Polar Ice Extent

[Gray-Wolf]

Hi Guy's! Sat in Welsh Wales at the moment (Dinas Cross, just outside Fishguard) so I'm a bit limited in my 'Arctic resources but ,suffice to say, I feel this is the year the thin/rotten ice will begin to show it's hand (my judgment) so I'd expect a few 'surprises' later on in the season with the rate of 'extent' decline continuing at a faster rate (for longer) than the past recorded autumn declines.

It's as was posted earlier by stew, if 'rapid decline' toward a seasonal pack is occurring then, natural variations aside, you'd expect to see it!

We are at the thin end of the wedge now (Ice mass has been declining for over 100yrs ......apparently) so the opportunity for 07-esque melts should be there in the pack (and enhanced from 07' by the loss of ice mass since) so there is little excuse for not seeing a continued decline in ice mass this year, apart from 'extreme weather' of course, and for this to be reflected in the final 'ice extent' figure.

I think folk would be daft to think of anything other than a 'Top 4' min figure and maybe an 07' type final figure is ,as stew said, to be expected (all things considered)

Edited July 28, 2010 by Gray-Wolf

[BornFromTheVoid]

This thread has gone very quiet recently...

We have had a good example example recently of the difference between counting sea ice area as requiring 15% or greater, as in the IJIS site, and 30% or greater, as with CT. Over the last few days the melt rate on the IJIS site has slowed somewhat, allowing us to move up past 2009, to the 3rd lowest ice extent and closer to average.

At the same time, on the CT site, we have been moving further from average.

This seems to be courtesy of a now very large area (over 1 million km2?) of extremely fragmented ice on the Bering side of the Arctic.

There is now also the chance that over the next week this area will continue to melt rather quickly, as there seems to be a near constant flow of very warm uppers moving in from Eastern Siberia. We could see some very impressive ice area drops over the coming week or so (I imagine) if the forecast is accurate.

Looking further afield into the borderland of FI, high pressure looks like setting up over the Arctic, which could result in wind patterns similar to 2007 and increasing flow out through the Fram strait...

[stewfox]

We have had a good example example recently of the difference between counting sea ice area as requiring 15% or greater, as in the IJIS site, and 30% or greater, as with CT. Over the last few days the melt rate on the IJIS site has slowed somewhat, allowing us to move up past 2009, to the 3rd lowest ice extent and closer to average.

At the same time, on the CT site, we have been moving further from average.

This seems to be courtesy of a now very large area (over 1 million km2?) of extremely fragmented ice on the Bering side of the Arctic.

[

There is now also the chance that over the next week this area will continue to melt rather quickly, as there seems to be a near constant flow of very warm uppers moving in from Eastern Siberia. We could see some very impressive ice area drops over the coming week or so (I imagine) if the forecast is accurate.

I would have thought CT would be a bit ahead of IJIS in picking up a fragmented decline.

To be fair I would expect a 1 million loss in the next 10-15 days as we have seen in most years, although from different starting points of course. Do we get those losses from the Bering side each August I don’t know ?.

I would hope for a levelling out after 2/3 weeks into August , clearly that didn’t happen in 2007 or 2008.

We def on for sub 6km2 and if no levelling out next 2/3 weeks maybe a sub 5km2or below.

Anything under 5km2 and humble pie comes out of the fridge.

Last 6 weeks and everything to play for .

Edited July 30, 2010 by stewfox

[oldsnowywizard]

there is a time delay on CTs figures compared with IJIS, one would expect CT to show less of a decline next week. o degree 2m temps will get more widespread now so its the warm air and wind which will be the major factors for ice melt.

[BornFromTheVoid]

I would have thought CT would be a bit ahead of IJIS in picking up a fragmented decline.

To be fair I would expect a 1 million loss in the next 10-15 days as we have seen in most years, although from different starting points of course. Do we get those losses from the Bering side each August I don’t know ?.

I would hope for a levelling out after 2/3 weeks into August , clearly that didn’t happen in 2007 or 2008.

We def on for sub 6km2 and if no levelling out next 2/3 weeks maybe a sub 5km2or below.

Anything under 5km2 and humble pie comes out of the fridge.

Last 6 weeks and everything to play for .

I dunno if that's normal, I think a 1 millionkm2 loss over the next 15 days would put us half way between 08 and 07 on the IJIS graph, and on CT it would have us below 09's minimum by mid August, so I doubt the loss will be that bad, well I hope it won't be anyway!

As for whether we get that loss every year, I suppose it depends on whether we're comparing with the long term average or recent averages. Going by the long term, we've already lost the entire average summers worth of melt from the East Siberian Sea, Beaufort Sea and the Arctic Basin, and we're only a few 10s of thousands off with Chuckchi and Laptev sea. So anything more is just going to drive it much further from the norm. As for recently, unfortunately the comparison section on CT isn't working at the moment and neither are the archive charts so can't check at the moment.

