I had to chuckle at the cacophony of Twitfests going on today over this new study from Marcott et al. I especially liked the Mother Jones headline being Tweeted: “The Scariest Climate Change Graph Just Got Scarier”.
It rather reminds me of some people being fearful of certain religious icons.
![marcott-A-1000[1]](http://wattsupwiththat.files.wordpress.com/2013/03/marcott-a-10001.jpg?quality=83)
Yes, be afraid, very afraid, of that “unprecedented” (there’s that word again in the abstract) 0.7C temperature rise is the message I suppose. While the MSM will trumpet this I’m sure, we’ll get down to finding out just how good the science is. One potential problem is that the pollen data median sampling of 120 years, which is 4x the 30 year climate normals periods used today. That’s pretty low resolution for a study that is focusing on 2000 years and leaves lots of opportunity to miss data. Further, when they say the last 100 years was the warmest (with higher resolution data) they really aren’t comparing similar data sets when the other data has a 120 year median sampling.
Here’s the press release:
Press Release 13-037
Earth Is Warmer Today Than During 70 to 80 Percent of the Past 11,300 Years
Reconstruction of Earth history shows significance of temperature rise
March 7, 2013
With data from 73 ice and sediment core monitoring sites around the world, scientists have reconstructed Earth’s temperature history back to the end of the last Ice Age.
The analysis reveals that the planet today is warmer than it’s been during 70 to 80 percent of the last 11,300 years.
Results of the study, by researchers at Oregon State University (OSU) and Harvard University, are published this week in a paper in the journal Science.
Lead paper author Shaun Marcott of OSU says that previous research on past global temperature change has largely focused on the last 2,000 years.
Extending the reconstruction of global temperatures back to the end of the last Ice Age puts today’s climate into a larger context.
“We already knew that on a global scale, Earth is warmer today than it was over much of the past 2,000 years,” Marcott says. “Now we know that it is warmer than most of the past 11,300 years.”
“The last century stands out as the anomaly in this record of global temperature since the end of the last ice age,” says Candace Major, program director in the National Science Foundation’s (NSF) Division of Ocean Sciences. The research was funded by the Paleoclimate Program in NSF’s Division of Atmospheric and Geospace Sciences.
“This research shows that we’ve experienced almost the same range of temperature change since the beginning of the industrial revolution,” says Major, “as over the previous 11,000 years of Earth history–but this change happened a lot more quickly.”
Of concern are projections of global temperature for the year 2100, when climate models evaluated by the Intergovernmental Panel on Climate Change show that temperatures will exceed the warmest temperatures during the 11,300-year period known as the Holocene under all plausible greenhouse gas emission scenarios.
Peter Clark, an OSU paleoclimatologist and co-author of the Science paper, says that many previous temperature reconstructions were regional and not placed in a global context.
“When you just look at one part of the world, temperature history can be affected by regional climate processes like El Niño or monsoon variations,” says Clark.
“But when you combine data from sites around the world, you can average out those regional anomalies and get a clear sense of the Earth’s global temperature history.”
What that history shows, the researchers say, is that during the last 5,000 years, the Earth on average cooled about 1.3 degrees Fahrenheit–until the last 100 years, when it warmed about 1.3 degrees F.
The largest changes were in the Northern Hemisphere, where there are more land masses and larger human populations than in the Southern Hemisphere.
Climate models project that global temperature will rise another 2.0 to 11.5 degrees F by the end of this century, largely dependent on the magnitude of carbon emissions.
“What is most troubling,” Clark says, “is that this warming will be significantly greater than at any time during the past 11,300 years.”
Marcott says that one of the natural factors affecting global temperatures during the last 11,300 years is a gradual change in the distribution of solar insolation linked with Earth’s position relative to the sun.
“During the warmest period of the Holocene, the Earth was positioned such that Northern Hemisphere summers warmed more,” Marcott says.
“As the Earth’s orientation changed, Northern Hemisphere summers became cooler, and we should now be near the bottom of this long-term cooling trend–but obviously, we’re not.”
The research team, which included Jeremy Shakun of Harvard and Alan Mix of OSU, primarily used fossils from ocean sediment cores and terrestrial archives to reconstruct the temperature history.
