Thursday, 15 December 2016

NOAA’s 2016 Report Card on the Arctic

NOAA’s 2016 Report Card: The Arctic is Shouting Change


14 December, 2016

From winter to spring to summer to fall, it’s been an odd year for the Arctic. And according to Donald Perovich, one of the authors of NOAA’s 2016 Arctic Report Card, the Arctic isn’t just whispering change, it’s not foretelling change, “it’s shouting change.



(NOAA’s Arctic Report Card presented at the American Geophysical Union this morning. Video source: AGU.)
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Winter and spring of 2016 saw very warm temperatures in the northern polar region of our world. There, Arctic sea ice extent maximum hit its lowest values ever recorded in March. During summer, cooler, cloudier conditions prevented a complete meltdown by the time of sea ice minimum in September. However, sea ice extent bottomed out at second or third lowest on record in most of the major monitors. Moving into October, November and December, Arctic sea ice failed to refreeze at typical rates as extraordinarily warm temperatures were reinforced by pulses of air rising northward from the middle latitudes. At times, the gap between previous record low years and the new record lows seen during November of 2016 were as much as 1.1 million square kilometers. Now it is practically certain that average sea ice extents throughout 2016 will hit a new record low overall.

Arctic Warming at Least Twice as Fast as Rest of World

Much of this melt was almost certainly driven by the record warm Arctic temperatures seen during 2016. And according to NOAA, this year shattered all previous high marks for Arctic heat by a big margin — hitting 3.5 degrees Celsius warmer than 1900. Overall, this rate of warming is at least twice as fast as the rest of the globe.

arctic-warming-trend
(Arctic heat during 2016 centered over recently seasonal and annual ice free regions in the Chukchi and Barents seas. It’s an indicator that sea ice loss since 2007 and related loss of albedo [reflectivity] is starting to have the predicted heat-amplifying effect. Image source:NOAA.)

And all this extra heat has not only had a significant and substantial impact on sea ice — it is hammering the Greenland ice sheet, forcing the permafrost to rapidly thaw, and increasing the incidence of algae blooms related to ocean acidification.
Greenland Melt and Permafrost Thaw

In Greenland, the average annual rate of land ice loss is now 230 billion tons per year. This despite the fact that warming in the Greenland and Barents seas is helping to drive increased rates of precipitation in Eastern Greenland. So far, much of the precipitation is coming as snowfall. And this increase is helping to mitigate some of the mass losses due to melt across Greenland (see Marco Tedesco’s comments in the video above). However, as Greenland continues to experience surface warming, precipitation is likely to come more and more as rain — which will only further help to accelerate melt.

NOAA also notes that added Arctic heat has substantially altered the permafrost. Increasingly, this region of frozen soil is given over to thaw. As a result, profound changes to the Arctic landscape are ongoing. In wet regions, the permafrost is giving way to thermokarst lakes. In drier zones, the moisture that was locked into the soil and preserved by permafrost is being steadily lost — which is one of the primary drivers of drought and related wildfire hazards now being experienced in Canada, Siberia, and Alaska.

arctic-carbon-sink-to-source
(As permafrost thaws, microbes within the soil break down carbon and begin to emit methane and carbon dioxide. According to NOAA, “the warming tundra is now releasing more carbon into the atmosphere than it is taking up.” Image source: NOAA.)

Overall, the permafrost is emitting more and more methane and carbon dioxide as it melts and as microbes in the thawed soil activate. And consensus science now indicates that, on balance, this thawing ground is now emitting more carbon than it is taking in. This is a step change from its previous state — when the frozen land acted in concert with the boreal forests as one of the world’s primary carbon sinks (please also see: Beyond the Point of No Return).

Large Algae Blooms Indicator of Ocean Acidification

During 2016, the Arctic also saw a continuation of large algae blooms popping up in regions near the receding sea ice edge. This happens as high nutrient waters liberated by ice allow sunlight to produce a riot of plankton and algae growth. 

These minute life forms take in atmospheric carbon. But as they die, they transfer this carbon to the ocean. As a result, and as Jeremy Mathis noted in the press briefing this morning (see video above), Ocean acidification increases.

Conditions in Context — The Arctic Screams Change

The above indicators present a picture of an Arctic undergoing rapid climate destabilization. As a result, everything from weather patterns, to the rate of sea level rise, to Northern Hemisphere growing seasons are likely to see some impact from these Arctic changes over the coming years and decades. In addition, loss of sea ice and likely harms to life in the Arctic Ocean due to warming, habitat loss, and ocean acidification will remove food sources for local communities. NOAA researchers identify some potential positive outcomes — such as increased commerce, ship traffic, tourism, and mineral extraction. However, negative impacts, especially sea level rise, city-threatening wildfires, and potential loss of key food sources present considerable near and middle term threats to local communities and nations. In addition, if new fossil fuel sources are exploited in the region, it will only add to the current problems presented by warming. As a result, there is a high likelihood that the net impact to the region will be negative as species are threatened or go extinct and numerous communities are lost to the rising seas or endangered by worsening fires.
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Hat tip to Vic


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