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As you know, I did use snow cover in June for my submission to SIPN July report, where I predicted 4.61 M km^2 for the Sept minimum. The final NSIDC number for the Sept minimum is 4.63, which makes my entry the closest of all SIPN entries, and makes it look like I know what I'm talking about :o) I had noticed that, Rob. Well done!
Toggle Commented 4 days ago on 2015 minimum overview, part 2 at Arctic Sea Ice
I think it's reasonable, although mainstream opinion (I believe, haven't done a survey) is between 2030 and 2040. I personally believe it could happen at any particular melting season under exceptional circumstances, like weak initial ice state because of a cloudy winter, heavy preconditioning during May and June, followed by a July we saw this year (or warmer), and then a warm, stormy August. At the same time some negative feedback might kick in, or some unforeseen natural variability keeping things on a plateau*. Of course, that would be a reprieve, nothing more. Whether the Arctic practically melts out before 2030 or after 2050 is not all that relevant (especially if human societies keep opting for business-as-usual). It's about the process, not the end result, as the consequences are most probably already upon us and becoming more and more visible. * I don't want to think about it, but it could just as easily be the opposite: positive feedback kicking in, unforeseen natural variability kicking off the turbo.
Toggle Commented 6 days ago on 2015 minimum overview, part 2 at Arctic Sea Ice
Neven, So they essentially quantified a reason for a feedback that they already knew existed and was affecting the long-term trend? Bob, my understanding - based on this BBC article - is that they didn't really quantify all that much, but rather found evidence for the heat eddying upwards. Like the mission's chief scientist, Jennifer MacKinnon, says: "The strength of [these currents] has been incredible," Dr MacKinnon said. "We now need to disentangle what the contribution of that process is to the multi-year, inexorable decline of the sea ice." And the NSIDC's Dr Julienne Stroeve comments: "I think it is quite important to understand this type of mixing of warmer ocean waters at depth with the sea ice," she told the BBC. It will be crucial, Dr Stroeve added, to quantify exactly how much heat is reaching the ice and how much melting it has caused. "In 2007 more than 3m of bottom melt was recorded by [an] ice mass balance buoy in the region, which was primarily attributed to earlier development of open water that allowed for warming of the ocean mixed layer. But perhaps some of this is also a result of ocean mixing."
Toggle Commented 6 days ago on 2015 minimum overview, part 2 at Arctic Sea Ice
I think Barry meant September average or monthly minimum instead of 'anomaly'.
Toggle Commented 6 days ago on 2015 minimum overview, part 2 at Arctic Sea Ice
It's clear - and always has been - that heat in the ocean plays and has played a big part in the long-term thinning of the ice pack (read my blog post on Ocean Heat Flux for instance). They haven't documented the effect per se, but rather one of the possible reasons of the effect, the others being ocean currents bringing heat into the Arctic (again, see that blog post), and heat coming in through the ice-albedo feedback. Unfortunately it's very difficult to quantify, but scientists are working on that. It's important stuff, not just because of the implications for AGW etc.
Toggle Commented 6 days ago on 2015 minimum overview, part 2 at Arctic Sea Ice
AiG, there's a graph for 'decline in spring snow cover' on MA Rodger's website that runs until Feb 2015. Here's a bar graph for Spring with trend line from Rutgers University Global Snow Lab. And here's Fall and Winter. As you can see the latter two have upward trends, which probably has to do with all that open water at the end of the melting season dumping moisture in the atmosphere. Still, this negative feedback is quickly overcome in Spring and Summer. I'm still surprised at that. But maybe Spring/Summer snow cover has now reached a limit, I don't know. It'd be interesting to see if the snow line has retreated further North.
bobcobb, I haven't yet looked into it as much as I should have, but yeah, this could be a serious positive feedback. There's enough heat in the lower layers of the Arctic Ocean to melt all of the Arctic sea ice many times over.
