The National Snow and Ice Data Center reports:
Atmospheric circulation patterns in August helped spread out sea ice, slowing ice loss in most regions of the Arctic. NSIDC scientists expect to see the minimum ice extent for the year in the next few weeks. While this year’s minimum ice extent will probably not reach the record low of 2007, it remains well below normal: average ice extent for August 2009 was the third-lowest in the satellite record. Ice extent has now fallen below the 2005 minimum, previously the third-lowest extent in the satellite record.
Not a big surprise — see “NSIDC: Record low Arctic ice extent unlikely in 2009.” Since the 2009 arctic extent AREA is no longer that close to 2008 levels, which set the record for minimum ice VOLUME, it seem unlikely 2009 will set a volume record (see “Will we see record low Arctic ice VOLUME this year?“).
The long-term trend remains the same (see “Human-caused Arctic warming overtakes 2,000 years of natural cooling, ’seminal’ study finds“) and hence the medium-term also remains the same (see North Pole poised to be largely ice-free by 2020: “It’s like the Arctic is covered with an egg shell and the egg shell is now just cracking completely”).
NSIDC has some good analysis of the summer 2009 melt seasons to put this in some context:
Conditions in context
In the beginning of August, the rate of ice loss was fairly slow. In the middle of the month, the loss rate sped up, and then slowed again. On average, the decline rate was close to the 1978 to 2000 average for past Augusts. Ice extent declined by 55,000 square kilometers (21,000 square miles) per day during August, compared to 66,000 square kilometers (25,000 square miles) per day in August 2007 and 79,000 square kilometers (31,000 square miles) per day in August 2008. But because of the higher-than-average rate of ice loss in July, average ice extent for August 2009 was still far below the 1978 to 2000 average extent for the month.
On September 2, Arctic sea ice extent dropped below the minimum extent for 2005. This year is now the third-lowest ice extent in the satellite record, with one to two weeks left in the melt season.
The minimum ice extent for the year will probably occur in the next two weeks. NSIDC scientists are closely monitoring conditions and will report the minimum when it occurs.
August 2009 compared to past years
Arctic sea ice extent for August 2009 was the third lowest August since 1978, continuing the downward trend observed over the last three decades. Only 2007 and 2008 had lower ice extent during August. The long-term trend indicates a decline of 8.7% per decade in August ice extent since 1979….
Winds spread ice, enhance melt
The pattern of high pressure over the Beaufort Sea that had characterized much of the summer broke down in early August. The August atmospheric pattern was dominated by low pressure over the Beaufort and Chukchi seas, and high pressure over Greenland and the Atlantic side of the Arctic. This pattern led to winds blowing from the south and southwest into the Beaufort Sea, contributing to melt and poleward ice motion in this area. By contrast, winds from the north favored a drift of ice towards the Siberian coast.
Studies by Mark Serreze, Masayo Ogi, and other researchers have shown that low-pressure patterns promote spreading of the ice pack, a process known as divergence. While ice divergence increases extent, it can also accelerate melt because there are more dark, open-water areas between the floes to absorb the sun’s energy, promoting melt on all sides of the floes.
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Now that 2009 is in the books, do you think the NSIDC should conform the black line average to 30 year climatology standard?
Hmm! 2008 recovery was 450,000 sq.km
Looks like 2009 recovery has increased to 600,000 sq.km
I wonder what 2010 will yield?
PaulK,
The 30 year standard is that value, not for arbitrary reasons, but because that is how long it takes to get strong statistical significance from the global temperatures.
The arctic ice signal is tronger, and 20 years suffices. The satellite measurements start only at 1979, so there are only 30 years, and no way to compare this data to a longer term average in the past. However, if you wish to use more years of data but are willing to live with less precise measurements, then http://en.wikipedia.org/ wiki/ File:Seasonal_extent_1900-2008.jpg shows that the baseline from 1900 to 1950 is level and steady at 11 million square kilometers, making the current sea ice area minimum HALF.
It would have been nice if you could have pointed out that we all live in a three-dimensional world where ice extent now matters far less than ice thickness, represented by its volume — the graph only shows a two-dimensional world and says nothing at all about the fact that the volume of the ice is about half what it was a couple of years ago, a far worse outcome than the figure on ice extent.
