Ms Grette specifically commented in the presentation that the warming in MIS 31 was attributed to orbital forcing..

Note: My comment only refers to the video presentation of the research, as I have not been through the article.

Nevin, Thanks - great to share this video and great research! It was interesting to see that prior warmth periods appear to relate less closely with CO2 level (MIS 31, 1.1mio years ago was 6-7 degrees warmer than now with CO2 at 300ppm), that extreme warmth was more frequent in interglacial periods than expected, but more alarmingly (though possibly less surprising) that ice sheets are much more adaptive than anticipated and will react, as temperature moves up or down.

Neven, I agree that this should generally hold true, but as we saw by the end of July/early August 2012, the melting happened further north in the Chuckchi/East Siberian area isolating the MYI arm in this area with open water on all sides as a consequence. Split starting end July: http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/ARCHIVE/20120730.jpg Rapid disintegration by Aug. 9, 2012: http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/ARCHIVE/20120809.jpg It was based on this experience from 2012, I was struggling to understand that even if in general a branch of MYI might be able to hold the melting away from the central ice pack until freezing sets in again, why the MYI arm for this particular year was considered to offer any barrier. This could be a feature of the new reality in the Arctic that increased water temperatures and increased forcing will isolate any thicker ice layer that is not consolidated in the central pack at highest possible latitude much quicker now, and based on what we saw last year it would be surprising if the minimum SIA this summer extends significantly beyond the current area of MYI, but let's see..

@jdallen_wa, Thank you very much for the link to this article. I have not seen an update, but I do not think there is much disagrement on the arguments or conclusion of the article: Once you have open sea water, it will drastically alter the heat absorption capacity, as it changes from a highly reflective to a highly absorbing surface. This causes in-situ rapid increase of SST, so there is no need for inflow from the Atlantic or Pacific oceans in order to provide conditions for strong bottom melt - the sun and then wind to move the ice across the heated waters will do it. Related to a 'barrier' of MYI to project against inflow therefore also does not seem relevant to me, both since influx from exterior oceans will go beneath the sea ice, and because the MYI pack is much better protected, when the circumference is at a minimum, somewhat reducing the events of ice moving across heated sea surface waters. This seems correct to me, but I would also appreciate more insightful feedback and critisism.

Dodger back on April 29 called the MYI in Chuckchi a Stronghold and 'protective barrier' and the lack of this MYI would 'expose the central pack to influx of warm SST'. This is what I do not understand. To me, the MYI 'arm' reaching Chuckchi was like a lone hero riding to the castle of the enemy to defend his home, only to find himself to be the first to be shot down, having done nothing to protect his home. The MYI branch in the Western Arctic ended up isolated and melted away completely, being hundreds of miles from the central pack and thereby having no impact on central pack melting. And with Pacific water inflow creeping under the Arctic surface waters, the impact of the inflow should be primarily the vertical heat transfer and not mixing of Arctic surface waters with warmer Pacific waters. I would like to understand, if I have these mecanisms wrong, but I just do not understand the 'stronghold' or 'protective' here. The shape of the current MYI pack seems better suited to withstand the oncoming melt season.

To Neven, As always; amazing work on the winter analysis - really great reading to sum up what happened in the past season! On the comments regarding a protective arm of MYI towards the Pacific: I don't get it. It may be my lack of foundational knowledge, but from all sources I have read, inflow from the Atlantic or the Pacific never happens at the surface, because the local Arctic waters with relatively low salt content will stay above the inflowing salty waters from the outside oceans. Inflow therefore happens at depth both when these are caused by ocean currents as well as by surface weather patterns and will have no immediate interaction with any ice in the Arctic. If the wind is pushing north from Bering into Chuckchi, the inflowing water should therefore slide in below the local Artic waters and ice. Or does inflowing water in fact get in and mix at the surface level, even hundreds of miles into Chuckchi and the Arctic Ocean?

