Arctic Sea Ice

Dire Straits

There are blogs where people go to get information on certain subjects. When they have a particular question they ask it in the comment section and usually the blogger - who has an above average knowledge of the subject most of the time - will answer the question. This blog is not such a blog. Actually, it's the exact opposite. I, the blogger, do not know a lot about the Arctic and so I'm hoping people will post comments to clear things up for me. Because I have questions, a lot of questions.

Take for instance the MODIS satellite images Gareth from the Hot Topic blog mentioned in the comment thread of my previous blog post. The Arctic mosaic (a composite of several pictures) offers a stunning view of what is actually going on in the Arctic. But how do you interpret what you see? It's been only this year that I have started to check these images, and particularly the one displaying the Nares Strait.

The extra interest on my part is mainly due to this excellent piece by Patrick Lockerby called The Broken Bridges of Nares (sounds a bit like the title of an exciting fantasy book, doesn't it). Lockerby uses pictures from MODIS to show how and when the Nares Strait ice broke up in previous years and April 2010.

Ice bridge locations, adapted from image by P. Lockerby, source: ice-glaces.ec.gc.ca/

As Lockerby writes:

After the long Arctic Winter, the Nares Polynya should have formed an ice bridge. It hasn't. The Lincoln Sea should have healed its fractures. It hasn't. (...) In 2007 the open Nares Strait discharged about 10% of the total ice loss. (...) There is a potential for ice loss this year far greater than the all-time losses of 2007. The Nares Strait and Lincoln Sea areas should be surveyed as a matter of urgency.

So that's what I've been doing ever since, survey the Nares Strait and Lincoln Sea (though that probably isn't what Lockerby had in mind). And when you click on the MODIS Arctic mosaic where the Nares Strait and Lincoln Sea are, you get a closer view of that region:

Sea ice extent update 1: lovely colours

I'll be regularly writing updates on the current sea ice extent (SIE) as reported by IJIS (a joint effort of the International Arctic Research Center and the Japan Aerospace Exploration Agency) and compare it to the sea ice extents in the period 2006-2009. The JAXA graph is favoured by almost everyone, probably because it looks so nice compared to other graphs (like the one by Arctic ROOS, the University of Bremen and the Danish Meteorological Institute). All the years have a nice colour of their own which makes it easy to eyeball the differences between trends. Most of the betting on minimum SIE is based on the IJIS data. NSIDC has a nice explanation of what sea ice extent is in their FAQ.

June 7th 2010

When I checked the IJIS website early this morning yesterday's melt was reported as 103K km² (which I tend to call a century break, based on the snooker term, a sport that is almost as slow and captivating as the Arctic summer ice melt). But as I knew this number is always revised 12 hours later I decided not to make myself look ridiculous so soon by posting this number as the 5th century break this season (more on that in a few days). The revised number was 10,667,813, making yesterday's melt 80,937 square km, the largest melt on this date in the period 2006-2010, though not a century break.

Here's the current difference between 2010 and previous years:

• 2006: -201K

• 2007: -258K

• 2008: -439K

• 2009: -373K

So for the time being 2010 has a comfortable lead (which can vanish in a few days by the way, so doesn't mean much). In previous years the melt wasn’t anything spectacular for another 3 weeks or so, although 2007 started it’s amazing run around the 20th of June with 18 century breaks in a little over 40 days. We'll see what happens.

My prediction FWIW: When meteorological conditions approach those of summer 2007 there's a very good chance 2010 will set new records.

I'll be ending these updates with a picture of the tidy graph with the lovely colours I mentioned at the start of the post:

Welcome to this blog!

The Arctic, the area north of the Arctic Circle (66° 33’N), never garnered much attention, except perhaps for a few periods in the past where the general public would admiringly follow the feats of heroic explorers such as Alfred Wegener, Roald Amundsen or Nils Ekholm. But there's a shift taking place in the way this huge and barren part of the planet is perceived. More and more scientists and members of the public are taking an interest in what is happening up north and the reason for this is Global Warming.

As early as 1938 people like Guy Callendar, one of the great figures in the history of climate science, suggested that an increase of CO2 might be acting "as a promoter to start a series of imminent changes in the northern ice conditions." Early Global Circulation Models, imperfect as they were and still are, also indicated that an increase in heat accumulated at the equator due to greenhouse gases would inevitably be transported to the Poles, leading to such things as Arctic amplification. Signs that this is happening are increasingly being witnessed in the Arctic.

One of the main indicators is the state of the sea ice in the Arctic regions that waxes and wanes along with the seasons. The sea ice melts during the summer months and in winter open ocean water quickly refreezes again. But not all of the sea ice disappears during the summer melt. An area of thick ice that has accumulated over several years (known as multi-year ice), comprising several millions of square kilometres, remains at the end of the melt season in September. However, as predicted, the total has been declining over the past few decades. In fact, the decline seems to be accelerating and it is no longer a question if, but when the Arctic will see its first ice-free summer.