[JR: Jeez, I think I've been one of the few people to repeatedly make that point -- and I did so again in this piece.]
Neil, you noticing that you’re looking at only two of three measurement dimensions when you compare square kilometers?
Here’s a graph that will show you how Arctic ice breaks down into “new” 2 year old ice.
http://nsidc.org/ images/ arcticseaicenews/ 20090406_Figure5.png
What you’ll see is that while there was a small uptick in 1-2 year old ice in 2009 that old ice continued to disappear.
Furthermore, getting excited about a single data point while overlooking the larger picture is doing yourself no favors.
Almost any data includes point to point variability. To focus on a short point run can be very misleading. If you scan back over the history in the presented graph you can see several incidences where the graph jags up, but none of those were followed by a continuing recovery of Arctic ice.
(Pick cherries only from cherry trees. Those other cherries generally turn out to be bitter.)
Now, as to your question….
I’d expect, at least wouldn’t be surprised, by a decrease in 2009-10 ice recovery. Oceans just hit a new all-time (current era) high. If the Arctic is starting with warmer water and the winter portends to be warmer due to an ongoing El Nino, conditions don’t look good for lots of freezing. Not the sort of thick ice that can carry through a warm Arctic summer.
Hmmm. Yes but what about the Antarctic. It’s nearly at record highs, and not to forget that our satellite recods only go back 30 years, as compared to Earths 4 billion year history, most of wich was so warm thar most of our planet had never even seen a snowflake untill we entered the current Ice house climate we are in today. So sure the warming seems bad to us, but this is nothing. Remember we only have accurate records of 30 years or so, that is a blink of an eye in Earths history.
The arctic ice melt is not exactly ‘accelerating’ is it?
[JR: Yes, it is. I'd suggest you look at the Volume post.]
It would be expected for >2 year old ice to still be on the low end within 2 years of the record 2007 thaw. Just as you see an increase in the 1~2 year in the graph you will see an increase in the >2 year ice if the same graph is prepared this coming February.
Thanks for your advice Bob. I am still studying your comments together with the response from Thomas.
Temperatures up in the Arctic seem to have been colder through 2009. I think this will continue. I expect to see more ice up there at the maximum and a continued rise in minimum sea extent next year
The open-water areas indeed absorb solar radiation, but also radiate heat back into space. My learned climatologist Colleagues (I am a plain physical chemist) seem to forget about this compensating factor.
[JR: Yeah, Einstein, you figured out something that thousands of top climate scientists and every leading journal reviewer missed! So who shot JFK?]
Oh, so they know about it? So, why do they play surprised when the “thin, prone-to-melting, I-year old ice” just doesn’t want to melt, contrary to their most solemn “predictions”?
Just several months ago the public was fed the theory that this thin ice would melt and all the poor polar bears would drown. And now what? For the second time since the 2007 minimum the minimal summer extent is larger than the previous year’s. How does it feel when hard reality just doesn’t want to reconcile with a political agenda, supported with junk science?
[JR: Huh? The Arctic ice is losing AREA faster than every climate model had predicted. And the VOLUME loss has simply been staggering, but you deniers are stuck in a 2-D world where if the catastrophe doesn't occur in two days, then all the science is wrong, but then again, if it did, you'd just say, well, it was too late to do anything. Try reading the scientific literature or my extensive posts on the subject before you come back here and waste my time and my readers' time.]
I agree Joe that we sceptics are “taking heart” from the increasing ice extent area. We may be delusional in our opinions, but nothing is certain in this world. We can only await this year’s maximum and next year’s ice minimum.
If the ice extent heads back down towards the 2007 minimum I think we will all have to shut up.
If, however, the minimum ice extent continues to rise then, despite cries of our two dimensional view of life, our voices will grow louder.
[JR: Who really cares? You folks are not "skeptics" -- real scientists are skeptics since they can be convinced by the evidence. It doesn't matter what happens in the real world -- you folks will still find something (it was a little cool today!) to push as proof of your misguided views. I'm glad to see that you understand you may be delusional. Now find another place to push your delusions.]
Delusions can go both ways. As can real-world data (not to mention climate models).
I say we watch the data and see what happens. Cyclic, real data is notoriously hard to extrapolate linear trends from. Still, all the argument must be fun for some to do and others to watch or we wouldn’t all be here.
Let’s try to be scientific and civil, please.