Since Princeton’s Dr. Michael Oppenheimer conflated weather with climate last week, proclaiming a short lived heat wave as “This is what global warming really looks like” in a media interview, it seems only fair to show what real science rather than what he and Dr. Trenberth’s government funded advocacy looks like. I can’t wait to see how Dr. Michael Mann tries to poo-poo this one. – Anthony
From Johannes Gutenberg-Universität Mainz: Climate in northern Europe reconstructed for the past 2,000 years: Cooling trend calculated precisely for the first time
Calculations prepared by Mainz scientists will also influence the way current climate change is perceived / Publication of results in Nature Climate Change
An international team including scientists from Johannes Gutenberg University Mainz (JGU) has published a reconstruction of the climate in northern Europe over the last 2,000 years based on the information provided by tree-rings. Professor Dr. Jan Esper’s group at the Institute of Geography at JGU used tree-ring density measurements from sub-fossil pine trees originating from Finnish Lapland to produce a reconstruction reaching back to 138 BC. In so doing, the researchers have been able for the first time to precisely demonstrate that the long-term trend over the past two millennia has been towards climatic cooling.
“We found that previous estimates of historical temperatures during the Roman era and the Middle Ages were too low,” says Esper. “Such findings are also significant with regard to climate policy, as they will influence the way today’s climate changes are seen in context of historical warm periods.”
The new study has been published in the journal Nature Climate Change.Was the climate during Roman and Medieval times warmer than today? And why are these earlier warm periods important when assessing the global climate changes we are experiencing today? The discipline of paleoclimatology attempts to answer such questions. Scientists analyze indirect evidence of climate variability, such as ice cores and ocean sediments, and so reconstruct the climate of the past. The annual growth rings in trees are the most important witnesses over the past 1,000 to 2,000 years as they indicate how warm and cool past climate conditions were.
Researchers from Germany, Finland, Scotland, and Switzerland examined tree-ring density profiles in trees from Finnish Lapland. In this cold environment, trees often collapse into one of the numerous lakes, where they remain well preserved for thousands of years.The international research team used these density measurements from sub-fossil pine trees in northern Scandinavia to create a sequence reaching back to 138 BC. The density measurements correlate closely with the summer temperatures in this area on the edge of the Nordic taiga.
The researchers were thus able to create a temperature reconstruction of unprecedented quality. The reconstruction provides a high-resolution representation of temperature patterns in the Roman and Medieval Warm periods, but also shows the cold phases that occurred during the Migration Period and the later Little Ice Age.In addition to the cold and warm phases, the new climate curve also exhibits a phenomenon that was not expected in this form.
For the first time, researchers have now been able to use the data derived from tree-rings to precisely calculate a much longer-term cooling trend that has been playing out over the past 2,000 years.
Their findings demonstrate that this trend involves a cooling of -0.3°C per millennium due to gradual changes to the position of the sun and an increase in the distance between the Earth and the sun.”This figure we calculated may not seem particularly significant,” says Esper. “However, it is also not negligible when compared to global warming, which up to now has been less than 1°C. Our results suggest that the large-scale climate reconstruction shown by the Intergovernmental Panel on Climate Change (IPCC) likely underestimate this long-term cooling trend over the past few millennia.”
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Orbital forcing of tree-ring data
Jan Esper, David C. Frank, Mauri Timonen, Eduardo Zorita, Rob J. S. Wilson, Jürg Luterbacher, Steffen Holzkämper, Nils Fischer, Sebastian Wagner, Daniel Nievergelt, Anne Verstege & Ulf Büntgen
- Received 27 March 2012 Accepted 15 May 2012 Published online 08 July 2012
Solar insolation changes, resulting from long-term oscillations of orbital configurations1, are an important driver of Holocene climate2, 3. The forcing is substantial over the past 2,000 years, up to four times as large as the 1.6 W m−2 net anthropogenic forcing since 1750 (ref. 4), but the trend varies considerably over time, space and with season5. Using numerous high-latitude proxy records, slow orbital changes have recently been shown6 to gradually force boreal summer temperature cooling over the common era. Here, we present new evidence based on maximum latewood density data from northern Scandinavia, indicating that this cooling trend was stronger (−0.31 °C per 1,000 years, ±0.03 °C) than previously reported, and demonstrate that this signature is missing in published tree-ring proxy records. The long-term trend now revealed in maximum latewood density data is in line with coupled general circulation models7, 8 indicating albedo-driven feedback mechanisms and substantial summer cooling over the past two millennia in northern boreal and Arctic latitudes. These findings, together with the missing orbital signature in published dendrochronological records, suggest that large-scale near-surface air-temperature reconstructions9, 10, 11, 12, 13 relying on tree-ring data may underestimate pre-instrumental temperatures including warmth during Medieval and Roman times.
