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A Negative Warming Feedback

And a very positive thing it is at that

1 min read

A report this fall in Wiley's Global Change Biology reports on a negative feedback from global warming—that is to say, a feedback that makes things better rather than worse. The article in a relatively obscure scientific journal caught the notice of a news service reporter rather belatedly, and that report got my attention later still, but I'm passing it along because so much of the news from the climate front is bad while this—however modest--is a jolly good thing by comparison.

Worst-case-scenario thinking about climate change tends to assume that things will be even dire than models predict because of unrecognized, undiscovered, or underestimated positive feedbacks. There are two notable examples, both big: the feedback from reflective ice in the Arctic and Antarctic flashing to absorptive blue water, as warming takes place; and the feedback from melting permafrost, which could release vast amounts of methane into the atmosphere. (Radiative absorption was underestimated in early climate models, and methane release is hard to predict in current ones.) 

But in a September issue of Global Change Biology, members of the British Antarctic Survey report their discovery that as Antarctic ice has melted, large blooms of marine plants called phytoplankton have been flourishing in waters exposed. The phytoplankton have the potential to absorb roughly 3.5 million metric tons of carbon per year, roughly equivalent to the carbon "sink" represented by tropical rain forest covering 6-17,000 hectares. Lead author Lloyd Peck conceded that this is a small number when compared with the 7 billion tons of carbon ejected by human activity into the atmosphere each year. But he said that as more Antarctic ice melts, the new phytoplankton blooms "have the potential to be a significant biological sink for carbon." 

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