystem researcher at the University of Oxford in the United Kingdom, points out that ranchers and other rainforest cleaners usually do not burn trees when it rains or when the air is wet. But because El Niño dries out the air inside the rainforest, tree clearers now burn trees as well. This not only exacerbated the harsh conditions, but also caused some uncontrollable fires. In September of this year, Berenguer visited Pará in the north.

Warming waters are also an important factor

The third factor contributing to the severe drought in the Amazon is the anomalous warming of the waters in the North Atlantic.

Maria Assunção Dias, a climatologist at the University of São Paulo in Brazil, points to climate change as one of the causes of the warming of the sea. The warming of certain waters has affected the intertropical convergence zone. Karina Lima, a geographer at the Federal University of Rio Grande do Sul, points out that this region, which surrounds the Earth near the equator, is one of the main meteorological systems in the tropics, as well as an area where clouds and rain are formed. The region has shifted north, away from northern Brazil.

All of these factors have combined to cause a record drought in the Amazon this year. In 1912, 1925, 1983, 1987, 1998, 2010, 2016 and 2023, the Amazon suffered droughts and even extreme droughts, but severe droughts were "becoming more frequent," Díaz said.

What's even more worrying, Getty said, is that El Niño is just beginning, so "it's not going to get better for a while." Díaz also pointed out that if the sea surface temperature in the tropical Pacific Ocean is 2.5°C warmer than average, there could even be a "super El Niño". The World Meteorological Organization (WMO) reported on November 11 that there is a 8% chance that El Niño will continue at least until the end of April next year.

It's hard to predict when the next drought will hit the Amazon, and Lima says climate change is disrupting the timing of El Niño, which is a serious blow to the Amazon rainforest, which is already suffering from deforestation, a warming climate and a dry climate.