New Study: Two Thousand Years of Northern European Summer Temperatures Show a Downward Trend

Re-Bloggedd From http://www.WattsUpWithThat.com

In a paper published in the Journal of Quaternary Science, Esper et al. (2014) write that tree-ring chronologies of maximum latewood density (MXD) “are most suitable to reconstruct annually resolved summer temperature variations of the late Holocene.” And working with what they call “the world’s two longest MXD-based climate reconstructions” – those of Melvin et al. (2013) and Esper et al. (2012) – they combined portions of each to produce a new-and-improved summer temperature history for northern Europe that stretches all the way “from 17 BC to the present.” And what did they thereby learn?

As the international team of researchers from the Czech Republic, Finland, Germany, Greece, Sweden and Switzerland describes it, this history depicts “a long-term cooling trend of -0.30°C per 1,000 years over the Common Era in northern Europe” (see figure below). Most important of all, however, they note that their temperature reconstruction “has centennial-scale variations superimposed on this trend,” which indicate that “conditions during Medieval and Roman times were probably warmer than in the late 20th century,” when the previously-rising post-Little Ice Age mean global air temperature hit a ceiling of sorts above which it has yet to penetrate.

Esperetal2014b

And so we continue to collect ever more real-world evidence for the fact, that there is nothing unusual, unnatural or unprecedented about the Earth’s current level of warmth. Read original Post and Comments –>

5 thoughts on “New Study: Two Thousand Years of Northern European Summer Temperatures Show a Downward Trend

  1. It’s interesting. I don’t have trouble believing it may have been warmer in Europe 1000-2000 years ago. But AGW wouldn’t be relevant on that scale, since really significant carbon releases began during the industrial revolution, about 200 years ago.

    I don’t think anyone believes humans are the ONLY thing that changes climate. The issue seems to be, do humans change it at all? And if so, should we do something about it?

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    • The relevance is that the default hypothesis is that nothing has changed. If nothing (of significance) has changed, then the natural processes that caused swings from warm periods to cold periods (for example over the last 10,000 years) still are what’s causing swings between warm and cold today.

      If the swings today are within the extent of swings in the past, then the hypothesis that something new is causing the swings is not supported. And, if the Medieval Warm Period (or Roman Warm Period or Minoan Warm Period or the Holocene Optimum) were warmer than today (which they are) then the hypothesis that CO2 is causing the current temperature rise is not supported.

      The CAGW Alarmists can make all the hypotheses they want, show that CO2 has risen X% since the depths of the Little Ice Age, and create models to support their hypotheses, but if the real world data do not show anything has changed from the record of the past, then the CAGW hypotheses fail.

      So, just saying that, “really significant carbon releases began during the industrial revolution, about 200 years ago” does NOT support CAGW theory. Unless the global warming industry can show that “this time is different” (in the data), then CAGW hysteria is bogus.

      BTW, the data show that this time is NOT different.

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  2. Bob, you say “If the swings today are within the extent of swings in the past, then the hypothesis that something new is causing the swings is not supported. And, if the Medieval Warm Period (or Roman Warm Period or Minoan Warm Period or the Holocene Optimum) were warmer than today (which they are) then the hypothesis that CO2 is causing the current temperature rise is not supported.”

    I think this is an error in logic. Because it was warmer in the past, we may have nothing to worry about. But just because it was warmer in the past and it’s getting warmer now, does NOT mean the causes are the same. If we understand the causes for past warming and they are different, then there’s still a cause for concern. Are you assuming that the changes that mitigated warming in the past will automatically work again for us, regardless of the causes?

    Incidentally, thanks for continuing the discussion. I disagree with you over what the data show and how to interpret the evidence and assess the risks, but I’m glad we can continue the dialog. I was banned from WUWT, after (from my perspective) they switched from issues to ad hominem and I defended myself. So it’s nice to see that sometimes people can disagree and remain civil.

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    • Hi Dan,

      Yes, you’re right that you can’t prove that today’s rise is caused by the same thing. You NEVER can prove an hypothesis – only falsify it or fail to falsify it (which lends credence but doesn’t prove it).

      My point though is that, in science, if you can’t show that the null hypothesis is false (that the swings are natural, in this case), then an opposing hypothesis is knocked out of the box immediately. Observed swings within the previous extent could be natural, so the data do not falsify the null hypothesis.

      That also was the whole point of the Mann (and Briffa) Hockey Sticks, which have been discredited. They were trying to show that the well documented Medieval Warm Period and the Little Ice Age didn’t exist, because without them, then the case for this time being different was stronger. McIntyre and others determined that Mann could use random series and still get a Hockey Stick. And, Briffa’s try depended on a single magical tree, without which there would be no Hockey Stick for him either.

      Once you concede that the several Warm Periods and the intervening Cold Periods took place, then there is zero support for CO2 – ie. what was it that CO2 was supposed to have caused?

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    • Hi Dan,

      I looked at the WUWT post you referred to (you made 49 comments!)[Correction: There were 49 mentions of your name in your an others’ comments.] Might I suggest:

      1. Stay away from the occasional insulting skeptic. Don’t allow them to take you off topic and onto their troll line. Stay on topic and polite.

      2. Comment in a conversational style. Preaching is a turn off. Big words (like delicatessen?!) sound preachy.

      3. Know the background on the subject. In this case, the 97% “studies” have been debunked ad nausseum (polls not measuring what they say, skeptics measured but not invited to participate, polls measuring response to irrelevant points [“Does climate change?”] used to show consensus on the real issues [“Is expected temp rise going to be catastrophic?” or “Is outlawing fossil fuels a better option than adapting?”]).

      4. Be familiar with skeptic hot button (and don’t push them). Skeptics don’t like being misrepresented (as in the 97% polls). Skeptics don’t like being called names (like the anti-semitic “Denier”). Skeptics don’t like bogus, peer-reviewed articles being used as reference (like Mann’s & Briffa’s discredited Hockey Stick). Skeptics don’t like logical fallacies (like Call to Authority, or correlation vs causation).

      5. Know even more on background. eg. ClimateGate shows that a handful of powerful Alarmists were keeping skeptic articles out of the journals, were intentionally misleading the public about the science, and were working to phony up the historic temperature data record.

      There’s a lot more, but you get the idea.

      Bob

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