Toggle Commented 6 days ago on 2015 minimum overview, part 2 at Arctic Sea Ice
In a couple of days, on October 6th, the Sea Ice Prediction Network is hosting a webinar: This webinar, entitled "The 2015 Sea Ice Outlook: Post-Season Discussion" will provide discussion of the 2015 summer sea-ice conditions, a review and analysis of outlooks contributed from 2008 to 2015, and discussion of the challenges and successes of predictions at the local scale. Julienne Stroeve, Larry Hamilton and Cecilia Bitz will be speaking. Be sure to register.
Toggle Commented 7 days ago on 2015 minimum overview, part 2 at Arctic Sea Ice
This is a continuation of Part 1, wherein I posted several graphs and maps depicting the 2015 minimum, and the weather conditions leading up to it (Tamino has a great blog post showing the long-term sea ice extent trends, all of them, not just the cherry-picked, meaningless one the GWPF... Continue reading
Posted 7 days ago at Arctic Sea Ice
Hi, Pete. Yes, I noticed. PIOMAS volume will be discussed in Part 2.
Toggle Commented Sep 26, 2015 on 2015 minimum overview, part 1 at Arctic Sea Ice
Cato, my impression is that the maximum had very little influence on the melting season. I know several commenters speculated about how 1 million km2 less than 2012 at one point, would surely mean that 2015 would break the record, but it simply doesn't work that way. That million had simply vanished after a couple of weeks. A maximum can be very high because during the last 2-3 weeks of the freezing season lots of thin ice is formed at the edge of the ice pack, because of wind pushing the ice outwards and low temps freezing the leads that pop up behind the floes (probably one of the main reasons of high Antarctic sea ice extent in recent years). Conversely, a max can be low because winds are compacting the pack and temps aren't low enough to freeze the open water. But at a certain point, after the melting season has started, thicker ice is reached, and other years catch up again. In theory though, if a max is low, say because of events on the Pacific side of the Arctic, and weather conditions are conducive to melting and absorption of radiation (sunny weather, warm temps from land because snow melts fast there) the head start could be capitalized. We saw some of that happen this year during June, but then the weather switched and action on the Pacific side stalled for several weeks. And that's how it goes most of the time.
Toggle Commented Sep 24, 2015 on 2015 minimum overview, part 1 at Arctic Sea Ice
Are you prepared to speculate yet about what 2016 holds in store for the sea ice in the Arctic? I'm always willing to speculate, Jim, but it's easier near the end of the freezing season. Along the way we get an idea of MYI transport into the Beaufort Sea and out of Fram Strait, volume, thickness distribution, amount of snow on the ice, temperatures, atmospheric pressure and cloudiness (read: outgoing radiation), etc. But I agree that events in the Pacific are highly intriguing. Of course, El Niño pushing out all that heat, but also the positive PDO and that so-called Blob in the North Pacific. We'll see how the Bering and Okhotsk Seas react to that (the small amount of sea ice there at the end of the freezing season was the main reason the maximum was so low and reached so early). What interests me right now in the Arctic is the absence of spikes on the DMI 80N temperature graph. I mean, SSTs have been reasonably high this melting season (see the comparisons I did for each ASI update), but apparently this heat either hasn't been released yet or it isn't crossing the 80° boundary. The last time that it took so long for spikes to show up was in 2009. As you can see on the CT SIA graph I posted in this blog post, the Arctic Ocean is being covered with fresh ice pretty fast, and if all that heat (also brought up by turbulence, as you say, thanks for that) doesn't get dumped in the air, but part of it stays in the water, insulated by ice and snow, this might play a role next year. So, that's my speculation for now. :^)
Toggle Commented Sep 24, 2015 on 2015 minimum overview, part 1 at Arctic Sea Ice
A week has passed by since the melting season ended and the minimum on all sea ice extent and area graphs has been reached. During this week I've been collecting images that show various aspects of this year's melting story, which will be accompanied by short explanations/interpretations. Such an overview... Continue reading
Posted Sep 23, 2015 at Arctic Sea Ice
The lowest point has been reached on all sea ice area and extent graphs, and so the melting season has ended. I'll have more on the details later this week, but here's a quick preview of one of the most important features of this melting season, and that's the decimation... Continue reading
Posted Sep 17, 2015 at Arctic Sea Ice
AbbottisGone, this depends on how much of the red disappears. We'll have to wait for the final numbers, but I'm expecting 5+ year ice to go down.
