"The carbon losses you have to have from soil to affect climate need to be fast and big," David McGuire of the University of Alaska, Fairbanks said. "There are two ways do that: mass erosion from slumping or along the coasts and rivers, and through fires." Last year, McGuire, who was not involved with Ping's research, ran computer simulations of what would happen if catastrophe struck vast swaths of Arctic tundra in the form of wildfires and massive erosion. "The most carbon we could get into the atmosphere was about 50 billion tons," he said, or about half of what Ping's team thinks is stored in the soil. That's not enough to make much difference by the year 2100, but Ted Schuur of the University of Florida thinks we need to look further into the future. In a paper to be published in the September issue of the journal Bioscience, he estimates that 1,672 billion tons of carbon are locked in Arctic permafrosts, much of it in Siberia. The carbon leak is slow -- he estimates it could only be as high as 1 billion tons each year worldwide, or about 10 percent of what is emitted today through human activity emissions. But over the next four centuries it could end up in the atmosphere, drastically altering Earth's climate. "The Ping paper is great so far as it goes, but it's only dealing with this one zone: North America," Schuur said. "That's like describing what an elephant looks like by talking all about its foot. We're trying to describe the whole elephant." If Schuur's estimate is right, Arctic soils harbor two to three times more carbon than is currently aloft in Earth's atmosphere. If it were to be released as greenhouse gases over the course of the next few centuries, the effect on the climate might not be noticeable by the year 2100. But by the year 2400 or 2500 it would be tremendous. "Right now there's about 780 billion tons of carbon in the atmosphere. And now you say you're going to take and slowly put much of 1,600 billion tons from the soil up there. That's going to have a huge effect on the heat-trapping capacity of the Earth," Schuur said. "Say you look at Earth in 500 years," he said. "It's probably going to be a very different place." Related Links: Michael Reilly's blog: Strike Slip University of Alaska, Fairbanks |
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