…A new Yale-led study in the journal Nature finds that warming will drive the loss of at least 55 trillion kilograms of carbon from the soil by mid-century, or about 17% more than the projected emissions due to human-related activities during that period. That would be roughly the equivalent of adding to the planet another industrialized country the size of the United States.
Critically, the researchers found that carbon losses will be greatest in the world’s colder places, at high latitudes, locations that had largely been missing from previous research. In those regions, massive stocks of carbon have built up over thousands of years and slow microbial activity has kept them relatively secure.
Most of the previous research had been conducted in the world’s temperate regions, where there were smaller carbon stocks….
…The study predicts that for one degree of warming, about 30 petagrams of soil carbon will be released into the atmosphere, or about twice as much as is emitted annually due to human-related activities …This is particularly concerning, Crowther said, because previous climate studies predicted that the planet is likely to warm by 2 degrees Celsius by mid-century….
…The study considered only soil carbon losses in response to warming. There are several other biological processes—such as accelerated plant growth as a result of carbon dioxide increases—that could dampen or enhance the effect of this soil carbon feedback. Understanding these interacting processes at a global scale is critical to understanding climate change, the researchers said. “Getting a handle on these kinds of feedbacks is essential if we’re going to make meaningful projections about future climate conditions…
T. W. Crowther et al, Quantifying global soil carbon losses in response to warming, Nature (2016). DOI: 10.1038/nature20150