Energy Secretary Rick Perry on Monday denied that man-made carbon dioxide emissions are the primary cause of climate change.
Asked in an interview on CNBC's "Squawk Box" whether he believed that carbon dioxide was "the primary control knob for the temperature of the Earth and for climate," Perry said that "No, most likely the primary control knob is the ocean waters and this environment that we live in."
Perry added that "the fact is this shouldn't be a debate about, 'Is the climate changing, is man having an effect on it?' Yeah, we are. The question should be just how much, and what are the policy changes that we need to make to effect that?"
Perry's comments fall in line with what Environmental Protection Agency administrator Scott Pruitt said in a March interview on the program. Pruitt said then that he does not believe carbon dioxide is a primary contributor to global warming.
Both men's views contradict the conclusions of scientists at Pruitt's own EPA as well as NASA, the National Oceanic and Atmospheric Administration and the United Nations' Intergovernmental Panel on Climate Change.
"It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century," the IPCC said in a 2013 report. Citing the IPCC report, the EPA said on its website, now removed, that "recent climate changes, however, cannot be explained by natural causes alone. Research indicates that natural causes do not explain most observed warming, especially warming since the mid-20th century." The EPA added, "it is extremely likely that human activities have been the dominant cause of that warming."
On Monday, Gavin Schmidt, a top climate scientist at NASA, tweeted that a paper he co-authored in 2010 used an almost identical phrase in its title - "principal control knob" - as the CNBC's Squawk Box used Monday. But the paper published in Science Magazine warned about the danger of "anthropogenic," or man-made, carbon dioxide continuing "unabated." The paper said that the high rate of atmospheric CO2 increase was "particularly worrisome" and that "the atmospheric CO2 control knob is now being turned faster than at any time in the geological record."
The Center for Biological Diversity took issue with Perry's comment about the oceans. "Perry has the science exactly backward," Shaye Wolf, climate science director at the center, said. "Far from being climate change's key cause, the world's oceans are actually another victim of greenhouse pollution."
Wolf added, "Our oceans absorb millions of tons of carbon dioxide a day, making them dangerously acidic. They've also soaked up most of man-made global warming's excess heat, putting tremendous stress on marine life."
It's true that over far longer time periods, other factors have driven changes to the Earth's climate, such as wobbles in the Earth's orbit around the sun. But in the most immediate period and in the current climate debate, scientists have made very clear that human emissions are the cause.
Perry said, however, that being a skeptic about the causes of climate change was "quite all right." He said, "this idea that science is just absolutely settled and if you don't believe it's settled then somehow you're another Neanderthal, that is so inappropriate from my perspective."
Perry is scheduled to testify three times this week on the Trump administration's proposed fiscal 2018 budget.
Perry has long avoided getting pinned down on mankind's contribution to climate change, and he has said that action on climate change should be weighed against economic costs. Although Perry urged President Donald Trump to remain in the Paris climate accord, Trump cited economic impacts when he announced his decision to pull the United States out of the climate accord. Trump drew on forecasts about impacts from a controversial report.
At his confirmation hearing for the energy secretary position, Perry brought up the politically sensitive topic, saying he believed the climate is changing and "some of it" is caused by "man-made activity." He added then: "The question is how we address it in a thoughtful way that doesn't compromise economic growth."
Citing Perry's assertion in his 2010 book that the planet was in a "cooling trend," Sen. Al Franken, D-Minn., asked him how much he thinks climate change is caused by human activity. "Far from me to be sitting before you today and claiming to be a climate scientist. I will not do that," Perry said, dodging the question.
Chris Mooney contributed to this article.
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