Wednesday, January 29, 2014

NSIDC: 2013 sea ice was at record highs for the satellite era, record high winter extent & summer minimum

An article published today in Nature Climate Change notes, 
"The National Snow and Ice Data Center report that 2013 was above average in sea ice extent — a record, for the satellite era, with the largest winter extent as well as the highest summer minimum. This is on top of a small but increasing trend, 1–4%, in Antarctic sea ice."
The article also says "weather events make the news but shouldn't be confused with climate change impacts," which Nature Climate Change will promptly forget as soon as the next summer heat wave.


Icy times

Nature Climate Change 4, 75 (2014) doi:10.1038/nclimate2131

Published online January 29, 2014

Weather events make the news but shouldn't be confused with climate change impacts.

Recent weather events are being discussed in certain circles as proof that climate change is not happening. The 'Polar Vortex' caused Arctic conditions in the United States but this is thought to be an extreme weather event with weak links to climate change (http://go.nature.com/MDd8oA). [Actually, no links to climate change] A number of ships became 'stuck' in Antarctic sea ice this austral summer over the Christmas–New Year holiday period. Social media and the internet were awash with comments on the irony of heavy ice trapping climate change, or global warming, researchers.
We often hear reports of the declining Arctic sea ice cover but much less attention is given to the Antarctic, which, in contrast to the Arctic, has slightly increasing sea ice cover. But why is there such a difference in climate change impacts on the sea ice at the two polar regions? Consider the different environments — the Arctic Ocean is semi-enclosed by land that provides a becalmed sea on which sea ice forms, whereas the Antarctic continent stands alone with sea ice growing from its edges in the circumpolar Southern Ocean. There the sea ice is more easily broken up by winds and waves from the open ocean and is able to drift away from the continent, north into warmer waters. Antarctic winter sea ice covers up to 18 million km2, which shrinks to around 3 million km2 by the end of the summer. [Thanks Nature Climate Change for just pointing out that climate change should cause a greater decrease in Antarctic sea ice than Arctic, as falsely predicted by climate models, and opposite of observations.]
The National Snow and Ice Data Center report that 2013 was above average in sea ice extent — a record, for the satellite era, with the largest winter extent as well as the highest summer minimum. This is on top of a small but increasing trend, 1–4%, in Antarctic sea ice (http://nsidc.org/arcticseaicenews/8 January 2014).
So, was the record ice extent the reason for the ships becoming trapped? Sea ice is a dynamic environment, with winds and ocean currents shifting the ice. Icebergs are an additional hazard to be dealt with. Ships use the best available information to plot a course through this environment, but it can all change very quickly. Katabatic winds, those that flow off the continent to the sea, normally clear the sea ice away from the coast but the wind direction for much of December was from the northeast. This pushed the ice towards the coast in the East Antarctic, where ice flows stacked together to create an impenetrable ice mass.
Working in the polar regions is unpredictable with even the best laid plans at the mercy of the weather. It is essential to our understanding of climate change and its impacts that research is undertaken in this remote and wild region. Hopefully the stranded scientists have gained some valuable data and insights from this experience

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