The chemical and physical characteristics of the fossils–including the species as well as their chemical composition and isotopic ratios–provide reliable proxy records for past temperatures by calibrating them to modern temperature records.
Analyses of data from the 73 sites allow a global picture of the Earth’s history and provide a new context for climate change analysis.
“The Earth’s climate is complex and responds to multiple forcings, including carbon dioxide and solar insolation,” Marcott says.
“Both changed very slowly over the past 11,000 years. But in the last 100 years, the increase in carbon dioxide through increased emissions from human activities has been significant.
“It’s the only variable that can best explain the rapid increase in global temperatures.”
-NSF-
A Reconstruction of Regional and Global Temperature for the Past 11,300 Years
1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, USA.
2Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, USA.
- *To whom correspondence should be addressed. E-mail: marcotts@science.oregonstate.edu
Surface temperature reconstructions of the past 1500 years suggest that recent warming is unprecedented in that time. Here we provide a broader perspective by reconstructing regional and global temperature anomalies for the past 11,300 years from 73 globally distributed records. Early Holocene (10,000 to 5000 years ago) warmth is followed by ~0.7°C cooling through the middle to late Holocene (<5000 years ago), culminating in the coolest temperatures of the Holocene during the Little Ice Age, about 200 years ago. This cooling is largely associated with ~2°C change in the North Atlantic. Current global temperatures of the past decade have not yet exceeded peak interglacial values but are warmer than during ~75% of the Holocene temperature history. Intergovernmental Panel on Climate Change model projections for 2100 exceed the full distribution of Holocene temperature under all plausible greenhouse gas emission scenarios.
===============================================================
UPDATE: Andrew Revkin emailed me a link to his piece where the issue is commented on by Mann and Robert Rhode of (BEST). Being a cheerleader, Mann has little useful to add, but Rhode has some useful comments:
The Marcott et al. results may refine our understanding the last 10,000 years; however, the broad picture of Holocene climate does not seem to have been significantly changed by their findings. Previous work had already pointed towards a period of early Holocene warmth somewhat higher than recent centuries.
…
In discussing their result, there is one important limitation that I feel deserves more attention. They rely on proxy data that is widely spaced in time (median sampling interval 120 years) and in many cases may also be subject to significant dating uncertainty. These effects will both tend to blur and obscure high frequency variability. They estimate (page 1, column 3) that only 50% of the variance is preserved at 1,000-year periods. This amount of variance suppression is roughly what you would expect if the underlying annual temperature time series had been smoothed with a 400-year moving average. In essence, their reconstruction appears to tell us about past changes in climate with a resolution of about 400 years. That is more than adequate for gathering insights about millennial scale changes during the last 10,000 years, but it will completely obscure any rapid fluctuations having durations less than a few hundred years. The only time such obscuring might not occur is during the very recent period when dating uncertainty is likely to be low and sample spacing may be very tight.
Because the analysis method and sparse data used in this study will tend to blur out most century-scale changes, we can’t use the analysis of Marcott et al. to draw any firm conclusions about how unique the rapid changes of the twentieth century are compared to the previous 10,000 years. The 20th century may have had uniquely rapid warming, but we would need higher resolution data to draw that conclusion with any certainty. Similarly, one should be careful in comparing recent decades to early parts of their reconstruction, as one can easily fall into the trap of comparing a single year or decade to what is essentially an average of centuries. To their credit Marcott et al. do recognize and address the issue of suppressed high frequency variability at a number of places in their paper.
Ultimately, the Marcott et al. paper is an interesting addition to the study of millennial scale climate variability during the Holocene. Their results are broadly consistent with previous findings, but the details are interesting and likely to be useful in future studies. However, since their methodology suppresses most of the high frequency variability, one needs to be cautious when making comparisons between their reconstruction and relatively rapid events like the global warming of the last century.
Revkin has a video interview with co-author Shakun also, see it here:
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So we are now convinced that the MWP, the Roman Period, the Minoan Period were all COOLER than today. The Dorset people of Newfoundland, Labrador and the Northern Arctic, did not have a warm spell that allowed the Inuit to move east 5500 years ago or so and ended their culture: the Inuit seized the north because it was LESS easy to live along the coast than in Alaska at that time.
