Sorry no graphics, no abstract or paper (not published yet, due Friday the 27th, I hate it when they do this) the Penn State press release was rather spartan. So I’ll provide this one showing Mann’s previous work where the Medieval Warm Period doesn’t much show up at all:
So here’s the question, the press release below mentions sediments. Place your bets now on whether the Tiljander sediment series remains inverted or not. (h/t to Leif Svalgaard) – Anthony
Past regional cold and warm periods linked to natural climate drivers
Intervals of regional warmth and cold in the past are linked to the El Niño phenomenon and the so-called “North Atlantic Oscillation” in the Northern hemisphere’s jet stream, according to a team of climate scientists. These linkages may be important in assessing the regional effects of future climate change.
“Studying the past can potentially inform our understanding of what the future may hold,” said Michael Mann, Professor of meteorology, Penn State.
Mann stresses that an understanding of how past natural changes have influenced phenomena such as El Niño, can perhaps help to resolve current disparities between state-of the-art climate models regarding how human-caused climate change may impact this key climate pattern.
Mann and his team used a network of diverse climate proxies such as tree ring samples, ice cores, coral and sediments to reconstruct spatial patterns of ocean and land surface temperature over the past 1500 years. They found that the patterns of temperature change show dynamic connections to natural phenomena such as El Niño. They report their findings in today’s issue (Nov. 27) of Science.
Mann and his colleagues reproduced the relatively cool interval from the 1400s to the 1800s known as the “Little Ice Age” and the relatively mild conditions of the 900s to 1300s sometimes termed the “Medieval Warm Period.”
“However, these terms can be misleading,” said Mann. “Though the medieval period appears modestly warmer globally in comparison with the later centuries of the Little Ice Age, some key regions were in fact colder. For this reason, we prefer to use ‘Medieval Climate Anomaly’ to underscore that, while there were significant climate anomalies at the time, they were highly variable from region to region.”
The researchers found that 1,000 years ago, regions such as southern Greenland may have been as warm as today. However, a very large area covering much of the tropical Pacific was unusually cold at the same time, suggesting the cold La Niña phase of the El Niño phenomenon.
This regional cooling offset relative warmth in other locations, helping to explain previous observations that the globe and Northern hemisphere on average were not as warm as they are today.
Comparisons between the reconstructed temperature patterns and the results of theoretical climate model simulations suggest an important role for natural drivers of climate such as volcanoes and changes in solar output in explaining the past changes. The warmer conditions of the medieval era were tied to higher solar output and few volcanic eruptions, while the cooler conditions of the Little Ice Age resulted from lower solar output and frequent explosive volcanic eruptions.
These drivers had an even more important, though subtle, influence on regional temperature patterns through their impact on climate phenomena such as El Niño and the North Atlantic Oscillation. The modest increase in solar output during medieval times appears to have favored the tendency for the positive phase of the NAO associated with a more northerly jet stream over the North Atlantic. This brought greater warmth in winter to the North Atlantic and Eurasia. A tendency toward the opposite negative NAO phase helps to explain the enhanced winter cooling over a large part of Eurasia during the later Little Ice Age period.
The researchers also found that the model simulations failed to reproduce the medieval La Nina pattern seen in the temperature reconstructions. Other climate models focused more specifically on the mechanisms of El Niño do however reproduce that pattern. Those models favor the “Thermostat” mechanism, where the tropical Pacific counter-intuitively tends to the cold La Niña phase during periods of increased heating, such as provided by the increase in solar output and quiescent volcanism of the medieval era.
The researchers note that, if the thermostat response holds for the future human-caused climate change, it could have profound impacts on particular regions. It would, for example, make the projected tendency for increased drought in the Southwestern U.S. worse.
Other researchers on the project were Zhihua Zhang, former postdoctoral fellow in meteorology now at the National Oceanic and Atmospheric Administration; Scott Rutherford, Roger Williams University; Raymond S. Bradley, University of Massachusetts; Malcolm K. Hughes and Fenbiao Ni, University of Arizona; Drew Shindell and Greg Faluvegi, NASA Goddard Institute for Space Studies, and Caspar Ammann, National Center for Atmospheric Research.
The National Science Foundation, the U.S. Department of Energy, NOAA, and NASA supported this work.
