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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Antbones says:
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?
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If you bothered to read all the comments you will see most of us are STILL saying tree rings are bad proxies.
kadaka (KD Knoebel) says:
July 9, 2012 at 5:53 pm
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?
The Chinese are all jumping off the Great wall at Noon everyday.
All this tells me is that if you try hard enough, you can find a piece of data to say whatever the hell you want it to say. Tree ring chronologies are by-and-large complete junk…
Using the same proxy, tree rings, allows you to construct both a cooling trend and an accellerating warming trend. This is enough evidence to completely discredit tree rings as a reliable indicator of temperature. Move on, nothing to see here.
Paul Coppin,
Yes, agree on most of the point. The key is that the tree/tree-ring is a quick response, whereas the canopy changes more slowly and in the end it is the competition within the canopy between trees which dictates the individual growth of the tree. There is a reason trees are fairly equally spaced whether in a tropical jungle or the siberian wilderness … and that is tree to tree competition … unless or until you get to the tree line.
However, I accept that the “optimum growth” within a canopy may also change, so that even in the long term, individual trees in a canopy may grow more in better conditions. Although it is not impossible they grow less as individual trees in overall better conditions! But it really matters very little, because there is no practical way to calibrate how growth of the canopy effects the growth of the individual tree.
“You are conflating trees with forests.”
Paul, I was very careful not to use the word “forest”, because by the time you are very far north, the canopy is so spread out that most people would not call it a forest. It is a patchwork of isolated trees whose spacing is largely dictated by available sunlight (a facet of the canopy)
Forest is an indication of the density of trees, canopy (as I use it) is an indication of the density of trees intercepting sunlight — the idea I’m trying to emphasise is that trees in the canopy are fighting “tooth and nail” (not sure what that is for a tree) to gain as much of the canopy as possible.
Tony
I agree with you, Oxford and Cambridge Universities have kept excellent records and are only about 100km apart but their rainfall is very different, don’t know why Mann had to go to Yamal, unless the area was made physically accessible by oil majors who do lot of explorations around there.
http://www.vukcevic.talktalk.net/Oxbridge.htm
As for good tomatoes take a fortnightly trip on the Scillonian.
J says: But it occurs to me, looking at the the photos of the trees in their paper, leaning over the lake, that the effect of competition for sunlight with other trees may be mitigated by the trees being lakeside
A shrewd observation – but it is still a competitive position, but the canopy now consists of any trees that can push out into the lake to catch the sunlight. However, that is why you often get specialist trees like willows that are evolved to maximise the opportunity in this particular niche.
I changed the proxy reconstruction graph to expand the y-axis and give it a zero line. It makes the warm/cool periods more obvious.
http://i46.tinypic.com/21oowag.jpg
With apologies to J.R.R. Tolkien…
One tree ring to rule them all,
One tree ring to follow,
No other rings above Yamal,
Lest warmist claims prove hollow.
Roman habiliments did not lend themselves to population booms. Colder weather affects all toga-wearers the same way: with decreased libido comes inevitable… er, decline.
I will buy some of the astrophysics and leave the tree rings for another day.
AndyG55 says:
July 9, 2012 at 11:43 pm
….Now I know we haven’t an abundance of horses at the moment, be have got lots more humans and more luvly CO2.
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ERRRrrrr, I hate to break it to you Andy but there are still a lot of horses now, at least in the USA. In 1850 there were only 4.3 million horses, by 1900 there were 21.5 million and by 1920, at the peak there were 25 million.
Today the Ag census lists 3.7 million equines but the National Horse Council lists 9.2 million. I would go with the National Horse Council numbers since the current Ag survey is only counting horses on “registered farms” (sells over $1000 of Ag products) and misses all the backyard horses like my 23 and all of the equines owned by my neighbors.
The 1911 world census listed in an article indicates a world population of about 90.9 million This would be near peak population. link
In the 2006 world census report, there are 58,372,106 horses in the world. I wonder if that “Official figure” is as far off as the USDA is from the National Horse Council figure.
Maybe those high temperatures in 1930 were because there were so many horses…
Think about this. If the USDA can not even get an accurate count of the number of horses in the USA how do we expect the “Government ” to be able to get an accurate reading of US temperature?
Gaudenz Mischol says:
July 10, 2012 at 1:23 am
“How many want to bet that the Warmists will now declare tree rings unreliable?”
And the skeptics will now accept the tree ring reconstructions…. :-))))))))))
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DOPE, bad science is STILL bad science and tree-ometers are bad science unless someone has managed a quantum leap discovery like isotope analysis in sea cores by Shacklton
Almost a Laplander says:
July 10, 2012 at 3:00 am
….And the treeline on mountains is a good calibrator. If the trees cannot grow nowhere near where they grew 800 years ago because it is too cold, then we can reasonably conclude that it was warmer previously…..
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Now that is an excellent use of trees to determine temperature/climate.
So Time in 1974 and Newsweek in 1975 actually got it right?!?
Lubos Motl says:
July 10, 2012 at 7:26 am
If I were just a little bit excited by temperatures than I am, I would surely conjecture that the Decline of the Roman Empire was sparked by the Decline of the temperatures.
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Just make that optimal growing conditions instead of just temperature. Temperature shifts also seem somewhat correlated to rain fall pattern shifts and poor harvests can do a tap dance on any civilization even ours.