Toggle Commented Sep 12, 2015 on Arm's race (and a storm) at Arctic Sea Ice
I'll bet Nanuk knows. Of course, he knows, he has the script! ;-) I'm about ready to call the 8th the minimum in JAXA--today's update will do it for me if there's no increase. I totally agree, Kevin. Thanks for calling it. Only hard-core compaction via an Arctic Dipole (high over American side, low over Siberian side) can prolong the melting season now. On the conditions that there's enough compaction potential, of course. But there's none of that in the current forecast. Frankly, I can't wait for next year's melting season! PS traveling home tomorrow.
Toggle Commented Sep 12, 2015 on PIOMAS September 2015 at Arctic Sea Ice
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: After an August volume drop that was above average (only 2008 and 2012 had larger drops in the... Continue reading
Posted Sep 6, 2015 at Arctic Sea Ice
Due to circumstances I'm going to be off-line for a week, but I expect to be back around the time the minimum hits.
During the melting season I'm writing (bi-)weekly updates on the current situation with regards to Arctic sea ice (ASI). Central to these updates are the daily Cryosphere Today sea ice area (SIA) and IJIS sea ice extent (SIE) numbers, which I compare to data from the 2005-2014 period (NSIDC has... Continue reading
Posted Sep 1, 2015 at Arctic Sea Ice
Reduced compaction seems the new summer normal Neven. It is a lot to do with a warmer Arctic, where there is a lack of temperature contrasts and apparently steadier persistent cyclonic activity. If I think correctly sea ice will eventually vanish completely during summer more without motion, melting in place, rather than pushed around and compressed. Thanks for a stimulating thought, Wayne. I think you may very well be right. And as for that dipole, the forecast is more and more tending towards its formation a couple of days from now (see this overview). As for the 'unflashing' and 'deconcentrating', there's an animation on the ASIF showing the changes between August 27th and 28th that perfectly shows the phenomenon, if one focuses on the Pacific side of the Arctic. As for compaction on the Siberian/Atlantic side, Wipneus put up this animation on the ASIF showing what happened in the last 10 days.
Toggle Commented Aug 29, 2015 on Arm's race (and a storm) at Arctic Sea Ice
I don't know about surpassing 2012, Wayne, but I agree that this year saw less Fram Strait export and compaction than 2011, 2012 and especially 2007. Unfortunately these things are difficult to quantify (at least for me), so I'm claiming this based on my subjective categorisation of those top 3 record years. Except for June this year there wasn't much of a Dipole, and the huge high pressure area during July was so big and central that it didn't cause as much transport as an intense high over the Beaufort Sea coupled with a low on the Siberian side would have. If you then add that there was more MYI and volume at the start of the melting season (albeit not spread out evenly over the ice pack, but mostly concentrated north of Greenland and the CAA), and that it took a long time for melt ponds to form and melting momentum to get going, it's actually very surprising that the current ranking situation is as it is. Sure, July was massive, and the MYI in the Beaufort and Chukchi (the subject of this blog post) took a very early hit on the chin from a sunny heatwave, but I'm still surprised. I expected something like 2013/2014, but slightly lower. This could still happen, of course, if cyclones keep things moving counter-clockwise and prevent compaction, but 2015 ending up close to 2013 and 2014 is as unlikely as ending up close to 2012.