I take it the guessing off the eventual minimum extent is based of the figures from the IJIS, yeah? Because on CT, we're already well below 5 million and below the average long term minimum extent!

there is a time delay on CTs figures compared with IJIS, one would expect CT to show less of a decline next week. o degree 2m temps will get more widespread now so its the warm air and wind which will be the major factors for ice melt.

What kinda delay is there? They both say 29th July on the sites. Are the images and graphs on CT updated at different times?

[oldsnowywizard]

yep the charts are from memory around 7 days behind.. the images of course are up to date.

[BornFromTheVoid]

yep the charts are from memory around 7 days behind.. the images of course are up to date.

Ah right, thanks. Wasn't aware of that.

[Gray-Wolf]

Back to the melt, sub 7mill pack today and ,should my fears be grounded, high melt figures (50,000+) possible until mid Sept (no 'plump up from collapsing ice this year). that's a potential for another 2,350,000 melt so we'd finish somewhere between 4 and 5 mill. Put in a few 'century breaks' and you can see why I'm thinking 4 mill as a final (any less would be a disaster,no?).

[BornFromTheVoid]

We're back below 2009 now aswell. It also looks like the Northeast Passage could be open any day now...

[J10]

Time for the latest update. The Current figures are at 7,380,625, this is 307,500 below recent term averages, with 1,283,815 below longer term averages. We are around 4 days ahead of recent averages in terms of ice loss. (i.e current figures = 28th July Average figures)

A contradiction this week, Ice Melt rates rose to over 80,000 but still there was a slight improvement over recent averages. (However current ice extent is still the lowest apart from 2007 in both series going back to 1979.)

We are now over 520,000sqft over 2007, which is the very least to be expected. Assuming the figures of 2002-2004 are long gone, This weeks figures are closing in 2009 and may be above that soon, however any catch of 2008 will not now happen in July. I will be checking the progress in relation to this in next weeks update.

Time for the latest update. The Current figures are at 6,915,938, this is 280,915 below recent term averages, with 1,220,831 below longer term averages. We are around 4 days ahead of recent averages in terms of ice loss. (i.e current figures = 4th August Average figures)

Ice Melt rates fell to 66,000 this week, and total ice extent went above the 2009 figures for a time, but this reversed today. Also there was a slight improvement over recent averages. (However current ice extent is still the lowest apart from 2007 in both series going back to 1979.)

Assuming 2007 and 2002-2004 figures cannot be reached, how do we compare with other targets.

2005 Below by 130,000

2006 Below by 227,343

2007 Above by 540,625

2008 Below by 287,656

2009 Below by 39,531

[The PIT]

So looking at the the glass half full jobbie a slight recovery continues. Plenty of time for the glass is empty people yet as the decline will continue for a few weeks yet.

[cooling climate]

For what its worth the high Arctic (north of 80 degrees) appears to be having a colder melt

season than has been the case the last few years. Still confident regarding my wag of 5.5

million km2.

http://ocean.dmi.dk/arctic/meant80n.uk.php

[BornFromTheVoid]

For what its worth the high Arctic (north of 80 degrees) appears to be having a colder melt

season than has been the case the last few years. Still confident regarding my wag of 5.5

million km2.

http://ocean.dmi.dk/arctic/meant80n.uk.php

It certainly has been very cold past 80N, the only problem is that it's only a relatively small area, and not really representative of general conditions across the arctic.

The majority of 80N didn't even melt in 07.

[songster]

So looking at the the glass half full jobbie a slight recovery continues.

Er... no? Current figures are the second lowest in recorded history, lower than both 2009 and 2008. How can that possibly be called a continuing recovery?

Looking at the broader picture, the key question is when the melt will begin to level off. 2008 showed rapid continuing ice loss through to the start of September and beyond, whereas 2009 showed a sharp decline in ice loss around the start of August. Whether 2010 follows the former pattern or the latter determines whether this year's ice loss will be disastrous, or merely extremely bad. If there's any kind of acceleration, we're into the realms of catastrophic. The state of the central pack is not good, looking at the MODIS images. I don't have the background to tell how much worse it is than 2007/8/9, but it's certainly no better.

[MR EXTREMES]

its good to see that the arctic has not fallen past 2007 not likely to either still low but plenty of time left for recovery.

as in recent years slight recoverys have happened just goes to show how unpredictable climate is and with things set to change inregards to climate cycles then recovery is still possible.

[BornFromTheVoid]

Er... no? Current figures are the second lowest in recorded history, lower than both 2009 and 2008. How can that possibly be called a continuing recovery?

