" expect most of you will not be surprised by Arctic collapse dramatically increases global warming. I was pleased to hear about it on BBC Radio 4. " Link to the original article in Nature: http://www.nature.com/nature/journal/vaop/ncurrent/full/nature11392.html

"I do not think that the graph shows minimum extent. Putting the near minimum value of 2012 in, is not correct." Yes, Kinnard's extent is for August (probably average). The 20th century data are a combination of a russian reconstruction, and the well known "crysophere" reconstruction ( http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seasonal.extent.1900-2010.png )

"I don't know why, but that actually made me laugh, so thanks, Alexander. Coincidentally I'm using the Kinnard graph for the piece that will be published tomorrow. But I might use yours too for a separate blog post in coming weeks. So thanks again!" It is a very good Idea to complete de Kinnard's figure with the 2012 record. However, I think that it deserves a better method than just adding the 2012 value. Here is the supplementary materials of the Kinnard's article: http://www.nature.com/nature/journal/v479/n7374/extref/nature10581-s1.pdf figure S1 shows the recent values. It seems that the "late summer" values (August) are a little bit higher than NSIDC record for the corresponding year. We should try to match the 1979-2000 NSIDC data with the Kinnard's data and then show the 2012 record with the appropriate scaling. All the Kinnard's data are available online: http://www.nature.com/nature/journal/v479/n7374/full/nature10581.html?WT.ec_id=NATURE-20111124#/supplementary-information

I see differences between the new "SMI index" figure http://neven1.typepad.com/.a/6a0133f03a1e37970b0167694a8ba3970b-pi and this old one published in 2011: http://www.greenlandmelting.com/uploads/1/3/0/5/13056389/7577718.jpg?1343568281 2007 was the second highest melting years, but not in the new figure... Change in methods ?

Relevant publications Polar lows as arctic hurricanes http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0870.1989.tb00362.x/abstract À hurricane-like polar low fuelled by latent heat flux http://onlinelibrary.wiley.com/doi/10.1002/qj.1876/abstract?deniedAccessCustomisedMessage=&userIsAuthenticated=false

"An excellent temperature graph provide by Chris Shuman, NASAfrom the Greenland Summit puts 2012 in perspective versus other years." The graph has been updated with the end-of-july "heat wave" event: http://jcet.umbc.edu/2012/07/nasa-72412-press-release-green.html

Summit, top of Greenland Ice Sheet (3199m), reports O°C / 32°F. http://www.summitcamp.org/status/webcam/ Actually, temperature is constantly above -4C/25F since about 36 hours: http://www.summitcamp.org/status/environmental/?period=week A new massive melting event ?

@Glacierchange Thank your for the data ! Is the plot regularly updated ?

"The melt reported by NASA this week was a rare weather event, as Dr. Wagner explains rather well." We will see tomorrow Last GFS weather forecast continues to see all Greeland above 0°C: http://imageshack.us/photo/my-images/19/rtavn3654.png/ IMHO, such global melt event should be analyzed in the context of positive trends in the surface melt. As reported in this study: http://www.igsoc.org:8080/journal/57/204/j11J003.pdf The authors observed that "After 1972, the maximum melt extent increased significantly (p < 0.01) by 22% (~3.7x10^5km^2)of the GrIS area". The figure 4 is also very informative. With a constant increase in melt surface since 1972, the probability of occurence of a global melt event should also increase. In fact, it was already predicted by J. Box: "In the 12 years beginning in 2000, the reduced albedo combined with a significant increase in downward solar irradiance yielded an accumulation area net radiation increase from 􀀀0:9 to 􀀀0:2Wm􀀀2. Another similar decade may be sufficient to shift the average summer accumulation area radiation budget from negative to positive, resulting in an abrupt ice sheet melt area increase. The ice sheet mass budget deficit is therefore expected to become more sensitive to increasing temperatures via the ice albedo feedback, especially in negative summer NAO index conditions. Future work should therefore be concerned with understanding potential tipping points in ice sheet melt regime as the average radiation budget shifts from negative (cooling) to positive (heating), as it seems the threshold of this has just been reached. It will take some time, perhaps years for the cold content of the firn to be sufficiently eroded to allow continuous summer melting and an ice sheet surface characterized by 100% melt extent. Further warming would only hasten the amplification of melting that the albedo feedback permits." http://bprc.osu.edu/~jbox/temp/Box%20et%20al.%202012%20-%20TCD%20-%20resubmitted%20after%20review%20round%202.pdf

" Well, this melt may prove to be not very exceptional after all. In fact, based on the forecast it may happen again this weekend." Indeed, last GFS forcasts all greenland above 0°C: http://img849.imageshack.us/img849/3793/rtavn6052.png Wunderground forcast for Summit: +1 max on Saturday: http://www.wunderground.com/cgi-bin/findweather/hdfForecast?query=Summit+greenland

I found a relevent reference from Dr Keegan: http://adsabs.harvard.edu/abs/2011AGUFM.C33C0661K The reference to previous melting events probably comes from this study, not yet published (only a congress abstract)

"I second that opinion. The Greenland ice sheet cores record more than 100,000 years of climatic history from the summit. Did nobody analyse melting lines in these cores earlier than 1750 ? If not, why not ?" An hypothesis could be that "melting lines" are only visible in fresh, not fully transformed ice, i.e. only at the top of ice cores...

Here is the last GFS temperature forecast for Saturday afternoon: http://img837.imageshack.us/img837/7664/rtavn905.png New global melt event ?

I'm a big fan of this blog, but only a silent reader, because of my difficulty to write in english, as a non-native english speaker... However, I think this article is very interesting in the context of the Watson River flooding: Large surface meltwater discharge from the Kangerlussuaq sector of the Greenland ice sheet during the record-warm year 2010 explained by detailed energy balance observations http://www.the-cryosphere.net/6/199/2012/tc-6-199-2012.pdf See fig. 8: "After passage through and underneath the ice sheet, meltwater collects in the proglacial melt river that runs past Kangerlussuaq. The freshwater discharge as measured at the bridge over Watson River in Kangerlussuaq is also illustrated in Fig. 8." Maybe someone could contact the authors to ask whether recent (2011-2012) data are available