Amazon drought raises fears of climate tipping point

The Rio Negro is one of the largest rivers in the world and a major tributary of the Amazon. It is the backbone of the rainforest ecosystem and is critical to the stability of the global climate. But much of the waterway is now dry.

An unprecedented drought has hit the region for weeks, causing water levels in the Amazon’s main artery to fall to record lows, wreaking havoc on local communities and the biome’s unique wildlife.

The direct victims of the drought are more than half a million people in the Brazilian state of Amazonas, who are suffering a humanitarian emergency as river transport in the region is hampered by a lack of water.

But drought also has a profound impact on Earth’s climate. As extreme heat and lack of water kill trees and spark fires, forests begin releasing large amounts of carbon dioxide, exacerbating the global warming process that scientists say is a significant factor behind droughts.

“This is starting a vicious cycle that is destroying the forest,” said Philip Fearnside, a scientist at the National Amazon Research Institute in Manaus.

“With the huge carbon reserves in the forest, the Amazon is at the center of a global warming problem that humans have no control over. If just a small amount comes out, that’s the straw that breaks the camel’s back. And the risk of that happening is increasing.” .”

In the port city of Manaus in the heart of the tropical rainforest, the water level of the river has dropped to 12.7m, more than 6m below the historical average for October, leaving docks deserted as the region’s rivers have lost most of their transportation functions.

More than 60 cities in Amazonas state, including Manaus, have officially entered a state of emergency, and the government is rushing to deliver basic supplies such as food, water and medicine.

“The river is our road, so going anywhere becomes impossible,” said Fredson Farias, who sells boat tickets at the port of Manaus. I estimate footfall is down 70%.

“Some parts of the river are 95 percent dry. We haven’t seen anything like this in a hundred years,” he said.

The immediate cause of the drought is a combination of an ongoing El Niño weather event, which warms the surface of the eastern equatorial Pacific, and unusually warm waters in the Atlantic Ocean above the equator.

These two phenomena suppress cloud formation, causing rainfall to drop dramatically. In the eastern Amazonian city of Belém, rainfall in September was only a quarter of normal.

In addition to the Rio Negro, one of the world’s largest rivers, water levels in the Amazon, Solimos and Madeira rivers have reached record lows and some have dried up.

Experts say the intensity of Pacific and Atlantic events – which are not themselves caused by human activity – is worsened by climate change.

Tim Renton, head of climate change and earth system science at the University of Exeter, said: “Global warming is clearly one of the causes of this unusual drought.”

“It increases warmth in the eastern equatorial Pacific, where El Niño is creating the usual warm pools. It also leads to unprecedentedly warm sea surface temperatures in the North Atlantic. “Both of these ocean heating patterns have contributed to the current drought. “

The situation is further complicated by unusually high temperatures. On October 10, the National Meteorological Institute reported a temperature of 40 degrees Celsius in Manaus, the highest temperature ever recorded nearly a century ago.

Heat and lack of rain create prime conditions for fires, which, like drought itself, can kill trees, damage ecosystems and cause more carbon to be released into the atmosphere.

A 2021 study in the United Kingdom and Brazil found that droughts and fires caused by El Niño in 2015-16 killed more than 2.5 billion trees and woody vines and released nearly 500 million tons of carbon dioxide.

Last month was the worst October fire season in Amazonas state since records began 25 years ago, with more than 3,400 fires reported, according to the state government.

The events have raised concerns that parts of the world’s largest rainforest are being pushed to so-called “tipping points”, where mass die-offs of trees mean the forest can no longer sustain the circulation of its aquatic ecosystems. This will lead to more droughts, more tree deaths and potentially dramatic climate swings in Latin America and around the world.

“Forests are declining,” Marcio Astrini, executive secretary of the Climate Observatory, told a Brazilian nonprofit. “It’s not going to happen across the board or at the same time, but in some areas you’ve gone through these inflection points.”

Several studies have shown that deforestation has been rampant in recent years and that some areas of the Amazon, particularly in the southeastern region of Pará state, have emitted more carbon than they absorb.

“You can expect more droughts like this to happen. That’s what the models are showing,” Fearnside said.

In the docks of Manaus, the effects of the drought are evident. Rapidly retreating rivers are being replaced by garbage-strewn sandbars. Health officials warn that contaminated water leads to an increased risk of disease, including hepatitis A and cholera.

Just outside the city, where the black Rio Negro meets the dusky Solimos to form the Amazon, drought has exposed rocky outcrops with faces carved into them. Archaeologists believe the markers may be as old as 2,000 years old.

With fewer boat departures, a pontoon dock on the Rio Negro was packed with cargo including Honda motorcycles, cleaning products, clothes and cereals. The port is a hub for supplies to remote villages deep in the rainforest.

“We are stuck in the city,” said Marilene Bonilia, sitting on the dock trying to sell trinkets to the small group of people who had arrived. “We are suffering.”

“Things have been bad before, but never like this,” said Ebido Santos, who oversees loading of river vessels.