Read this from Judith Currie
“we are to develop effective strategies for dealing with skeptics and if we are to teach students to think critically.”
She does not get it. The AGW people seem to think that there are no scientists that are skeptics and to question AGW makes one some sort of low life. I don’t think she understands the scientific method has been corrupted.
Roger Sowell (07:46:25) :
(Say, Anthony – how about we change the label for the Mann et al team to “liars?”) We’re the skeptics, they’re the liars. Just a thought. (I know, I know…Liars is too inflammatory and combative…need something softer but accurate)
How about “Hiders”? That should get them hopping mad.
REPLY: How about we just stop labeling people altogether and concentrate on what the science says? – Anthony
Pompous Git (22:05:42) : “The researchers found that 1,000 years ago, regions such as southern Greenland may have been as warm as today.”
The corpses of the Greenland dead are still there, frozen in the ice that used to be farmland…
Greenland at that time had trees growing wild in at least a few places. Woods. Forests. None since.
REPLY: How about we just stop labeling people altogether and concentrate on what the science says? – Anthony
Hear hear!
The political battle was lost long ago. So let’s get back to the scientific process and get these perverts of science prosecuted and discredited.
REPLY: and there you go again with the labeling “perverts of science”
Off topic a bit, but could not find a correct string to post, but thought I had noticed a trend that is just beginning. On 25 NOV, I read in my local news paper (yes, for the time being I subscribe to a three-dimensional version) that “slashing greenhouse gas emissions” has an “added benefit” of “preventing millions of premature deaths”. The local article was based on this from Yale University:
http://e360.yale.edu/content/digest.msp?id=2162
What I found significant, was that this type of press release may represent a subtle shift away from the warmists mantra that it is CO2 from man’s activities that is the main reason for proposed drastic political changes and governmental control of all things carbon, to a differing scare tactic based upon the noble pursuit of saving lives. We’ve seen this before, but I sense that this may become a direction of choice after the recent “climategate” issues. Notice the nod to “carbon black” or soot deposits and deep deposition of such material in the lung. All well and good, based on known responses to carbon in the lungs. Hard to argue against. Also, the referenced changes to cleaner fuels for food preparation away from the current dung burning in India – was this not covered in the Copenhagen Agreement proposed docuemntation? I smell rat dung…
“The researchers didn’t discover anything at all that has not always been known by historians or by anybody taking a walk in uphill parts of Europe and wondering why all those farms have been abandoned ( because it used to be warmer and farming there us to be feasable when now it is not ).”
The trouble is that such anecdotal evidence (Roman wine grape cultivation in Britain is another one that is frequently trotted out) is worth very little.
It reveals more about economics and standards of living than climate. It is more likely the farms were abandoned because sheep grazing became more profitable than growing crops on marginal land (as in the Highland Clearances of Scotland), that suboptimal farming became uneconomic because of agricultural imports brought about by improved communications or that rising standards of living made a poor life scratching a living on highland farms an unattractive option.
Similarly the Roman vineyards in Britain don’t say much about past climate: hobbyists and small commercial winemakers show it’s perfectly possible to produce wine in England today. But now we can easily and cheaply import wine from the other side of the world in a way the Romans could not.
That is why this sort of anecdotal evidence is almost useless and we need hard physical evidence.
Regarding the hockey stick, here’s Monckton’s long paper describing the shenanigans behind protecting it from criticism and “verifying” it, followed (pages 16-29) by summaries of 21 published papers that provide evidence of warming during the MWP. (Ten papers deal with Europe and the North Atlantic, eleven scientific papers address the period elsewhere on the planet.) Each summary occupies about half a page and contains a graph that illustrates key data points.
http://scienceandpublicpolicy.org/monckton/what_hockey_stick.html
ED says:
“That is why this sort of anecdotal evidence is almost useless and we need hard physical evidence.”
The frozen Viking bodies beneath Greenland’s permafrost are hard evidence.
As for anecdotal evidence, that’s what we’ve got, in effect, from the CRUsaders–stories.
PS–by “stories,” I mean stuff that’s been made up.
rootlake (05:53:25) :
Here’s a real hockey-stick for you: Google Trends data on ‘Climategate’:
Interesting that Sweden tops the US in searches for it…
Any swedes reading this, do you still have a free press in Sweden that could account for this??