Toggle Commented Aug 28, 2015 on Arm's race (and a storm) at Arctic Sea Ice
Your animation seems to show compaction of the ice as the concentration seems to go up. Labelling it as only melting seems a bit off. It never really is melting only, is it? There's also things like compaction and transport that define the shape of the ice pack. Still, we call it all a 'melting season' and not a 'melting, compaction, transport and everything that is smaller than the satellite sensor's resolution season'. Melting is a collective term for everything that decreases sea ice extent and area measures. As I wrote back in 2011: I introduced the term 'flash melting' in a recent SIE update. It was a pun on the term 'flash flooding' where lots of rain falls out of the sky in a short amount of time, causing creeks and rivers to flood very fast. In my view the term refers to large amounts of ice disappearing from the (Uni Bremen) sea ice concentration maps from one day to the next, almost invariably caused by a storm. In 2012, when announcing the coming of GAC-2012 (which caused massive amounts of flash melting), I described all the elements of 'flash melting': 1) Diverge the ice pack through wind force (gales), creating open water between ice floes and pushing ice floes towards warmer waters. 2) Churn the ice, fragmenting it into smaller pieces which are easier to melt out, turning floes upside down even, with their darker bottoms (due to algae etc) showing up. 3) Increase wave action, especially when there's no thick ice to dampen the waves, flooding floes with saltier water that melts the ice, but can also temporarily fool satellite sensors into thinking there's open water. Therefore some of the flash melting 'unflashes' the next day, and then flashes again, and unflashes, until it's really gone. 4) Increase vertical mixing of the waters below the ice. As for compaction, I think your conclusion is premature, simply because the winds haven't been blowing towards the pack, especially not since the storm arrived. If you look at this animation on the ASIF you can see individual floes moving away (at high speed, no less) from the pack. And look at how garbled the ice pack is in the last image. The storm is also accompanied by lots of clouds, of course. And just like things on the ground, or water I should say, can 'confuse' the satellite sensor, so can things higher up in the sky. What looks like compaction, may very well be clouds filling up the holes within the pack, creating the illusion of higher concentration. But just like some of the 'flash melted' ice flashes back into existence the next day (someone on the ASIF referred to it as 'peek-a-boo ice' :^D), some of that high concentration will deconcentrate again as soon as cloudiness decreases. However, there is compaction going on on the Siberian/Atlantic side of the Arctic, which is on the other side of that reasonably strong high pressure area, also visible on the UB SIC animations. There are hints in the forecast right now that all this disturbance on the Pacific side of the Arctic will be followed by a classic Arctic Dipole set-up, and that means we could indeed be seeing compaction of all that loose ice in and adjacent to the Beaufort and Chukchi Seas. If a Dipole comes about and stays put for a while, a second place behind the 2012 record melting season might still be a possibility. But it's too early to tell. Either way, after a slow start this melting season is ending in spectacular fashion.
Toggle Commented Aug 28, 2015 on Arm's race (and a storm) at Arctic Sea Ice
It would therefore seem reasonable to conclude that these seas have melted out lots of MYI also back in the 1980s and 1990s, just that the chance of the MYI melting out in summer if present in the Beaufort or Chuckchi has increased to nearly full certainty from what was previously quite likely. Maybe I should've said the Beaufort and Chukchi Seas and part of the Central Arctic Basin adjacent to them, to not confine myself to regional borders. What I was trying to get at, is this (the video is a great visual explanation): As the animation shows, Arctic sea ice doesn't hold still; it moves continually. East of Greenland, the Fram Strait is an exit ramp for ice out of the Arctic Ocean. Ice loss through the Fram Strait used to be offset by ice growth in the Beaufort Gyre, northeast of Alaska. There, perennial ice could persist for years, drifting around and around the basin’s large, looping current. Around the start of the 21st century, however, the Beaufort Gyre became less friendly to perennial ice. Warmer waters made it less likely that ice would survive its passage through the southernmost part of the gyre. Starting around 2008, the very oldest ice shrank to a narrow band along the Canadian Arctic Archipelago. The zone that used to be a transit for thick, old ice that would return back to its starting point (north of Greenland/CAA) is now a graveyard. This year is no exception. On the contrary.
Toggle Commented Aug 28, 2015 on Arm's race (and a storm) at Arctic Sea Ice
Thanks, P-maker. My Danish isn't up to par, but the poem seems to rhyme well. :-)
Toggle Commented Aug 28, 2015 on Arm's race (and a storm) at Arctic Sea Ice
As I write this, a storm is battering the ice pack on the Pacific side of the Arctic. It's not as huge as the Great Arctic Cyclone of 2012, but it's pretty decent as far as cyclones go, and it's doing its thing in that part of the Arctic where... Continue reading
Posted Aug 28, 2015 at Arctic Sea Ice