« Siberia burns | Main | Nares Strait 2012 Ice Arch Collapsing »


Feed You can follow this conversation by subscribing to the comment feed for this post.

Yvan Dutil

A complement of information hot from the press:



Wellwhaddayaknow. Thanks, Yvan.

Ghoti Of Lod

The PolarStern has been crossing the Fram at about 79N latitude for the past week or so.


From their meteorological reports it looks like they've just reached the edge of the pack ice in the last hour.


I wonder if they are taking temperature profiles along the was.

I also wish they had a webcam on board like the Healy has.

Doug Bostrom

A lot of work in this article. Thank you, Neven.

Wayne Kernochan

@Neven - Just wanted to say, imho, one of your very best posts. Deserving of a very wide audience. - w


Hi Neven,

This is a superb piece of work.

Christoffer Ladstein

I totally agree with the fellows above! State of art, and it also warm an old Geography heart to "rip up" old theory of all the currents out there:-).


Great stuff Neven! Thank you for all the work that you've put into this post.


Thanks a lot, everyone. It was a lot of work, but well worth it. Sorry for the long read, but it was hard to find a balance between simple and thorough. And I wanted to do that synthesis research paper justice, because it was so helpful.

I wanted to write about this for a while, but ever since Rob Dekker and Chris Reynolds had this conversation in the PIOMAS April 2012 thread I was determined to get a grip on ocean heat (because it almost certainly plays such a crucial role in Arctic sea ice decline). So my thanks go out to them too.

Ocean heat flux down, PDO and AMO left to go. ;-)


Let me add my voice to the plaudits. The long format seems to work well.



Good work from this corner as well. It's a complex subject, so needs some detail.

Otto Lehikoinen

Good work, Neven, and good work, all scientists who done this.

And what's happening on the other end of the Atlantic, one might ask. A couple of abstracts and possible research material wrt AMOC (well AMO too), Agulhas leakage seems to be the magic word on this: http://www.nature.com/nature/journal/v462/n7272/full/nature08519.html

The current systems on Drake Passage and Falkland/Malvinas are more important in the palaeoclimate studies it seems:

Espen Olsen

Nice work Neven!

Little ice around Svalbard is reducing the numbers of Polar Bears dramaticly ( you may need norwegian translation tools:

Pete Williamson

Great stuff.

You can go further south in the Atlantic and get confirmation of these trends from the 1990's onwards.

For example the Ellett Line covers a region of the Atlantic from Scotland to Rockall where about half the North Atlantic water crossover into the Nordic Seas.


That time series has been extended back further to 1948 by Met office shipping measurements to put the post 1990 changes in context.


The above is paywalled but the conclusion reads.

"The upper waters of the Rockall Trough have undergone a series of significant interdecadal changes over the past 60 years which are summarized below.

(i) A relatively warm period existed between 1948 and 1972, with winter surface temperatures of 9.68C.
(ii) Subsequently, there was a cooler period (9.28C, uSST) until about 1995.
(iii) The start of this cooler period (1972)coincided with the advent of the Great Salinity Anomaly, which itself lasted to about 1982 (minimum S800 ¼ 35.27).
(iv) There was a second, less intense freshening in the early 1990s (minimum S800 ¼ 35.30).
(v) A steady increase in u800 and S800 (to 108C and 35.41) has persisted from 1995 to almost the present day. This phenomenon, which is reflected throughout the northern North Atlantic, is linked to a changing balance in Subpolar and Subtropical Gyre waters.
(vi) Finally, there has been a steady decline in phosphate concentrations since 1996 (from 0.8 to 0.6 mM) that seems to be
linked to the increase in Subtropical Gyre water.

Most of these changes are linked to the movement and exchange of water masses in the northern North Atlantic, and it is
not possible to say whether the upward trends in heat and salinity
of the 1990s and the 2000s in the Rockall Trough will restart following their recent slowdown and partial reversal. Further, it is uncertain whether the changes of the past 15 years lie outside the
range of natural variability for the past 60 years or whether they
can be attributed to anthropogenic warming."

It's true that it's not impossible (in part) for the warming to come from the increase heat content but it's also not impossible (in part) to come from dynamical changes highlighted here. I guess the billion dollar question is the relative magnitudes of the 'in parts'.


Hi all,

Currently following football and tennis simultaneously with ice-melt, which is way outside my multi-tasking comfort level, but dimly suspect that the following may be a relevant postcript here:



Hi Neven.

