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Yes my priction for PIOMAS minimum changed from 2.5 to 2.2 K Km^3. I am a bit worried that looks a bit crazy alarmist but it had a better fit - RMSE of .55 instead of .6. Anyway we will see what the rest of melt season brings.

Wonder if this will provoke any reaction.


Crandles, as I was on line, my 'last words' before nighttime are for you.
Good work, daring on volume. I wonder how extent will look like with such low volume.
I'll have a better read tomorrow.
Sleep well.


Hi crandles,

I have been wondering if the shape of the ice sinewave pattern is changing so that the bottom is getting wider, more than it is getting deeper...

Amongst this spaghetti...


it seems, for example, that in 1996, the ice level declined, spent a few days bobbing along the bottom, and went up again.

In the recent, post-2007 period, the period at or near the bottom seems much longer. I'd suggest this is possibly a scenario where the melt collects all of the "low hanging fruit" earlier, but then has more difficulty melting the last bastions of ice in the Arctic Basin and Canadian Archipelago. Extra heat accumulated in the Arctic then goes into delaying the refreeze - leading to a graph with an even bigger bottom.

So, beware the fat-arse graph trap!

Aaron Lewis

It is in the nature of non-linear dynamic feed back systems that when they are out of control and seeking a new equilibrium, they exhibit behavior that is not predictable from the behavior of the system while it was "in control".

In statistics one must always compare (ice) to (ice). However, these days statistics on the Arctic is always a comparison of (ice) to (ice plus a lot of heat). Some times ice plus a lot of heat is ice, some times it is water, and sometimes it is water vapor. There is no way of predicting what ice plus a lot of heat will be by doing statistics on ice, unless we also do statistics on the heat. Nowhere, do I see a good heat balance on the Arctic. Even the accounting for the GIS leaves out latent heat.


>"beware the fat-arse graph trap!"

Also beware of the differing interpretations of the fat-arse.

One interpretation could be that we are getting down to difficult to melt MYI that takes a few years preconditioning and will then resume sharp downward trend.

Another interpretation might be that the tough to melt ice might be due to deep water meaning that there is little upward heat flux so that it is a near impossible job to melt it all with top melt only. This might mean a very long time before ice free situation is reached.

Another interpretation might be that it is just chance fluctuations that have given appearance of a fattening arse.

>"Nowhere, do I see a good heat balance on the Arctic."

I am taking it that PIOMAS ice volume is as good a measure as we have got. That suggests 1.1 K Km^3 less than last year at 30 June. Higher than the long term average but near the recent average, so no sign that we are slowing down in our rush to ice free there.

Charles Longway

Crandles - Great post!!!
Could export displace ice that is in a difficult to melt location? When I looked at the UB map today I see what looks like a wedge of ice pushing south in Fram. With weaker ice, could export cause more damage than in the past. Last year we had the suprise of flash melt, could we have flash export?



Well I think the ice would move faster if there is less ice resisting such movement. To me this suggests that the area exported might remain fairly similar despite the faster movement so that the volume exported is lower.

I would hope this is a negative feedback. It may already be built into trends but hopefully it could perhaps become a stronger effect as ice retreats.

Yes I agree about seeing a wedge moving towards Fram over past few days. I tend to see this as a weather event. It was certainly predictable from forecast weather patterns, Neven mentioned it. Such weather events have happened in the past and will occur again in future. Is there any reason to think frequency or strength is changing?

Bob Wallace

"area exported might remain fairly similar despite the faster movement so that the volume exported is lower"

That would happen if we were transporting more thin, FYI. But if it's thicker MYI going out then volume export will rise.

I suspect the first meltout will follow right after the Great Thick-Ice Flush of 201x.


Really good post, especially the discussion section.

time was limited and there may well be better schemes

With none of the approaches able to rule out a summer melt-out in the next few years, time is rather limited for all forecast attempts. No doubt the best hindcast will come from a physical model, but the statistical answers are available here and now.

So, thanks for a brave, reasoned contribution and post.


Thanks for the thanks. Will just have to see how quickly daring and brave turns to foolish.


Hi all,

SEARCH July is out:


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