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Wow! This is great stuff. The striking feature here is that wintertime volume numbers are reaally decreasing much more quickly than the smmer time numbers. This chart shows 12 more years to an ice free arctic winter.


I second that emotion - this looks like some fantastic grist to the mill.

Five cheers for bill!

(there goes my Sunday, though...)

Andrew Xnn

Holy Schmoely; this is absolutely fantastic!!!

Many many many thanks.

Would like to point out that there may be something of an anomaly in Sept 2007 as well.

The minimums in most years are fairly well rounded, while there appears to be something of a spike in that month. However, as we all know, there is an indisputable trend and it's just a matter of time before it all melts.


Pheeewwwww !!!! That's NICE.

I have lot of room and power on a good nice server, so I can offer to setup a place for this. I had also thought about offering some area to play with R... perhaps by managing the programs on Github, so everyone can play with the thing... so, I think it's time to start this project.

I'll try to setup that stuff by Monday, should be done by next Friday.

Neven, do you have my email address so we can exchange on this ?


Great job William. I think that there was discussion on the issue of aveage thickness earlier, but this graph really demonstates how the average thickness has declined. Through much of last fall/early winter, average thickness of the ice was under one meter. Your chart shows this to be a new trend.


Refresh my memory: at what thickness does sea ice readily fracture and become susceptible to wave action? Or does the age of the ice have more control over strength than the thickness does?

At any rate, I would like to see a map which uses both age and thickness to predict the likelihood of each discrete chunk of ice melting out in the coming summer. (Weather and currents are critical, but all other factors being equal, areas of stronger ice, older ice, edge ice, ridged ice, and so forth should be able to be teased out with a GIS.)

(I really should apologize if my comments and questions are Ice 101; my scientific background is strictly terrestrial.)


Thanks for a great post. And especially for offering

are there any other interesting analyses that people would like to see?

I've read Stoat's suggestion that increasing open water will provide a negative feedback that makes ice-free periods unlikely any time soon. At a glance, I don't see two volume growth regimes in these graphs (fast growth while open water lasts, followed by slower growth under ice cover), but - would proper stats analysis show it? And, as the open-water period for the central basin is very short, might other basins' data, with lower extent at minimum, show a change in rate of volume growth before/after the end of open water?

Thanks again for a thought-provoking piece.

Ron Broberg

Bill, my webhost claims I have unlimited space and bandwidth at rhinohide.org. If you like, I would be happy to host the files there. You can ping me at gmail.com by the handle of ronald.broberg.


Hi guys (and girls ?),

I'm happy to annouce that I managed to setup the stuff I was thinking about... Soon you'll be able to make your own "R" code on GitHub, or take others' code and play with it, and have it gotten and run by my server.

Stay tuned, more info to come soon !


Bill wrote his code in java, it's quite easy to read : is there a volunteer to translate it to "R"? So we can play with it and share it, in a (probably) very efficient way.

michael sweet

It is more complicated that just thickness and age. You also have to consider latitude. Ice closer to the pole melts slower than ice further south. NSIDC uses an algorithm that considers age and latitude for their forecasts of ice extent. (Does anyone know of a link to their data?). Soon age will not matter, all the ice will be first and second year. As the ice in the Canadian Archapeligo melts, new ice blows over from the higher latitudes. As the ice near Canada thins, more will blow over. That leaves more open water by Siberia.

Daniel Bailey

@ michael sweet

You might try looking here:

The Yooper

dominik lenné

Hi, I appreciate Your work very much.

I'm interested in the data table linked to above. If you could give a hint, why for each region not only colums "extent", "area" and "volume" are given but also 3 colums with the area title on top (e.g. "baffin", "baffin" and "baffin"). Also a word about the units would be helpful.


Your welcome, dlen.

My intention for the column headers is

TimeStamp Date central extent central area central volume baffin extent baffin area .....

but I realize that whitespace doesn't always travel well :[

As to units:

timestamp is seconds since 1970, and is used because that's the way the data files are named -- allowing me to debug things more easily.

Date should be self-explanatory

Extent and area are in km^2 (notice that the extent is always a multiple of 156.25, since the measurements are made on a grid whose spacing is 12.5 km).

Volume is in km^2 * m (kind of an awkward unit, but I chose it because km is natural horizontal unit, while m is the natural vertical unit -- plus it graphs better than the alternatives)


Ack, whitespace really doesn't travel well I guess I need whitespace so the:

TimeStamp < tab > Date < tab > central extent < tab > central area < tab > central volume < tab > baffin extent < tab > ....

dominik lenné

Ah, yess, I imported the data in excel and said to excel: "use blanks as separator". Somehow I guess it took the blank in the first line and split title *and* the numerical data into 2 columns. Something like that.

Thanks for the remarks.


Does anyone know when the TOPAZ thickness map will be updated? It seems to be stuck at Feb 24, and my hands are itching to make a PIPS vs TOPAZ animation.

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