Veli Kallio and R. Gates, I am visualizing what a localized cooling would do so far south with all that extra energy in the atmosphere from more distant regions.

Veli Kallio, Sounds at least plausible...do you have a timetable for these events to occur? How much ice would have to melt and how far from the edge of the ice sheet would this have to happen before we see these events?

2.4Mkm^2 The NAEFS 8 to 14 day forecast shows above normal temperatures over most of Siberia for that period which should melt more snow than normal there. It also shows North America to have below normal temperatures near the Arctic which should preserve snow there. Nevertheless the lack of snow in Siberia should have a greater influence. Much more of the ice is first year thinner saltier ice which will be more prone to melting earlier and will more likely lead to an earlier warming of the surface waters bringing warmer temperatures to the remaining ice. A fair portion of the older thicker ice has moved into the Beaufort Sea or near the Beaufort Sea in the Arctic Basin. Since this has mostly melted during the previous several years I expect it to melt this year too...likely even sooner because there is even less of it. The Bering Sea now has nearly an average ice area so warmer water should develop there sooner than last year and aid in melting out the Chukchi Sea sooner than last year. There are numerous polyanas. The wind could affect extent in September if a spreading event or a compaction event occurs near the minimum.

Steve, Western Washington State about 45.8 degrees north and 122.7 west in between the storminess in the Pacific and the cold weather farther east. My point is that it is far from cold in mid latitudes everywhere.

Currently on the West Coast of North America we are having a "Summer in March" event. Temperatures have been 22C to 26C for the past 2 days with abundant sunshine. The forecast is highs in the 20C to 22C for the next several days. Average high temperature for the first of April is around 14C to 17C according to the Weather Underground for my area. With one minor exception the weather this winter has fluctuated between warm and wet and trending warmer and drier as winter turned to spring. Just saying it is not cold everywhere. From the looks of things some of this warmer air has moved close to the Arctic Ocean. This warmth will at least affect the peripheral Arctic regions as it pushes northward.

Taxing carbon makes a lot of sense. Carbon can be taxed substantially, however it makes more sense to use the tax money to heavily subsidize solar power, wind power, and other "alternative" energy sources. This should result in a fairly rapid change of energy sources. I haven't addressed the complications of changing to a different source of electrical power either. Part of these carbon tax revenues would likely also need to be invested into energy storage systems to stabilize supply fluctuations that would occur using solar and wind power sources. Here in the United Stated Pacific Northwest some of the windmills have to be feathered at times because in combination with hydro power there is too much power for the grid to handle. One coal power plant has already been closed and another one is currently on the block to be closed soon.

I went to see the movie, "Chasing Ice," http://extremeicesurvey.org/ today. I highly recommend it on at least 2 levels: 1. The photography is absolutely astounding. James Balog and his crew take risks, endure boredom, equipment problems, and other difficulties to capture the most fantastic scenes of nature I have ever seen. 2. The implications of climate change come alive in their photography, especially the time-lapse movies. We can look at modeling, graphs, data, etc., but when the immensity of disappearing ice happens right before our eyes it startles and is very scary. The latest photos are mostly 2009, 2010, and a few in 2011 so they don't show the effects of the 2012 melt season, so, I expect even "greater" things are in the "can" so to speak. Also, in the movie, the Ilulissat Glacier calving shown was attributed to the 2009 calving event. It makes sense that the IPCC should also consider this documented evidence that is happening right before our eyes.

bluesky, If you have ever driven through the Clark Fork River Canyon in Montana you will notice that it is a narrow downhill sloping canyon exiting the large basin that otherwise confined Lake Missoula. Sounds pretty similar to the outlet fjords in Greenland.

In western Washington we have fog and low clouds that last for a week or more sometimes if no storms happen to come along to clear the fog. During periods when solar radiation is not great enough to clear the fog out(November 10 to February 1) under a typical scenario the temperature falls and ground fog under clear skies. Over the next few days the fog thickens and and lifts slightly and temperatures warm close to the ground below the fog which is now just a low stratus cloud. Typically, if this lasts for a week the bottom of the clouds is now about 200 meters above ground level and drizzle and light rain may fall with temperatures that may vary less than 1 degree C. over the course of a day or several days. I suspect that in the Arctic with ice free conditions and no storms to clear fog and low clouds, conditions would develop similarly and very little heat would be lost to space under those conditions.

Werther, Since there have been many large ice dam collapses(a hundred meters in height or more), it seems prudent to consider the possibility that ice dam structural collapses like these will happen in Greenland even if we don't think so or quite understand how they happen. One of the things I have learned is that if it has happened numerous times in the past it will happen under similar circumstances in the future whether or not anyone understands the process. It certainly looks to me like it won't be too long until parts of the GIS becomes similar enough to past conditions to allow for large ice dams to form. Also, I have read about ice structure in deep ice on this blog in the past or links from this blog. I searched for this/these reference(s) but was unable to find anything. If I remember correctly, ice under more than about 800 meters of top ice acts quite like a pliable solid and any plumbing that opens up by water pressure quickly closes as soon as the water drains. Dams would logically form at a critical interface from shallow ice where the water continually drains away to where the water floats the deeper ice because of the dam. I know this does not explain the upper portion of the deep ice where the water could conceivably drain away nor exactly how the process works. Nevertheless, large ice dams have formed and collapsed hundreds of times.

