Arctic Sea Ice

Arctic sea ice loss and the role of AGW

I like to think that it's pretty obvious that AGW has something to do with the rapid loss of Arctic sea ice. Or to quote Dr Jennifer Francis: How could it not? However, to prove it scientifically is another matter entirely. Dirk Notz and Jochem Marotzke from the Max Planck Institute for Meteorology have given it a shot. (image credit: Dirk Notz / MPI for Meteorology)

From ScienceDaily (hat-tip to the Yooper):

Arctic Sea-Ice Loss Didn't Happen by Chance

ScienceDaily (May 2, 2012) — The ongoing rapid retreat of Arctic sea ice is often interpreted as the canary in the mine for anthropogenic climate change. In a new study, scientists have now systematically examined the validity of this claim. They find that neither natural fluctuations nor self-acceleration can explain the observed Arctic sea-ice retreat. Instead, the recent evolution of Arctic sea ice shows a strong, physically plausible correlation with the increasing greenhouse gas concentration. For Antarctic sea ice, no such link is found -- for a good reason.

When scientists try to attribute some observed climatic change to a specific forcing, they usually use complex climate models. The scientists at Germany's Max Planck Institute for Meteorology (MPI-M), however, decided on a different strategy as they set out to identify the main driver for the observed sea-ice loss in the Arctic. Dirk Notz, lead author of the study that was now published in the journal Geophysical Research Letters, explains why: "Sea ice is so thin that it reacts very sensitive to the large natural fluctuations of weather and climate that prevail in the Arctic. Because these fluctuations are inherently chaotic, their specific timing cannot be reproduced by standard climate models. Such models therefore aren't necessarily the best tool to examine if natural fluctuations did cause the observed sea-ice loss."

(...)

"In the end, only the increase in greenhouse gas concentration showed a physically plausible link with the observed sea-ice retreat. We expect a decreasing sea-ice cover for increasing greenhouse gas concentration, which is exactly what is observed," Notz explains. The physical link between greenhouse gas concentration and sea ice is quite straightforward, he adds: "Greenhouse gases increase the downwelling thermal radiation. This radiation, in turn, is the major player in the heat budget of Arctic sea ice."

Read the whole thing here. Paper available here.

2011/2012 Winter Analysis

I'm starting this blog post off with a conclusion that was reached a while back already: sea ice on the Atlantic side of the Arctic looks vulnerable, sea ice on the Pacific side should be thicker.

Right, with that out of the way we can now look at various aspects of the 2011/2012 freezing season, and compare them to previous years, to be precise the previous freezing season of 2010/2011, and the freezing seasons leading up to and following that other record year: 2006/2007 and 2007/2008. Simply put: I'll be comparing 2007, 2008, 2011 and 2012 before their respective start of the melting season.

I'll try not to use too many words, but I'll be using a lot of images. Click on them images if you want a bigger version.

Ice age

I'll start with the AARI ice age maps. These images are for the end of April, and they look upside down, because it's from the perspective of the Russians who produced them:

Live blog: CryoSat results

This was the live coverage of the whole event. Please discuss below.

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On the ESA homepage it says:

Watch online: CryoSat results

Live from the Royal Society in London, watch the unveiling of the first map of the winter 2010–11 changes in Arctic sea-ice thickness measured by ESA’s CryoSat satellite. Join the event via live web stream Tuesday starting at 07:30 GMT (09:30 CEST – 08:30 UK time).

9.31: I have just managed to connect and am waiting for the broadcast to start.

9.32: Broadcast has started.

9.35: This is the audience:

9.37: It has started. David Williams from the UK Space Agency is doing a short introduction. Followed by David Willets, Minister of University and Education. Lauds the UK Space Agency, lauds Great Britain. :-)

9.45: It's Volker Liebig's turn, director of Earth Observation Programmes from ESA. Congratulates UK Space Agency with 50 year anniversary. Jumps to Arctic Sea Ice immediately, shows consecutive extent records. Shows Stroeve's graph of trend deviation from IPCC models. Arctic important for climate change, but also geopolitically and for shipping.

ASI 2012 update 1: a new beginning

During the melting season I'm writing (bi-)weekly updates on the current situation with regards to Arctic sea ice (ASI). Because of the demise of AMSR-E the IJIS sea ice extent (SIE) numbers are no longer central to these updates. Instead I now use Cryosphere Today sea ice area (SIA) numbers and compare them to the SIA numbers in the 2005-2011 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, sea ice extent, temperature and weather forecasts, anything that can be of particular interest. Check out the Arctic sea ice graphs webpage for daily updated graphs, maps and live webcam images.

April 22nd 2012

A new year, a new spring, a new melting season. After a very deceptive/instructive end of the winter season the Arctic sea ice is off to an extremely slow start. Of course there already were above average conditions in regions like the Bering Sea and Baffin Bay, and when two weeks ago a big high pressure system in the middle of the Arctic got a huge clockwise gyre going,the ice pack was pushed into the big, empty expanse on the Atlantic side of the Arctic (see Novaya Zemlya April 2012). But because temperatures are still quite low at this time of the year, the ice pushed southwards didn't melt and the leads that were created elsewhere quickly froze over.

