Policy Documents

Spencer-Denning Debate Highlights Heartland Climate Conference

James M. Taylor –
July 12, 2011

Colorado State University atmospheric science professor Scott Denning and University of Alabama-Huntsville principal research scientist Roy Spencer squared off in a spirited yet friendly keynote debate at The Heartland Institute’s Sixth International Conference on Climate Change, which took place June 30-July 1 in Washington, DC. Both scientists agreed human emissions of greenhouse gases are likely warming the planet, but they disagreed sharply on the key questions of the amount and the effect.

Denning asserted the science shows humans are not only warming the planet but are doing so at a rapid and dangerous rate. Particularly troubling, Denning said, is the effect rapidly industrializing nations such as China and India will have on global greenhouse gas levels during the rest of the century. We must act now to develop emissions-reducing technologies and implement them on a global scale to avert a climate crisis, Denning warned.

Spencer countered that atmospheric humidity and clouds are responsible for more warming in United Nations computer models than carbon dioxide emissions, yet humidity and clouds are not behaving in the real world as the models have predicted. Assigning a more realistic impact to humidity and clouds results in far less future warming than the United Nations computer models predict, said Spencer.

The debate was noteworthy for its substantive focus and constructive tone. The two scientists seemed to like one another and, unlike many other public debates between various global warming experts, the debate never became heated or testy.

A ‘Lukewarmer’
Dr. Patrick Michaels, a senior fellow at the Cato Institute and past president of the American Association of State Climatologists, kicked off the conference with a keynote presentation in which he described himself as a “lukewarmer.” Humans are influencing global temperatures, Michaels explained, but not enough for temperatures to rise any higher than the lower end of United Nations computer model predictions.

Michaels reported long-term trends indicate approximately 1.4 degrees of warming per century, not enough to produce significant problems.

Dr. Bob Carter, research professor at James Cook University in Queensland, Australia, explained in the conference’s final keynote session how alarmists are altering and misrepresenting important climate data. For example, Carter showed how Australian and New Zealand climate officials altered precipitation and temperature data to make it appear the nations have recently experienced dangerous warming and precipitation extremes, when the raw data show neither.

Heavy Proposed Costs
In addition to the keynote presentations, half a dozen panels discussed scientific, economic, and public policy issues related to climate change.

In a very informative panel on climate change economics, Dr. David Tuerck, professor of economics at Suffolk University, and Dr. David Schnare, a senior fellow at the Thomas Jefferson Institute for Public Policy, documented how global warming alarmists’ preferred alternative energy options substantially raise electricity prices while averting very little projected temperature rise.

Yale University professor of economics Dr. Robert Mendelsohn, the third person on the panel, emphasized he does not challenge the UN climate projections but does dispute the assertion that dramatic, immediate action will be beneficial in the long run. Mendelsohn advised small steps in the near term to reduce greenhouse gases, with larger steps being more cost-effective in future decades.

Mendelsohn did not shy away from challenging the UN’s economic assumptions. “If you don’t like the climate science in the IPCC, you really won’t like its economics,” Mendelsohn told the audience. “They’ve never met an economist that they like.”

Al Gore vs. King Kong
In the conference’s final panel, solar scientists Nicola Scafetta, Ph.D. of Duke University and Willie Soon, Ph.D. of Cambridge, Massachusetts explained the physics of why natural forces—particularly the sun—remain the primary drivers of global temperatures.

Atmospheric carbon dioxide concentrations may have some impact on global temperatures, but as Soon quipped, increases in carbon dioxide emissions have about as much strength relative to variations in solar output as Al Gore relative to King Kong.

James M. Taylor (jtaylor@heartland.org) is managing editor of Environment & Climate News.