Tropical forests are emitting more carbon than oxygen, study finds (2017) | Hacker News Reader

Tropical forests are emitting more carbon than oxygen, study finds (2017)

independent.co.uk

21 pointsgscott6 comments

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?

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?

If all "tropical forests" were in a single country, at 0.425 Gigatons per year of emissions that country would be the #14 most polluting in the world! [1]

The article above estimates 0.425 Gigatons of carbon dioxide per year being emitted by from the world's tropical forests. This is 1.3% of yearly global emissions! [2]

What if forests flipped from friend to foe, with poorly managed forests becoming liabilities?

[1] 2016 Carbon Dioxide emissions by country (http://edgar.jrc.ec.europa.eu/overview.php?v=CO2andGHG1970-2...)

[2] 2017 Global Carbon Dioxide emissions at 32.5 Gigaton (https://www.reuters.com/article/us-energy-carbon-iea/global-...)

I'm confused, is this tropical forests that still exist now emit more carbon, or land that used to be tropical forest release enough carbon to override the left over forest?

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