Aaron, Sam, I think you are a little optimistic about water wearing down granite and basalt quickly. Beacon Rock bore the brunt of the deluges in the gorge which washed away the pumice and tephra yet had minimal affect on the basalt core which stands about 600' high along the Columbia River near Bonneville Dam today. Even though a fair percentage of the water was rocks mostly 1' in diameter and smaller the basalt was barely affected. I live on the outflow deposits of these floods and rocks 1' and smaller form at least 100 layers a few inches to 10' thick in gravel bars up to a depth of 200'on top of an underlying clay layer and bedrock. I agree that if large floods from ice dam ruptures happened here over 100 times, then it will likely happen numerous times in Greenland as well. Soft material and loose gravel will be scoured out but I do not see the granite being affected much in time periods of a few days. I expect to see the flood like happened in Greenland last year repeated in numerous places in the future with the larger floods being several magnitudes larger as the breadth of the melting increases.

Thanks. Artful Dodger and others. I an thinking it only takes a small amount of water to float a large amount of ice especially in the right terrain. I have done the experiment of freezing a tapered jar mostly full of water then melting just enough to float the ice. It takes less than a tablespoon of water to float a pint of ice...not saying that a valley full of ice could be floated quite that efficiently however.

Everything I read here seems to get more and more troubling. I don't see any indications that this trend won't continue...albeit with possible stops and starts. I do have a few questions which I have seen alluded to in this blog previously: How much of the water from the melted ice is still trapped under the GIS? Will this water eventually be released in large avalanches and floods or will it gradually escape as the ice melts. Due to the history of the Missoula Floods I lean towards large avalanches and floods. What is the thinking of the ice experts. If you could direct me to information about this topic I would much appreciate it. Thanks.

Bluesky, yes it is important to help educate others about the dire consequences of climate change. I too find that there is a wide disparity between many other peoples' reality on this subject and what is actually likely to happen in the near future. Since the consequences of climate change seem mostly unknown or minimized in the minds of many people I know, it is important to help educate these people. I have sent a number of people to this blog to read and learn as I have done before them. Quite frankly, my beliefs about this particular problem parallel the beliefs and opinions of those here who are closest to the idea that this problem will be catastrophic in the not to distant future. It is important that this blog continues to help educate all of us already here and to help others get the best information available so they can educate themselves. Thanks, Neven and the others who contribute so much!

Terry, you are correct. I have seen ice form on freshwater ponds with temperatures as warm as 2C under very dry windy conditions. What is also surprising is how fast ice melts at 0.5C under high humidity conditions.

Peter Ellis, so do you think we should be greatly concerned about ice dams? It seems to me that events that have happened many times previously will likely happen again under similar conditions in the future.

"And, if you think like a mine engineer, and do a structural analysis of the GIS with moulins, and account for the structural strength of ice at various temperatures, then the GIS does not melt in place, but undergoes a progressive structural collapse resulting in a ice/water slurry with large horizontal velocities."--Aaron Lewis Aaron, it sounds like this would cause giant tsunamis. I live on 100 meters of layered sediments left from the series of Missoula Floods. I live near a road cut that exposes about 10 layers of this sediment about 20 meters high. The thickest layer is about 3 meters with most others being 1 to 2 meters thick. I first recognized these as flood deposits in 1961 when I was still in grade school. I finally put it together about 2 or 3 years later when I saw Dry Falls in eastern Washington. I finally read about the Missoula Floods (www.pbs.org/wgbh/nova/megaflood/) in about 1968 and everything made sense. I recently talked to a farmer from eastern Washington in the Yakima Valley who said he had a canyon which exposed about 100 layers of Missoula Flood Sediment. Similarly, I suspect that ice dams will build up in numerous valleys in Greenland. I takes very little water to float ice if it rises in cracks and collects at the bottom of the ice sheet. When the water rises high enough the ice will float dammed by the dam in the valley which will catastrophically collapse. i see no reason why this could not happen with minimal or even no water exposed on the surface releasing Possibly 1000 km^3 or more of ice and water causing large tsunamis. There is evidence that these types of floods have occurred in many places at different times over history like the St. Lawrence Seaway http://geology.gsapubs.org/content/38/4/383.full Oregon State University http://wave.oregonstate.edu/ has carried out tsunami research that suggests that these types of tsunamis would be indeed very large. Aaron, your comment about "large horizontal velocities" from an ice collapse in West Antarctica imply an even larger tsunami than from Greenland. I personally consider these types of events likely if not imminent but not sure how soon. Hopefully someone with more knowledge of ice sheet disintegration than I can help provide some answers. Also if this does happen how large do you think some of these tsunamis would be? So, Mdoliner43 this is something I have been thinking seriously about since I read about it in Scientific American circa 1993.