Guest Post by Willis Eschenbach
Inspired by this thread over at Bishop Hill’s excellent blog, I thought I’d write about sea ice. Among the many catastrophic things claimed to be the result of “global warming”, declining sea ice is one of the most popular. We see scary graphics of this all the time, things that look like this:
FIgure 1. Terrifying computer projections showing that we may not have any Arctic sea ice before the end of this century. Clearly, the implication is that we should be very concerned … SOURCE
Now, what’s wrong with this picture?
The problem with the picture is that the earth has two poles. And for reasons which are not well understood, when one pole warms, the other pole cools.
Looking at just the Arctic sea ice is like looking at someone who is pouring water from one glass to another and back again. If we want to see how much water there is, it is useless to observe just one of the person’s hands. We need to look at both hands to see what is happening with the water.
Similarly, to see what is happening in the frozen parts of the ocean, we need to look at global sea ice. There are several records of the area of sea ice. One is the Reynolds Optimally Interpolated dataset (Reynolds OI V2). A second is the National Snow and Ice Data Center (NSIDC) record. Finally, we have the Hadcrut Ice and Sea Surface Temperature dataset (HadISST1). All of them are available from that most marvellous resource, the KNMI data portal .
It turns out that the NSIDC and the HadISST1 records are nearly identical. The correlation between the two in the Arctic is 0.995 (1.0 is perfect agreement), and in the Antarctic it is 0.999. So in Fig. 2, I have not shown the NSIDC dataset, but you can imagine that there is a third record almost identical to the HadISST1 dataset. Here is what has happened to the global sea ice area from 1982 to the present:
FIgure 2. Global Sea Ice Area 1982-present. Data from satellite observations.
As you can see, while it is certainly true that the Arctic has been losing ice, the Antarctic has been gaining ice. And the total global sea ice has barely changed at all over the period of the record. It goes up a little, it goes down a little, it goes nowhere …
Why should the Antarctic warm when the Arctic cools? The short answer is that we don’t know, although it happens at both short and long time scales. A recent article in Science Magazine Online (subscription required) says:
Eddies and the Seesaw
A series of warm episodes, each lasting several thousand years, occurred in Antarctica between 90,000 and 30,000 years ago. These events correlated with rapid climate oscillations in the Arctic, with Antarctica warming while the Arctic was cooling or already cold. This bipolar seesaw is thought to have been driven by changes in the strength of the deep overturning circulation in the North Atlantic Ocean, but some have questioned how completely that process can account for the fine details of Antarctic warming events.
Keeling and Visbeck offer an explanation that builds upon earlier suggestions that include the effects of shallow-water processes as well as deep ones. They suggest that changes in the surface salinity gradient across the Antarctic Circumpolar Current were caused by the melting of icebergs discharged from the Arctic, which allowed increased heat transport to Antarctica by ocean eddies. This mechanism produces Antarctic warming of the magnitude observed in ice core records.
However, not everyone agrees that this is the full explanation. Henrik Svensmark adds another factor to what may be happening:
The cosmic-ray and cloud-forcing hypothesis therefore predicts that temperature changes in Antarctica should be opposite in sign to changes in temperature in the rest of the world. This is exactly what is observed, in a well-known phenomenon that some geophysicists have called the polar see-saw, but for which “the Antarctic climate anomaly” seems a better name (Svensmark 2007).
To account for evidence spanning many thousands of years from drilling sites in Antarctica and Greenland, which show many episodes of climate change going in opposite directions, ad hoc hypotheses on offer involve major reorganization of ocean currents. While they might be possible explanations for low-resolution climate records, with error-bars of centuries, they cannot begin to explain the rapid operation of the Antarctic climate anomaly from decade to decade as seen in the 20th century (figure 6). Cloud forcing is by far the most economical explanation of the anomaly on all timescales.
Regardless of why the polar see-saw is happening, it is a real phenomenon. Ignoring it by looking just at the Arctic leads to unwarranted conclusions about what is happening to sea ice on our most amazing planet. We have to look at both hands, we have to include the other side of the ice, to see the full situation. The real answer to what is happening to global sea ice is …
Nothing.
