Study quantifies global soil carbon loss due to warming

UCI biologists Steven Allison and Kathleen Treseder are part of a Yale-led global study appearing in Nature that says global warming will drive the loss of at least 55 trillion kilograms of carbon from the Earth’s soil by midcentury, or about 17 percent more than the projected emissions due to human-related activities during that period. This would be roughly the equivalent of adding to the planet another industrialized country the size of the United States. For decades, scientists have speculated that rising global temperatures might alter the ability of soil to store carbon, potentially leading to the release of huge amounts of carbon into the atmosphere and triggering runaway climate change. Yet thousands of studies worldwide have produced mixed findings on whether soil’s storage capacity will actually decrease – or even increase – as the planet warms. Researchers in the Yale-led effort found that carbon losses will be greatest in the world’s colder places, at high latitudes, which had largely been missing from most previous analyses. In those regions, massive stocks of carbon have built up over millennia, and slow microbial activity has kept them relatively secure. “We’ve been monitoring warming impacts on Alaskan soil for almost a decade, but now we can see what happens globally when we combine our data with dozens of other studies,” Allison said. The picture is not encouraging, Treseder added. With a planetary warming of 2 degrees Celsius predicted by midcentury, additional carbon being released from the soil and into the atmosphere could make tackling climate change even more difficult.