The Arctic has had a hot winter. And although it’s not yet sure if the sea ice extent has reached its annual maximum yet, judging by NSIDC data it seems likely that total winter sea ice surface is in 2014 the lowest second only to the Arctic winter of 2011 – which still stands as the record-lowest winter ice extent since satellite measurements began.
The 2013-2014 winter clearly saw less sea ice recovery than the previous winter – of 2012-2013. A relatively ‘good Arctic winter’ can generally be explained through observed dominance of the positive phase in the atmospheric air pressure pattern known as the Arctic Oscillation, whereas relatively warm Arctic winters, as the current one, are generally accompanied by a negative AO – which allows for the cold air to settle at a lower latitude, as people in the US can testify (‘Polar Vortex’ of 2013-2014).
Concerning the trend: relatively high and low Arctic winter sea ice extents do not change the general picture: ice is clearly declining on a multi-decadal base – and ice loss is generally faster in summer than in winter, in the sense that the annual ice graph is getting ‘steeper’ as thinning of the Arctic sea ice (another clear trend) makes the remaining sea ice more vulnerable to elevated summer temperatures and as stretches of open water form, the albedo effect, which is only active in summer (as there is no Sun in winter). This also means that -under given meteorological circumstances- summer melting can occur rapidly – and therefore neither a ‘good’ or a ‘bad’ Arctic winter are much help in forecasting the summer melting – for which the summer melting-record of 2012 (after a ‘good winter’) is indicative, clearly shown as the dotted line in the above graph.
© Rolf Schuttenhelm | www.bitsofscience.org