Re. Mike G (20:03:56) :
“Anthony,
We see a few comments wondering about GISS anomoly in the arctic compared to the lack of anomoly on the DMI actric temperature graphic linked on your page. But, I haven’t run across an answer to any of them. Seems like a comment on this would be a good post. Forgive me if I missed the answer in a comment somewhere.”
I second this. DMI uses K as opposed to C, but just quickly eyeballing I so not see more then two to four degrees at most of K warming, if that. Why is DMI so different then GISS?
The Arctic Ocean is the least saline of all the oceans – usually about 12-15% less than the norm of around 3.5% (35,000ppm) salt content for the other oceans. The reasons for this are: i) the huge inflow of fresh water from gigantic rivers in Canada and Russia, and ii) the almost total surrounding of the Arctic Ocean by continental masses.
Fresh water freezes at higher temperatures than sea water, so the less saline the Arctic Ocean is – especially the top few tens of metres – the more likely it is to freeze. Fresh water is less dense than sea water and therefore has a tendency to lie on top.
On a local basis, Arctic Ocean salinity must be related to the amount of fresh water entering it from Canada and Russia. This, in turn, is dependent on: i) the amount of continental precipitation, and ii) the amount of water extracted by man for irrigation and industrial purposes.
A couple of useful references are given below.
The salinity of the Arctic Ocean – summer and winter:
http://www.amap.no/mapsgraphics/go/graphic/winter-and-summer-surface-water-salinity-in-the-arctic-ocean-and-adjacent-seas
http://www.amap.no/mapsgraphics/go/graphic/distribution-of-potential-temperature-salinity-and-density-across-the-arctic-ocean-and-the-greenland
If the difference in Arctic Ocean salinity was just a few per cent, it would probably not have a significant effect, but it can vary enormously and sometimes be up to 20% less in some of the upper surface areas, when compared with the rest of the planet’s oceans.
I cannot see how anyone can make any judgement on the reasons for changes in the extent etc of the Arctic ice cap, without first measuring and considering the effects of changing salinity levels, both at a local and a regional level.
SandyInDerby (03:40:29) : Thanks for the link to the BBC item on business-as-normal in the Gulf Stream.
We’re always ready to criticize alarmist news items. I think that the BBC and the scientists they are reporting on, deserve credit for such (what’s the opposite to ‘alarmist’?!) reports.
Dear Mr. Eschenbach –
It seems to be the nature of the internet – whether at liberal or conservative websites – that ad hominem attack is the preferred method of discourse.
Your article looks at the combined total of polar sea ice without regard to differences at each pole. I point that out and you compare me to Aunt Hildegard’s tea cart.
You may say all you wish about tea carts, but your logical framing remains fundamentally flawed. One may combine the sea ice totals of both poles, but the climate implications are separate if there is dramatic, long-term change at one pole alone.
You see, I agree that there is no compelling evidence of Mark’s Serreze’s “death spiral” – but I also expect a rigorous structural analysis in any rebuttal.
Which your article lacks.
Wow, a generally great post until this part:
“The real answer to what is happening to global sea ice is …Nothing.”
Now is there a way to adjust the 2006-2007 Arctic Ice Extent a bit lower to make the current recovery seem more impressive? 😉
Re: Leif Svalgaard (Mar 29 04:55),
Leif, what happened 11-12 may 1999?
LinkText Here
[snip – let’s leave Nazism out of the discussion]
Here are some sites I monitor to track Arctic temperature and sea ice.
Arctic Temperature:
http://ocean.dmi.dk/arctic/meant80n.uk.php
Arctic sea Ice:
http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm
http://arctic-roos.org/observations/satellite-data/sea-ice/ice-area-and-extent-in-arctic
http://arctic.atmos.uiuc.edu/cryosphere/
Mike Haseler (01:43:57) :
This’ll make you puke! … http://www.ldnews.com/news/ci_14774756
Barf. Gee, thanks.
Climate science “skeptic” Mann says “there is firm grounding for some climate science assertions, such as that humans are responsible for a rapid increase in carbon dioxide levels in the atmosphere, that global warming is shrinking polar ice sheets and Ice Age glaciers, and that the last half of the 20th century was warmer than any 50-year period in the last 1,000 years.”
