Climate change sceptics lose vital argument says the New Scientist. This is a novel twist on a paper in Nature: Gulf Stream density structure and transport during the past millennium; David C. Lund, Jean Lynch-Stieglitz and William B. Curry; doi:10.1038/nature05277. The editor says of it: an analysis of sediment cores from the Florida Straits, where the Gulf Stream enters the North Atlantic, has been used to reconstruct a record of the past 1,000 years. The results suggest that the Gulf Stream was weakened during the Little Ice Age (AD 1200-1850), a time of unusually cold conditions in the North Atlantic region, particularly Europe, implying that changes in Atlantic Ocean circulation had an impact on climate during historical times.

NS asserts that this may explain why MBH (aka the Hockey Stick) doesn’t show the Little Ice Age, since it makes it a regional phenomenon. Um? the cooling that resulted was confined mainly to the northern hemisphere, says Lynch-Stieglitz – which indicates it was a regional effect. Michael Mann at Pennsylvania State University in University Park, who constructed the hockey stick graph, has always argued that if this were so, the little ice age would not show up on a global temperature record. This is odd: MBH has only for the NH anyway… The idea that the LIA was regional and/or more of a redistribution is a standard one; its not really clear how this result adds anything to it. I suspect this is NS getting somewhat carried away.

Comments

  1. #1 Gerard Harbison
    2006/11/30

    Problem is, it’s not clear that the Gulf Stream/North Atlantic Drift actually has much of an effect on Europe’s climate.

    http://www.americanscientist.org/template/AssetDetail/assetid/51963?fulltext=true&print=yes

    [Despite that piece, it will still have some impact, even if the very large-scale effects are often over-spoken - W]

  2. #2 Brian S.
    2006/11/30

    Does the NS article support the idea that LIA was a redistribution within the region? That would help explain why LIA didn’t show in MBH.

    [Well, the NS article is supposedly based on the nature article, but appears to add new things of its own. The "redistribution" bit os nothing new, though, and I don't see why the Gulf Stream stuff adds anything to the argument. RC may post on this... -W]

  3. #3 Lubos Motl
    2006/12/02

    Don’t worry, I don’t understand the argument either. The graphs from all papers seem to agree that the period of the Little Ice Age was cooler than the 20th century on the whole Northern Hemisphere, to say the least, regardless of the interpretations of this fact.

    If someone thinks how to twist, spin, and overhype various conceivable arguments, she should realize that the argument of Nude Socialist about a possible non-existence LIA is a double-sided sword, by the way. ;-) At any rate, the “definitive” form of this extremely vague and shaky pseudoargument of Nude Socialist is probably suspicious to most readers with IQ above 100.

  4. #4 Alexander Ac
    2006/12/03

    Lubos, do these papers also show, that “Little Ice Age” was cooler on the WHOLE globe. This is what matters. Local changes in temperature are well known, these are climate changes of second order ;-)

    http://www.realclimate.org/index.php/archives/2006/11/revealed-secrets-of-abrupt-climate-shifts/
    well, think globally, do locally

  5. #5 Organic Chemistry
    2007/02/22

    I agree with Gerald H, you just can’t tell.

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