Historical Minimum in Sea Ice Extent

The Arctic sea ice extent index calculated by a University of Bremen research team led by Dr. Georg Heygster reached a new historical low point of 4.24 million km² on September 8. The previous one-day minimum was 4.27 million km² on September 17, 2007 (Figure 1). The usual melt season is not yet over, however, so 2011 extent could decline further. All three graphs in this post will be updated through the end of the season.

 

Figure 1

The Uni Bremen sea ice index goes back only to the start of satellite observations in 1972, but the researchers suggest that ice cover may not have been this low for thousands of years before that.

A few days ago, September 6, the Arctic sea ice cover area index published by Cryosphere Today reached an historical low point as well (Figure 2).

 
Figure 2

A third index, estimated Arctic sea ice volume (from the PIOMAS team at University of Washington group) had already passed record lows by late August (Figure 3).

 
Figure 3

The Uni Bremen researchers announced the new ice extent minimum in a press release (in German). An English translation of the text, provided by Dr. Heygster, appears below (or go here for a version with graphics).

Arctic sea ice extent small as never before

 Alerting message from the Arctic: The extent the the Arctic sea ice has reached on Sep. 8 with 4.240 million km2 a new historic minimum. Physicists of the University of Bremen now confirm the apprehension existing since July 2011 that the ice melt in the Arctic could further proceed and even exceed the previous historic minimum of 2007. It seems to be clear that this is a further consequence of the man-made global warming with global consequences. Directly, the livehood of small animals, algae, fishes and mammals like polar bears and seals is more and more reduced.

The work group of Georg Heygster at the University of Bremen observes since many years the the sea ice at both poles. With the support of the ESA/GMES project Polar View, daily maps  of the sea ice extent are publicly provided at  http://www.iup.uni-bremen.de/seaice/amsr/. The retreat of the summerly sea ice since 1972 amount to 50%. For algae and small animals living at the lower side of the ice, less and less living environment remains since they need a certain time to settle there. They are at the beginning of the food chain for fishes, mammals and also man.

The extent of the Arctic sea ice shows a pronounced yearly cycle, with about 15 million km2 in March and five million km2 in September. In 2007 however, it was only 4.267 million km2, the previous smallest value since start of satellite observations in 1972, and most probably since the last climate optimum about 8000 years ago. The current value is 27,000 km2 or 0.6% lower and could even be undercut in the next weeks. The ice maps of the University of Bremen show also that in this year, the Northwest and Northeast passages are simultaneously ice free. This had happed for the first time in 2008, and in 2009 the German shipping company Beluga has traveled it commercially for the first time. Recently, it was crossed in the record time of 8 days only by a tanker, traveling from Huston, Texas to Map Ta Phut, Thailand.

Already in July the new record minimum had been expected because in this month the sea ice extent was minimum, compared with the same month in other years. Due to the high sun elevation and long days in July, the sea ice extent in this period is climatologically more important than that of September. The increased insolation into the open water heat it up, leading to an additional sea ice melt from the bottom and delays formation of new ice in autumn. Moreover, the sea ice retreat can no more be explained with the natural variability from one year to the next, caused e.g. by weather influence. Climate models show rather, that the reduction is related  to the man-made global warming which, due to the ice albedo effect, is particular pronounced in the Arctic: an ice area melted by a small temperature increase will then as open water have a much darker surface, absorb more solar radiation as before which causes an additional heating.

In contrast to the minimum in September, the yearly maximum in March decreases less (Figure 3): despite the reduced in in summer, in winter large areas of the arctic ocean freeze up. However, this first-year ice is clearly thinner than multiyear ice having survived one summer. Therefore, in summer first-year ice melts much easier than multiyear ice and after a historic minimum, the ice cover needs even in an unchanged climate several year to fully recover. Observation of the last years show further, that the sea ice thickness reduces, so that the total mass of Arctic sea ice decreases even more drastically than the sea ice extent.

The daily sea ice maps of the University of Bremen are based on observations of the Japanese microwave sensor AMSR-E, in orbit on board the NASA spacecraft Aqua. The institute receives the data from two servers in the US and Japan and produces the maps based on these observations.

