Global Warming Could Unlock Carbon From Tropical Soil

https://www.nytimes.com/2020/08/12/climate/tropical-soils-climate-change.html

 

By Gabriel Popkin
    Aug. 12, 2020

Humble dirt could pack an unexpected climate punch, according to a new study published Wednesday in the journal Nature. An experiment that heated soil underneath a tropical rainforest to mimic temperatures expected in the coming decades found that hotter soils released 55 percent more planet-warming carbon dioxide than did nearby unwarmed areas.

If the results apply throughout the tropics, much of the carbon stored underground could be  released as the planet heats up.

“The loss rate is huge,” said Andrew Nottingham, an ecologist at the University of Edinburgh, who led the study. “It’s a bad news story.”

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If the entire tropics were to behave similarly, the researchers estimate that 65 billion metric tons of carbon would enter the atmosphere by 2100 — more than six times the annual emissions from all human-related sources.

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By warming only the soil, the Barro Colorado Island experiment did not capture how plants would fare under warmer conditions, said Tana Wood, a U.S. Forest Service ecologist who is leading the Puerto Rico experiment. If plants were to photosynthesize more, for example, they could take up some of the carbon dioxide that soils release, making the overall impact on the climate less severe. “This is only telling half the carbon story,” she said. (Her team is warming both the soil and the air with infrared heaters and measuring how plants and microbes respond.)

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