A Flip in the Arctic Tundra: It's Now a Carbon Dioxide Source

Forget what you learned in grade school science class: The Arctic tundra is no longer the carbon sink it once was. "The tundra, which is experiencing warming and increased wildfire, is now emitting more carbon that it stores, which will worsen climate change impacts," NOAA Administrator Rick Spinrad said in a press release. "This is yet one more sign, predicted by scientists, of the consequences of inadequately reducing fossil fuel pollution." The research behind that finding and others—for instance, that the Arctic is warming more rapidly than the global average for the 11th consecutive year—appeared in the NOAA's annual Arctic Report Card released Tuesday. More:

• Historically: The New York Times explains that for millennia, the moss, lichens, and other vegetation of the tundra have taken in carbon dioxide and stored it, as all plants do. But when these plants died, the carbon dioxide wasn't released. Instead, it "is entombed in the frigid soil, where it no longer helps warm Earth's surface."
• Now: Twila Moon, lead editor of the Arctic Report Card, likens the carbon-filled permafrost to chicken in the freezer. So long as that chicken stays frozen, microbes don't touch it. But "once you have that chicken out of your freezer, it's thawing and all those microbes are getting to work, breaking down the chicken, making it rot. The permafrost is really doing the same thing": As warmer temps cause the ground to thaw, soil microbes reactivate "and consume the newly available carbon, releasing it into the atmosphere as methane and carbon dioxide," per NPR.

• The wildfire angle: An increase in high-latitude wildfires is also exacerbating things, reports the Guardian. It explains: "Wildfires not only combust vegetation and soil organic matter, releasing carbon into the atmosphere, but they also strip away insulating soil layers, accelerating long-term permafrost thaw and its associated carbon emissions."
• Positive notes: The Times reports the report did contain some positive findings. For one, the Greenland Ice Sheet's annual ice loss was the lowest it has been since 2013 due to above-average snowfall and below-average melting.

(More Tundra stories.)