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Neven

Over at the Wunderblog Dr. Jeff Masters has an interesting blog post: Hot Arctic-Cold Continents pattern is back

PIPS 2.0 predicts 60 km Sea Ice displacement today offshore of Nord in the Fram Strait.

It looks like them arrows got a bit bigger still:

I don't know how long I can keep up this hibernation thing. ;-)

Artful Dodger

Andrew, start with Eisenmana and Wettlaufer (2008) "Nonlinear threshold behavior during the loss of Arctic sea ice". Another excellent paper is Notz (2009) "The future of ice sheets and sea ice: Between reversible retreat and unstoppable loss".

Google Scholar will allow you to find full text editions of both papers, and articles which cite these papers. The critical issue is albedo flip as sea ice turns into open ocean. I'm working on an analysis which I plan to post over the Holidays.

Kevin McKinney

So the summer-ice-free-to-winter-ice-free question lives? Well, I'll stay tuned.

It'd be disingenuous to call this a Christmas gift (tho' it doesn't cost you anything except time!)--but I've a new article up as of yesterday. It's a bit artsy, a treatment of water and climate science via an extended metaphor, and is being received well so far.

Comments and corrections are particularly welcome from those here. . .

http://hubpages.com/hub/Water-Is-A-Dancer

Neven

It looks like those big arrows resulted in the first extent decrease since the end of the melting season: -2,656 square km. Even bigger arrows are forecasted for tomorrow:

Neven

Who ever said hibernating is boring, better think again. ESA reports:

AGU participants were also treated to the latest results from the newest Earth Explorer, ESA's CryoSat ice mission, Europe's first mission dedicated to monitoring Earth's ice fields.

Tommaso Parrinello, ESA's CryoSat Mission Manager, said, "AGU is the first international conference where the preliminary results of the CryoSat mission have been presented.

"We are now getting ready to open the data to the science community next month. This is another important milestone scientists have been waiting almost a decade for."

Neven

It looks as though 2010 will be the nr 1 lowest trend again tomorrow, as those big arrows caused a 41,406 square km extent decrease reported today by IJIS. The forecasted arrows for tomorrow are slightly shorter:

BTW, the AO index has gone through the basement. Has it dipped below last year's negative extreme yet, I wonder.

Andrew Xnn

Artful;

Thanks for the references to those papers.
Looking over them, I see that they are exploring and building simple models for tipping points. Also comparing stability of sea ice to continental ice sheets.
However, they appear to be a long ways away from quantifying the time period.

Neven;

Hot Arctic - Cold Continents is indeed back.
Last week it was colder in Atlanta than it was in Iceland.
That won't last for long, but from your Jeff Masters/Jim Overland link, there is a discussion as to what's normal for the Arctic.... High Pressure or Low.

Typically during the winter the Arctic is dominated by low pressure. However, lately high pressure has dominated and to me that actually makes more sense. It also suggest a possible mechanism for a tipping point especially if this were to become the norm during the summer.

Gas Glo

>"BTW, the AO index has gone through the basement. Has it dipped below last year's negative extreme yet, I wonder."

No, though off the bottom of the graph you linked, the forecast pages have larger ranges and these show it has only got down to about -4.6

http://www.cpc.noaa.gov/products/precip/CWlink/daily_ao_index/ao_index_mrf.shtml

It averaged -4.2 for whole of February 2010 and IIRC reached -6 on a daily basis.

Phil263

SIE went down by 41,406 sqkm on the 17th. Compaction rather than thawing I suppose as SIA is still growing steadily according to CT.

Pete Dunkelberg

So does it all add up to Wait and see for a couple more years?

If SIE went down by compaction rather than blowing away, that is more or less in line with the discussion in Notz 2009. But the remark there: "The fact that a nonlinear heat transport into and out of the polar regions removes the instability was explained in detail by North (16)" is not too convincing. What if the nonlinear transport of energy is into the arctic? In any case the latest AO chart (which I started following last winter) made me exclaim Yikes! I was hoping last winter that this would not become a pattern. Is there increased precipitation aka snow in the Arctic as well as a little farther south?

Melting point of salty ice - lower, but how does multiyear ice come to have less salt?

Greg Wellman

(commenting on two separate threads)

Summer ice-free conditions may not be "stable" but it could be a century or more from the first ice-free summer to the first ice-free winter, even assuming high GHG emission scenarios. Let's face it, in winter the pole is without sunlight for six months, and much of the region is in complete darkness for five months. It would take *way* more GHGs than we have to prevent heat loss to space from taking the surface temperature well below freezing. The new ice may be much thinner than before (warmer water underneath) but it will form.

