tag:blogger.com,1999:blog-1367053740188758246.post2772110455680613903..comments2023-06-21T00:39:34.443-07:00Comments on Dosbat: What is the future of Arctic Sea Ice? Part 1.Chris Reynoldshttp://www.blogger.com/profile/16843133350978717556noreply@blogger.comBlogger7125tag:blogger.com,1999:blog-1367053740188758246.post-14389579410315616122014-04-25T07:27:14.069-07:002014-04-25T07:27:14.069-07:00Nightvid,
There's the simple fact that until ...Nightvid,<br /><br />There's the simple fact that until now, which the pack typically thins over summer, you don't get large holes within the pack.<br /><br />It's feasible that might change as the Central Arctic region transitions to a sea ice free state. But on balance I think there is reason for doubt about whether it is feasible to melt out the Central region with ice thickness around 2m. More in my next post (should be tomorrow morning).<br /><br />Adam,<br /><br />I agree. Especially with regards weather having greater impacts. <br /><br />As to what will happen as the pack continues to thin, I think we'll see lower concentrations in late summer. And area may go down faster than extent.Chris Reynoldshttps://www.blogger.com/profile/16843133350978717556noreply@blogger.comtag:blogger.com,1999:blog-1367053740188758246.post-15440361182918393912014-04-24T03:26:33.176-07:002014-04-24T03:26:33.176-07:00Area vs Extent - missed that, schoolboy error. :-/...Area vs Extent - missed that, schoolboy error. :-/<br /><br />I may have this wrong, but the way I see it is, at 1-2M km2 though, it really wouldn't take much weather to double or halve the amount. <br /><br />For example the difference between 2012 and 2013 min in both measures was similar to the difference between the two, and roughly 1-2M km2 (I've rounded massively, but they're all within that ball park).<br /><br />Therefore, once we're down to frequent <= 2M km2 amounts in either, it's basically a die roll from year to year. <br /><br />Of course, it would also mean some years could get a doubling from the previous year, too.<br /><br />One extra though, is that would extent start to proportionally larger than area at those levels? Or would sparser ice clear out more quickly, and leave mainly fast and solid ice meaning the two measures (ignoring melt ponding) would get closer?<br /><br />Does anyone have a model of what happens when you get down to those levels, and what form the ice will take?<br />Adamnoreply@blogger.comtag:blogger.com,1999:blog-1367053740188758246.post-91503970544523673752014-04-23T15:17:19.352-07:002014-04-23T15:17:19.352-07:00Chris,
I don't think there is any good reason...Chris,<br /><br />I don't think there is any good reason to believe the ice has to melt from the edges inward - it certainly didn't do that in late August 2006 or early August 2012.<br /><br />When the ice in the central Arctic in May is thinner than the top plus bottom melt that results from the conditions that season, it will melt, regardless of how far in the ice pack it was early in the season!Nightvidhttps://www.blogger.com/profile/03320916322586904305noreply@blogger.comtag:blogger.com,1999:blog-1367053740188758246.post-55760560855283005722014-04-23T10:00:26.970-07:002014-04-23T10:00:26.970-07:00Carmiac,
I had hoped to post part 2 yesterday, bu...Carmiac,<br /><br />I had hoped to post part 2 yesterday, but I've decided on a slightly different tack and won't have the time to crunch the numbers until the weekend. Sorry to leave you 'hanging'. Essentially my argument hinges on whether volume loss will continue in the Central Arctic and whether it is possible for ice 2m thick to melt all the way from the peripheral seas through the Central Arctic in one season.<br /><br />Adam<br /><br />Actually I've not read that HCTN report. Thanks. <br /><br />I see that as you say figure 4.1.2 shows area under 1 million kmsq by around 2030. Overland/Wang propose that virtually sea ice free should be considered as under 1 million kmsq extent, not area. So at 1 million area extent will be somewhat higher.Chris Reynoldshttps://www.blogger.com/profile/16843133350978717556noreply@blogger.comtag:blogger.com,1999:blog-1367053740188758246.post-3720857590736376612014-04-23T08:36:40.001-07:002014-04-23T08:36:40.001-07:00Okay, I've found it and it seems I was wrong. ...Okay, I've found it and it seems I was wrong. I think I was misremembering this paragraph from Dr Slingo's oral evidence as referring to a sea ice model, when it probably refers to one of the HadGEM models:<br /><br />"We run quite a sophisticated sea ice model that includes the volume of ice, and it is fair to say, yes, there is a decline in the volume of ice. The observational estimates are still very uncertain, and we are looking forward now to the new measurements from CryoSat-2, which will give us a much better sense of the thickness of ice around the Arctic as opposed to just the extent of ice."<br /><br />From: http://www.publications.parliament.uk/pa/cm201213/cmselect/cmenvaud/171/120314.htm<br />Written evidence here: http://www.publications.parliament.uk/pa/cm201213/cmselect/cmenvaud/171/171we15.htm<br /><br />Report (pdf) here: http://www.metoffice.gov.uk/media/pdf/p/i/HCTN_91.pdf<br /><br />None of this will be new to you - it's all from Feb/Mar 2012. Sorry for the noise.Adamnoreply@blogger.comtag:blogger.com,1999:blog-1367053740188758246.post-42699386183952429252014-04-23T08:04:37.584-07:002014-04-23T08:04:37.584-07:00A few years back (2012?) the UKMO did a report (po...A few years back (2012?) the UKMO did a report (possibly for the House of Commons) that referred to their sea ice model and its projections for future loss.<br /><br />IIRC it did a far better job than even CMIP5 (as you'd hope). Unfortunately though I can't remember any more than that and search of their website throws nothing up. <br /><br />Their 2012 page on the Arctic states 2030 as likely the rough earliest date for < 1M km^2, though.<br /><br />If I find the report I'll post a link.Adamnoreply@blogger.comtag:blogger.com,1999:blog-1367053740188758246.post-62536621449241459052014-04-22T11:38:44.795-07:002014-04-22T11:38:44.795-07:00Great way to leave on a cliff hanger! Just from lo...Great way to leave on a cliff hanger! Just from looking at the volume and thickness charts, I've thought there might be a natural feedback to slow down the drop in September minimum for a while. I'm very interested to see what you have to say about the mechanism and its strength.Carmiachttps://www.blogger.com/profile/04680426526131572343noreply@blogger.com