Comments

[Lord Soth]

To put proper perspective on this, we can now say that Sea Ice Area, Volume and extent are statistically the same as 2007.

So depending on how you count pixels, you are going to get numbers above and below 2007.

It would be nice to get signicantly more melt, to say that 2011 is statistically the winner, but im not sure if this is going to happen.

Things were a lot easier in 2007, when we knew by early August that the 2005 record was toast.

[L. Hamilton]

Volume for sure is below 2007. I think it's likely that extent will fall further too, but we'll soon find out.

[dorlomin]

In May 2007, if you have been laughed at and belittled across the blogosphere for suggesting something like a 20% drop in sea ice extent in the near term. Today those same people will try to dismiss this as nothing to worry about.

The unimaginable has become the mundane.

[AmbiValent]

Lord Soth: Area and extent may be similar, but according to PIOMAS, volume is just 2/3 of the 2007 value. In other words, the ice lost 1/3 of its thickness.

(Almost all of this loss actually happened last year, when the deniers claimed the lack of a new area or extent minimum meant the ice was "recovering")

[Kevin O'Neill]

I've thought for sometime that 2007 wasn't an anomaly - that it ushered in a new ice regime. The extent and area charts reinforce the idea that a step-change occurred.

Chris R's Dosbat blog http://dosbat.blogspot.com/ led me to play around with the NCEP/NCAR Reanalysis package. I was running the same graphs for pre and post-2007 and ran into something that makes no sense to me. I'm sure it's because I have no idea what I'm looking at, but the pre and post 2007 differences are striking.

http://s256.photobucket.com/albums/hh197/ktonine/?action=view&current=potentialtemp2000s.jpg

These are the potential temperature cross-sections from 157E to 238E and 72N to the pole; This quadrant is basically centered on the Bering Strait so it includes most of the East Siberian Sea, the Chukchi, and the westernmost Beaufort. These are seas that now routinely see open water during large portions of the melt season.

I'm at a loss trying to explain these graphs. The winter months don't show any obvious pattern, but once the sun comes up we get these large negative anomalies below 300mb for the post-2007 years. It's also interesting that the vertical profile for March-May seems centered on 80N. Coincidentally, that's where much of the ice edge will reside in August and September.

Anyone have a clue what I'm looking at?

[Kevin O'Neill]

I should add that I understand what potential temperature is - and in fact the air temperature graphs are essentially identical to the potential temperature.

I'm just at a loss trying to figure out the process that leads to negative air temperature anomalies throughout the melt season post-2007 as opposed to pre-2007.

[Peter Ellis]

Hmm, so the upper atmosphere is cooler? Could this simply be a reflection of, well, reflection? If the sea's absorbing more heat, then less of it is being bounced back up to the higher layers of the atmosphere?

[Lord Soth]

AmbiValent

Sorry, what I wanted to say is that our current 2011 minimun extent and area is statistically the same as 2007, and the current volume is statistically the same as 2010.

However the net effect is: the ice is in the worst shape it has ever been, for thousands of year.

[Kevin O'Neill]

Peter, the pattern emerges in March when everything is pretty much covered in ice. This is pretty high up (20,000 - 30,000 ft?). There had to be a shift in upper atmosphere circulation or ????

[Neven]

Kevin O'Neill, maybe Wayne Davidson can help you out.

[Kevin O'Neill]

Peter, I think you're at least half right. Stratospheric cooling is a signature of global warming. So it's probably due to reduced reflection - but probably due to GHG not the seas. I still find it odd that it's so pronounced pre and post-2007 given what we see in extent and area.

[Ned Ward]

Completely off-topic, but there's no "open thread" and this is kind of cool:

Greenpeace's humongous North Pole ad

The organization got artist John Quigley to partially recreate da Vinci's Vitruvian Man on a melting ice pack near the Pole.

[Bfraser]

Once again this year, I have analyzed the TOPAZ pixel data and come up with an estimate of minima for the year:

4.367 Sept 3 Extent

2.825 Sept 1 Area

3.364 Sept 6 Volume

[Bfraser]

Oh, I forgot to mention, that this is based on their run on 9/7, so there could easily be changes next Wednesday....