Dave.
I dont think even the communist Russians HAD to buy Pravda like I HAVE to pay for the BBC propaganda which I get.
Aunty Beeb used to be a proud old lady but now she is a tired old whore with her pants down taking it from global government.
Shame on you aunty.
No-one’s mentioned this yet. (I think).
Mann is still using the Tiljander sediment series inverted according to Jean S over at CA.
DaveE.
Rudolf Kipp (04:50:05) : Dear Anthony, for a recent article I have prepared a map of locations showing evidence for the MWP. Maybe you find that helpful. (here is a Google translation of the according article)
This is a fantastic piece of work, Rudolf, well worth publishing the Medieval Warm Period material here as a counterweight to this latest uu@Michael Irwin. One request: it would be nice to have the map able to fit my 1024 x 768 pixels screen!
BTW I want to know if uu@Michael Irwin has used a new phony proxy for the Pacific…
REPLY: I plan to publish it, I just can’t keep up with the demands being made on me and my time at the moment – Anthony
And looking at the ‘y’ axis, all accurate to within 0.1 deg C — quite the proxies!
@ur momisugly Tenuc (11:24:44) in reply to Roger Sowell (07:46:25) :
“Regarding CRU et al, perhaps a kinder term than ‘liars’ would be bender – appropriate, perhaps, because of their propensity to manufacture hockey sticks.”
The antonym for sceptic is gullible, not liar. In any case, I suspect bender would not approve of the term bender as a synonym for liar.
Is the Tiljander series the same as David Kaufmann’s Korttajarvi series, or is this another instance of flipped data in a “Team” paper?
From http://www.eastangliaemails.com/emails.php?eid=1010&filename=1252154659.txt:
@ur momisugly Lucy Skywalker (12:40:20) :
“Greenland at that time had trees growing wild in at least a few places. Woods. Forests. None since.”
From http://www.gh.gl/uk/facts/nature.htm
“Flora and fauna are determined by the Arctic climate. The vegetation is characterised by an absence of trees. However, in sheltered valleys in South Greenland there is rock birch, mountain ash, alder and willow scrub. Grain cannot ripen in Greenland.
The overall vegetation is low rock and tundra plants: mosses, lichen, heather, crowberry etc. In North Greenland most rocks are bare or with a low vegetation.
Since 1981 the Greenland Arboretum near Narsarsuaq in the south has reserved an area of 500 acres. Through extensive transplanting of trees from other alpine and subarctic timer-line areas, botanists are trying to establish a woodland. So far, 68,000 small trees comprising almost 75 species have been transplanted.”
During the Viking settlement, structural timber came from North America since none was available locally. The Greenlanders exported mainly walrus tusks (used as an ivory substitute) and polar bear skins. Imports from Europe amounted to ~4.5 kg/person/year, mainly iron as there were no known deposits of bog-iron in either Greenland, or at the N. American settlement at that time.
@ur momisugly Ed (13:02:11) : “The trouble is that such anecdotal evidence (Roman wine grape cultivation in Britain is another one that is frequently trotted out) is worth very little.
It reveals more about economics and standards of living than climate.
[snip]
Similarly the Roman vineyards in Britain don’t say much about past climate: hobbyists and small commercial winemakers show it’s perfectly possible to produce wine in England today.”
Shows how much you know about economics 🙂
England currently produces wine from grapes one year out of ten according to the winegrowers association. Nine years out of ten, they need to either add sucrose (cane sugar), or use vacuum distillation to remove some of the water. Sucrose was insanely expensive during the MWP and didn’t become affordable until the settlement of America several hundred years later. Perhaps you have some evidence that they had access to vacuum distillation equipment from the 19thC.
To get an idea of how expensive sucrose was, one of the Henry kings managed to muster almost 1.5kg (3lb) of sucrose for a banquet. The accumulation of this huge (for the time) amount took several months.
Lucy Skywalker, thanks for the lovely graphic, never seen it before.
Pompous Git (15:36:02) :
Thanks for correction. So there are a few trees growing naturally in sheltered valleys in South Greenland today – plus the arboretum I heard about but discounted for the post as it’s “artificial” tending and pretty recent. However, I doubt the paragraph which says that the Vikings had to import structural timbers and seems to suggest there were no forests in the Greenland MWP. My info source suggested clearly that trees grew in some sheltered areas of Greenland at that time, where no trees exist today.