Wow, great work by Wipneus and Chris! Neven, Also helping to explain the difference from last year should be the consolidation of ice along the CAD and Alaskan north coast that happened in the winter of 2011/12, which is then contrasted by the strong Beaufort gyre this year. If anything positive could be said, it should be that while SIA right now is equal to 2012, the SIE (according to ROOS) is less than last year, meaning the ice pack is relatively more compact this year, with high latitude areas faring better than last year - even if cracked. East Siberian Sea only melted out completely in '07, '08 and '12, and this year stands a chance of retaining a minimum ice layer to help reduce the heating of Arctic surface waters during the main summer months. But as many have commented, the ice is broken, and may just melt out at an unprecedented rate this year..

The nature is probably the best engineered solution to take care of excess carbon: ftp://atitlan.ethz.ch/docs/se/Grace_et_al.,_1995.pdf But this is a laissez-faire solution, which does not appeal to our problem-solving approach to fix the world, so I agree with the comments that humankind will end up engineering something that will be much less effective than the ecosystem, and will have other negative consequences - like the plastic balls..

@Paul Beckwith, The idea itself that we should geoengineer ourselves out of this problem to me, is the whole reason why we are having this problem. We wanted safe agricultural lands, so we cut down the forest and eliminated a number of wild animal species (at least in most of Western Europe). We wanted energy so we started burning coal, oil, and then natural gas. We wanted more energy, so in addition to fossil fuel, we enrich uran, establish wind power, hydroelectric plants with redirection of large water systems, etc. with further significant consequences to the environment. In addition, we don't like that material deteriorates, so we created plastics. What these developments have in common is that we never realized the full consequences, or wanted to be bothered with them. Even with what is unfolding in front of us related to AGW, plastics seems to be a more comprehensive threat to humanity in the long term, as every part of the Earth is being infested with these hormon-impacting molecules that do not break down in centuries. Geoengineering is just us trying to fix an immediate problem without consideration of the consequences - a perfect example of human intervention.

With the unusual cold temperatures we saw in Feb/March combined with very extensive cracking, we should expect high volume increase as discussed in the last PIOMAS update. So now we have the ice, but it is cracked ice, so should still be a more fragile state than last year. Did anyone speculate on causes for the cold spell in Feb/March? It is interesting that apparently the low automn/early winter SIA would cause higher air humidity and precipitation causing the very high NH snow cover positive anomaly in Dec 2012 - could this to some extent delay the otherwise warming climate, at least for some winter months in the NH, or were air temperatures as much above normal as usual for recent years??

Ice drift speed; Nightvid Cole brought the chart with expected ice drift speed for 3/17, which looks alarming especially due to the drifting towards Fram Strait. The question I have: I would assume that the ice pack has a tendency to spread out since there is less resistance in spreading rather than compacting, and also since the higher temperatures over open water should create 'off-shore' winds towards open water further spreading the ice. If that is correct (?), what would be 'normal' ice drifting speed and when is it considered 'high/above normal'?

Espen, I'm here too, in Nærum, waiting for the snow to come later today and tomorrow - and finally for spring to arrive sometime soon..

@Espen, I agree; volume is the true indicator of Arctic sea ice conditions, but what the data is also showing is that even when volume and area was crushed like last year, the ice will rebuild - as thin FYI. Although conditions are very different, the Arctic will soon (if not already) look much more like the Antarctic, where the vast majority (or maybe all) of the sea ice will melt out each summer and then reform in a thin, fragile state every winter.

And for the high-pressure area and FS export: Since the high-pressure area has moved this far 'east' towards Zemlya Georga (http://ocean.dmi.dk/arctic/weather/arcticweather.uk.php), wouldn't this turn the wind pattern immediately above Fram Strait in a Westernly direction potentially reducing ice export or at least reducing MYI export via FS, while the high-pressure is stretched this far towards the Atlantic?