[Steve Bloom]

The da Vinci reference is cool. but for maximum impact I would have gone with a profile of the Wicked Witch of the West.

[Paul Klemencic]

I have taken a picture of a graph of various SIEs and date adjusted reported values from my spreadsheet and put it on google docs. The estimated Bremen extents are there, as hollow points, with some reports from Larry and Bremen themselves in solid points.

Comparing SIE data

[Twemoran]

Paul - Don't know if it would help or hurt your case, but at arcticio under zooms is a section with daily radar imaging that gets under the clouds.

[L. Hamilton]

Paul, that's an impressive effort. I'm still agnostic on the issue of time lags, but very interested in your efforts comparing the different time series to each other and to maps.

One impression from watching the UB data is that unsmoothed daily values can be noisy, so the variations are not all physical.

[Andrew Xnn]

With so much exposed water in the arctic, there will likely be an exceptional amount of ice forming this winter. Of course, even if as much ice formed during the winter of 2007/8, since volume is <2007, 2012 is unlikely to be as much a recovery year as 2008.

[Bob Wallace]

Andrew, is there any data supporting large extent or volume refreezes following big melt years?

Eyeballing the Arctic Sea Ice Extent and Volume graphs on this page I don't see a relationship between hard melt and hard refreeze. Most of the time the deepest summer drops seem to be followed by rather typical freezes. 2008 popped up a little higher, but not high in terms of what had been happening historically.

2006 max volume was lower than normal which, I would guess, set up the 2007 melt. The refreeze while larger than 2006 is pretty much in line with 2004 and 2005.

It all looks like variation around a declining mean to me....

[Kevin O'Neill]

Bob -

Looking at annual volume loss and the following winter's volume increase, Excel gives me a correlation coefficient of .55 for the entire PIOMAS dataset (1979 - 2010). The last ten years are slightly higher at .61

I interpret that to mean: as more ice is lost, more ice is created.

[Bob Wallace]

Thanks, Kevin.

Looking closely at the extent sinusoidal graph it does look like the first months following a deep melt do show quicker extent growth.

So, this would suggest perhaps a dampening factor on the route to a full meltout. Whether this is a strong enough effect to actually prevent a meltout is questionable.

It seems that rising atmospheric and ocean temperatures would override at some point. I suppose seeing a slowing of volume loss would be a clue.

[Christoffer Ladstein]

And less ice in the Arctic lead to a change in the albedo, which at least in a decade or 3 will lead to a Hotter World; see the attached article, just released:
http://www.agu.org/pubs/crossref/2011/2011JD015804.shtml

Feedbackmechanism will most likely be more clouds when ice is gone, hencefort less albedo, but so much is still in the land of uncertainity!

[Russell McKane]

It's a petty Champaigne is powered by carbon Dioxide. Ironic really for this is no real cause to celebrate. I am still following daily this post , there has been too much to digest to get time to post much, but the prediction provided by ti2 as posted in "an observers prediction" is running very close. I'm not talking stats here guys, but shape with the exception of siberian sea slushies prediction is spot on if not a bit concervative, More eat out in the greenland sea than I drew, I should have followed the image more. What will happen to the East Siberian is yet to play out. I will post some final comparisons once we get a minimum. Then I want to spend some time working on issues Paul rightly raised.
Russell

[Christoffer Ladstein]

For those earlier in the season questioning Børge Ouslands whereabouts, I just came across a scientific article based upon his snowdepth observations crossing the North Pole at several occasions, written by S. Gerland & Christian Haas:
http://www.igsoc.org/annals/v52/57/a57A212.pdf

[Phil263]

Thanks Christopher. I was the one who enquired about Borge Ousland whereabouts.

[Russell McKane]

I just checked out ocean temperature on Polar view comparing Sept nine 2011

http://i1111.photobucket.com/albums/h470/treformpainter/Global%20warming/OceanTemp20119Sept.jpg

With Sept 10 2007 (sept 9 not available)

http://i1111.photobucket.com/albums/h470/treformpainter/Global%20warming/OceanTemp200710Sept.jpg

There is a lot of heat left in the ocean compared to same time 2007 so we could assume that there is a bit more melt to go. Whether this amounts to extent loss could depend a lot on what that strong SLP over the central arctic does at the moment. BUt the freeze back surely won't start for a while yet.

