The Amazon rainforest now emits more CO2 than it absorbs

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The Amazon rainforest now emits more carbon dioxide than it can absorb, scientists first confirmed.

Emissions amount to one billion tonnes of carbon dioxide per year, according to a study. The giant forest was previously a carbon sink, soaking up the emissions that caused the climate crisis, but now causing it to accelerate, researchers said.

Most of the emissions are caused by fires, many of which are deliberately started to clear land for beef and soybean production. But even without fires, warmer temperatures and droughts mean the southeast Amazon has become a source of CO2 rather than a sink.

The growth of trees and plants has absorbed about a quarter of all fossil fuel emissions since 1960, with the Amazon playing a major role as the world’s largest rainforest. The Amazon’s loss of capacity to capture CO2 is a clear warning that cutting fossil fuel emissions is more urgent than ever, scientists have said.

Research has used small planes to measure CO2 levels up to 4,500m above the forest over the past decade, showing how the entire Amazon is changing. Previous studies indicating the Amazon was becoming a source of CO2 were based on satellite data, which can be hampered by cloud cover, or ground measurements of trees, which can only cover a tiny part of the vast region. .

Scientists said that the finding that part of the Amazon was emitting carbon even without fire was of particular concern. They said it was most likely the result of deforestation each year and fires making adjacent forests more vulnerable the following year. Trees produce much of the region’s rains, so fewer trees mean more severe droughts and heat waves, and more tree deaths and fires.

The government of Brazilian President Jair Bolsonaro has come under heavy criticism for encouraging more deforestation, which peaked in 12 years, while fires peaked in June since 2007.

Luciana Gatti, from the National Institute for Space Research in Brazil, who led the research, said: “The first very bad news is that burning forests produces about three times as much CO2 as the forest absorbs. The second bad news is that places where deforestation is 30% or more have carbon emissions 10 times higher than places where deforestation is less than 20%.

Fewer trees meant less rain and higher temperatures, making the dry season even worse for the remaining forest, she said: “We have a very negative loop that makes the forest more vulnerable to uncontrolled fires. “

Much of the wood, beef and soybeans from the Amazon are exported from Brazil. “We need a global deal to save the Amazon,” Gatti said. Some European countries have said they will block an EU trade deal with Brazil and other countries unless Bolsonaro agrees to do more to fight the destruction of the Amazon.

The research, published in the journal Nature, consisted of taking 600 vertical profiles of CO2 and carbon monoxide, which is produced by fires, at four sites in the Brazilian Amazon from 2010 to 2018. It found that the fires produced approximately 1.5 billion tonnes of CO2 per year. year, forest growth removing 0.5 billion tons. The billion tonnes left in the atmosphere is equivalent to the annual emissions of Japan, the fifth largest polluter in the world.

“This is a truly impressive study,” said Professor Simon Lewis of University College London. “Flying every two weeks and keeping consistent lab readings for nine years is an incredible achievement. “

“The positive feedback, where deforestation and climate change results in a release of carbon from the remaining forest that reinforces further warming and carbon loss, is what scientists feared was happening,” he said. “Now we have good evidence that this is happening. The story of the well at the source in the southeastern Amazon is yet another stark warning that climate impacts are accelerating. “

Colorado State University professor Scott Denning said the aerial research campaign was heroic. “In the south-east, the forest is no longer growing faster than it is dying. This is bad – moving the planet’s most productive carbon absorber from a sink to a source means we need to phase out fossil fuels faster than we thought. “

A satellite study published in April found that the Brazilian Amazon released nearly 20% more carbon dioxide into the atmosphere in the past decade than it absorbed. Research that followed 300,000 trees over 30 years, published in 2020, showed that tropical forests absorb less CO2 than before. Denning said, “These are complementary studies with radically different methods that come to very similar conclusions. “

“Imagine if we could ban fires in the Amazon – it could be a carbon sink,” Gatti said. “But we are doing the opposite – we are accelerating climate change. “

“The worst part is that we don’t use science to make decisions,” she said. “People think converting more land to agriculture will mean more productivity, but in fact we are losing productivity because of the negative impact on rain. “

A study released Friday estimated that Brazil’s soybean industry is losing $ 3.5 billion a year due to the immediate surge in extreme heat that follows destruction of forests.

This article was modified on July 14, 2021. The reference to the transition of forests “from a sink to a source” of carbon had been expressed backwards in a first version.


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