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Comment by sparrish | Hacker News Reader

I'm confused. How are tropical forests emitting carbon? Even if the title is misleading and they mean the areas that used to be tropical forests (deforested areas), how are these bare areas, which are now clear cut or used for farming, emitting carbon? I don't see any explanation in the article. Can someone explain?

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Exposed earth typically emits carbon dioxide. It's not "emit" in the way a breathing mammal would, more that the carbon in the organic material is oxidized at a greater rate because it's exposed to the atmosphere.

Before deforestation, carbon would be pulled from the atmosphere by trees, turned into plant material, fall to the ground as dead leaves or whole dead trunks and be sequestered into the soil as they broke down and were buried.

“In many cases throughout the tropics you have selective logging, or smallholder farmers removing individual trees for fuel wood. These losses can be relatively small in any one place, but added up across large areas they become considerable."

Also, the research paper itself has a helpful satellite map in the appendix: https://sci-hub.tw/10.1126/science.aam5962

I can't read the original paper, but the article seems to be conflating the tropics and tropical forests, which are normally two distinct things. Perhaps the study says that the tropics (the region between the Tropic of Cancer and the Tropic of Capricorn) are now no longer a carbon sink, because the tropical forests have been so degraded?

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