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There is less easy ice on the periphery in the first half of the year also, but volume loss has skyrocketed in that period. Recent years have had significantly more overall volume loss than years before 2007. Most likely the explanation is that ice is becoming steadily thinner. This allows insolation to increasingly dominate the melting season. More ice will melt at the peak and early in the season. Less ice will melt late as insolation decreases. It's possible that less available ice to melt will also become a factor at the end of the year.,2098.0.html
Toggle Commented Jul 13, 2017 on PIOMAS July 2017 at Arctic Sea Ice
NeilT- The ice did not recover more quickly the first 3.5 months of the freeze season in 2012. At the start of 2013 it was still comfortably in record territory. From January to mid-March it set a record for refreeze though. Why the late spike? It wasn't temperature. For the first 2/3rds of that period it was warmer than average, and colder the last third. The most likely explanation is significant storms. Just like a storm in summer will cause greater melting due to mixing, a storm in winter will cause greater freezing. You probably remember that this was the time that many people in this forum were following the large ice cracks. Also, the Piomas thickness chart showed that the ice had been heavily pushed to the east that winter.
Toggle Commented Sep 14, 2014 on Ever sailed to 85N? at Arctic Sea Ice I saw this and thought of this post. This is one cruise I'd be really interested in going on. I don't have a spare 20,000 though. Do you think these sorts of cruises would help by drawing more attention to the Arctic? Or would it hurt by being just another environmentally questionable activity?
Toggle Commented Sep 13, 2014 on Ever sailed to 85N? at Arctic Sea Ice
"many sceptics also gave great value to your work, a pity you have lost that trust." Please. Who are you trying to kid? The overwhelming majority of "skeptics" are doing everything they can to avoid the truth. There is no trust to be lost. As for avoiding politics, that is impossible. The Republican party has made denying science one of their primary planks. It needs to be pointed out as often as possible that they have no credible basis for their extreme anti-scientific views.
Toggle Commented Sep 16, 2011 on And now, a word for our sponsors at Arctic Sea Ice
Does anyone have a good guess of how much sunlight/weather/SSTs relatively contribute to ice melt at different points in the season? Or, put another way, how much of the variance in ice melt is explained by sunlight/SSTs? I was under the impression that SSTs were more important at the end of the melting season. SSTs are still very warm this year. Unless they are always a small factor it seems strange that people are so confident this year's minimum has been reached.
Toggle Commented Sep 14, 2011 on The fat lady's singing at Arctic Sea Ice
Is there a concise post somewhere that explains the different methodologies that Bremen, IJIS and NSIDC use? Are these the only 3 groups tracking arctic ice? What does NCEP/NOAA do? I think a post explaining all the different agencies and their basic methods would be useful.
Chris R, I don't see the problem with 2007 that you do. A certain amount of melt each year will be caused by random weather patterns. 2007 was a truly exceptional weather year. When you smooth out the random weather variations on the volume/area/extent curves they all show a steady pattern of accelerating decline. Now I'm not saying that random weather/simple trend lines necessarily explains everything, but it seems close enough to what you would expect that there doesn't seem to be a huge need to invoke some unknown third factor.
On the AMASIE graph, it's pretty clear that the 30 year straight line they use is not the best fit. A 15 year straight line would give a far steeper decline curve and match the recent data much better. Are there any scientific reasons to choose the 30 year line over the 15, or is it just excessive caution? Is there anyone here who thinks their 30 year trend would more accurately predict future melt than a 15 year trend line? Personally, if I were betting I might go even steeper than the 15 year trend.
Not to take things too far off topic, but the last few posts raise a philosophical issue. First of all, Katia will not hit the US, so we are discussing hypothetical disasters here. Climate change is going to increase the incidence of extreme weather events in the future(and probably in the present as well). The simple way to think of this is of a loaded pair of dice. No specific event was caused by CC, but each specific disaster was made somewhat more likely by it. There are those who say that we should never point out that a specific event was influencedd by CC, out of decency, accuracy or whatnot. This seems disingenuous to me. Never admitting specific damage caused by climate change is exactly what the climate deniers would want. Instead, I think we should start identifying those disasters that were made more likely by CC(assuming the science is better than speculative). Obviously there shouldn't be any morbid celebration over the suffering of others. But on the other hand, people need to be constantly reminded of the practical consequences of global warming because there are far to many people who are in complete denial.
I realize his opinion is based on trends. I was trying to point out that the trend is decreasing too fast to make it the strict arbiter of reasonableness. Maybe the fast-melt advocates just had a really lucky decade, but with each passing year it's more likely that they are right and the mainstream consensus is wrong.
First of all, while volume measurements are less accurate, it isn't exactly throwing darts at a wall. But lets look only at extent and area- there is now a 30 year trend that shows the arctic will be seasonally ice free in 20-30 years. Since just a few years ago some scientists were predicting that the ice would last 100+ years, this is a pretty extreme change. While predicting the exact year is impossible, I think it is quite reasonable to publicize the fact that the arctic is melting way faster than predicted in earlier climate models. At this point, all the statistics are on the side of the "alarmists". But let's suppose that you now want to reject the statistical argument since it clearly doesn't show what certain groups would want it to. Do you have any scientific reasons why the 30 year trend is likely to reverse itself in the near future?
It looks like the two competing trends must be reconciled soon. The volume trend seems to show a virtually ice free arctic by 2015. The area trend is much slower, with the ice free date appearing to be around 2040. Why is the area trailing the volume by so much? Will the decline in volume eventually force the area to catch up? Are there other factors that are going to slow the volume trend in the near future? Is it reasonable to assume that the ice free date will be between 2015-2040, or are both trends going to be superseded by a well hidden third trend? On the one hand, an ice free arctic in a few years might be the shocking event that the world needs to wake up to the reality of global warming. On the other hand, I don't think we should be making strong predictions until we have good answers to those four questions. The skeptics have quite the propaganda machine. We can't afford to make any significant errors in predicting certain events too early. Maybe the best approach would be just to publicize the obvious trend-lines along with a few potentially relevant factors, and tell the public that they should draw their own conclusions. Let them think that they are figuring out what is going to happen rather than being told. The general public might never reach a correct conclusion about something as complicated as a proper forcing value, but the arctic data seems simple enough that just handing them the raw data might get them to invest more into the idea of global warming.
I am actually curious about the albedo question. How much faster is the entire planet likely to warm once the arctic is seasonally ice free? Most global warming questions are easy to find answers to, but I've had trouble finding much on this.
Toggle Commented Aug 19, 2011 on Polar ice caps can recover at Arctic Sea Ice
Has anyone correlated CAPIE with sea ice extent 1, 2 and 4 weeks later? This seems like a simple test that would give us a better idea of the extent to which CAPIE values might predict future ice melt.
Toggle Commented Aug 15, 2011 on CAPIE hits record low at Arctic Sea Ice
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Aug 14, 2011