(hope those photobuckets work -it;s the first tim I've used it)

[r w Langford]

Russell; I checked out the Polar View site but cannot find the way to the ocean temperature graphs. This looks like a great source of info for us. Can you tell me where to look to access this ocean temperature information on their site?
Thanks

[HenkL]

Some ice will be on the move today.
Research vessel Polarstern (84°36'N 149°54'E, 15Z) measured winds of 8 Bft (35 kt) from the North. Pressure 990 hPa, temperature -3,6°C, temperature water -1,0°C.

[Andrew Xnn]

Here is some data on km3 of arctic sea ice that formed and melted for the various years. I'm sure these numbers could be updated with 2011 data and the newest satellite models. However, the trend towards more ice melting and forming each year suggest that they are linked and I believe most physic based models for arctic sea ice recognize this phenomena as well.

Year Formed Melt
1979 15540
1980 14693 14733
1981 13282 15830
1982 14801 14631
1983 15332 14340
1984 14486 15250
1985 15612 15471
1986 15390 13709
1987 14825 15055
1988 14827 15140
1989 14101 15568
1990 14304 15340
1991 16160 16145
1992 15222 13843
1993 14137 16547
1994 15945 15707
1995 13369 15591
1996 15653 12887
1997 14315 14988
1998 15888 16734
1999 15995 16344
2000 15167 15282
2001 15140 14406
2002 14222 15910
2003 14924 15647
2004 14475 14971
2005 14899 15097
2006 14545 14836
2007 13024 16659
2008 16960 16776
2009 15588 16150
2010 15467 17246

[Pete Mason]

The NSIDC chart today is disapointing http://nsidc.org/data/seaice_index/images/daily_images/N_stddev_timeseries.png

Does anyone do a chart of charts - an average of the various observations? How significant are the NSIDC observations compared to the Bremen ones? Are there any other significant daily studies?

[Andrew Xnn]

A little more about the melt vs formation data:

It appears that on average there is an increase in melt of about 38 km3 every year.
There also appears to be on average an increase in formation of about 15 km3 every year.

The additional formation is about 40% of the melt.

[Bob Wallace]

Thanks for that data Andrew.

I rearranged it to show annual melt followed by annual freeze and then sorted on melt.

What I found is that for the ten largest melt seasons the ice recovered less than what was lost 9 out of 10 years. The average recovery was 94%.

For the ten least melt years the following freeze was about the same as the loss (101%). The middle years fell in the middle (98%).

While heat might be quickly lost and some initial freezing might happen quicker it looks like the total amount of freezing might be a function of climatic conditions during the winter.

I suspect we're paying a lot of attention to September ice levels and not enough to April. I'm guessing that regardless of how much it melts in the summer the climatic conditions that exist over winter control the amount of ice present when the melt starts.

Then as atmosphere and oceans warm the April volume is dialed down.

Strip all the ice off of the surface and while initial freezing might be accelerated, if there aren't conditions in the winter to make more ice than is typically melted off, the next summer will melt it all. I don't see a high melt 'superball' effect.

(Half cup of coffee post. Have your way with it....)

[Bob Wallace]

BTW, the only year of the big melt ten in which more ice formed than was melted was 2007.

One might guess (I'm guessing) that 2007 was a freak melt year (as Neven talks about in his #20) and the ice just snapped back to the average winter range.

[maltose]

Extent for U Bremen had another drop for Sept. 10th. Can anyone take a ruler to the graph to see what the new record is? Thanks.

[Kevin O'Neill]

Neven - thanks for referring me to Wayne Davidson with my stratospheric cooling questions. He's taken the time to answer a couple of my questions.

http://eh2r.blogspot.com/2011/06/arctic-ocean-sea-ice-holding-by-veil-of.html

[Russell McKane]

r w Langford
Can you tell me where to look to access this ocean temperature information on their site?
Sorry keep forgetting this site is new for most of you. The interactive archive is available at
http://www.seaice.dk/test.N/
It runs on Java so is difficult to grab images unless you go the print screen / photoshop route.
The ocean temperature maps are amsr.n.To which can be accessed from the top drop down menu.