Nice to see such an important subject addressed so well on my first visit back this summer season.

"Ocean heat flux, Maslowski" - pretty much my four favorite words in understanding the coming Arctic sea ice summer disappearance.

I'll have to get more Parmigiano-Reggiano and popcorn for the 2012 season...

Rob Dekker

Neven, you outdid yourself here.
What a great overview article about one of the most elusive aspects of Arctic sea ice development.

Long-term ocean heat flux under the ice has been notoriously difficult to measure accurately, as Kwok and Untersteiner so clearly acknowledge. And yet, it is the most important aspect of Arctic warming especially affecting thick, MYI ice on decadal time frames.

I feel honored that the discussion I had with Chris Reynolds triggered your interest in researching this topic.
For those who have not read through that discussion, here is a brief summary :

Basic physics (of ice growth and ice melt) suggest that heat from 'above' (such as warmer Arctic winters, or increase in GHG forcing directly over the Actic) will cause ice thickness to be reduced by a percentage independent of it's thickness. For example, warming of Arctic winters over the past few decades would explain something like 20% reduction in ice thickness, and with that, a 20% (or more, due to albedo-amplification) reduction in ice-extent/area is readily explained.

Basic physics also suggests that heat from 'below' (ocean heat flux) will mostly affect thick ice, and have much less effect on thin ice (FYI). In fact, ocean heat flux puts a hard limit on how thick ice can grow in winter.

So, if atmospheric heat (warmer winters) is the cause, then ice extent and volume reduction should be roughly the same, relatively speaking.

However, submarine ice draft measurements, and ICEsat freeboard measurements suggests that we lost some 75 % of ice volume over the same multi-decadal timeframe as we have lost 20% of ice extent, and this is presented in the results from the PIOMAS volume data.

Thus, I suggested that since the ice volume reduction numbers are much higher than the ice extent numbers, this serves as evidence that under-ice ocean heat flux is increasing, and the main cause of ice volume reduction over the past few decades.

Basically, what I'm saying is that atmospheric heat flux reduces extent and area, while ocean heat flux reduces volume.

The question is, when will the two ends meet ? When will ice thickness be reduced so much by ocean heat flux that atmospheric heat will simply knock out the thin ice that is left over...

That question is much more difficult to answer, although the flux numbers suggest that we are rapidly getting closer to a collapse...


Thanks, Rob, Anu. Ocean heat flux is crucial, so I'm glad I finally wrote this thing as a handy reference.

Jim Williams

Thanks Neven.


Found this via a wild search route.
@Neven: Better read and detail then the ScienceDaily articles dealing with the same subject matter.
@Rob "That question is much more difficult to answer, although the flux numbers suggest that we are rapidly getting closer to a collapse..."
Great terrifying instincts there. Do not think that even you at that time could have guessed what has happened this year.

John Christensen

Coming back to re-read this - what a great article!

I may just have to print all the images and hang them next to my office desk for suberb decor and inspiration!!

R. Gates

I had somehow missed this post last year Neven. Wow! What an excellent summary of such an important topic. Everyone interested in the topics of climate change and the Arctic should keep this bookmarked. And shame on other climate blogs for not picking this up. I am going to make sure to link to it at every opportunity when posting on other sites.


Thanks, John and R. Gates. It seems putting 'Best of Blog' in the right hand bar was a good idea. :-)

Personally, I think this is one of the most useful things I've written here, because the ocean is so important in what is happening to the Arctic sea ice.

R. Gates

I agree 100% with both of your comments Neven. The failure of sea ice models to fully account for this ocean heat flux to the Arctic, both because lack of data and lack of proper model dynamics is certainly one reason they've been so grossly off in predicting the rapidity of the sea ice demise.

Brian Chandler

The volume of ice formed in the Winter appears to be increasing as well as the volume of ice melting in the Summer. Not difficult to imagine with the disappearance of the deep cover of snow on the multi year ice. Already the snow from many Fall storms fall in open water diminishing the cover. How much of that cover gets blown into open water rather than redistributing on the ice pack could also accelerate the melt. That snow and it's trapped air no longer insulate the layers below. So there may be a period where the volume of ice formed in the Winter continually increases. This would not be a contradiction to global warming. b

Brian Chandler

oops Missed the first paragraph. Thanks Neven for such a good summary! It is easier to follow with the much needed explanations.

The comments to this entry are closed.