Rodger, thanks for the methane graph. It's a very good collection of data + presentation to have. A detail though: "Methane is the second most important greenhouse gas...." It's so easy to forget water vapor and clouds and NOx but we shouldn't.

This paper although not a surprise, may add some clarity to the overall sea ice picture: Eisenman et al. 2010 Consistent changes in the sea ice seasonal cycle in response to global warming Abstract The Northern Hemisphere sea ice cover has diminished rapidly in recent years and is projected to continue to diminish in the future. The year-to-year retreat of Northern Hemisphere sea ice extent is faster in summer than winter, which has been identifed as one of the most striking features of satellite observations as well as of state-of-the-art climate model projections. This is typically understood to imply that the sea ice cover is most sensitive to climate forcing in summertime, and previous studies have explained this by calling on factors such as the surface albedo feedback. However, in the Southern Hemisphere it is the wintertime sea ice extent that retreats fastest in climate model projections. Here, we show that the inter-hemispheric differences in the model projections can be attributed to differences in coastline geometry, which constrain where sea ice can occur. After accounting for coastline geometry, we fnd that the sea ice changes simulated in both hemispheres in most climate models are consistent with sea ice retreat being fastest in winter in the absence of landmasses. These results demonstrate that despite the widely differing rates of ice retreat among climate model projections, the seasonal structure of the sea ice retreat is robust among the models and uniform in both hemispheres.

News flash from the RC cosmic rays & clouds topic: #55 Jeff Pierce says: 28 Sep 2011 at 6:41 AM Interesting timing. It looks like we might be in the middle of a Forbush decrease right now… http://neutronm.bartol.udel.edu/~pyle/Spectral.png (note, this updates real time, so you view this in the future, it won’t show the decrease in Cosmic rays near the poles that I see.) There was a coronal mass ejection that just hit the Earth (http://spaceweather.com/archive.php?view=1&day=26&month=09&year=2011). muoncounter, you seem to know your stuff in this area. Can you weigh in on this?

While waiting for October here are a couple notes from Alaska: Observations of Climate Change from Indigenous Alaskans http://www.usgs.gov/newsroom/article.asp?ID=2931&from=news_side http://www.startribune.com/blogs/130529403.html The temp dropped below 32 on Saturday in Barrow, AK for the first time since June 29th. 85-day streak > 32 is longest on record! Previous record 68 days. The average temperature over the streak was 41.9°. The September average temp has been 5.2 degrees above normal. Average first freeze is September 7th in Fairbanks - have not had a freeze yet. This is the 6th year in a row the first freeze has taken place after September 20th.

The Rabett notes that Eric May has a heavy handed history: http://rabett.blogspot.com/2011/09/why-doj-dont-love-eric-may.html So that explains part of it - only part of it.

Bremen falls through the trap door, fat lady recalled for encore? http://iup.physik.uni-bremen.de:8084/amsr/ice_ext_n.png

Andrew: For 80N temperatures to be below average, it means that there has been below average exchange or air masses north of 80N and south of 80N. In other words, north of 80N has been more isolated than it generally does. Well, some pretty chilly air escaped and made it as far as Minnesota.

dorlomin: "only" "Pliocene\ Miocene type temperatures?" Summer heat waves would be more than inconvenient. With the faster water cycle, storms even without high wind speeds will be more than inconvenient. With climate disruption disrupting agriculture and ocean acidification disrupting our seafood, the price of a meal will be more than inconvenient. Neven: Good post. However this fatalism "The collective consciousness changes at its own pace." is contrary to the post, and certainly not what the professional deniers think. Nor what you really think, I think. Understanding changes in the Arctic is very valuable and helpful to the "collective consciousness" as well as to participants here. I thank everyone here for all your Arctic analysis. Keep it up! This will be part of what moves the collective consciousness toward serious emissions reduction sooner.

That's an emissions scenario question. If we run CO2 up to nearly 1000 ppm as some would if they could, survivors will experience a much warmer world and much higher seas than such recent times.

Maltose, too late. Bremen is up again. http://iup.physik.uni-bremen.de:8084/amsr/ice_ext_n.png

Bremen says extent increased. http://iup.physik.uni-bremen.de:8084/amsr/ice_ext_n.png

Bob Wallace, thanks a lot for your remarks and link on Jacobson!

