The University of Colorado made a serious mistake in the press release that I cited. This press release was issued well before the paper was available, and of course the paper itself was not made available to journalists. It was hidden behind the AAS paywall.
I wrote to the press officer at UC on Friday, he responded Saturday night, on a holiday weekend, to his credit, here is my exchange:
Re: question about press releaseFrom: Gifford H. MillerSent: Saturday, September 05, 2009 8:02 PMTo: Anthony Watts – mobileSubject: Re: question about press releaseIndeed, this is a typo, Anthony. Not sure how it escaped my attention.The sentence should read: “The research team assembled high-resolution records of climate for the past 2,000 years and found that the cooling trend reversed in 20th Century.“I have passed the correction to our PR folks and it should be fixed soonThanks for catching thisGifford Miller
I looked at the Kaufman paper press release on EurekAlert as well as here:http://www.colorado.edu/news/r/bff9b4f453f2f9e1aa1e5d1b699d8525.html
In the second paragraph there is this sentence:“The research team assembled high-resolution records of climate for the past 2,000 years and found that the cooling trend reversed in the mid-1990s.”Is this correct? Is this a typo and instead should it say “mid-1900’s ” ?
Thanks for your consideration. Anthony Watts
The last sentence of paragraph 2 now reads:
“The research team assembled high-resolution records of climate for the past 2,000 years and found that the cooling trend reversed in the 20th century.”
It was originally stated as:
The research team assembled high-resolution records of climate for the past 2,000 years and found that the cooling trend reversed in the mid-1990s.
I’ve received some criticism for using the press release and acting on it to look for such a change in the 1990’s per the press release. While that criticism would be valid if the press release and the paper were both made available to me at the same time, the fact is they were not.
This method of pushing a scientific paper via press release, ahead of the paper’s actual journal release, and then hiding it behind a paywall is unprofessional and stinks. If the science organization wants to be seen as credible, then they need to make both the press release AND the paper available to journalists at the same time.
This idiotic “press release but no sci paper” policy needs to be changed. I’ll have more on this soon. As it stands, I’ve going to avoid UC press releases until they change the policy and I encourage others to do the same.
There’s a lot of buzz about regarding the Kaufman et al paper published today in Science which claims a recent reversal on a long term Arctic cooling trend and “found that the cooling trend reversed in the mid-1990s.” In the NOAA internal newsletter I cited yesterday, NOAA claims that the “According to the most recent Arctic Report Card, the Arctic Ocean continues to warm”. OK fair enough, we’ll have a look.
|Figure A1. Arctic-wide annual averaged surface air temperature anomalies (60°–90°N) based on land stations north of 60°N relative to the 1961–90 mean. From the CRUTEM 3v dataset, (available online at www.cru.uea.ac.uk/cru/data/temperature/. Note this curve does not include ship observations.|
Note the trend from 1980 to present. Note also that there are few weather stations above 60N and even fewer on the Arctic Ice itself. The data is relatively sparse and interpolation/gridding/averaging is employed to come up with the coverage all the way to 90N. We’ll get back to this.
Let’s first get an understanding of the Kaufman paper. Here’s the abstract. We can’t get a look at the full paper or publish it here yet since it is behind the AAS paywall. If somebody has an external link to it, please advise.
Recent Warming Reverses Long-Term Arctic Cooling
Darrell S. Kaufman,1,* David P. Schneider,2 Nicholas P. McKay,3 Caspar M. Ammann,2 Raymond S. Bradley,4 Keith R. Briffa,5 Gifford H. Miller,6 Bette L. Otto-Bliesner,2 Jonathan T. Overpeck,3 Bo M. Vinther,7 Arctic Lakes 2k Project Members
The temperature history of the first millennium C.E. is sparsely documented, especially in the Arctic. We present a synthesis of decadally resolved proxy temperature records from poleward of 60°N covering the past 2000 years, which indicates that a pervasive cooling in progress 2000 years ago continued through the Middle Ages and into the Little Ice Age. A 2000-year transient climate simulation with the Community Climate System Model shows the same temperature sensitivity to changes in insolation as does our proxy reconstruction, supporting the inference that this long-term trend was caused by the steady orbitally driven reduction in summer insolation. The cooling trend was reversed during the 20th century, with four of the five warmest decades of our 2000-year-long reconstruction occurring between 1950 and 2000.
