Published: Oct. 7, 2014 By

In recent debates hosted by theDenver Post, candidates were asked a series of yes-or-no questions by the moderators. One of those questions was, “Do you believe humans are contributing significantly to climate change?” Republican gubernatorial challenger Bob Beauprez and sixth district incumbent Republican Congressman Mike Coffman both answered “no,” putting them in clear contrast with the established scientific consensus on the issue. 


The coal-fired Craig Station power plant in northwest Colorado is the state's largest single source of CO2 emissions. (Wikimedia Commons)

Both tried to clarify their answer later in the debate.

“Are we going to end or alter the path that Earth’s evolution is going to take? I don’t think so,” said Beauprez.

“On the climate change issue, I just think the science is not quite settled,” said Coffman.

While Beauprez’s campaign website does not mention climate change, Coffman’s does. It states, “The role that carbon emissions, from human activity, have on climate change is still a subject of debate.”

In an interview with CU News Corps, Kevin Trenberth, a climate scientist at the National Center for Atmospheric Research, called this statement “emphatically wrong.”

“The human component is so far outside natural variability in many ways,” Trenberth said. “The estimates suggest that any natural variability has, if anything, worked against the warming.”

The scientific consensus that humans are contributing significantly to climate change is well established, and has been for quite some time. In 2006, the American Association for the Advancement of Science concluded, “The scientific evidence is clear: global climate change caused by human activities is occurring now, and it is a growing threat to society.” In 2012, the American Meteorological Society summarized, “It is clear from extensive scientific evidence that the dominant cause of the rapid change in climate of the past half century is human-induced increases in the amount of atmospheric greenhouse gases.” In fact, nearly 200 science organizations from around the world hold the position that human activity is causing climate change.

Furthermore, a 2010 study published in the Proceedings of the National Academy of Sciences found that 97 to 98 percent of the climate researchers most actively publishing in the field support the basic tenets of human-caused climate change. In another study, researchers examined nearly 12,000 studies on climate change between 1991 and 2011 and found that, among those expressing a position, 97.1 percent endorsed the consensus position that humans are causing climate change.

While uncertainties remain regarding exactly how climate change will manifest itself in the coming decades and centuries, there is virtually no debate within the scientific community on whether human activity is the dominant cause of recent warming, putting Bob Beauprez and Mike Coffman’s debate comments firmly out-of-step with the scientific literature on the subject.