Further, the historical records, plantings of vinyards, wheat, cheery trees, all indicate that the vegatation of those periods only did as well as today further south than today. Greenland and Iceland were not as warm as today. The climates of Scotland, Norway and Denmark were never as pleasant and conducive to civilization and living outdoors as they are today. The Romans went to Britain because they thought a tough life with poor growing conditions was where people produced goods of value to the Empire.
Hmmm. Methinks we need less silos in academia. Perhaps some “social” could be organized between the History, Anthropology and Climate Science Departments.
Better question, did they ask Steve McIntyre to be a reviewer?
Michael Mann even gets an “I told you so,” in Borenstein’s piece:
Go tell it to the Vikings?
What was that Mark Twain quote about science?
I see in climatology circles, desperate times call for more desperate distortions.
Abstract
Surface temperature reconstructions of the past 1500 years suggest that recent warming is unprecedented in that time.
=========
Now let’s define some terms in this first sentence:
We have “suggest”, “recent”, and “unprecedented in that time”.
Suggest is a “get-out-of-jail-free” card, recent will come back on the data, as will, unprecedented in that time.
Nothing was said, that didn’t have a cover story.
———-
Science by tabloid ?
The real question is whether they used Mannian statistics to generate their hockey stick. Looks pretty suspicious from the graphs. I’ll wait for McIntyre or other tireless sleuths to wade through the details . . .
1. This is data linking temperature with pollen count, how do we know that the increase of temperature is not causing the increase in pollen count (increased land available for growth, longer growing seasons, etc) ?
2. Does the full report state at which point in the temperature graphs we hit those 20% – 30% times of higher temperatures that they mention? (I see the last 2k years as a flat line, so if we go by thier report, years 11300 – 2000 BP should show those higher temps, right?)
3. If that grey line is Mann’s temperature line… does that mean the pollen count is showing a temperature increase years before the measured increases in Mann’s graph? (for that matter, can pollen data be a proxy that can smooth out that much more than tree ring data?)
Yes the first thing I saw was it was armer 29 to 30 % of recent history, doesn’t that make it fraudulent to use the term “unprecedented” ? answers on the back of an open big oil cheqyue please!!
It is beneficial to flatten the paleo temperature record as much as possible. Low spatial and temporal sampling can be advantageously employed to effectively low pass filter any temperature transients that may have existed. Better yet is the use of tree rings, which respond to so many different forcings that temperature dependencies are completely smeared out.
It allows the climateers to argue that almost immeasurably small global temperature changes can result in huge changes in ice and sea levels. For example, a change in global T of a few tenth’s of a degree can be argued as sufficient to move us from the MWP into a mini ice age. The climate sensitivity must be ginormous! We are all doomed!
How come the graph in this story does not resemble the one a Andy Revkins site or the story on MSNBC.com which is much less misleading?
http://science.nbcnews.com/_news/2013/03/07/17225440-warming-fastest-since-dawn-of-civilization-study-shows?lite.
1. This is data linking temperature with pollen count, how do we know that the increase of temperature is not causing the increase in pollen count (increased land available for growth, longer growing seasons, etc) ?
… I seem to have an extra “not” in there… Do we know how they eliminated other factors to prove only temperature is causing the increase of pollen?
Again calls into question the love of the word “unprecedented”.
Now they agree that 20 to 30% of the last 10,000 years was warmer than the present and they choose to spin it the other way? Of course!
It seems the dictum “we must get rid of the Medieval Warm Period” lives on.
chris y says:
“It allows the climateers to argue that almost immeasurably small global temperature changes can result in huge changes in ice and sea levels.”
Prof Lindzen has commented on that:
This chart shows a rational view of the planet’s past temperature, using a normal y-axis.
Not so scary, is it?
Shakun and Marcott were on the team who published the paper last year that reversed the thinking on the subject of whether increases in CO2 occurred before or after periods of warming. They “proved” it occurred before periods of warming and therefore concluded that CO2 was the likely cause of the warming.
I wouldn’t have expected any less.
Here is the paper I referred to in my post above:
http://www.nature.com/nature/journal/v484/n7392/fig_tab/nature10915_F2.html
Looks like another bunch of pseudo scientists is getting into the business of writing science-fiction now. Its very lucrative and why not – everyone else is doing it. Its very cheap to do just get a bunch of random samples draw a graph load a paper with Eco-babble and presto the money keeps flooding in. No peer reviewer would dare criticize for fear of being marginalised and wiped off the available list. Yes folks the new World Order.