At the Bottom is a user manual link which gives more detail on what the main men options are or mean.

ON the right is a second menu which allows you to Overlay every thing from ice drift to satalite passes Use toggle and colourize to control data. ( experiment with this one its rich in help.) Ie I am using it to give exact LAT LONG grid so I can map the Heally trip with the images they took while overlayed on an Ice concentration graphic. {Hope to have this out after the minimum is passed - good education for next year :) }.

By the way if you change the N in the URL (test.N) with an S you get the same for Antarctica.
Hope this helps and enjoy the play.
Russell

[Pete Dunkelberg]

Maltose, too late. Bremen is up again.
http://iup.physik.uni-bremen.de:8084/amsr/ice_ext_n.png

[Chris Biscan]

I got Bremen with a 1/64th per inch measuring system in photoshop using the graph markers directly centering the marker lines.

at 4,175,000km2 (+/- 10,000km2

and NSIDC at 4,245,000km2

Jaxa won't come close for many reasons..Id love if Neven would let me write a guest blog post on it.

I would like to write the blog post on why the min's are so much different for the first time using AMSR-E.

after 30-40 hours of research Iv'e learned a ton about it. And I would take A mix of Bremen and NSIDC year as the min extent and Jaxa needs to be thrown out and look into making a mirror verson with the ASI version but 12.5km2 grids.

I could shed some amazing light on this.

I might write a post tonight about it. Let me know Neven

[maltose]

Thanks Chris and Pete. It seems Bremen updated early.

[Bob Wallace]

Neven's email is up in the right hand corner.

Cobble together a rough draft/idea paragraph and send it to him.

[Twemoran]

Believe Ward-Hunt is now West Ward-Hunt & East Ward-Hunt

The sliver of ice holding it together looks like it finally headed north, possibly due to the last spring tide of the season.

http://lance-modis.eosdis.nasa.gov/imagery/subsets/?subset=Arctic_r03c03.2011253.terra.250m

Too late to have much effect this year, but next year with only FYI bonding them to each other either or both remaining fragments could be history.

[Russell McKane]

Twemoran - Image you posted is not of Ward Hunt but of the ice on East Greenland Fram straight, land fast ice from recent comments. Ward Hunt is Noth and west of his image.

[Russell McKane]

Opps, Sorry it is there - lost it in the cloud. I like its new shape now - reminds me of a Snow leapard on the hunt - or perhaps a polar bear mid leap.

[Neven]

Jaxa won't come close for many reasons..Id love if Neven would let me write a guest blog post on it.

Chris, my mail address is in the menu bar. TypePad doesn't tell me your mail address.

[Ned Ward]

Paul K. writes: I have taken a picture of a graph of various SIEs and date adjusted reported values from my spreadsheet and put it on google docs. The estimated Bremen extents are there, as hollow points, with some reports from Larry and Bremen themselves in solid points.

Hi, Paul. Nice work ... but where do the "estimated Bremen extents" come from? Just curious.

[Michael Fliss]

Twemoran, when you mention the "sliver of ice" are you speaking of the ice just north of Ward Hunt Island? Are you saying that soon the Ward Hunt Ice Shelf will fracture and separate from its grounding line?
Considering how quickly the epishelf lake drained in 2002, change can occur in a very short time. I was looking at images of this ice shelf from 2002, 2010, and 2011 day 239 and the ice shelf to the west of Ward Hunt Island looks similar in all 3 and similar to the image from day 253.

http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=45463

http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r03c03.2011239.terra.250m&vectors=none

[Twemoran]

Michael - The 'sliver' I was referencing was a narrow spit of ice south of Ward Hunt Island that had been joining the fast ice west of the island to that east of the island.

The latest iteration of photo seems to have a small cloud obscuring the area, but I can assure you that when I accessed it clear water could be seen across the fjord.

I'm not sure what effect loosing this thin, bridging piece will have, but feel that anything acting to support either section would buttress both against the forces acting to break them up. The smaller section east of the island might be particularly susceptible to tidal action during the next melt season.

