One of Earth's biggest carbon sinks has been overestimated
The results contradict a widely accepted assumption in climate models that biomass and soil carbon will increase in tandem in the coming decades and highlight the importance of grasslands in helping to draw down carbon.
BY Josie Garthwaite
Earth MattersClimate Change
March 24, 2021
Carbon dioxide in the atmosphere fuels plant growth. As carbon levels rise, it’s appealing to think of supercharged plant growth and massive tree-planting campaigns drawing down the CO2 produced by fossil fuel burning, agriculture and other human activities.
Under a scenario where atmospheric carbon dioxide doubles pre-industrial levels, the researchers estimate carbon uptake in grassland soils will increase 8 percent, while carbon uptake by forest soils will remain roughly flat. (Image credit: iStock)
New research published March 24 in Nature, however, suggests that when elevated carbon dioxide levels drive increased plant growth, it takes a surprisingly steep toll on another big carbon sink: the soil.
One likely explanation, the authors say, is that plants effectively mine the soil for nutrients they need to keep up with carbon-fueled growth. Extracting the extra nutrients requires revving up microbial activity, which then releases CO2 into the atmosphere that might otherwise remain locked in soil.
https://earth.stanford.edu/news/one-earths-biggest-carbon-sinks-has-been-overestimated#gs.ylsvej