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I’m sure Steve McIntyre will give this paper a thorough examination for the same sorts of issues we’ve seen before in MBH98. Hopefully he won’t have to beg for years to get the data for replication like he did with Mann.
h/t to WUWT readers “Typhoon” and Dr. Leif Svalgaard
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Either (mad) Mann will respond that he’s Bored of the (tree) RIngs,
or he’ll complain that:
“I talk to the trees
But they don’t listen to me”….
er, no, we should be listening to them (provided it’s more than one, and not cherry-picked
(shades of George Washington saying, ‘I cannot tell a lie, I cherry-picked that tree….’).
Good to see that a study comes out that corroborates what rational minds have been
saying and observing about climate/weather and cycles thereof: even better to see that
it’s passed the gauntlet of peer review.
Hope that we can get more data from various sources in case the Mann-handlers
want to use these trees to create hockey sticks. Briing on the ents….
Difficult that there are more factors than just temperature that affect tree growth,
though I imagine there are ways to check if environmental stress (nutrients,
competition from other trees, fires, etc.) is also involved…
Let the “War of the Rings” begin!
At RC, the take away message I got, was that this study has a unique feature, in that the divergence from the modern temps does not happen. Therefore MM, ES and GS say that this has a very good chance to help move the science along. (They are not all ogres all of the time). As always, we must wait for the next crew to use the new method to see if there are serious flaws in it.
Neville says:
July 9, 2012 at 3:50 pm
> Does this only apply to the NH? Are there SH studies that show a similar result?
The title says “Northern Europe”, the abstract says “trees originating from Finnish Lapland,” so I imagine the answer to the first is they don’t know, and the latter probably doesn’t have much terrain that has a similar overall thermal regime with trees.
The Earth keeps gaining a relatively small amount of mass, online I see estimates from 10^7 to 10^9 kg per day, with the mass of the Earth about 6*10^24 kg. The Earth’s orbital speed over time should be slightly slowing due to drag from whatever particles are out there. I would think both of those would lead to the Earth getting closer to the Sun.
So why is the Earth moving away from the Sun? Is the Sun shedding so much mass (and energy that was mass) that its gravitational force is weakening?
Looks like an interesting study of summer temperatures in northern Europe over the last couple of thousand years.
If you look at http://en.wikipedia.org/wiki/File:Holocene_Temperature_Variations.png it seems to match the long term decline in temperatures over the last 8000 years.
I guess the Romans were more industrialized than we ever imagined. Since global warming has been a hoax, can we get our money back?
Wow… And just last year you were posting stories about how bad tree ring proxies were… I guess if it fits your agenda it’s ok?
http://wattsupwiththat.com/2012/03/20/another-reason-trees-dont-make-good-treemometers-new-tree-ring-data-bias-discovered/
When the vikings found Greenland, it was green. They had to move when it got cold again.
Billy Liar says:
July 9, 2012 at 3:29 pm
Why not just accept that they are unreliable indicators of past climate?
========
It isn’t the trees that are unreliable, it is the “calibration” methodology used by some climate scientists. A Lucia showed on her web-site, the divergence problem is a result of calibration.
It is interesting to note that this study does not demonstrate the divergence problem, which suggests that it does not have the calibration flaw found in the papers such and Mann and more recently Gergis.
My latest study of ring around the collar has determined that climate change is caused by switching from using Tide in my laundry.
Leo G says:
July 9, 2012 at 5:46 pm
At RC, the take away message I got, was that this study has a unique feature, in that the divergence from the modern temps does not happen.
===========
The divergence problem is a mathematical artifact of calibration. Formally known as “selection on the dependent variable”, it is a statistical flaw in the methodology that creates bias in the results. This bias leads to divergence at the calibration boundaries, and misleading results over the proxy period.
In other words, it isn’t the trees that are at fault. It is the knuckleheads looking at the tree cores that have improperly applied amplifier technology to statistics, thinking they were inventing a better way to look at noisy data. What they invented instead was a way to amplify noise, while making it look like signal. They fooled not only themselves, but most of the world as well.
Wow, the Medieval and Roman Tag Team has been undisappeared?
Antbones:
July 9, 2012 at 6:09 pm
Wow… And just last year you were posting stories about how bad tree ring proxies were… I guess if it fits your agenda it’s ok?
http://wattsupwiththat.com/2012/03/20/another-reason-trees-dont-make-good-treemometers-new-tree-ring-data-bias-discovered/
Thanks for pointing out the dichotomy here. I don’t want to be “hoisted on my own petard” as it t’war.
