New paper from JE Hansen, M Sato

[dnmun]

http://www.columbia.edu/~jeh1/mailings/2015/20150921_IceMeltPredictions.pdf

move it where appropriate. love your blog. exceptional quality of postings.

[Neven]

Welcome and thanks for posting, dnmun. One tip: a short summary or your opinion of the paper would make the topic more appealing to reply to, instead of just a link.

But interesting paper. I was notified of it as I'm on Hansen's mail list, but I thought it had to do with SLR paper discussed elsewhere on the Forum (where a link to this paper has also popped up).

[bligh8]

I fail to understand why the loss of the Arctic sea ice was not be included in his Amplifying
Feedback remarks.  Surely the Arctic sea ice which is now in horrible condition will be gone in the summer months by 2020 if not sooner. The resulting rise in Arctic water temperatures would accelerate the ice melt in Greenland, and as water temperatures rise this would become a major factor in the future.


http://www.carbonbrief.org/blog/2013/03/climate-impacts-of-nearly-ice-free-arctic-summers/

[crandles]

Surely the Arctic sea ice which is now in horrible condition will be gone in the summer months by 2020 if not sooner.

Surely?

Why?

Piomasmaxminmeltfreeze by crandles57, on Flickr

In 2012 the downward path looked like exponential decline but the models said a gompertz shape. Surely it now looks like the models were right and the downward trend is likely to be slow?

I don't get the mentality of this board: When the trend is sharply downward but models say trend will slow down, opinion tends to be 'wow look at that trend the Arctic sea ice will soon be gone'. When the trend levels off opinion then tends to be 'wow look how horrible the state of the ice is', we are definitely in a new regime, and implying we are bound to get another big step down soon in spite of the shallow trend. This occurs despite adequate explanations of why there was a fast downward trend that cannot continue.

Not sure whether this is just wishing for catastrophe,
or just clearly showing up a bias towards believing in CAGW, or
wanting to believe that what they are watching is important.

Whatever the reason, there seems to be dismissal of idea things won't be as bad as catastrophists are making out.

(I do expect the trend to continue downward. Yes, 4 parameter gompertz fit almost certainly gets the trend too shallow too soon and/or currently is leveling out at values that are too high. So perhaps I am going over the top showing that as the trend.)

[jai mitchell]

perhaps I am going over the top showing that as the trend

Perhaps you can show the 8-year trend?

less than this will over emphasize a two-year period with residuals that are significantly above the 2-sig mean  -  this would be a certain hit on any technical analysis.

[bligh8]

2012 was a exceptional year, but in no way distracts from the general decline or trend observed since 1979.
Why?

I felt this gentleman puts purty good reasoning behind his remarks and he's certainly qualified to do so.

I'm not really wishing for anything, but merely pointed out that Hansen left this aspect out of his paper, rather the ice is gone in 2017 or 2035 it's going and will effect the melt in Greenland.

[crandles]

Perhaps you can show the 8-year trend?

If you wish:

PIOMASMaxMinMeltFreeze (2) by crandles57, on Flickr

8 year trendline reaches zero in 2062. Of course could decide to pick 7 years or 9 years or .....

2062 sounds quite late to me and 4 parameter gompertz levels off unrealistically if I show later than 2016. Last 8 year trend seems to match the Gompertz fit slope for 2015 quite well, but I am not sure that that means anything