Looks to me like a decline from 1988-2007, and flat to up since.
Are we not yet at the stage for “rotten ice” claims or are those passé (since the ice is getting thicker every day…)
Its the flat line variety of a spiral……
Yes, the flat line. It’s an interesting thing to think about. The last 4 summers have seen a 70% reduction in the maximum to minimum ice extent. In the 1980s it was 56%, in the 1990s it was 59% and from 2000-2006 it was 61%. I’m guessing this summer will be similar to the last four. So while 2007 was not a death spiral, perhaps it did help cause a switch to a new seasonal ice loss state.
Hi Dr. Stoeve. Hoping not to be impertinent.
Would the above not be a function of the general global increase in temperature?
Is it unreasonable to expect that if global temps reverse course that so will the trend in reduction to become a rate of increase?
No worries, PJB. Certainly by a new seasonal ice loss state, it could be a variety of things. I’m first thinking of a thinner ice pack, which was clearly observed to happen after the 2007 minimum, which then makes the ice cover more sensitive to atmospheric forcing. With a thinner ice cover, open water areas tend to develop earlier in the melt season, helping to enhance the ice-albedo feedback. A thinner ice cover is also more easily moved around by the winds, with impacts on the amount of ice transported out of the Arctic Basin and on compacting of the ice cover.
But then we also have warmer temperatures. Looking at near surface air temperatures from 1979-2011 and deriving anomalies with respect to a 1979-2010 mean, you clearly see the last decade has been warmer in all seasons than the previous two decades. Some of that will be an artifact of reduced sea ice cover, some from advection of warm air into the Arctic. I don’t think it’s unreasonable to expect that if temperatures were to drop that ice would grow back, and several climate model simulations have shown just that. So no tipping point in the climate models. I guess the question is what will cause temperatures to reverse? And how many years would you need? Some simple modeling shows that the ice extent comes back quickly (within a 2-3 years) whereas the ice volume takes a bit longer (5-10 years). This simple calculation while using the Los Alamos sea ice model and forced with NCEP Reanalysis data did not include coupling with the Ocean, which cannot be neglected. In fully coupled GCMs with GHG mitigation scenarios you do end up with some recovery, but not a full recovery.
“Yes, the flat line. It’s an interesting thing to think about. The last 4 summers have seen a 70% reduction in the maximum to minimum ice extent. In the 1980s it was 56%, in the 1990s it was 59% and from 2000-2006 it was 61%. I’m guessing this summer will be similar to the last four. So while 2007 was not a death spiral, perhaps it did help cause a switch to a new seasonal ice loss state.”
So you are practically saying that the ice seen at the end of 1970’s is the NORMAL amount, that is your Holecene optimum, and is what we need to spend trillions on getting back to. Who are the ‘Climate Change Deniers’ now?
The laughable thing is that it is all still here anyway! The water is all still here, changing states every year as it has since the ice-ages began.
why would sea ice extent correlate to global temperatures when there’s lots more nearer and stronger factors at play such as local temperatures, winds, sea currents etcetc
lol, well, determining local temps seems to be quit a trick…….Omn, check this out….
Steve feel free to expand and expound if you wish….
Here’s DMI’s temp record above 80 degrees north….. I’m sure we’re all familiar…
Here’s GISS’ interpretation of this June’s temps up in the polar region.in a reply to myself…….can’t get July’s yet….. but we know what it’ll show.
Note! I changed the base period of GISS’ map to the same as DMI’s 1958-2002. Weird huh?
Here’s GISS’s for those who are playing along at home.
Thanks for that, Julienne. “A new seasonal ice loss state” is a far more rational and sensible description than “death spiral”, and one that few people could take issue with given the observational evidence.
My take is that the increase in summer ice melt over the last 30 years has been associated with the increase in Arctic Ocean Heat Content :
Assuming Bob Tisdale’s figures are somewhat correct, it certainly passes my “eyeball test!” (:-
What may, or may not, happen in the next 20 years or so is anyone’s guess, IMO. All we can do is pull up a chair and watch.
Certainly ocean heat content is a large player, and it’s that “player” that Dr. Maslowski has used in his arguments for a rather fast transition towards an ice-free summer state. I would like to see more studies quantifying the amount of ocean contribution to sea ice loss. The buoy data from this summer though doesn’t seem to show much anomalous bottom melting, so I’m thinking it hasn’t been a huge player this year, but the buoys are basically point measurements so it’s hard to know how representative they are for the entire Arctic Basin.
Julienne, you asked a question about which temperature set to trust….
….this is why so many of us do not trust any of them
Atmospheric temperature measurements biases on the Antarctic plateau
Christophe Genthon, Delphine Six, Vincent FavierLaboratoire de Glaciologie et Géophysique de
l’Environnement, CNRS/UJF, Saint Martin, d’Hères, France
Matthew Lazzara, Linda KellerAntarctic Meteorological Research Center, University of Wisconsin-Madison, Madison, USA
Observations of atmospheric temperature made on the Antarctic plateau with thermistors housed in naturally (wind) ventilated radiation shields are shown to be significantly warm biased by solar radiation. High incoming solar flux and high surface albedo result in radiation biases in Gill (multiplate) styled shields that can occasionally exceed 10°C in summer in case of low wind speed.
What was sea ice like in the 1920’s and 1930’s? There must be some records going back that far. Was the sea ice more like now or more like 1980?
Thanks for the instructive answer.
On a somewhat more theoretical note, would this type of system be in a sort of dynamic equilibrium and necessarily have nodes or pivot points around which it would oscillate? The presence and various phases of the AO as well as other oceanic and atmospheric currents would also have to be in relative harmony with the various states of quasi-equilibrium, wouldn’t they? Thus, all of the mentioned phenomena would just be markers on the cyclical curve?
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