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Aaron Lewis

While 2012 did not make record minimum thickness, I fear that ice quality is poor. At this point, I expect that the ice is more fractured, warmer, and weaker than in previous years.

idunno

Looking at the second graph, it seems that the actual values are fairly consistently to the left of the predicted values (lower in Spring, higher in Fall).

I know Chris R (dosbat, link left margin) has been exploring the collapse in PIOMAS volume in late Spring.

Wonder if there is any better fit than the "exponential trend" delineated by the dotted lines in graph 2?

Arne Perschel

In an earlier post I read that the CT area data pointed out that 2012 has broken some 140 daily records. Can anyone tell me how many daily records have been broken on the PIOMAS graph this year? The lines are so distinctly lower each year than the previous that it seems we are almost approaching full 365-day homeruns.
Also it might be interesting to publicly talk about the percentage that is lost each year relative to the previous.
From this graph http://img.photobucket.com/albums/v224/Chiloe/12_Climate/sea_ice_PIOMAS_min.png for example, one can read that we've seen a 17,5% drop this year. That's like Usain Bolt running the 100m dash in 9,58s one year and in 7,90s the next year.

Wipneus

Aaron: 2012 did not make record minimum thickness

Indeed, the decline in volume is entirely due to the decline in area/extent.

What is more, thickness has not changed very much after the huge decline in 2010. Years 2010, 2011 and 2012 have very similar thickness at the end of summer.

So did thickness hit a plateau? If so, when volume keeps falling, we can expect again record low area/extent in 2013.

Allow me to sketch the possibilities under the assumption that thickness does not drop:
For CT area 1.9 Mm2 and NSIDC September extent 3.0 Mm2 when volume drops slightly (2700 km3).
When the volume follows the exponential extrapolation (<2000 km3), the values for CT area and NSIDC extent could be 1.4 Mm2 and 2.2 Mm2

Of course between now and 2013 thickness may decrease and/or volume decline may halt. I cannot see any indication of either yet.

If the negative feedbacks still want to kick in, it is high time they do.

Wipneus

idunno: Looking at the second graph, it seems that the actual values are fairly consistently to the left of the predicted values (lower in Spring, higher in Fall).

Interesting way to look at that.
Remember though that PIOMAS comes with uncertainties. Those are estimated bigger than the differences you observe. IOW, they may be entirely in the non real, modeling world.

Glenn Tamblyn

The PIOMAS anomaly graph is declining in usefulness. Their algorithm for removing the seasonal cycle is being overwhelmedby the larger swings in the seasonal cycle in the last few years.

Simple take-home from all of this comes from Wipneus' trend graphs. We are totally on track for an effectively ice free late summer Arctic within 2-4 years, depending on local weather conditions in any one year. I say effectively because there will probably be a refuge north of Greenland & Ellesmere that might hold out for several years.

Perhaps a useful metric of 'an ice free Arctic' is ice free everywhere except x kilometers north of Greenland & Ellesmere.Or perhaps simply an effectively ice free Arctic is one where the North Poleis ice free.

2013, 2014? Depends on the weather each year.

You have to have some sympathy for the guys working in Sea Ice modelling. Still a newish field, but it is evolving faster than their research can keep up with it. Modellers in other fields like Atmospheric or Oceans don't have to cope with modelling the oceans boiling dry or the atmosphere blowing away. But the Sea Ice guys need to model the terminal phase of the very thing they are modelling.

Jim Williams

Hi Glenn. I think the definition of "essentially ice free" people have been using is less than 1 million square kilometers.

LRC

"What is more, thickness has not changed very much after the huge decline in 2010. Years 2010, 2011 and 2012 have very similar thickness at the end of summer."
The thickness may not be changing, BUT the quality of that thickness is getting much worse.
When a light weight ice breaker can break a 10m ice floe we really have to redefine thickness and also find out how those ice floes are influencing the condition of the water.
Ignoring the fact of quality is just as bad as ignore the fact of loss of ice IMO.

idunno

Hi all,

A new website, run by some part of the Dutch government, apparently...

http://www.climatedialogue.org/

...kicks off with a discussion of Arctic Sea Ice, with essays from Walt Meier, Ron Lindsay and Judith Curry.

Neven

Indeed, idunno. I've just finished a blog post about it.

wayne

Idunno

Judith Curry's Sea ice dissertation is amongst the worst ones I have ever read. She has a good grasp of the basics, and then really screws up the prognosis and projections.

First off the transpolar current really is nearly a constant, so exiting sea ice through Fram Strait over the last 20 years is a non news event, it will happen whether the AO is positive or Negative. Long term Animations seen here on Neven's site show that. The latest key shrill dismissive, the famous storm of early August 2012 is a non issue as well,

Here is Julienne Stroeve a real ice expert:

"Julienne Stroeve says:

August 27, 2012 at 12:32 pm

Theo, we don’t have the data/analysis in at this point to say exactly what the storm did (i.e. what sizes of floes did it break the ice-pack up into, what were the SSTs, how far were the ice floes transported, how much thick the ice was when it was broken up, how much melt happened as the ice pack spread out, etc. etc. What we do know is that the winter ice was thinner than last winter (from Cryosat) and that immediately after the storm, ice concentrations were already low in that region prior to the storm, and SSTs were colder than normal immediately after the storm, with warm water below. Then the SSTs increased later in the month.
I can’t quite understand the desire to ignore the fact that the ice is thin and prone to melting out. If you remember, 2002 was dominated by cyclones all summer. So why didn’t all those storms result in ice extent below 5 million sq-km?"