As this seems to be our current open thread a few comments on ice from here: - SIA is similar to 2012 at this time, but SIE (from ROOS) is a bit lower this year, which I see as good news, as the pack is less spread out (in spite of all the cracks, or does SIA calculations have challenges with this kind of comprehensive fracturing?) - Kara and Barents are doing better than last year, while Bering and Okhotsk are lower than last year, so that ice surface (SIA) but also relatively more volume this year is in the Arctic bassins rather than exteriour to this? - Finally, I just find it remarkable that SIA is able to climb to 13.796mkm2 after the meltout last summer, but the only thing to retain from that is that SIA is what it is, while volume is the true indicator of Arctic sea ice health... And thank you all for comments and feedback - I will respond as other work allows. The discussion can seem to become a bit paradigmatic at times - 'we' and 'them', but as often stated I am not challenging AGW, which would be quite foolish - just trying to better understand the nuances of the climate in which AGW is becoming an ever-stronger element.

A-Team, Wow, this is a great and very detailed image! If I am reading it right, it seems many of the "fresh" cracks have a temperature of -22.5C, while neighboring ice is 7-9 degrees colder. I was wondering with the ice temperatures displaying like this, if it would be possible to calculate how much heat convection/freezing is going on in those cracks, or if it would be necessary to have air temperatures to assess the heat release?

Glacierchange: Jacobshavn Glacier retreated 6-8km from 1875-83, i.e. 1km/year, which is quite substantial, given also that air temperatures arguably were lower during that period. From 1929-31 (where the DMI article refers to a pulse of warm water inflow from the Irminger Current), it retreated 4km in two years - an average of 5.5meters per day for two years. The retreat almost came to a complete stop from 1964-2001, where the Arctic ice is otherwise showing strong indications of decline. If ocean currents are a small side-effect and AGW impact on atmospheric conditions the main effect, and the two were already strongly correlated, how is this then possible? Lastly, the glacier reacts to the IC pulse of 1997 with very strong melting, and as the DMI article argues, the fjord stays deep far inland, so there is no reason for the retreat to slow, allthough the projections of course are challenging. Clearly, we are observing the combined effect of rising temperatures and other factors (DMI argues that NAO is involved with changes in the Irminger Gyre), and while several have pointed to the correlation between melting induced outflow via Fram Strait and AW inflow increase, I have not seen any discussion of a NAO/AGW link, but may have missed that?

@Steve and Kevin, Sorry Steve, the Fram Strait article has multiple links. One is: http://oceanrep.geomar.de/11885/ This article argues that there is a strong connection between changes in ocean currents and Artic surface cryospheric conditions (centered around Svalbard here, where the effect is most pronounced). AGW of course started back when we started changing our landscape, clearing forest cover, building dams, and changing water flows centuries ago, and that should have had some impact on climate and weather patterns. However, to say it's naive to assume that intrusions of AW, or other advections of warm water into the Arctic, are independent of AGW. is unreasonable simply because it has been shown in the article above as well as the DMI article above that changes in currents and intrusion of warmer water has had measurable impact in the 1930's (both in Western Grenland and Fram Strait), in the 1860's, and sooner, where we must agree that AGW related to CO2 cannot have been a factor. Since then I agree a lot of things have changed, and as one of the articles discusses, it is difficult to separate whether increased inflow into the Arctic is causing the excessive outflow, or if increase outflow due to melting is causing extra inflow today. Whichever is the case, the melting and inflow of AW seem to reinforce each other, and who knows: If increased AW inflow has been in place since 1860's, helping to slowly warm the deeper AO water layers, causing a slow and steady increase in vertical heat convection (and vertical water movement, when the temperature exceeds 4C), it may very well last another century, and being reinforced by the increase of CO2, it may also not return to an opposite state as easily - or not at all.

@Steve Bloom, Regarding the Irminger Current and natural variability vs AGW: As you have seen on images for the Jacobshavn Glacier, there were significant periods of glacier retreat between 1851 and 1931, where roughly half of the glacier tongue was lost, the other half lost since 1931. What is your take on that?

