Watt about the remarkable correllation – Arctic sea ice?

Watts Up With That (WUWT) has a new post, from the Hockey Schtick, called remarkable correlation of Arctic sea ice to Solar cycle length. The post reports on a paper published by the Danish Meteorological Institute (DMI) which discusses a link between Arctic sea ice and Solar cycle. As far as I can tell, this is a scientific report to the DMI and not a peer-reviewed article. The WUWT posts reports that

The paper adds to several others demonstrating that Arctic sea ice extent and climate is controlled by natural variations in solar activity, ocean & atmospheric oscillations, winds & storm activity, not man-made CO2.

Really? If you want to read the paper, a PDF copy can be downloaded here. Maybe the crucial part of the paper is the first few lines of the abstract (which the WUWT post includes but doesn’t highlight). They are

The extent of ice in the North Atlantic varies in time with time scales stretching to centennial, and the cause of these variations is discussed. We consider the Koch ice index which describes the amount of ice sighted from Iceland, in the period 1150 to 1983 AD.

So, this paper is only discussing sea ice variations in the North Atlantic and these variations are determined using sightings taken from Iceland. This paper is not, in any way, discussing the full Arctic sea ice extent.

The paper does go on to say

In view of the large significance observed we suggest that the correlation of 0.67, between multi-decadal modes in the Koch ice index and the solar cycle length, is indicative of a relationship not due to chance.

I’m not a fan of simply using a strong correlation to imply some relationship without necessarily trying to understand the underlying physical processes involved. However, it may well be that the extent of sea ice observable from Iceland does depend on Solar cycle. The Sun clearly plays a dominant role in defining our climate. The paper concludes by saying

The considerations of the impact of natural sources of variability on arctic ice extent are of relevance for concerns that the current withdrawal of ice may entirely be due to human activity. Apparently, a considerable fraction of the current withdrawal could be a natural occurrence

So, the report does actually try to link their results with the currently observed drop in Arctic sea-ice extent (and volume/mass). Given that their paper is based on sightings taken from one point in the North Atlantic (Iceland), I would suggest that this is a rather large extrapolation.

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24 Responses to Watt about the remarkable correllation – Arctic sea ice?

  1. uknowispeaksense says:

    It certainly isn’t a peer reviewed paper and so should be referred to simply as a report. The deniers are loving this report. None of them have actually read it and so are happy to ignorantly go along with the massive extrapolation inferred by Watts and friends.

  2. Indeed. In fact, I was quite surprised by the last sentence in the report. It seems like a massive extrapolation from these observations. Plus there’s observations and analysis that suggests that sea ice extent didn’t vary significantly in the first half of the 20th century, so there isn’t really evidence to support the idea that what we’re going through now is dominated by some natural (non-CO2 related) process.

  3. This report goes contrary to what we know about the main reasons sea ice has been changing in the arctic based on a local dataset that’s used to draw conclusions about the whole arctic ice sheet… What happened to their claim that anything before satellites isn’t reliable as it doesn’t include the entire arctic ice sheet?

  4. I’ve only just noticed that this report appears to have been published in 2005. Hmm, wonder why WUWT decided to highlight it now. Running out of things to say?

  5. Lars Karlsson says:

    The abstract says “,,,the period 1150 to 1983 AD.” So this paper cannot be used to explain the Artic sea ice decline during the last 30 years.

  6. dana1981 says:

    Standard bunch of WUWT BS (Bad Science). Aside from the data not actually being an Arctic sea ice extent record, and the usual correlation = causation error, the use of solar cycle length irritates me to no end. I’ve never seen anybody even try to explain physically why the length of the solar cycle should impact the Earth’s climate as opposed to the amount of solar radiation reaching the planet’s surface. The argument is based entirely on mathturbation, equating correlation with causation. Having a physics background, I absolutely hate unphysical arguments like this.

    Another pet peeve is the Scafetta climatology argument (astronomical cycles are causing global warming!). Ironically Scafetta also has a physics background.

  7. Indeed, I’d missed that quite important part of the abstract 🙂

  8. Yes, you’re quite right. Sometimes when I reread my posts I think that I’m being way too soft. This is really one that I should have either completely ignored (given that it’s already 7 years old) or torn to shreds! Still waiting with bated breath for Andrew Neil’s corrections to your recent article 🙂

  9. dana1981 says:

    Yeah we’ll see if he responds. He almost seemed to be backing out by using the excuse that my comments were ‘just on a blog’. But he also seems to be gathering info (via Twitter) on ocean warming and asking Tol about the bogus claim that we’re “hiding data” from the consensus paper. So if he does respond, I expect him to make some sort of claim about the ocean heat content record being too short or something, and claim that we’re “hiding data” because we haven’t given Tol our restroom break logs yet. It should be riveting.

  10. FrankD says:

    There is a further problem with the specific area they have looked at. While local sampling in some parts of the Arctic can correlate tolerably with overall sea ice area (Laptev Sea or the Canadian Archipelago would probably give reasonable results), the sea north of Iceland is one of the least reliable. The prime cause of interannual variation in total area is variation in currents and weather. When these combine to favour low coverage, most of the additional ice lost is carried out of the Arctic Basin through the Fram Straight to melt around Iceland.

    Thus a high Koch Index can mean either that total area is particularly high or that a huge amount of ice is being carried out of the basin through the Fram Strait (and thus total area, particularly on the Siberian side, is particularly low). Equally a low Koch Index may indicate low total area or that the Fram Current/Arctic Dipole combination was weak that year, little ice was carried out through Fram Strait and the overall health of the ice was particularly good.

    We have a lot of data points for it, but this metric is a singularly unreliable measure of the overall health of the ice cap.

  11. David Sanger says:

    The paper also says “We only use the years where the SCL(1,2,1) index is well defined – namely 1558-1625 and 1695-1980.”

  12. David Sanger says:

    And has anyone thought to ask Peter Thejil (https://twitter.com/hotblack43) if he still stands by the 2005 study, or agrees with the WUWT use of it ? Dana?

  13. Tom Curtis says:

    One feature of the report I find particularly disappointing is the lack of discussion of the Maunder Minimum. It is clearly visible in the seventeenth century with no sunspot cycle length recorded. If sea ice extent is strongly controlled by solar activity, then the Maunder Minimum must surely be a periods with a very large sea ice extent. By the Koch index, however, it has a minimal extent. Given that solar cycle length is taken as an index of solar activity, surely this discrepancy required discussion.

  14. Interesting comment, thanks.

  15. Thanks. I’ve sent him a tweet asking if he had any comments.

  16. NevenA says:

    Yes, published in 2005, and what happens to solar activity after that and how does it explain the 2007, 2011 and 2012 crashes? Not only in the Greenland Sea, but Arctic-wide, of course.

    You might have noticed too that Watts has given up on reporting on Arctic sea ice altogether. And with reporting I mean copypasting NSIDC monthly summaries. I’m very surprised at that. Apparently the Arctic isn’t part of the planet he’s living on.

  17. I have cited you id Facebook dispatches. 🙂


    Long live blogscience!

  18. dana1981 says:

    Unbelievable – Andew Neil cited this paper (claiming it’s “new”) in his response to my post. I guess we know where he gets his climate information now.

  19. I know, I saw that. Also interesting that the only climate scientists (yourself excluded) he mentions by name were (unless I missed some) were Phil Jones, Judith Curry and Roy Spencer. I’m busy writing a response at the moment but have to pick up my son in a short while from his summer camp so may not finish until later this evening.

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