Pete, multiyear ice comes to have less salt through a process called "brine rejection". As the ice forms the first time, it naturally has more pure bits and more salty bits, all jumbled together. (The bits that form first are more pure, and the salt gets concentrated in the other bits that get trapped in between, and then freeze later.) The next summer, as the ice warms, the saltiest parts melt while the pure bits don't (or melt less and slower). So the brine from those salty bits flushes down through the ice leaving only more pure ice, which eventually compacts to fill those voids, on timescales determined by the temperature and weather. (e.g. a little rain or surface melt can infiltrate from the surface and fill voids.)

Artful Dodger

Hi, Phil. Sea Ice Area is actually going down as well as Extent (cf. AMSRE Sea Ice Area). CT Area data typically lags 2 or 3 days, and has an irregular release schedule. Most of the decrease in Area and Extent is occurring in Hudson Bay as four days of Easterly winds associated with the strong DA have pushed warm water into new sea ice (do a blink animation beginning Dec 14 on Arctic Sea-Ice Monitor by AMSR-E

Hi Pete. New salty sea ice becomes fresh sea ice over 2-3 years, if it survives the Summers, in a process called "Brine rejection" (search this blog for previous discussions). For a good primer on sea ice, read Light on Arctic Sea Ice.

Neven

Thanks for the info, Gas Glo. I have indeed mixed up daily and monthly numbers.

FrankD

I've been playing with PIOMAS figures lately. I note the PIOMAS anomaly graph has a linear trend superimposed, but the data is pretty obviously not linear. The maximum anomaly does not correspond with the minimum volume, so its hard to read for info on when we will reach "zero ice".

A linear trend has a R-squared of around 0.85, where a 2nd order polynomial is .925. Probably, an s-curve would be better, but I don't know how to do them.

Anyway, I graphed the monthly figures: average of all anomly data for the month + mid-month daily average (apples and oranges, I know, but it suited my purpose).

What comes out? A better than 50% probability of an ice free September by 2016, with the ice free period increasing by almost a month each year. By 2023, there is a good likelihood of five months ice free, from mid-July to mid December. After that it slows down somewhat, but March and April, the last months remaining, reach zero around 2032-33.

I've posted the results here:
http://img543.imageshack.us/img543/2145/piomasmonthlyvolumes.png

I'd appreciate any thoughts on how to improve this - I have a good body of data behind it, its really just a question of the best way to slice and dice it. As I say, a 2nd order poly gives artificially quick zeroes, but since a lot of people mean less that 10 of the onlg term average when they say "zero" it kind of balances out.

FrankD

Oops - that last sentence should read: "As I say, a 2nd order poly gives artificially quick zeroes, but since a lot of people mean less that 10% of the long term average when they say "zero", it kind of balances out."

FrankD

Lodger, wrt to your blink comparison, also note the changing conditions in the Bering Strait - it looks like another pulse of warm water has flowed into the Chukchi Sea (?). Less that the Hudson Bay changes, but that side of the Arctic is still quite low (Bering and Okhotsk @ 50% of normal, Chukchi (by AMSR-E) not the best).

Gas Glo

Cryosat ice mission returns first science

http://www.bbc.co.uk/news/science-environment-12025283

Is data on heights of arctic ocean surface relative to gravitational level, not ice volume yet.

Jon Torrance

Sadly, no, not yet. This is only the water level so far, not information on how high the ice surface is above the water.

Gas Glo

Happy New Year

Quiet here so I thought I would mention:

IJIS JAXA displaying extent again - still lowest for time of year but gap has narrowed.

NSIDC Dec extent 12m and area 10.02m are lowest on record Decembers.

AO year averages -1.04 beating previous record of -.95. Pattern might indicate a cycle and we are coming to the time of peak negative values. 10 year average is nowhere near record yet.

UAH global temp record just missed out on beating record still held by 1998 though diff is nowhere near statistical significance.

Volume betting on intrade on arctic ice being a record has increased now 426 indicating that up to US$ 4,260 could be at stake. The last price was 38 indicating a 62% chance of a record low this year. The range became surprisingly narrow down to 38 - 39.9 but is currently 20.5-40 so this indicates the chance of a record low ice extent could well be more than 62%.

Any more tit-bits I have missed?

Neven

Hi GG, there's an Open Thread 3 now with quite a few interesting things contributed to the general discussion.

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