According to the NRSP, Clark completed his graduate studies at the University of Waterloo and at the Université de Paris Sud (Orsay) in isotope hydrogeology and paleoclimatology. 
Clark is a professor in the Department of Earth Sciences at the University of Ottawa.
He was a Science Advisor to the Natural Resources Stewardship Project (NRSP), and is a “scientist on call” to the Competetive Enterprise Institute (CEI) a group that has also referred to him as an “Arctic specialist.” 
Stance on Climate Change
“I am compelled to disagree that there is a consensus of scientists who agree that this [climate change] is the consequence of human activities. While the melting of permafrost, retreat of glaciers and waning of the permanent ice pack may be alarming, it is only alarming to those unfamiliar with past changes in climate in the North. Paleoclimatologists recognize such events as part of natural changes wholly unrelated to CO2 concentrations in the atmosphere. In fact, the waxing and waning of ice shelves, along with glaciers, ice caps and pack ice are largely related to changes in solar inputs.” 
“Solar activity of the last hundred years, over the last several hundred years correlates very nicely on a decadal basis, with sea ice and Arctic temperatures.” 
February 4, 2018
In January 2018, more than 200 scientists endorsed an open letter calling on the American Museum of Natural History (AMNH) to remove climate change denier Rebekah Mercer from its board and to “end ties to anti-science propagandists and funders of climate science misinformation.” The New York Times reported that those among the AMNH letter calling for Mercer to step down were Michael E. Mann, director of the Earth System Science Center at Pennsylvania State University, and Katharine Hayhoe, director of the Climate Science Center at Texas Tech University. 
Clark was among a group of climate change deniers who responded with their own open letter, calling for the AMNH “not to cave in to this pressure.” The letter was signed by numerous individuals with ties to groups funded by the Mercer Family Foundation such as Will Happer of the CO2 Coalition; Richard Lindzen, a fellow at the Cato Institute; and Craig Idso, the chairman of the Center for the Study of Carbon Dioxide and Global Change. There are a number of signatories affiliated with the Heartland Institute, which has received over $5.78 million from the Mercer Family Foundation since 2008. 
“The Earth has supported abundant life many times in the geological past when there were much higher levels of carbon dioxide in the atmosphere. It is quite likely that future generations will benefit from the enrichment of Earth’s atmosphere with more carbon dioxide.
“Make no mistake, the agitators are not defending science from quackery — quite the contrary!”
February 9, 2012
In an interview for Canada’s Financial Post, Clark defended the extraction of tar sands oil:
“The pollution and emissions from the oil sands have been greatly exaggerated. Killing the oil sands would be to the great detriment of all Canadians, from aboriginal groups to engineers and other workers alike. It is greener energy than many other sources.” 
He further suggested that the consumption of tar sands oil is not a significant contributor to climate change and minimized the effect of CO2:
“The oil sands contribute very, very little to global CO2. If one believes in global warming, then one must accept that the oil sands contribute very, very little to warming. Shutting down those operations would do nothing to reducing CO2 emissions. … CO2, however, has had no apparent impact on the warming periods.” 
March 8, 2007
Clark was on the “writing team” for the Fraser Institute's 2007 independent summary for policymakers (ISPM).
The ISPM's conclusion is that “there will remain an unavoidable element of uncertainty as to the extent that humans are contributing to future climate change, and indeed whether or not such change is a good or bad thing.” 
December 12th, 2007
Clark signed an open letter to the Secretary-General of the United Nations alleging that that the “UN climate conference taking the World in entirely the wrong direction.” 
- Natural Resources Stewardship Project (NRSP) — Past Scientific Advisory Board member. The NRSP is now defunct. 
Competetive Enterprise Institute (CEI) — Clark is listed by the Competetive Enterprise Institute (CEI) as an “Arctic specialist” and media contact. ExxonSecrets also lists Clark as a “scientist on call” for CEI. 
Clark recently co-authored Critical Topics in Global Warming which was published by the Fraser Institute in 2009. The paper, edited by Ross McKitrick, advertises the ISPM as a credible scientific source and goes on to describe how the “causes and consequences of global warming are more fiction than fact.”
“NRSP People: Dr. Ian Clark,” The Natural Resources Stewardship Project. Archived January 20, 2009.
“Are Global Warming Disasters Really on the Way?” The Competetive Enterprise Institute, May 12, 2004.
“Letter to the editor of The Hill Times,” The Natural Resources Stewardship Project, March 22, 2004. Archived February 10, 2009.
“Greenhouse effect is a myth, say scientists,” Daily Mail Online, March 5, 2007.
“Independent Summary for Policymakers: IPCC Fourth Assessment Report” (PDF), The Fraser Institute, March 2, 2007.
“Open Letter to the Secretary-General of the United Nations,” Science and Public Policy Institute, December 13, 2007.
“NRSP People,” Natural Resources Stewardship Project. Archived February 6, 2007.
“Independent Summary for Policymakers
IPCC Fourth Assessment Report” (PDF), The Fraser Institute, March 2, 2007.
“Are Global Warming Disasters Really On the Way?”, Competitive Enterprise Institute, May 12, 2004.
“Heartland Experts: Mr. Ian Clark,” The Heartland Institute. Accessed March 1, 2012.
Robin Pogrebin and Somini Sengupta. “A Science Denier at the Natural History Museum? Scientists Rebel,” The New York Times, January 25, 2018. Archived February 13, 2018. Archive.is URL: https://archive.is/tAIv4
Graham Readfearn. “Climate Science Deniers Defend New York’s American Museum of Natural History From Calls to Drop Trustee Rebekah Mercer,” DeSmog, February 6, 2018.
mnh18-feb4-petitionletter (PDF - Untitled). Retrieved from Watts Up With That.
“Deniers:Scientists:Ian Clark,” ExxonSecrets Wiki.
Joseph D'Aleo, Olavi Kärner, Richard C. Willson, and Ian Clark. “Solar Changes and the Climate” (PDF, Supplementary Analysis of the Independent Summary for Policymakers), The Fraser Institute.
“Ian Clark (geologist),” Wikipedia.