Conversation

Below is an excerpt from a long and beautifully photographed report in Nature about changes occurring in the Amazon rainforest, changes that are happening "sooner than predicted."

TITLE: Trouble in the Amazon

SUBTITLE: The rainforest is starting to release its carbon. Is it heading towards a tipping point?
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Luciana Gatti, a climate scientist at the National Institute for Space Research in Brazil, is part of a broad group of researchers attempting to forecast the future of the Amazon rainforest. The land ecosystems of the world together absorb about 30% of the carbon dioxide released by burning fossil fuels; scientists think that most of this takes place in forests, and the Amazon is by far the world’s largest contiguous forest.

Since 2010, Gatti has collected air samples over the Amazon to monitor how much CO2 the forest absorbs. In 2021, she reported data that showed that the Amazon forest’s uptake — its carbon sink — is weak over most of its area. In the southeastern Amazon, the forest has become a source of CO2.

The finding gained headlines around the world and surprised many scientists, who expected the Amazon to be a much stronger carbon sink. For Carlos Nobre, a climate scientist at the University of São Paulo Institute of Advanced Studies in Brazil, the change was happening much too soon. In 2016, using climate models, he and his colleagues predicted that the combination of unchecked deforestation and global climate change would eventually push the Amazon forest past a “tipping point”, transforming the climate across a vast swathe of the Amazon. Then, the conditions that support a lush, closed-canopy forest would no longer exist.

Gatti’s observations seem to show the early signs of what Nobre had forecast. “What we were predicting to happen perhaps in two or three decades is already taking place,” says Nobre.

The large-scale deforestation seen from the air is the most visible threat to the Amazon. But the forest is suffering in other, less-obvious ways. Erika Berenguer, an ecologist at the University of Oxford and Lancaster University, UK, has found that even intact forest is no longer as healthy as it once was, because of forces such as climate change and the impacts of agriculture that spill beyond farm borders.

Gatti first visited Santarém in the late 1990s, when most of the farming in this part of the Amazon was practiced by smallholders for subsistence purposes. Now, she’s astounded by the scale of destruction that has ravaged the jungle. While passing over one huge, newly razed parcel of Amazon forest, Gatti’s voice crackles over the plane’s intercom. “They are killing the forest to transform everything into soy beans.”
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FULL REPORT -- https://www.nature.com/immersive/d41586-023-02599-1/index.html

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