The PIT may have been referring more to the last month or so, rather than recent years. Still, extent is not everything and as you mentioned, the images from modis still look quite bleak.

[Gray-Wolf]

And whilst we hold onto those thoughts let's remember we are not amid a 'perfect storm' up there in the Arctic this year. Have we not had a lot of folk pointing to 'temps' and synoptics as some kind of 'saviour' from the horrors of 07'? As for Pit's "continued recovery" we would need it defining as to what and where I think otherwise it's just more rubbish posted to make fools feel good........should they need to listen to such....

as in recent years slight recovery's have happened

No 'collapsing perennial' this year bb, just melt.

Do the sum's. 5m thick pack calves into 2m slabs (as Dr B. witness last year). The ice island is 3km wide and 18km long. How much more ocean do the 2 by 5m slabs cover compared to the original block?

If we've lost the last of such (as MODIS attests to) then how much less 'spread' do we have the potential for this summer?

Edited August 1, 2010 by Gray-Wolf

[Gray-Wolf]

I think the other thing we need 'mull over' is why , when we have another 'average summer' across the pole, ice figures are falling so fast and are placed so highly on the charts?

God only knows how the ice would have fared had we seen another 07' synoptic up there!!!

[4wd]

I think the other thing we need 'mull over' is why , when we have another 'average summer' across the pole, ice figures are falling so fast and are placed so highly on the charts?

Temperatures are well below normal up there so it's not because it's warmer then ?

[sunny starry skies]

But surely the dominant drivers of melt are wind export and ocean temperatures, which are not declining? The only thing that is 'saving' the pack this year is synoptics unfavourable for surface melt and wind export. Yet we have record low ice volumes. A 2007-type season would destroy the current pack.

I think Arctic monitoring is going to run into a bit of bother because of the reliance on extent as a measure rather than area or volume. Extent (which is area with >15% ice) can be fooled by fragmented, spread-out ice, much as we obviously have this year. Area is slightly better, but clearly does not take into account that the ice is much thinner than it was just a few years ago. Volume measures (bring on Cryosat-2!) are going to be the only thing truly recording Arctic ice decline.

Area graph:

http://www.ijis.iarc.uaf.edu/seaice/extent/AMSRE_Sea_Ice_Area.png

Some more interesting observations here:

http://neven1.typepa...xtent.html#more

and here:

http://tamino.wordpr...-ice-curiosity/

There is really obviously no 'recovery' in Arctic ice - in fact it's quite the opposite when you look at the ice as compared to previous years, but 'extent' measures may not record the fullness of that decline. We may be fooled into thinking we have longer with a polar sea ice cap than we actually do.

sss

Edited August 2, 2010 by sunny starry skies

[BLAST FROM THE PAST]

Temperatures are well below normal up there so it's not because it's warmer then ?

No its because we've been in warm PDO, warm AMO and El Nino. Its supposed to be warmer according to pro AG warming but as its not then attention turns to AGW warming the oceans, they have been in coincided natural warm cycle. Oceans are now in cooling phase and it won't happen overnight as some will demand just like the melt didn't occur overnight when we switched to warm ocean phase 30+ years ago. The real fact is that we aren't going near 2007 despite having gone through an El Nino [we should have if things were as dire as proposed along with the warmest ever year thus far,?? and AGW and El Nino]. They aren't great but one must take note that 'global' sea ice is at NORMAL levels which means down under the antarctic isn't about to collapse into the sea, its at near record high levels.

The big thing for me is the change of patterns, the failure for numerous large warm plumes to enter the arctic due to the jetstream shifting south....this is the beginning of the turnaround IMHO. Time will tell as always.....and we do have time.

BFTP

[Devonian]

Temperatures are well below normal up there so it's not because it's warmer then ?

Who says temperatures are well below normal?

[4wd]

It looks significantly below average through the melt period.

[Devonian]

It looks significantly below average through the melt period.

Yes, according to DMI it has been colder than normal N of 80N. Perhaps, since you accept this data, we'll stick with it in the future. I wonder (only that, I don't want to be called a scaremonger or alarmist) if we'll see something like 2007 when temperatures N of 80N were below normal for much of the summer but were above it for much of the rest of the year? Or, I wonder if we'll see a cold late summer and Autumn in the Arctic and an early ice up. I don't rule out either...

Of course, the Arctic isn't that area N of 80N. And, if you go back through the DMI data, it's clear ice amount in the Arctic isn't just to do with temperatures N of 80N.

[4wd]

So is there a graph somewhere covering a wider area?

Through 9 months of the year it will still freeze easily enough if it's 1 or 2C above average.

The melt period is when a couple of degrees might be relevant.