Greenland ice cores show that 9,100 of the past 10,000 years were warmer in Greenland than in any one of the past 100 years. The temperature fluctuations derived from the Greenland ice cores delineate the Holocene Climatic Optimum, Egyptian, Minoan, Roman, and Medieval Warm Periods and their relative warmth, as well as intervening cool periods such as the Little Ice Age. Serious climate reconstructions should begin (and could even end) with a thorough reading of the works of Dr. Hubert H. Lamb (“Climatic History and the Future” would be a good place to start), the founder of the Climatic Research Unit at the University of East Anglia. None of the Mann-ian et al works give even a nod of recognition to the high bar Lamb established by demonstrating the enormous volume of studies by many scientists supporting natural climate change. Before today’s researchers can build a tower to celebrate their theories of anthropogenic climate change, they first need to tear down the Great Wall that Lamb and others constructed demonstrating thousands of years of natural, often dramatic, climate change. The evidence to date is that they are still working at taking the first brick from the Wall.
pottereaton,
Shakun & Marcott take the position that ∆CO2 causes ∆temperature. But empirical evidence shows just the opposite cause and effect: changing temperature causes changes in CO2 to follow.
It is obvious from that empirical data that changes in temperature cause changes in CO2, not vice versa. Only in climastrology do scientists claim that computer models trump real world evidence.
Pure propaganda. But the scary thing is… millions of left-leaning sheeple will lap it up and recite it as gospel.
Y’know, it may be an attempt at ‘come clean’ honesty…. they could have sat back happily with Mann’s “current warming is unprecedented in the last 1500 years” (with all the smoothing involved in that!
But instead they have come out with a paper showing that in fact 20 to 30% of the Holocene was warmer than today.
Something I love to point out to my CAGW alarmist friends. (well, they are mostly not really CAGW alarmist, having not thought about it very much, they just tend to believe what they are told in this case).
Note the paragraph about IPCC projection seems to be obligatory in any recent publication (I’d suspect it is now a requirement of most reviewers) and gives no indication of the actual opinion of the article writers on the matter.
A bit more detail here:
http://simpleclimate.wordpress.com/2013/03/07/projected-warming-set-to-exceed-civilisations-experience/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+ResearchBloggingAllEnglish+%28Research+Blogging+-+English+-+All+Topics%29
Seems to disprove my theory above … they are perhaps just doing the usual “here is a proxy temperature record, now please look over here at the model ‘projections’ .., yes, the same ones we showed you last time….!”.
And to me, their figure B on that page makes it look a bit like we are in the process of saving ourselves from the next ice-age.
Years before present is defined as Years before 1950 in the data file.
It starts at 10 with a 0.6C so the 0.6C blade at the end of the hockey stick chart is really 1940 .
And was it 0.6C in 1940 compared to the 1961-1990 average which is what their paper states was used as the baseline. Snicker. Not according to NCDC, GISS or Hadcru.
It was only 0.1C according to Hadcrut3, 0.02C according to Hadcrut4, -0.06C according to GISTemp, and -0.13C according to the NCDC.
And they cut off the data at the point where the last ice age was just ending so that one could not see if their methodology would extend back in time and reach the generally accepted -5.0C of the last glacial maximum, which it clearly would not since they have the Holocene maximum at only +0.4C.
These type of reconstructions made Mann famous and well-funded and allowed the warmers to feel better about their theory. Marcott and Shakun want to join the club.
Someone should have a go at the database file – Database S1.
http://www.sciencemag.org/content/suppl/2013/03/07/339.6124.1198.DC1
I can also make such a graph. I just apply a low pass filter with a cutoff frequency of 1000 years and leave the last 100 years unfiltered using GISS data.
pollen? really??
just like tree rings they will increase with water… decrease without it.. Increase with CO2… Decrease without it… Increase with warmth… decrease without it… and it is all relevant to minor changes in all of these…
And we paid for this in grant monies?
NOT AGAIN…. and MANN to boot..
Garbage In = Garbage Out