He makes three assertions; the first is debatable, and alarmist in nature. Yes, we’ve certainly added some to the rise in atmospheric C02 levels. The second says polar ice sheets and “Ice Age glaciers” are shrinking. Yes, they did shrink, coming out of the LIA. We warmed up, how awful. The glaciers started receding at the end of the LIA, surprise, surprise. The snows of kilimanjaro have almost disappeared – oh, right, that’s because of deforestation, not C02. Oops. Well, the Himalayas, at least are disappearing rapidly, and will be gone by 2035, right? Oh, wait, the actual evidence shows that they are stable, and in many cases advancing. As far as the polar ice sheets melting, nope not much evidence of that either.
Finally, what does he bring out but his infamous hockey schtick! Talk about Mannufacturing your own “evidence”!
Yeah, Mann, you’re a skeptic. And Bigfoot exists, as well as the Loch Ness monster, and don’t get me started on UFO’s.
Lennart,
From NASA:
the solar wind that blows constantly from the Sun [b]virtually[/b] disappeared — the most drastic and longest-lasting decrease ever observed.
Dropping to a [b]fraction of its normal density[/b] and to half its normal speed, the solar wind died down enough to allow physicists to observe particles flowing directly from the Sun’s corona to Earth.
“virtually disappeared” and a “fraction of its normal density” does not mean that it stopped…just lower than previously measured. The bare denial of your implications was in the very bit of evidence you used to make your assertion. Better luck next time when it comes to critical thinking.
If skating is the problem then, the next winter, the Catlin Expedition should skate along all the length of the Thames river.
Why are you so worried about what natures does or does not, seriously you should be worried about the catastrophic changes in most of the first world economies, it seems like you are walking looking at the sky while going straight to a precipice.
BTW God is merciful, if you wish an armageddon you will have several at the same time: Would you like it California´s big one, then, a few days after the New La Madrid caldera eruption, just to begin with the amusement?
“Sean Peake (06:35:23) :
Willis, sorry about this but it seems U of Colorado disagrees with you:
http://www.colorado.edu/news/r/f595fae00e6b451d4016ab9a43a049f8.html
Wikipedia on entire Greenland ice sheet “2.85 million km³ of ice”
Colorado “A 2009 study published in GRL by Velicogna, who is a former CU-Boulder research scientist, showed that between April 2002 and February 2009, the Greenland ice sheet shed roughly 385 cubic miles of ice. The mass loss is equivalent to about 0.5 millimeters of global sea-level rise per year.” This is 1605 Km3 over 7 years or near enough 230 Km3/year. Divide that into 2.85 million Km3 and you get 12,391 years for Greenland’s ice to disappear at the current rate. By then we will probably be well into the next ice age.
Bob Tisdale (03:44:49) :
With that, I replicated your results, and then did a couple further transforms. First, I took the seasonal difference, and then I smoothed it with a high degree of smoothing, to see the very low frequency, long term, behavior. This is the result:
http://i42.tinypic.com/2lvb5ts.jpg
In viewing this, bear in mind, that since these are “differenced,” that when the lines are positive, that is warming, and when they are negative (below the zero line) that is cooling. I’m not sure this is strong support for Willis’ position, but there are certainly times where it has been the case that when one region was cooling, the other was warming:
~1904
~1920
through much of the 1950’s and 1960’s
since the mid 1990’s
However, since the 1960’s, the trend in the trend has been opposite in the two hemisphere’s — moving from less cooling to more warming in the North, and from less warming to more cooling in the South. That broadly supports what Willis is saying, I think.
Peter Miller: There is no statistically significant amount of water being diverted from the Arctic Ocean basin for agricultural or industrial purposes in Canada. The three main rivers, the Mackenzie, the Back and the Coppermine, have no dams, no diversions and barely any inhabitants—the Mackenzie River proper is sparsely populated (perhaps 25,000 people along its 1,700 KM length), the 860 KM Coppermine has only one permanent settlement of 1200 people (at it’s mouth) and the 970 KM Back is uninhabited. I’ve paddled on all three.
Lennart S Sweden (07:36:09) :
Leif, what happened 11-12 may 1999?
Apart from being my birthday, not much.