[Michael Fliss]

Twemoran, thanks for your observations. The Ward Hunt, as have the Ayles and Markham, will cease to exist, sooner than later. The fractures are deep and the fresh water from the epishelf lake is no longer there to add ice to the bottom of the shelf. It will exist as icebergs in the beaufort to intimidate the oil interests.

[Espen]

Twemoran and Michael,

We have a situation similar up between the Petermann and Humboldt glaciers, some big lakes are now seen in the area.
http://ocean.dmi.dk/arctic/image_container.php
Espen

[Espen]

Humboldt / Petermann
Something wrong with that link above here is a new:
http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r03c03.2011253.aqua.250m

[L. Hamilton]

Small drop in CT area, to a new slightly lower minimum: 2.9047396

Graph updated but it looks the same.

[Seke Rob]

Larry,

In my own chart, I've printed the data labels for 2007+2007 in red and 3 decimals ;>)

The YTD average sea ice area keeps falling. Through Sep 10 it's -1.233 million sqkm, where 2007 continues to lack by the 70K it's been meandering on, i.e. -1.163 for first 253 days of the year.

As I posted in the 1st up-tick thread, on a lighter note, this than makes it the 9th day of sub 3M, where 2007 had 15, the last on September 19.

[Seke Rob]

Fun with statistics [for popcorn lovers], Antarctica just lost a near century at CT (95K), the Global at -2.296 million [See Chart]. Nearly 2K short of beating 2007 on the 365 rolling mean. Look at that serrated blade which 2011 turns out to be during the boreal summer of our planet.

[L. Hamilton]

SR, your global graphic is much more entertaining than mine. I've been occasionally tracking global anomalies for just two years, 2007 (previous minimum) & 2011, like so:

http://img.photobucket.com/albums/v224/Chiloe/Climate/sea_ice_CTglobal_anom_2007_2011.png

[Twemoran]

Espen - I've been watching those lakes for some time, and they do appear larger than in past years.
Any idea on what effect they might have on Humboldt?
Could a drainage cause sub-glacial lubrication that would speed the advance, or would outflow cause the northern edge of the glacier to melt away from the rock face?

[Twemoran]

I've been trying to get data on the age of the (former) ice bridge between Kronepins Christian Land and Perry Land.

Patrick last year said "If the shorefast ice north of Flade Isblink lasts into the winter, it will be the oldest ice on Greenland's shores: a mix of old bergs, and ice up to about 5 years old."
I've found no indication that it has ever been seen to be open, although most sources seem to refer to it as "usually frozen"

The earliest reference I've come across was a 1952 traverse by foot between Prinsesse Thyras and Prinsesse Margrethes Islands. They found the distinct undulating surface found on Ellesmere Island ice shelves in the more southerly half of their trek while the northern parts were described as flat.

Although flights must have regularly approach this area going and coming from Nord I've yet to find a photo or description of the area in it's present state.

The bergs that recently calved seem to my aged eyes to show a three dimensional character which if true might indicate rather extreme age.

http://ocean.dmi.dk/arctic/image_container.php

Any help in resolving this one way or the other is appreciated.

[Espen]

Twemoran

Yes they are certainly getting big those "lakes" or "inland fjords" of north west greenland, much bigger than ever before, whether they will flush down the petermann slope or the humboldt remains to be seen. The area flade isblink was open before but the remaining shore ice on the Nes or Cap is living its last days.

[Daniel Bailey]

@ Twemoran

"Could a drainage cause sub-glacial lubrication that would speed the advance"

Short answer: perhaps some. Significantly? Probably not.

Discussion here (Zwally Effect).

The Humboldt doesn't have a bedding grade that would lend itself to sudden surges (see above link), unlike the traditional monsters of Petermann, Zachariae or Jakobshavn (more discussion of that here).

[Twemoran]

Espen

You are correct - I found an image from August 31 2002 posted by Patrick Lockerby in Science 2.0 that shows the channel north of Flade Isblink not only open, but with much less ice than this year.

Thanks for pointing me in the right direction.