Soil Carbon Sequestration May Take Thousands of Years, Not Decades
Soil may not be pulling as much carbon out of the atmosphere as scientists previously thought, according to a paper published last week in the journal Science. And “that could be a big setback in our global climate efforts,” the Washington Post reports.
Most carbon sequestration models to date haven’t used radiocarbon dating to determine the age of carbon stored in soil samples, even though it’s already a standard, very accurate method used in a range of archaeological studies. When a team from the University of California Irvine applied the technique to soil samples from 157 sites around the world, they began to second-guess past estimates of the time it takes carbon to enter the soil.
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“They found that, in the real world, soil carbon was generally a lot older than the models had been reporting, the Post notes. “In fact, the researchers found that the old models had been underestimating the age of soil carbon, on average, by a factor of more than six.”
The researchers came up with a few explanations for the discrepancy—but the bottom line is that carbon may not be entering soil rapidly enough to help reduce global warming this century.
“The results suggest the process can take a lot longer than scientists previously assumed—up to thousands of years, instead of just tens or hundreds,” writes the Post’s Chelsea Harvey. “Worldwide, soil’s carbon sequestration potential this century may only be half what we thought it was.”