- Ph.D., professor emeritus of physical geography and quaternary geology.
Karlen is a retired professor in the department of Physical Geography and Quaternary Geology from Stockholm University.
Stance on Climate Change
“Newspapers should think about the damage they are doing to many persons, particularly young kids, by spreading the exaggerated views of a human impact on climate. As far as I can see the IPCC 'Global Temperature' is wrong. Temperature is fluctuating but it is still most places cooler than in the 1930s and 1940s. It will take about 800 years before the water level has increased by one” meter.” 
“By relying on statistical reconstruction of the last 1000 years, using only the temperature patterns of the last 140 years instead of actual temperature readings, the IPCC report and Summary missed both a major cooling period as well as a significant warming trend during that millennium, said Karlen.
“'The [IPCC report] relies extensively on an attempt to reconstruct the global climate during the last 1000 years,' said Karlen. 'This reconstruction shows neither a Medieval Warm Period nor a Little Ice Age. But extensive evidence shows that both these events occurred on a global scale and that climates fluctuated significantly.'” 
Karlen's name appeared in an advertisement  published by the Cato institute published an advertisement  in major newspapers including the Washington Post, the New York Times, the Washington Times, and the Los Angeles Times that questioned President Obama's stance on climate change. 
PolitiFact also evaluated Cato's claim  that “There has been no global warming for a decade now,” and found it to be false.
March 4, 2008
Created by the International Climate Science Coalition (ICSC )—a group of climate skeptics directed by Tom Harris —the declaration concludes that “attempts by governments to legislate costly regulations on industry and individual citizens to encourage CO2 reduction will slow development while having no appreciable impact on the future trajectory of global climate change.”
January 2, 2008
Karlen's name appears on the Lavoisier Group 's submission to the Garnaut Climate Change Review. One of their first assertions is that “There is no scientific consensus on the causal connection between anthropogenic carbon dioxide and global climate control. The weight of genuinely reputable scientific opinion is now firmly against any such connection.”
Their advice to the government is to “Wait and See” because “We do not know what the
climatic future is…” 
February 5, 2007
Was listed as an “author” of the Fraser Institute's Independent Summary for Policymakers  which concludes that “There is no compelling evidence that dangerous or unprecedented changes [in climate] are underway.”
The report was coordinated by Ross McKitrick  and the writing team included numerous global warming deniers such as Joseph D’Aleo , Madhav Khandekar , William Kininmonth , Christopher Essex , Ian Clark , Tad Murty , and James J. O’Brien .
December 13, 2007
Karlen signed a 2007 open letter  to the Secretary-General, along with another “100 prominent scientists,” which declared that the “UN Climate Conference [is] taking the world in entirely the wrong direction.”
The letter proclaims that CO2 is a “non-polluting gas that is essential to plant photosynthesis” while the “IPCC's conclusions are quite inadequate as justification for implementing policies that would markedly diminish future prosperity.” 
Karlen was a signatory to the 2006 open letter  to Prime Minister Stephen Harper, titled “Open Kyoto to Debate,” which urged inaction on climate policy while denying the reality of climate change. 
Karlen was part of a group  assembled by Science and Environmental Policy Project (SEPP ) created to critique the IPCC's third assessment report (TAR). SEPP is headed by the prominent denier Fred Singer  and has received at least $20,000  from ExxonMobil between 1998 and 2000, as well as funding from Shell and Uniroyal. 
The group contained 14 unnamed “climate scientists” that made up SEPP's “Science Integrity Team.” The team set out to present its findings “in plain English” to congress and the media—findings which suggested a lack of significant or human-caused global warming.
Their findings were summarized as follows:
- “The earth's atmosphere has not warmed over the past 20 years.”
- “The last century is not the warmest in the last 1000 years.”
- “Man's use of fossil fuels has not had a perceptible effect on global climate.”
- “Even if the earth were to warm slightly, and atmospheric CO2 were to increase, the effects would be mostly beneficial.”
- “The only support for serious future warming comes from theoretical climate models - but they give only imperfect simulations of the real atmosphere, are not validated by actual observations, and are incapable of making valid predictions.”
A search of 22,000 academic journals shows that Karlen has published over 40 peer-reviewed articles.
“Editorial: Global warming 'consensus' a fiction ,” The Orange County Register, January 1, 2008.
Bruce Sullivan. “SCIENTISTS SAY GLOBAL WARMING THEORY IS A LOT OF HOT AIR ,” Science and Environmental Policy Project, MAy 30, 2000. Archived March 25, 2007.
Jonathan Hiskes. “Cato’s skeptic ads draw a flurry of responses ,” Grist, April 2, 2009.
“CLIMATE EXPERTS WHO SIGNED MANHATTAN DECLARATION ,” International Climate Science Coalition. Accessed January, 2012.
“Submission from the Lavoisier Group to the Garnaut Climate Change Review: Issues Paper 1 Climate Change: Land use – Agriculture and Forestry” (PDF ) The Lavosier Group, January 2, 2008.
“Open Letter to the Secretary-General of the United Nations ,” December 13, 2007. Reprinted by the Science and Public Policy Institute.
Open Kyoto to debate ,” National Post, April 11, 2006.
“What's wrong with U.N. climate science: An independent scientific review of the IPCC's Third Assessment Report ,” (News Release) The Science and Environmental Policy Project, May 25, 2000. Archived February 15, 2007.
“NRSP People ,” Natural Resources Stewardship Project. Archived January 31, 2007.
“Who We Are ,” Stolkholm Initiative for rational climate policy. Accessed January, 2012.
“Curriculum Vitae: Fred Goldberg” (PDF ), klimatbalans.info. Archived January 31, 2012. Archived .pdf on file at DeSmogBlog..
“Wibjörn Karlén ,” Wikipedia entry.
John P. Bluemle. “Some Thoughts on Climate Change” (PDF ), NDGS Newsletter, Vol 28, No. 2. Archived .pdf on file at DeSmogBlog.
“Scandinavia-gate: Climate cooling, but scientists 'hide the decline' ,” Climategate, February 15, 2010.