Here’s the press release from EurekAlert:
Long-term cooling trend in Arctic abruptly reverses, signaling potential for sea rise
|IMAGE: An illustration showing an abrupt reversal in Arctic cooling despite an increasing distance between the sun and Earth during the Arctic summer solstice.Click here for more information.|
A new study led by Northern Arizona University and involving the University of Colorado at Boulder indicates Arctic temperatures have reversed from a long-term cooling trend and are now the warmest they have been in at least 2,000 years, bad news for the world’s coastal cities facing rising seas in the coming decades.
High northern latitudes have experienced a long-term, slow cooling trend for several millennia, the result of a wobble in Earth’s rotation that has been increasing the distance between the sun and Earth and decreasing Arctic summer sunshine. The research team assembled high-resolution records of climate for the past 2,000 years and found that the cooling trend reversed in the mid-1990s.
The decade from 1999 to 2008 was the warmest in the last 200 decades and corresponds with a continuing buildup of human-generated greenhouse gases in Earth’s atmosphere, said lead author Darrell Kaufman of Northern Arizona University. “Scientists have known for a while that the current period of warming was preceded by a long-term cooling trend, said Kaufman. “But our reconstruction quantifies the cooling with greater certainty than ever before.”
Since the Earth is still moving away from the sun — it’s about 0.6 million miles further during the Northern Hemisphere summer solstice than it was in 1 B.C. — it appears greenhouse gases began “overriding” the natural cooling of Earth in the middle of the last century, said Professor Gifford Miller of CU-Boulder’s Institute for Arctic and Alpine Research, a study co-author. “We expect the Arctic will continue to warm in the coming decades, increasing land-based ice loss and triggering global increases in sea-level rise,” he said.
The study was published in the Sept. 4 issue of Science. Other institutions participating in the study included the National Center for Atmospheric Research in Boulder, the University of Arizona, the University of Massachusetts, the University of East Anglia in Norwich, England, and the University of Copenhagen in Denmark. The study was funded by the National Science Foundation.
The research team reconstructed past temperatures on a decade-by-decade basis during the past 2,000 years using information gleaned from ancient lake sediments, ice cores, tree rings and other samples. As part of the study, the decade-by-decade climate data reconstruction was compared with sophisticated climate model simulations run by NCAR researchers.
The NCAR climate simulations agreed closely with the ground-based Arctic data used in the study, said NCAR scientist David Schneider, a co-author on the study. “This result is particularly important because the Arctic, perhaps more than any other region on Earth, is facing dramatic impacts from climate change,” Schneider said. “This study provides us with a long-term record that reveals how greenhouse gases from human activities are overwhelming the Arctic’s natural climate system.”
The new Science study dovetails with a report published earlier this year by the U.S. Climate Change Science Program on changes in the Arctic and at high latitudes. The CCSP study’s five lead authors — including Miller and CU-Boulder INSTAAR Director Jim White — concluded climate warming in the Arctic and at high latitudes likely will continue at a rapid pace given human-caused changes in Earth’s atmosphere.
Arctic temperatures have reached their highest level in the past decade, averaging 2.5 degrees Fahrenheit higher than would have been expected if the 2,000-year cooling trend had continued through the latter part of the 20th century and into the 21st century, said Kaufman. Kaufman received his doctorate from CU-Boulder in 1991 while studying under Miller at INSTAAR.
Previous research has shown that Arctic temperatures increased three times faster during the 20th century than temperatures in the rest of the Northern Hemisphere — a phenomenon known as “Arctic amplification,” said Miller, also a professor of geological sciences at CU-Boulder. The amplification is caused by decreased Arctic sea ice and an increased absorption of the sun’s heat by exposed ocean as well as “darker” land areas caused by decreases of Arctic snow and ice, he said.