A CT comparison makes the storm result not impressive:

http://igloo.atmos.uiuc.edu/cgi-bin/test/print.sh?fm=08&fd=02&fy=2012&sm=08&sd=06&sy=2012

The CT threshold for ice was different than NASA,

Now pause on August 2 on this NASA animation:

http://www.youtube.com/watch?feature=player_embedded&v=9Gsr1503TNg

So on one hand the storm caused open water (NASA), while CT shows open water where NASA didn't have.

Case closed, enough written, Judith Curry is some sort of representative for the contrarians, she jumped tribes, from the science one, to the pre 19th hysterical superstitious gang.
What she offers is not a dialogue but a slanted contrarian propaganda piece.

Doomcomessoon

When speaking about ice volume. Does anyone of you guys know about some recently updated volume measurements from other significant ice caps, like the greenlandic or antarctic ones?

I have been searching a litle bit one the internet, but I can't uncover any data from after 2009. Taken in consideration my relatively poor googling skills, I do still believe that there is some recently updated data form gravity field measuring satelites (like the GRACE satellites) or something similar out there. Especially data giving a more detailed picture of the greenlandic ice volume. Does anyone have a link.

crandles

Total ice sheet mass loss in 2011 was 70% larger than the 2003-09 average annual loss rate of -250 Gt y-1. According to satellite gravity data obtained since 2002, ice sheet mass loss is accelerating.

Per Arctic report card:
http://www.arctic.noaa.gov/reportcard/greenland_ice_sheet.html

crandles

The detail later is:

GRACE satellite gravity solutions (Velicogna and Wahr 2006) are used to estimate monthly changes in the total mass of the Greenland ice sheet (Fig. HTC19). From the end of April 2010 through the end of April 2011, which roughly corresponds to the period between the beginning of the 2010 and 2011 melt seasons, the ice sheet cumulative loss was -430 Gt, 70% (or 2 standard deviations) larger than the 2003-09 average annual loss rate of -250 Gt y-1. This 2010/2011 mass loss is equivalent to a eustatic sea level rise contribution of 1.1 mm, and is the largest annual loss rate for Greenland in the GRACE record (2002-present), 180 Gt more negative than the 2003-09 average. 2005-2006 had almost as much mass loss as 2010-2011, when evaluated between April/May points. Using GRACE data, Rignot et al. (2011) find an acceleration of Greenland ice sheet mass budget deficit during 1979-2010, in close agreement with an independent mass balance model.

Fig HTC19 shows monthly unsmoothed values to end of 2011.

John Christensen

Hi Neven,

Considering the unprecedented melting this year (to say the least), I was amazed to see this graph: http://ocean.dmi.dk/arctic/meant80n.uk.php
(Danish-based DMI has lots of amazing stuff..)
What I find amazing here, is that it appears that from mid-April to mid-August the mean Arctic temperature was pretty much on average the whole time.
However, during the winter and also since mid-August, temperatures have been considerably above normal, which would be expected due to lack of sea ice and therefore increased heat exchange.
From an amateur perspective, it therefore seems like the melting this year was caused by lack of sea ice built up during the winter (and generally lack of sea ice from prior years, rather than warm weather during spring or summer. The storm and other things played in as well, but what is up with the lack of excessive summer heat and the melting?? Please help me understand.
Thanks!

Neven

Hi John,

Yeah, DMI has some of the best maps out there (I use them a lot).

Some points concerning your question:

1) Those aren't actual measurements, but modeled data. Still very useful, of course.
2) It's temps above 80N (not the whole Arctic).
3) Much of this area remains ice-covered all the way to the minimum (see here). Now as long as there's ice there, temps can't get much above 0, because warm air gets cooled off by the ice.

That's basically it. As soon as the area above 80N starts melting early in the melting season, say June or July, you will see the temperature trend make the same erratic up and down movement you see during the rest of the year.

John Christensen

Hi Neven,

Thank you for the quick response.

I can understand that when the temperature is at maximum at 272-273K/0C, it will not change due to the energy release from the melting ice, but I am more surprised to see that by mid-April the temperature is at normal, which is 255K/-18C/0F and far from melting point, and then follows the average mean temperature based on 1958-2002 data onwards to end-May, indicating that central Arctic air was not warm at all in the period where CT reached almost an overall low on SIA for day 150. When increased heat influx was breaking up the ice everywhere else at a record speed, why didn't it show in the central Arctic mean temperature, or is this model just not capable of showing that?

Thanks again.

Misfratz.wordpress.com

Glenn

You have to have some sympathy for the guys working in Sea Ice modelling. Still a newish field... need to model the terminal phase of the very thing they are modelling.

On the other hand, this provides a massive opportunity for young scientists to make a name for themselves, so it would be a pretty exciting time to work on sea-ice modelling.

Also, while we look to be quite close to an effectively complete melt-out in September, the sea-ice will still come back during the long polar night for many years to come. I don't know how much the Arctic would have to warm for the Arctic ocean to store enough heat to prevent sea-ice formation over the winter, but I would guess at a very large amount.

Thus the focus of sea-ice modelling will switch pretty quickly to forecasting the timing of the opening and closing of the major shipping routes, rather than the annual minimum (which will in the relatively near future always be close to zero).

This sort of transition was one of the reasons given for the mooted (but now aborted) merger between the British Antarctic Survey and some other NERC research institute (was it NOC?).

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