See the following papers for more information on global temperatures and various proxies which show significantly more climate variability than Mann shows
http://people.iarc.uaf.edu/~sakasofu/pdf/two_natural_components_recent_climate_change.pdf * *
http://www.clim-past.net/3/569/2007/cp-3-569-2007.pdf
http://www.freesundayschoollessons.org/pdfs/climate-history.pdf
See presentation by Dr. C Loehle called BROKEN HOCKEY STICKS, 1500 YEAR CYCLES AND OCEAN COOLING
http://www.heartland.org/bin/media/newyork09/PowerPoint/Craig_Loehle.ppt#283,16,Best-fit
The fact that the MWP occured in Antarctica was demonstrated by
Quaternary glacial and climate history of Antarctica
Ólafur Ingólfsson
Published in: J. Ehlers & P.L. Gibbard (eds.) 2004:
Quaternary Glaciations – Extent and Chronology, Part III. Elsevier, pp. 3-43.
section 7.3
“There was then a renewed withdrawal phase between c. 1 – 0.5 ka BP, correlated by Baroni (1994) and Baroni & Orombelli (1994b) with the Northern Hemisphere Medieval Warm Period (ca. 1000-1300 A.D.). Moraine ridges containing fossil marine shells then show a glacial readvance in Terra Nova Bay after 0.5 ka BP, which Baroni & Orombelli (1994b) suggested might correspond to the Little Ice Age glacial expansion in the Northern Hemisphere. Möller (1995) described a system of minor, fresh-looking thrust moraines in Granite Harbour, Victoria Land, which he suggested were formed by repeated oscillations during general retreat of the ice front. The youngest thrust moraine post-dates, 1910 A.D., when the English Terra Nova Expedition surveyed the area, and Möller (1995) concluded that the moraine ridge system was formed in connection with a Little Ice Age glacial expansion. ”
So why does M. Mann wait so long to recognize the obvious?
“England currently produces wine from grapes one year out of ten according to the winegrowers association. Nine years out of ten, they need to either add sucrose (cane sugar), or use vacuum distillation to remove some of the water.”
I have not been able to find any reference to this one year out of ten, only that sucrose is added to increase the alcohol content and quality of the wine. I think it is fairly safe to assume that what would have been considered acceptable in Roman Britain could fall well below modern commercial standards. It is a mistake to assume that simply because modern tastes would demand the addition of sugar that people living on the far edge of the Roman Empire would have had the same requirements.
One might as well argue that Roman Britain must have been warmer than today because they didn’t have gas central heating and they would have been too cold otherwise.
I made a comment above about the hockey stick shape of the ENSO (Nino 3) in Mann’s paper.
I’ve thought about that some more and, one could end up with that scenario if one was building in a cooler overall ocean starting about 150 years ago.
The ocean surface has warmed by about 0.4C to 0.5C so one could make the assumption that both the Nino 3 and North Atlantic were, on average, about 0.5C cooler going back in time.
Its just that I have seen other ENSO reconstructions which do not have this -0.5C built in. The equatorial Pacific has not warmed like the rest of the oceans – there was an upward trend until about 1944 and then the average has been stable since then.
So, Mann can use a lower Nino 3 average in the past if he wants to but he should be citing the other reconstructions and noting why his is different.
Ed read;
Science 9 October 1998:
Vol. 282. no. 5387, pp. 268 – 271
DOI: 10.1126/science.282.5387.268
Past Temperatures Directly from the Greenland Ice Sheet Dahl-Jensen etal.,
A Monte Carlo inverse method has been used on the temperature profiles measured down through the Greenland Ice Core Project (GRIP) borehole, at the summit of the Greenland Ice Sheet…………….
The Last Glacial Maximum, the Climatic Optimum, the Medieval Warmth, the Little Ice Age, and a warm period at 1930 A.D. are resolved from the GRIP reconstruction with the amplitudes -23 kelvin, +2.5 kelvin, +1 kelvin, -1 kelvin, and +0.5 kelvin, respectively.
To recap:-
Climatic Optimum +2.5, the Medieval Warmth +1, the Little Ice Age -1, and a warm period at 1930 A.D +0.5.