Commentary

Human-Caused Climate Change Less than Expected

President Obama is determined to do something about global warming, telling Congress in his State of the Union address that if they won’t act on it, he will.

The president’s refrain is familiar, but unfortunate. Obama continues to ignore new science suggesting that the threat posed by human-caused climate change is substantially less than previously thought.

Obama’s brand-new pick to head the EPA, Gina McCarthy, is a fresh signal that the administration favors knee-jerk policies to restrict emissions, even when they are unsupported by available data and would hamper the economic recovery.

Congress, with its wait-and-see attitude, has taken the right approach. Now, if only the president and his EPA would see the light.

A good place to start is a just-published study by a research team led by Dr. Peter Stott, a climate expert from the U.K.’s Met Office Hadley Center, which finds that climate model projections of an alarming temperature rise are inconsistent with past observations.

New science is telling us that the old science was unjustifiable and overly extreme.”

When Stott and his colleagues forced the amount of global warming predicted by climate models to equal the amount of warming that has actually been observed, the future temperature rise projected to accompany human greenhouse gas emissions dropped rather substantially. In other words, the better climate models match the past, the less scary the future looks.

Big surprise: My colleagues and I published the same thing in the scientific literature more than 10 years ago.

What makes the new findings particularly interesting is that Dr. Stott was an author of the most recent climate assessment report from the United Nations Intergovernmental Panel on Climate Change (IPCC). Stott specifically contributed to the chapter on global climate projections, which included the possibility that human greenhouse gas emissions could lead to rapid increases in global temperatures.

His new work now indicates that the IPCC climate projections have been exaggerated on the high side.

Stott is not alone in his findings. Within just the past two years, no fewer than seven peer-reviewed studies have been published in the scientific literature that have concluded that the earth’s climate sensitivity—that is, how much warming that will accompany a doubling of the atmospheric carbon dioxide concentration — is likely to be substantially lower than the IPCC’s determination.

All of these studies have largely ruled out entirely the IPCC’s high-end values.

James Annan, a leading researcher into constraints on estimates of climate sensitivity, and author of several of the new studies on the topic, has long thought that the IPCC high-end climate sensitivity values were unjustified.

Annan suggests that the IPCC is increasingly acting in a wholly unscientific manner, accusing the IPCC of “having firmly wedded themselves to their politically convenient long tail of high values, their response to new evidence is little more than sticking their fingers in their ears and singing ‘la la la I can’t hear you.’”

This would perhaps be amusing if the IPCC were not considered by many — including the president and the EPA — to be the leading authority of climate change, past, present and future.

To base its findings that greenhouse gases “threaten the public health and welfare of current and future generations” and to justify regulations on greenhouse gas emissions, the EPA relies strongly on the IPCC reports.

When the president says that it is “the overwhelming judgment of science” that our greenhouse gas emissions are making all manner of extreme weather worse, he is referring largely to the IPCC reports.

Since the IPCC is erring on the high side of things, so too must be the EPA and the president.

This situation is unacceptable. It is time to step back and take stock, not rush into action.

The earth’s average temperature has largely remained unchanged over the past 16 years. During this same period, the annual global emissions of greenhouse gases have increased by nearly 50%.

Together, this combination is straining the credibility of climate change alarmism predicated on the idea that the earth’s climate is extremely sensitive to greenhouse gas emissions from the consumption of fossil fuels to produce our primary energy supply.

Increasingly, both Mother Nature and the science of her behavior are telling us that climate change and its impacts will be moderate, making global “lukewarming” the more apt description. Adaptation is a more preferable course than mitigation.

The more time we give climate science the chance to explain climate observations, the better and more accurately informed we become.

New science is telling us that the old science was unjustifiable and overly extreme. We should make sure that any attempts at climate action don’t prove to be the same.

Paul C. Knappenberger is assistant director of the Center for the Study of Science at the Cato Institute.