During the melting season I'm writing (bi-)weekly updates on the current situation with regards to Arctic sea ice (ASI). Central to these updates are the daily Cryosphere Today sea ice area (SIA) and IJIS sea ice extent (SIE) numbers, which I compare to data from the 2005-2014 period (NSIDC has a good explanation of sea ice extent and area in their FAQ). I also look at other things like regional sea ice area, compactness, temperature and weather forecasts, anything of particular interest.
May 19th 2015
Here it is, the first Arctic Sea Ice update for the 2015 melting season, and boy, are we off to a flying start. But more about that later. First a quick overview of what's been happening the last few years.
After the 2007 melting season smashed the 2005 record minimum, it was equalled by the 2011 melting season and subsequently smashed itself by the 2012 melting season. Although the 2013 melting season didn't bode well at all, given the trend and the massive amount of first-year ice, the Arctic sea ice had its traditional post-record rebound after a cold and cloudy melting season.
This (volume) rebound had all but vanished at the start of the 2014 melting season, but again the melting season started out cold and cloudy, after which the sea ice hardly moved during the rest of the melting season. And so there was a similar rebound to the one following the 2013 melting season. However, this time the volume rebound was larger and lingered on through winter.
One would think the ice pack would be strengthened and more resistant to weather conditions at the start of the 2015 melting season. But this also depends on how the volume is distributed across the pack, and as we saw in the 2014/2015 Winter analysis I posted 10 days ago, all of the volume has piled up in the Central Arctic and the Canadian Archipelago, the sea ice's last safe haven. This basically means that as far as the periphery of the Arctic sea ice pack is concerned, there is no big difference with the other post-2007 years. This melting season could turn out to be another rebound, but it might just as well go as low as 2007, 2011 or even 2012. The only thing we know for certain, is that the Arctic won't see below 1 million km2 of sea ice come September, the definition of 'ice-free'.
The outcome is obviously determined by weather conditions, but this month and June are particularly important for what I like to call melting momentum. This momentum is determined by the amount of melt ponds that form on the ice pack during these two months, as they soak up more solar energy that would otherwise be reflected. 2012 had a relatively sunny and warm start of the melting season, after which a stable decrease couldn't be thrown off by weather that was less conducive to melting. And that's how the record was broken, compounded by the Great Arctic Cyclone in August. Conversely, 2013 and 2014 had cold and cloudy starts to the melting season, and this couldn't be made up later on during bouts of sunny weather.
And so melt ponds will be the main theme of this first phase of the melting season. In fact, I'm going to obsess over them in the next two months and report on them outside of the ASI updates. The amount of melting momentum decides whether the melting season has a chance of breaking records.
Off we go.