Bob Wallace, agreed, I had read that, but is it believable? "other factors" hint Rampal

“It’s hard to predict the future of Arctic sea ice.” William Crump observed earlier that the demise of multiyear ice creates new territory for first year ice to form in and occupy year after year. Steele et al. find mostly bottom melt using this model: "2. Methods [5] Our main analysis tool is model output from a coupled sea‐ice‐ocean model of the arctic seas, the pan‐Arctic ice ocean modeling and assimilation system (PIOMAS) of Zhang and Rothrock [2003]." Does the model overestimate volume and thickness? Note the investigations of Rampal et al.: http://web.mit.edu/~rampal/rampal_homepage/Publications.html. Jacobson wants to clean up the transportion sector, and who doesn't? But as for cooling the Arctic, how much can that do vs other factors? Perhaps after this year's minimum SIE there could be a thread just for analysis of papers. For now, it would nice to have definitive explanation of why Bremen and IJIS show current extent lower/higher than 2007 at this date.

Janne Tuukkanen: "It sounds like a long shot to connect something born near Cap Verde to Arctic ice, but these systems bring winds with them." Some surprising corelations turn up. The Naval Graduate School thesis of Megan M. Stone, LONG RANGE FORECASTING OF ARCTIC SEA ICE (pdf) is an example. Conclusion: Our results indicate that viable long-range forecasts of October SIC in the Beaufort Sea are possible via the use of Beaufort Sea SIC and Caribbean SSTs at lead times of one to five months. While our results show a definite correlation between these two variables and October SIC in the Beaufort Sea, we suspect that there are additional factors and dynamics that play an important role in the variability of SIC in the Beaufort Sea. Our study is meant to emphasize how advanced data sets and methods can be used to generate skillful long-range forecasts of sea ice amounts in the Arctic for use in operational planning by the U.S. Navy.

Did Prof Mandia say "statistically overdue?" I suggest that this phrase be reconsidered. Think about it, or look up "exponential waiting time."

"All in all, a lot of natural" (or anthropogenic) "catastrophes in the past 2 years." Yes, a couple. Or five comment pages worth for 2010. For the USA this year, Hurricane Irene hasn't come ashore and may not but if you look at Capital Climate and keep clicking Older posts at the bottom, extremes keep coming longer than you can keep clicking.

Tom Z, are you familiar with the tropicalista Tom Zé? http://en.wikipedia.org/wiki/Tom_Zé --- I'm not sure this great ice-empiricist blog would be much improved by digging into why various models under-predict the melt. Instead that might bog the blog down. For my part I seem to read a climate paper or a good chunk of one if it's long most days, although I don't start with that intention. For the Arctic Sea Ice blog, I think keeping up with the ice is the important thing. The new paper by Rampal et al. brings more physics to the Arctic models. This will add understanding of the process. I hope the pdf will be available soon. But now I only want to bring http://chronicle.com/blogs/wiredcampus/the-public-playing-a-molecule-building-game-outperforms-scientists to your attention.

For a good bit of perspective on models one might look at http://www.realclimate.org/index.php/archives/2011/08/cmip5-simulations/ and follow the link to Schmidt, G.A, 2010: Enhancing the relevance of palaeoclimate model/data comparisons for assessments of future climate change. J. Quaternary Sci., 25, 79-87, doi:10.1002/jqs.1314. ... and the conclusion may be that it is best to keep on watching the ice closely.

Rampal et al. abstract. Perhaps the flurry of Arctic models will settle down by 2014. For now this empirical blog is as good a source on the Arctic as any. I encourage you again to look into heat sources including ocean currents and to think about how you might synthesize all that you know into a coherent explanation. Start thinking now; the ice won't last forever, and who better to write its story? Ten years from now this year's climate, this year's models and this years Arctic will be history.

