A regional approach to the medieval warm period and the little ice age

A regional approach to the medieval warm period and the little ice age“. Anthony Watts jabbers about the Medieval Warm Period and Little Ice Age again, using a paper by Dr. Fredrik Charpentier Ljungqvist by a history grad student at Stockholm University titled “A regional approach to the Medieval Warm Period and the Little Ice Age“. Has it been submitted? Reviewed? Published? Who knows.

Funny how denialists are always pointing out regional evidence to try to challenge global climate trends. Well, it’s not really funny, it’s kind of boring and a predictable intellectual bankruptcy. Strange that there’s no whining about Urban Heat Islands and sneaky “corrections” to proxies or mutterings about the failings of computer models, etc. when the denialists think the result suits them.

The paper, using only use northern hemisphere locations, claims that the Medieval Warm Period and Little Ice Age were global although they seem to have somehow happened a different times in different regions. Hmmm. But this is the first sentence of Dr. Ljungqvist’s concluding remarks:

The presently available palaeotemperature proxy data records do not support the assumption that late 20th century temperatures exceeded those of the MWP in most regions, although it is clear that the temperatures of the last few decades exceed those of any multi-decadal period in the last 700–800 years. (Emphasis mine)

Anthony seems to find the Greenland reconstruction fascinating, as it plays in to his meme that “it’s been warmer in the past, so why worry about this warmth (which isn’t happening).”

Greenland and China temperature reconstructions from Ljungqvist, 2010. Anthony apparently sees a global MWP and LIA in both, I see two regions responding differently.

5 thoughts on “A regional approach to the medieval warm period and the little ice age

  1. “A Regional Approach to the Medieval Warm Perioad and the Little Ice Age” (Nov24,2010)

    There is a link to the paper at the end of the WUWT article.

    PRESENT TEMP……….The paper was published in 2010. Yet the instrumental global temperature graphs all end in 2000. This is an obvious failing in a paper comparing Medieval temperatures to current temperatures.

    Statistical smoothing arguments aren’t relevant. There is an expectation that hockey stick graphs will show the current temperature as a reference point. Even if it is only a discrete point.

    REGIONAL(?)……….Soon & Baliunas (in 2003) were not successful in their skeptic effort to find a global MWP, because of the many flaws in their paper. But at least they did try to combine global proxy temperatures statistically.

    Cherry picking is the term that comes to mind when looking at his map of proxy sites, whatever his original intentions. The map shows even more of a northern bias, than does his list.

    “We have been able to present regional reconstructions for
    1) warm season temperatures of Scandinavia north of 60°N,
    2) warm season temperatures for northern Siberia,
    3) annual mean temperatures for Greenland,
    4) warm season temperatures for the Alp region of Central Europe,
    5) annual mean temperatures for China, and
    6) annual mean temperatures for the whole of the North American continent.”

    WHY MWP (?)……….The paper does take away the skeptics rationale for seeking a warmer global MWP. They want to find for the MWP an explanation (or a cycle) that would also explain post 1975 warming, that is now ocurring in a time of low solar activity.

    “…The medieval period with high temperatures, had a general high solar activity…
    “…the warming trend has probably also been amplified in the last decades by anthropogenic greenhouse gas emissions (IPCC,2007).”

  2. Those of your readers interested in what the paper actually says, and the basis for its conclusions, can find a copy here http://bit.ly/RegionalApproachMWPLIA. Not noted as peer reviewed and perhaps not (yet) published, but people honestly interested in understanding the intricacies of the subject should find it useful.

    regards SME

  3. Could someone write a paper aligning the historical and archaeological evidence of the MWP e.g. according to Jared Diamond’s “Collapse”, North American Indians had just abandoned Greenland when the Norse arrived. That seems strange if the climate was to balmy. Monckton used to claim the graveyard at the Norse ruin of Havsley Church was now permafrost – which is complete nonsense. In fact, the Church is subsiding into the clay. There must be evidence of the indigenous flora and fauna of the time – from what I can gather, it was much the same as the 20th century. There are also some written records. Can some aspiring PhD student in history or archaeology be given the task?

  4. CORRECTION……….My objections are to his overall conclusions. Not to his focus on regions where more detailed information exists.

    “…the key question of to what extent earlier warm periods have been as HOMOGENEOUS IN TIMING AND AMPLITUDE in different geographical regions as the present warming.” (emphasis added)

    But, why weren’t the graphs displayed all together, stacked, in order to show the TIMING. He’s trying to show consistent 10th century warming.

    And shouldn’t the graphs vertical scales be the same, when discussing AMPLITUDE??? To show why, in this case, he arrives at a negative result.

    CONCLUSION……….”The presently available palaeotemperature proxy data records do not support the assumption that late 20th century temperatures exceeded those of the MWP in most regions…

    “late 20th century”….sounds like Soon&Baliunas (2003). 2000 may be appropriate for comparisons to old papers. But 2010 is the obvious reference point that should be included.

    “in most regions”….Whatever he’s shown in his six regions doesn’t yet over rule the Northern Hemisphere’s temperature records. To do that he would have to add in the other regions and combine the data.

    HIS OTHER PAPER……….Presumably that is what he did in Ljungqvist (2010). It is included in our paper’s first graph. The graph shows similar MWP’s, and the agreement mentioned in the abstract. And it shows that the highest temperatures are in 2000.

    “A New Reconstruction of Temperature Variability in the Extra-Tropical Northern Hemisphere During the Last Two Millenia” Ljungqvist (Sep, 2010)

    “Our temperature reconstruction agrees well with the reconstruction by Moberg et. al. (2005) and Mann et. al. (2008) with regard to the amplitude of the variability as well as the timing of warm and cold periods, except for the period c. ad 300-800, despite significant differences in both data coverage and methodology.”

  5. NOTICE……….the difficulty that I had with this paper. Per usual, there’s a lot of skimming over the stuff I don’t understand, looking for ‘an error of its ways’. In amateur debunkdom it’s usually the VIOLATION of accepted AGW canon that is recognized first. And then you look for the MISSTEPS that lead to it.

    Here I quickly lept from the conclusion backwards to a misinterpretation of his regional details as only being the ‘means to that end’.

    WUWT WEIRDNESS……….(Is it just me? I remember a “Dr” before the author’s long name, in the earliest WUWT posting.)

    Second thoughts led down a creepy path. WUWT article authors can range from the legitimate (sometimes only partially quoted) to the DIY (recent instrumental temperatures being smeared by tree ring data). So its WUWT’s fault when the research becomes seemingly ad hominem.

    And in this case we learn that the grad student in the history department is also the author of two papers in a journal of physical geography.

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