An article discussing how warmer Atlantic Water started entering the Arctic from 1860's, but that SST in the Fram Strait did not increase before around 1950: (Werner, Kirstin, Spielhagen, Robert F., Bauch, Dorothea, Hass, H. Christian, Kandiano, Evgeniya, Zamelczyk, Katarzyna, Atlantic Water advection to the eastern Fram Strait – multiproxy evidence for late Holocene variability, Palaeogeography (2011)): After ca 1750 AD decreasing planktic foraminifer fluxes indicate very cold conditions. High IRD contents are attributed to heavy sea ice conditions found also in historical observations and instrumental records. IRD may have also been produced by melting Svalbard glaciers. Subpolar planktic foraminifers in the 150-250 µm fraction and planktic δ 18O values indicate strengthened Atlantic Water inflow after ca 1860 AD. However, low fluxes and planktic foraminifer assemblages of the 100-250 µm fraction suggest cool surface water conditions until the mid of the 20th century. Changes in all studied proxies indicate warmer temperatures for the past few decades (see Spielhagen et al., 2011) and coincide with positive Atlantic Water temperature anomalies and a retreating sea ice margin for the ca last 100 years (Divine and Dick, 2006; Polyakov et al., 2004, 2005).

@Robert, Agree that we are witnessing an unprecedented gamble with our environment. Still, I live in a country - Denmark - where only a couple of percent of the land surface has remained unchanged by man, everything else having been turned into utility for man. How are we to know how to respect the environment, if we have none left? We buy some rain forest shares, so that others cannot do what we did, but we do not stop what we are doing at all. Wind power fields are established, but we open a new oil field as well. I anticipate this experiment will only end when fossil fuel is gone, - the wealthy will surely survive and we no longer appreciate what remains to be lost.

On DMI and ocean currents, see especially page 5 of this article from Nature: http://ocean.dmi.dk/staff/mhri/Docs/Holland_et_al_NatureGeoscience2008.pdf

Al, So AGW has warmed the Atlantic water currents into the Arctic by 1.25-1.5 degree celcius in 32 years, and also caused a temperature increase of the same magnitude in the Fram Strait inflow back in the 1860's? And DMI, which certainly is not a GW skeptic institution, is just wrong when they link warming ocean currents to multi-decadal cycles rather than AGW?

@Robert Fanney, Please see e.g. Tracing Atlantic Water Signature in the Arctic Sea Ice Cover East of Svalbard from 'Advances in Meteorology', vol. 2012, page 6: The data from the Arctic and Antarctic Research Institute (AARI) collection were used [30]. We consider two water layers: 100–200m and 200–300m (Figure 7). This choice is explained by the features of AW transformation in the AIW discussed in Section 2. Provided that the concept of AW intensive mixing in the upper part is correct the layer shallower than ∼200m initially contains the heat, which is totally released upwards and laterally during the FSBW transit from Fram Strait to the Laptev Sea. The layer below ∼200m retains a large portion of its initial heat content up to where the AIW terminates its full circuit around the Arctic Ocean interior. Within the considered time interval (1979–2011) the temperature in both AW layers coherently increased. However, this increase was not monotonic, but rather cyclic with an 8–10-year period. The background positive trend is 1.5◦ per 32 years in the upper layer and 1.25◦ per 32 years in the lower layer. It is worth mentioning that after the most recent temperature increase, which culminated in 2007, the temperature did not drop back to the initial point as happened earlier, but remained about 1◦C higher in both layers, leading to the conclusion that AW in the Arctic Ocean is shifting to a new warmer state [31, 32]. Hence, there is no doubt that the heat input to the Arctic Ocean interior has substantially increased since the end of the 1990s. The question is has this increased heat input provided the major forcing of the documented change in ice properties in the WNB? The article then moves to conclude: Time series of FSBW temperature in Fram Strait feature a monotonic increase after the mid-1990s, consistent with shrinking ice cover. This coincidence provides solid ground for the hypothesis that a substantial amount of the AW heat in the WNB is able to reach the under-ice layer and contribute to the ice melting from below. I have previously referred to another article that also documents an increase in temperature for the AW inflow on the Fram Strait Branch starting in the 1860's, and DMI has an article that the increase in glacier speed for the Jacobshavn Glacier is due to multi-decadal changes in the temperature of the Irminger Stream, and is not linked to AGW. As I have stated before I am not denying the effect of CO2, but I fear the world at large will not be much bothered once we have the first ice free Arctic summer - which will be soon. Therefore, my vain hope is that other factors are at play as well, as we are otherwise just headed in the wrong direction much too fast..