Funder et al. 2011 is a wonderful paper and a wonderful addition to this blog. It starts on a wonderfully empirical note: Driftwood on Greenland’s raised beaches and shores originates from transocean drift from Asia and America. The voyage takes several years.... and ends with this long paragraph (breaks and bolding inserted by me) arriving at specific significant room for improvement in climate models: In general, our sea-ice record for North Greenland follows the Holocene climate development, with an early warm period followed by declining temperatures, which were punctuated by relatively warmer and colder intervals (17, 25). The reduction of the HTM sea ice in northern Greenland fits with the simulated ice distribution and surface temperature in orbitally forced ECHAM5/JSBACH/MPI-OM (EJM) and LOVECLIM general circulation climate model simulations (3, 4, 10). A tentative first approximation of the large-scale changes associated with the observed ice retreat north of Greenland can be obtained by selecting among the numerical experiments performed with the LOVECLIM model those that are the most similar to our observations [experiments E3 to E5 (3) and fig. S3]. In this exercise, our records would correspond in the model to an Arctic Ocean sea-ice cover in summer at 8 ky B.P. that was less than half of the record low 2007 level. The general buildup of sea ice from ~6 ky B.P. agrees with the LOVECLIM model, showing that summer sea-ice cover, which reached its Holocene maximum during the LIA, attained its present (~2000) extent at ~ 4 ky B.P. (fig. S3). However, despite the similarities at large scale and the long-term trends between model and observations, the complementarity in sea-ice abundance between East (Ellesmere) andWest (Greenland), which is seen especially during the HTM, is not simulated in the climate models. The largest reduction in the EJM is indeed seen in the eastern part of the Arctic in association with an enhanced oceanic circulation and net northward heat transport (4). However, there are no signs in the EJM or in LOVECLIM of a concurrent simulated increase in the West. It has been seen in recent years that there is a strong influence on the sea-ice variability from the large-scale atmospheric flow anomalies and associated wind stress (1, 2, 23, 24), and the importance of wind-stress is also known from basic sea-ice physics. Thus, it is likely that the model deficits are related to a too-weak large- scale AO-type flow response to the orbital forcing during the HTM. Such troubles in reproducing past sea-ice variations may also have an impact on future simulated regional changes using the same models. Therefore, improved understanding of these inconsistencies is important. [breaks and bolding inserted] Along the way we gain interesting food for thought like At ~2.5 ky B.P., an era of dramatic centennial fluctuations in driftwood abundance and of change of source areas began. and also learn more about the famous MWP. What a great experience for a team with many graduate students (I presume) to collect data along 500 km of wild, cold coast and then publish an important paper in Science! What a refreshing change of pace for this blog, excellent as it is, to look at a much longer perspective than "which way is the wind blowing at this moment."

aha! Lodger that's the one. Thanks again. Meanwhile back on the ice, this looks like a good time to study pure melting in place. What is known about the import of heat by ocean currents?

Thanks for those links, Lodger. I seem to recall something else as well. Sea water keeps getting denser as it cools toward freezing (at nearly 2 kelvins below the freezing temperature of pure water). So the coldest water keeps sinking until there is enough of a stack of very cold water to slow the sinking enough for the upper water to freeze before it sinks. On the other hand, if the Arctic surface waters became very fresh for some reason, say a collapsing ice sheet, the Arctic sea might freeze as fresh water does, leading to a much greater extent and a severe winter. I hope the chance of this is below .1.

Thanks Tzupancic1 for posting this reference: Kinnard, C., Zdanowicz, C.M., Koerner, R.M., and Fisher, D.A. "A changing Arctic seasonal ice zone: Observations from 1870-2003 and possible oceanographic consequences. Geophysical Research Letters 35(2): art. L02507, 2008." "Notes: Changes in the extent of seasonal ice were investigated using historical and satellite observations for the period 1870-2003. The seasonal ice zone (SIZ) has been gradually expanding since 1870, with a marked acceleration over the past three decades, and has migrated north to encompass all peripheral Arctic seas. The expansion of the SIZ may be increasing the salinity of the upper Arctic Ocean, consistent with recent observations. The migration of the SIZ over continental shelves may also be enhancing the formation rate and salinity of Arctic deep waters, which are subsequently advected to the convective region of the Greenland-Iceland-Norwegian Sea, thereby influencing the formation of North Atlantic deep waters and related global thermohaline circulation." 1. I find no free pdf of this paper. A note from the redoubtable Neven blog would probably motivate the authors to put it online (ditto for other papers). 2. Isn't Arctic salinity now decreasing in some areas due to the de-permafrosting of Siberia? It would not be at all nice if the Arctic sea became fresh enough to freeze from the top down. I believe Lodger once posted a link explaining the freezing process but I can't find it now.

"Man, this is exciting!" Perhaps one day when the ice is gone someone will write an epic poem about it in Old Norse. And a scientific book explaining how it went down. Will that be possible? Can you synthesize? It's reported here like a boxing match. ;) What's the scoop on heat import? The roles of melting in place vs blowing away? I don't expect anyone to have all the answers off the top of your head, I just want to plant some thought-questions.