No offense Viddaloo, but talking about ice-free 365 days is deeply unrealistic. Yes, the ice is in serious trouble. Yes the first complete summer melt-out (with "complete" still allowing for quite a bit of ice clinging to the CAA and Greenland shores) could happen in the 2020s, although the PIOMAS trend line would suggest more the late 2030s. But a year ice-free at the north pole (thankfully!) requires a lot more CO2 than we've yet released. It's just not a physically possible scenario under current conditions.

I assume the deadline for submission was a few weeks back, but yeah, anyone whose estimate was over 5 is out of the running. 4.3 seems pretty likely.

Hi KZ. I'm an infrequent commenter here, and I'm definitely not going to get into who said what about who ... instead, I'd like to ask you a pretty straightforward question. You said "I am not particularly concerned about the impact of global warming." My question is "Why not?" Possible answers could include, but are certainly not limited to (a) you believe we will soon curtail emissions, such that atmospheric concentrations (CO2+equivalents) never exceed say, 2x pre-industrial (b) you believe that the amount of warming from any given amount of emissions will be less than the central estimates given in the IPCC reports (c) you believe the actual effects of elevated temperatures on rainfall patterns, crop growth and sea level will not be harmful to most (or all?) human (and animal?) populations ... I'll stop there. I don't wish to put words in your mouth, I'm just asking you to elaborate on why you don't think this is a big deal. Thanks, Greg

Neven, what's the correct answer for an underground water tank - fiberglass?

Old Leatherneck, are you sure it was a toy *sailboat*? http://en.wikipedia.org/wiki/Paddle-to-the-Sea

Well, during the winter, sea ice accumulates "from the underside". During melt season it mostly melts from the underside too, but also melts on the surface. Therefore, unlike on land where an object would progressively get buried deeper (in an accumulation zone anyway) I think an object on sea ice would tend to remain on top. Of course there's caveats - if the object is heavier than water, and the ice its on gets into a rafting event, the object could slide into the water (or get pushed in). So the question becomes how long a chunk of ice at the north pole in 1800 could survive intact without getting flushed out the Fram or winding up in a violent rafting event that tosses the object down a crack. Maybe a few cycles around the gyre? A few decades? Or postulate that that particular chunk gets rafted onto some basically immobile ice stuck to Ellesmere ... the object could still be there, although its odds are getting slimmer. One thing's for sure, it won't be anywhere near the north pole anymore. Just north of Ellesmere seems the only reasonable location.

3.8 million sq km We don't generally get back-to-back records and this year is starting slow, but PIOMAS has the total volume lower than last year, so we're not talking "recovery".

A-Team, a couple of years ago the trouble with PIOMAS for "civilians" was that it was only gridded - it was popular demand that led them to put out a daily single summary number. I don't know what "extra" information was released that Wipneus and Chris used. Perhaps one of them can explain what it was that was beyond the normal PIOMAS output. Or maybe it was just the normal output, but the latest batch for March. Erimaassa, maybe Neven is a fan of Eli. (http://rabett.blogspot.com/) :-)

Donald, presumably Nevin doesn't want to pay for a real security certificate (which is only really needed if you're doing commerce of some sort). As said (but perhaps not well explained) in the post above, you can either create an exception in your browser to accept this, or use http instead of https. Think of it like this: there are really three levels of security: http - no security, your packets can be read anywhere along the path they take. https without certificate - you get encryption. https with certificate - encryption plus you're guaranteed the website hasn't been spoofed (which matters if it's a bank, but who is going to spoof Nevin's forum?)

Scarlet (freeway blogger), I just wanted to say I've been a fan of your work for years. It's brilliant.

I looked at CT this morning and suspected this post might be coming :-) Wow, what a year.

Nares strait is an interesting case this year. Peterman (2012) is making about 1 knot southbound (has just entered Kane Basin) but sea ice doesn't seem to be taking the same flow. The path of the giant berg is presumably indicative of the main current flow, but perhaps there's a surface wind or wind-driven current going northbound. The polynya in the Lincoln Sea would then be in-situ melt, or just pushed clear, from that surface current. Its shape certainly reminds me of the "bubble" that a light fluid jet can blow in a surrounding medium.

At a rough guess, the albedo forcing from a 6 million sq km snow deficit for NH June would be significantly more than a 2 million sq km arctic ice deficit. However the snow deficit is shorter lived ... they are probably comparable over NH summer. Does anyone know if this has been well quantified?

I changed my CT vote down one bin, so I'm going for 2.75 now. Probably conservative as CT currently has 2.92(!)

I finally pulled the trigger on the August poll. 4.25 and 2.85, so I'm betting on two new records, but by small amounts. If a compaction event occurs I'll be quite a bit off though.

Kevin, that's a very engaging review you wrote. I found one tiny factual mistake you might want to correct - in the caption of the photograph of Barry Saltzman. Barry Saltzman died in 2001, at the age of 69, not in 1969.

Espen, Not just by kayak. I believe a guy named Henry Larsen made that same left turn in 1944 :-)

"Yep, the ground stays below sealevel all the way into central greenland basin. Similarly for ilulissat glacier" That topo map from wikipedia disagrees. It's very close, and the map isn't a very high resolution, but it's the highest rez map of Greenland's bedrock elevation I've seen. So, is there a well-substantiated source for sea level channels to the central basin?

With the arch broken, looks like Kane Basin won't take too long. http://lance-modis.eosdis.nasa.gov/imagery/subsets/?subset=Arctic_r03c02.2012183.terra.1km

Thanks for that link Alberto. I was initially mislead by the first graph until I carefully read the captions of the first and second graphs to see precisely what they were showing. One caveat though - the second graph takes length of day into account, but it says "top of atmosphere", so the optical depth of the atmosphere may matter as WhiteBeard said. OTOH, scattering mostly just spreads the energy out - only a small amount is entirely back-scattered.

Another big drop in the CT area measure. Air temps, cloud cover and ice distribution *appear* favorable for a continuation of this trend for a few days.

The last couple of days of the IJIS graph have me hearing Tom Petty. (Free Falling...) It's still probably less than a 50% chance to beat the 2007 daily low extent, but pretty close to. IJIS Area is dipping under the 2007 line. Uni Bremen on the other hand has 2011 extent lower than 2007 for today. It's all within minor weather fluctuations, so all we can really say is that the death spiral continues.

Heh, just because yesterday I noted the IJIS area graph for 2011 touching the 2007 area and seemingly ready to cross it ... today it flatlines with zero change in area. Meanwhile IJIS extent seems determined to thread the needle between 2007 and 2008. Nonetheless, such low numbers in a year whose weather was nowhere near as favorable to melting as 2007's indicates further deterioration in the overall state of the ice.

Breaking: 2011 IJIS area falling below 2007 IJIS area. http://www.ijis.iarc.uaf.edu/seaice/extent/AMSRE_Sea_Ice_Area.png Not quite there yet, but pushing for a new record.

Twemoran, I agree on both points. Some days the crack in the Peterman is better resolved than others, but I'm not yet convinced it's widening. The Humboldt appears to be calving like crazy, with much of it coming from the side of that "bulge". When I look at the ice in Kane Basin, it seems to me that there's two bands of it - a western band made of sea ice that's come down Nares Strait, and an eastern band that appears to be mostly bergs calved off the Humboldt. Anyone else see it that way? Meanwhile Disko bay is pretty crowded with bergs from Jakobshavn Isbræ.