I have YET to see someone give a straightfoward explanation of the HOW and WHY “tree rings” can determine ANYTHING except the favorable or unfavorable nature of the growing season. Certainly it’s ONE data point, but a 130 year old tree, cut on the grounds of my church in 1996 has a growth ring from 1988 which is MINIMAL, and comes from a “drought” type summer. I’m certain there are some “over all average warm due to moisture trapping” summers, which could be found on that tree, which would show “phenominal” growth.
Then we have that old 018/016 “chestnut”. Aside from the isotope enrichment which has been established in tropical thunderstorms (can readily be measured) I’ve found the arguements with regard to fractional distilation and snow fall/other precipitation in general and the “correllation” to tropospheric temperatures to be completely bogus!
Thus when it comes to the SURFACE (say 0 feet above ground level) to 1000 feet above ground level temperatures, aside from the “instrumental record” dating back to the advent of themometry, I think really…we are clueless. AND NO ONE WANTS TO ADMIT IT!
Max
I don’t see a hockey stick.
1. Did they archive and make available ALL data, used and not used, meta-data, and code?
2. I don’t see the instrumental temperature tacked on to the end. Doesn’t that invalidate the study?
Anybody got Mann’s twitter ravings on this paper?
I wonder if they’re going to try and get another editor fired/resigned/demoted? Maybe the publisher will opt to post all email correspondence to them about this paper?
And I’m not convinced anyone really knows temperatures convincingly from past eras based on wood core studies. Manipulated tree ring prophecizing by the ‘team’, (I wish I could make team in even lower lowercase. Is there a bottomcase we can use for the team?), has soured me on wood seers and seeresses. I’d like to see some extraordinary evidence to prove correlation of tree rings to definitive temperature measurments (in hundreths of a degree or tens of degrees, whatever).
Climastrology 101: Pay attention students. In this class we will learn that:
1. Treemometers accurately record maximum summer temperatures as variations in the density of the wood in their rings.
2. Wood density variations in their rings also accurately reflect changes in solar insolation through time.
3. Solar insolation changes since the time of Jesus are unquestionably the result of long-term oscillations of orbital configurations.
4. Therefore, from the rings, we will be able to calculate that the forcing of solar insolation changes since the time of Jesus was up to four times as large as the net anthropogenic forcing since 1750.
5. Finally, we will correlate the wood density data with coupled general circulation models that take into account albedo-driven feedback mechanisms (since the time of Jesus) to conclusively demonstrate summers have cooled substantially since the time of Jesus.
Any questions?
The day will come that it will be regarded that it is a fools errand to use tree rings as a proxy for annual temperatures. It will be noted that temp, H2O, timing of the delivery of the H2O, and many other variables affect the growth of a tree.
However, since Mann began this game and made the rules, the hand must be played. The players in Mann’s game of tree tricks have/will be exposed. In the end, tree ring tricks and omissions can and will be used in the upcoming racketeering trials.
In the meantime I will use tree posts to attach my glass bulb thermometer for temp with an accuracy of about +- 1F, depending on the lighting.
I believe the big takeaway from this study is the solar forcing methodology. It appears to indicate we are headed towards another glaciation in the not too distant future. That is something we should all be concerned about.
“an increase in the distance between the Earth and the sun.”
The Earth is moving away from the sun?
We’re doomed!
At least they seem to have a biologist, maybe dendrochronology?
Can’t see an actual statistician… but there could be one with that sort of major among that group..
Anyway, sure beats Mann, who knows very little about either dendrochronolgy or statistics.
I must echo the concerns of others here, specifically;
1. If tree rings aren’t great thermometers, then they aren’t great thermometers. Agreeing or disagreeing with your position neither increases or decreases their accuracy.
2. These are summer temperatures and the changes in warming/cooling are mostly in the winter. So it is another piece of the puzzle but hardly a game changer.
3. The trees are from a smalll geographical region in Northern Europe. This is a regional study and is no more indicitive of global temps than the CET or GISP2 ice cores.
4. It’s a tree ring data set. As Max points out above, tree rings only really show whether it was a good or bad growing season. I have yet to see a paper that explains why we can assume that a particular season was good or bad due to temperature and not due to other factors effecting growth.
It is an interesting paper, but I’m sceptical about the validity of tree rings.
They used to have good parties at JGU 🙂
No coverage on this yet at NYT, BBC, CNN, or NPR. Set the clock and the countdown to historic bias.