Your link says that the solar wind “Dropped to a fraction of its normal density and to half its normal speed”, not that is stopped [usual hype]. The Earth encountered a small ‘bubble’ in the wind with very low density. Around the bubble things were quite normal. Interestingly, the magnetic field in the bubble was normal [even a bit higher than usual. You can see the evolution here: http://hirweb.nict.go.jp/sedoss/solact3/do?d=1999,5,5
Compare with recent:
http://hirweb.nict.go.jp/sedoss/solact3/do?d=2010,03,09
The density graph [green] should have an extra decade at the low end, so it doesn’t look like it has gone away.
John Egan (07:06:37) :
Dear Mr. Eschenbach –
but I also expect a rigorous structural analysis in any rebuttal.
I did not see any rigorous structural analysis in your comments.
Just a few What Ifs.
A.C. Osborn –
The fact remains, that the article in question contains a huge and serious assumption –
That the overall total of sea ice is a parameter that negates variation at either pole.
Not to mention that the author ends with the statement “Nothing.”
Such an argument is patently false.
Unfortunately, there are as many “true believers” on one side of the climate argument as the other. People like Lucia Liljegren are rare, indeed.
PS – If I recall, I wasn’t the person posting an article on a website.
Vincent (06:36:41) :
Anu,
“He believes the ice, which has been a permanent feature for at least 100,000. . .”
So which ancient people had satellites 100,000 years ago? The Neandethals perhaps, or could it have been the Clovis people?
I think you will find that it was Piltdown man that first discovered the correlation and that CC/AGW adherents are his direct descendants.
Just for reference, here is that silly IPCC projection chart updated to 2010 with data from CT.
http://i40.tinypic.com/2nuud12.jpg
R. Gates (07:07:51) : Wow, a generally great post until this part:
“The real answer to what is happening to global sea ice is …Nothing.”
Seems like a good assessment to me.
Kate (06:34:54) :
Fresh on the heels of my concern for the corruption of democratic processes, James Lovelock says “It may be necessary to put democracy on hold for a while” in “the fight against climate change”.
One of the main obstructions to meaningful action is “modern democracy”, he added. “Even the best democracies agree that when a major war approaches, democracy must be put on hold for the time being. I have a feeling that climate change may be an issue as severe as a war. It may be necessary to put democracy on hold for a while….”
Exactly right — that’s why the US has always postponed its Presidential elections during wartime, right, *Mister* Lovelock?
Democracies don’t put democracy on hold during emergencies — dictatorships do.
I’m covering your six whenever you want to close for the kill, Kate. Go get ‘im!
John Peter: I absolutely agree. I posted that link in the hope that Willis would take it apart, much like you did. Besides, I always thought that when glaciers and icecaps melted they retreated instead of galloping into the sea. I commented on the Accuweather GW blog where I found the stoory that the researchers behind the study were likely experiencing a Rocky Mountain High when they came to their conclusion. It is also interesting to see how someone (who could that be?) has tied-in GW into Post Glacial Rebound on Wikki—altho’ one person has added that a citation is needed (http://en.wikipedia.org/wiki/Post-glacial_rebound)
Ok, this is related to an earlier post on late season ice extent. It now appears that the 30% (in addition to the 15% reported earlier on this blog) ice extent is increasing according to DMI. This is the first time I can recall the seasonal max 30% ice coverage occurring this late in the season, particularly after already having started declining for the year.
@John Egan
‘ but one must acknowledge that the Arctic sea ice drop in 2007 was dramatic. Arctic sea ice in 2009 was still well below 30-year norms – although it has recovered somewhat. Granted that there is only 30 years of satellite data – with much older anecdotal data. 2007 may have been an outlier event, but it behooves one to act with prudence.’
It was only dramatic because it was put into a fictional context with disastrous proportions. Put in a more rational and real context, it’s not that dramatic not even in the short period of 32 years of satellite measurements.
So it behooves one to act with reason and rationality, lest you scare yourself silly of every imagined “hideous” anomaly in a statistician’s graph. :p
Pamela Gray (06:03:06) :
I think it is time to ask for the “computer model code” from these people, especially as a string relates to the process of freeze, melt, and transport. I have a hunch several of the folks here would find many calculation errors in how ice freezes and melts in the Arctic after controlling for wind and current.
So why haven’t these ‘folks’ done it already?