Conditions have turned this year into a copy of 2010, worse even, with extent and area numbers approaching the long-term averages. Whether the situation remains like this, or whether trend lines start falling of a cliff like they did in 2010, is the first big question of the melting season.

Without further ado, let's have a look at the numbers.

Sea Ice Area (SIA)

Here's the current SIA graph based on CT data:

The 2012 trend line is clearly jutting out. SIA had been going down very hard in the first week of April, but since then we have seen a substantial slowdown, with lots of days of SIA increase. The numbers make it more than clear that 2012 is behind all the other years in the 2005-2012 period, and thus 8th out of 8 years.

The current difference between 2012 and the other years is as follows:

Novaya Zemlya April 2012

It's time to have another look at the region surrounding Novaya Zemlya, and see how the current situation compares to previous years, as the situation in the Kara and Barentsz Seas has been mightily intriguing this year. In the western Kara Sea, the basin between Novaya Zemlya and the Siberian coast, we saw a very early retreat, that except for last year has been unparalleled. Just like last year it froze over again when the winds turned, opened up again around the start of the month, and is yet again closing (see animation below), probably for the last time, with solar radiation coming into play now.

Here's the comparison with previous years, based as always on images from the Uni Bremen sea ice concentration map archive:

Things are looking much more 'normal' than they did over a month ago, except for the Barentsz Sea that seems to have reached an all-time low this year. As already mentioned the western Kara Sea has frozen up again. Not completely, but the difference with many other years is negligible. Another big difference is how the edge of the ice pack, under the influence of a persistent and large high pressure system over the central Arctic, has moved southwards in the past couple of weeks, enveloping both Svalbard and Franz Josef Land. That's quite a difference with the situation a little over a month ago, when both Svalbard and Novaya Zemlya looked circumnavigable on the LANCE-MODIS satellite images for a day or two:

Another source of info on MYI

Just when you thought you knew it all, someone shows up with something new. That someone is Bob Wallace commenting in the latest post on CT SIA long-term regional graphs. And that something is this website showing the age of Arctic sea ice: Arctic Ice Age.

This website has animations for each month of the past 28 years, based on data provided by James Maslanik and Chuck Fowler, which are also used for the NSIDC March and September analyses of ice age distribution. It's a great tool to compare ice age distributions from year to year, and it even has an animation showing the weekly development of the 'ice year' since the start of the freezing season up to present. The only minor quibble is that this animation is still showing the freezing season starting in 2010.

But I'm definitely not complaining. Just like the CT SIA long-term regional graphs, this is the kind of info that makes it visually crystal clear to even the layest of lay persons what is going on in the Arctic. Thank you for putting this out there.

Good news for polar bears

Recently I wrote a post on Arctic pollution, describing the deposit of toxic mercury through bromine 'explosions'. This subject utterly depresses me. But luckily it isn't all doom and gloom for the polar bears, at least with regards to pollution.

Apparently the concentration of PCBs and other industrial poisons in polar bears has gone down in the past decade. CFKs, PCBs have been or are being reduced, maybe GHGs are next? Because accumulating poisons is one thing, but loss of Arctic sea ice is even more dangerous for polar bears and many other creatures (such as homo sapiens).

From the Alaska Dispatch:

Long-term regional graphs

The good people of the Polar Research Group at the University of Illinois at Urbana-Champaign that produce the Cryosphere Today webpage, a monolith in the collective consciousness of Arctic aficionados, have yet again done something great by adding long-term SIA anomaly graphs - spanning the 1979-present period - to their regional graphs. This will make it so much easier to put events into perspective.

Here for instance is the graph for the largest region, the Arctic Basin:And the graphs for this year's mega-extremes, the Bering and Barentsz Seas:

PIOMAS April 2012

Another month has passed and so here is the updated Arctic sea ice volume graph as calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) at the Polar Science Center:

Still on a par with last year.

Wipneus produces many excellent PIOMAS graphs. I'll start with his latest creation, the graph for which he calculated the "expected" 2012 values, based on the same date values of 1979-2011 and an exponential trend. A caveat from Wipneus: "Note that the (not indicated) statistical error bars are quite large."

As a bonus I have finally come round to making a new graph, one that very crudely shows average ice thickness across the Arctic, by simply dividing the PIOMAS volume numbers (km3) by the Cryosphere Today area numbers (km2), and multiplying them by 1000 to get the average thickness in meters:

NSIDC Arctic sea ice news April 2012

Interesting bits from the NSIDC monthly analysis:

Arctic sea ice enters the spring melt season

Arctic sea ice reached its annual maximum extent on March 18, after reaching an initial peak early in the month and declining briefly. Ice extent for the month as a whole was higher than in recent years, but still below average.

As the melt season begins, researchers look at a variety of factors that may contribute to summer ice melt. While the maximum extent occurred slightly later than average, the new ice growth is very thin and likely to melt quickly. Ice age data indicate that despite the higher extent compared to recent years, the winter sea ice continues to be dominated by younger and thinner sea ice.