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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That is a false premise. It invalidates an argument that uses it.
John
I’ve had a quick look at the data, and it seems to be a mixture of different behaviours.
One set of five series shows a peak around 9k years ago, a dip from 7k-3k and a rise to the present day.
Another set of around thirty five series shows pretty much of nothing. It looks like random noise.
And the third set of around twenty series shows the holocene optimum we know, with a peak around 2 C warmer than today.
(There were a few others that didn’t cover a long enough interval to make a proper comparison, I think.)
The ‘Holocene Optimum’ series have been mixed in with a bunch of ‘random noise’ series and some ‘Holocene dip’ series which has the effect of bringing the Holocene peak down to below a degree. All they have to do then is paste the instrumental temperature series on the end. (Note, the end spike is not in any of the 73 series.)
Of course, that might be saying that the Holocene peak did not occur everywhere, and that in many places the temperature didn’t change, which is how they’re interpreting it. You would need to look at the individual data sources to tell.
Whether the Holocene Optimum was global or not, it’s definitiely very naughty to splice on the instrumental record and talk about anything being ‘unprecedented’. The proxy data smooths anything going on at less than 300-3000 years (figure S18 in the SI). Apples and oranges.
“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.”
So 20% – 30% of the last 11,300 years was at least as warm as today. If that is the latest and best reconstruction, the result should be more widely known. That’s a huge change from the claim of “unprecedented”.
Steven Mosher says:
March 8, 2013 at 9:10 am
=============
I knew it !!
I can never find your “cv” when I need it.
It bothers me when people disparage you.
Of course, your writing style is inflammatory at times, but what the heck.
I always listen.
This article is so dishonest in its wording.
“‘This era is warmer than 80% of the time in the last 11,300 years’?!? BTW: did you remember to tell people that the last glacial period ended 12,500 years ago…What’s that you say? You remembered but you deliberately omitted it because it would hurt your attempts at fearmongering…Why thank you for being so candid with us.”
It’s too bad the global warming cult will never be this honest with the global community.
Steven Mosher says: March 8, 2013 at 8:41 am
“…I said show YOUR WORK. not point to somebody else’s.
plus, you haven’t answered the question….”
Now you’re just being silly.
Sure, we get the point; Nice work by Marcott etal …
…. just some poor emphasis on their part, their smoothed chart data with spiky instrumental record tagged on is a bit deceptive, and it was followed poor and dramatized headlining and reporting by almost everyone else.
“Steven Mosher says: March 8, 2013 at 9:10 am, Funny story. I started undergrad as a physics math major ( won some math competitions as a kid– like Mcintyre) but wasnt really challenged by those two areas.”
Right… except McIntyre has a degree in Mathematics.
“Philosophy, Literature and linguistics were a lot harder, so I got BAs in those.”
So do you have BAs in English and Philosophy or Philosophy, literature and linguistics? I am only interested in what the degree from the university you attended actually says on the piece of paper.
“I wandered into computational linguistics and of course to work in information theory ( as it pertains to textual analysis) I needed to go back and take stats courses. Since I was on a full ride scholarship I could basically sit in any classes I wanted. never bother to pick up a degree, already had too many.”
Of course! Too much trouble to pick up the degree.
The rest of your mentioned “experience” relates to the defense aircraft industry and anecdotes, nothing science related. “Operations Research” is a very vague job title that can mean almost anything. You could have been associated with any number of projects but your actual contributions to them could be almost anything. You forgot to mention you wound up doing sales and marketing at Northrop. Which is not something an engineer or scientist goes into.
Writing technical reports is something an English major should be able to accomplish so long as they have enough people to ask questions to.
“u.k.(us) says: I knew it !!”
You knew what? That he has no scientific education or experience and forgot to mention a bulk of his career is in sales and marketing? Don’t fall for resume padding. It is obvious to anyone with experience reading resumes and hiring personnel. People in sales are usually very good at this.
It is not hard to find his CV, it is right here,
http://www.linkedin.com/pub/steven-mosher/1/b07/27b
THE LITERARY HISTORY OF THE WORLD
(by the same authors)
Methodology: We averaged the page contents of 10000 books spanning all topics, ages, and regions of the world.
Results: Our results show unprecedented recent developments.
We obtained a uniform 5% gray. Except for a slightly (1%) lighter tone in the upper third of the page. Likely due to the presence of titles.
As our results did not match the What’s Up With That page, since yesterday we used the actual What’s Up With That page instead.
Our evidence shows that FOR THE FIRST TIME IN 1000 YEARS, ACTUAL LETTERS FORMING ACTUAL WORDS WERE USED YESTERDAY. On What’s Up With That.
This is a frightening development, from a relaxing gray to letters. Especially since it all happened in a single day.
Expert modeling by a literary consensus group shows that continuing this trend, by the end of the month, every surface on Earth, inanimate, vegetal or animal, will be black, covered with letters.
Life as we knew it is in grave danger.
A trillion dollars a year to be used on clean communications might not be enough to stem the problem, as humanity is already almost too late for meaningful action.
PS The authors thank the media for making this their top subject of concern since yesterday.
It is interesting that they acknowlege the early holocene was much warmer than now.