|2011-03-29 13:34:22||Yet more positive feedback to GW|
Study: Climate-driven vegetation change by boreal forests is yet another positive, amplifying feedback
Co-author: "What we're seeing is a system kicking into overdrive. Warming creates more warming."
March 28, 2011
Back in 2005, Science published an analysis, “Role of Land-Surface Changes in Arctic Summer Warming,” which explained how reduced snow cover and albedo (reflectivity) in the summertime Arctic landscape, caused by global warming, has added local atmospheric heating “similar in magnitude to the regional heating expected over multiple decades from a doubling of atmospheric CO2” (Science, subs. req’d).
That same Science study warned “Continuation of current trends in shrub and tree expansion could further amplify this atmospheric heating 2-7 times.”
The new study looks at a completely different effect:
Well, actually, the permafrost permamelt contains a staggering “1.5 trillion tons of frozen carbon, about twice as much carbon as contained in the atmosphere, much of which would be released as methane. Methane is 25 times as potent a heat-trapping gas as CO2 over a 100 year time horizon, but 72 times as potent over 20 years!
Going back to the 2005 Science study, the point is that if you convert a white landscape to a boreal forest, the surface suddenly starts collecting a lot more solar energy. That trend is occurring now, as seen in these two photos from a recent ScienceNews article, “Boreal forests shift north.”
“Upper photo taken in 1962 shows tundra-dominated mountain slope in Siberian Urals. A 2004 photo of the same site, below, shows conifers were setting up dense stand of forest.”
A 2008 study warns that the warming-driven northward march of vegetation poses yet another threat to the tundra. That study, “Frequent Fires in Ancient Shrub Tundra: Implications of Paleorecords for Arctic Environmental Change,” finds:
The concern is not so much the direct emissions from burning tundra. As the article concludes:
The image hows just how much the fire changes the albedo (reflectivity) of the tundra landscape.
A new, very conservative study by NOAA and the National Snow and Ice Data Center — which doesn’t even consider these various amplifying feedbacks in the region — finds that that the thawing permafrost feedback will turn the Arctic from a carbon sink to source in the 2020s, releasing 100 billion tons of carbon by 2100.
Again, the people out there who think R&D or an energy quest is going to stop us from multiple catastrophes are deluding themselves and others. We need to start aggressive mitigation now as every major independent study concludes.
Related posts and amplifying feedbacks:
Is it too late baby, now...?