“With less sea ice in winter, the ocean returns the heat stored in summer to the atmosphere, resulting in warmer winters throughout the Arctic,” said Miller.
“Because we know that the processes responsible for past Arctic amplification are still operating, we can anticipate that it will continue into the next century,” said Miller. “The magnitude of change was surprising, and reinforces the conclusion that humans are significantly altering Earth’s climate.”
“As we are confronted with evidence of global warming, it is extremely helpful to be able to use paleoclimate data to provide context for today’s climate relative to the range and trajectory of recent climate regimes,” said Neil Swanberg, director of NSF’s Arctic System Science Program.
The BBC did a better job of reporting the story and included a graph from the paper. This paper supposedly ties all of the 20th century Arctic warming to greenhouse gas emissions… There’s one tiny problem with the paper’s claim…
Kaufman et. al. w/ my annotations
And here is that graph Dave annotated:
OK that’s one problem. Here’s another. Both Kaufman et al and NOAA claim recent Arctic warming. In the case of the Kaufman paper, they specifically claim they “found that the cooling trend reversed in the mid-1990s.”
Since we can’t really look at the Hadley CRU data since it is held under lock and key despite the repeated FOI requests so that analysis and verification can be performed, we can’t really analyze it pertaining to NOAA’s claim of warming. Since NOAA and HadleyCRU use many of the same stations above 60N (they’d have to since there are so few) it seems reasonable to assume they share similar data in the Kaufman et al paper.
Fortunately there is another Arctic temperature data source available we can look at to compare against. And that is from the Danish Meteorological Institute (DMI). Like NOAA, they offer a dataset that shows temperature in the high latitudes.Here is what they say about that dataset and how it is obtained.
The daily mean temperature of the Arctic area north of the 80th northern parallel is estimated from the average of the 00z and 12z analysis for all model grid points inside that area. The ERA40 reanalysis data set from ECMWF, has been applied to calculate daily mean temperatures for the period from 1958 to 2002, from 2002 to 2006 data from the global NWP model T511 is used and from 2006 to present the T799 model data are used.
The ERA40 reanalysis data, has been applied to calculation of daily climate values that are plotted along with the daily analysis values in all plots. The data used to determine climate values is the full ERA40 data set, from 1958 to 2002.
Here is the most recent DMI graph of Arctic temperature:
Note that the blue line represents the “melting point” of ice in Kelvin or 0°C/32°F The green line represents the average climate from 1958 to 2002, i.e. the “baseline”
I don’t have time to get into a detailed analysis of the raw DMI data this morning as I have other duties, but I do have time to do a visual check that is just as telling.
Kaufman et al claims they “found that the cooling trend reversed in the mid-1990s.” That should easy to spot in the DMI graphs if it exists. So I animated the entire set of DMI graphs from 1958 to 2009. See if you can spot the temperature spikes or the “…cooling trend reversed in the mid-1990s.” signature.
click for full sized animation
Watch the top of the bell curve above the blue line. See any big changes? I don’t. Note that in the animation above, due to a slight change in DMI’s graphical presentation for 2008 and 2009, I had to graphically fit 2008 and 2009 to match the rest of the animation framework so that there would not be a distracting jump at the end. The data is unchanged in doing this.
One of the most common claims of alarmists is that the Arctic is “melting” and that implies a temperature cause in their statements. But as we see, during the critical melt window, the DMI data seems to hold right along the climatic normal.
One thing about DMI, if you go to their main web page, http://ocean.dmi.dk/english/index.php you don’t find any alarming pronouncements about Arctic melting or temperature reversal like you do at NOAA.
Others like NASA say the wind pattern changes is more of an issue, blowing the sea ice southward. Perhaps NOAA and Kaufman should look more closely at before making grand claims.