Climate change and deforestation have turned much of the Amazon basin from a sink to a source of CO2 emissions, potentially turning humanity’s greatest natural ally in the fight against global warming into an enemy, researchers said Wednesday.
Hundreds of high-altitude air samples collected over the past decade have shown that the southeastern Amazon, in particular, has gone from being a “sink” to a source of carbon dioxide, a major greenhouse gas, the journal Nature reported.
Terrestrial ecosystems around the world are critical as the world struggles to limit CO2 emissions, which exceeded 40 billion tons in 2019. Over the past half-century, plants and soil have consistently absorbed more than a quarter of those emissions, even as CO2 pollution has increased by 50 percent. The Amazon is home to about half of the world’s tropical rain forests, which absorb and store carbon more efficiently than other vegetation.
If the Amazon, where 450 billion tons of CO2 is trapped in trees and soil, becomes a permanent source rather than a “sink” for CO2, the fight against the climate crisis will become much more difficult.
According to the study, several factors contributed to the transition in the eastern Amazon. “Deforestation and forest degradation are reducing Amazonia’s ability to act as a carbon sink,” the authors note.
Since 1970, the region’s rainforest has been reduced by 17 percent, mostly to make way for pastures to raise cattle and grow the crops that feed them. Forests are routinely cut down by fire, releasing huge amounts of CO2 and reducing the number of trees that can absorb it.