Lubos Motl says:
July 10, 2012 at 7:26 am
If I were just a little bit excited by temperatures than I am, I would surely conjecture that the Decline of the Roman Empire was sparked by the Decline of the temperatures.
with a little help from my ancestors fighting not only Romans but your ancestors too, across frizzing Europe all the way from Baltic down to the Balkans, ending the Roman rule there.
We are all friends now, until the next big freeze.
The Earth is cooling 0.3 degrees C per millennium, because … increases in the distance between the Earth and the sun. WAIT, WHAT?!!!
Since when is the earth rapidly flying away from the Sun? I mean if distance to the sun is even a 1% factor in that, within a few million years, life on Earth would be doomed!
I hope the circular reasoning demonstrated in the last two sentences of the abstract are not an indication of the quality of the work
It seems to be time to remind people of this work
http://wattsupwiththat.com/2008/06/13/surprise-leaves-maintain-temperature-new-findings-may-put-dendroclimatology-as-metric-of-past-temp
The post refers to this study
http://www.nature.com/nature/journal/v454/n7203/abs/nature07031.html
I used to have a link to an unpaywalled version of the complete work, but it has gone dead. Here is the abstract
“The oxygen isotope ratio (18O) of cellulose is thought to provide a record of ambient temperature and relative humidity during periods of carbon assimilation1, 2. Here we introduce a method to resolve tree-canopy leaf temperature with the use of 18O of cellulose in 39 tree species. We show a remarkably constant leaf temperature of 21.4 +/- 2.2 °C across 50° of latitude, from subtropical to boreal biomes. This means that when carbon assimilation is maximal, the physiological and morphological properties of tree branches serve to raise leaf temperature above air temperature to a much greater extent in more northern latitudes. A main assumption underlying the use of 18O to reconstruct climate history is that the temperature and relative humidity of an actively photosynthesizing leaf are the same as those of the surrounding air3, 4. Our data are contrary to that assumption and show that plant physiological ecology must be considered when reconstructing climate through isotope analysis. Furthermore, our results may explain why climate has only a modest effect on leaf economic traits5 in general.”
Trees grow in the ground but, like all photosynthesizing plant species, they grow from the air. A tree’s root system provides water and nutrients that can influence or limit plant growth, but the variable record provided by tree rings is primarily a record of the photosynthesis occurring in the tree canopy. If that canopy, where all the controlling reactions are happening, is maintaining itself within a much narrower range of temperatures than the ambient air, it would seem to be very difficult to construct any logical biological or chemical pathway for a tree to be able to encode an accurate record of the ambient temperature within itself.
This work enjoyed an almost Warhol like brief moment of celebrity, not much more than a couple of weeks, and then pretty much went down the memory hole.
tonyb says:
July 10, 2012 at 7:44 am
……Whilst everything may be vey green things havent set-i havent been able to grow outdoor tomatios for 5 years, which when you look at the cet decline over the last decade speaks volumes that we need a plan b (cooling) as well as a plan a (Warming)
tonyb
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Yes that is what is really worrisome about the whole mess and I do not see our governments addressing the issue instead I see governments catering to corporate greed.
In march of 2008 …USDA Undersecretary Mark Keenum, [said] “Our cupboard is bare.” U.S. government food surpluses have evaporated…
The following are the big winners in the biofuel scam and the 2008 food riots in over thirty countries.
Archer Daniels Midland profits soar to 550 percent
Archer Daniels Midland, Monsanto, Cargill,
Monsanto record breaking profits
Cargill record breaking profits
This is where it gets very interesting.
And that is the complex interplay between the speculators in food derivatives, bankers lending “investment capital ” to those speculators and the corporations like Monsanto (seeds) Cargill (grain traders) and Archer Daniels Midland (biofuel producer) who have “Convinced” governments that grain storage is so passé. The starvation related deaths of children has no real place in that interplay.
In light of that information Lester Brown’s “Grain Reserves” Shell Game is an interesting read. The shearing of the sheep or insider trading comes to mind.
The recent trumpeting of the hot weather in the USA might also have something to do with grain trading as well as CAGW. Global Wheat, Soy and Corn Reserves Decline as Demand Grows, Crops Falter
Lester Brown on the Russian wheat crop failure last year.
So a 2+1/2 months supply is now the rule of thumb for the world’s grain reserves. The US government has made “Hoarding” sort of illegal BTW.
This article shows just how ‘interconnected’ and vulnerable our food supply now is http://www.businessweek.com/articles/2012-07-05/drought-stalks-the-global-food-supply
At least it matches up now with other studies showing the LIA to be the coldest period in the Holocene, with an overall downtrend.
I believe this data to be reliable. But I also believe this chart supports that increased CO2 may contribute to warming.
Yes, this trendline shows cooling…from zero AD. But take a close look at the data from time point of the industrial revolution, or even as recent as the turn of the 20th century. if you did, the trend line would steeply incline upward.
I didn’t think this had to be pointed out but I guess it does. The issues is NOT that the earth has never been warmer, can’t get warm on its own, etc. The issue is does adding CO2 above and beyond naturual causes increase the rate of warming beyond what we can safely adopt to.
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The signal coming from trees is very noisy, because they are very robust and adaptive, which makes them unreliable as thermometers. (That’s why some of the oldest living things on Earth are trees).
Instead pick some other plant or crop which is known to be temperature sensitive. Then look for its presence or absence in historical layers. When it gets warm, it should be able to thrive further northwards.
Vinyards, for example.
I was just watching an old 1990 episode of Agatha Christie’s Poirot the detective and he said to his sidekick Hastings, “Did you know the world is cooling 3 degres every 12,000 years.