Energy Secretary Rick Perry downplayed the role of human activity in the recent rise in the Earth’s temperature, saying natural causes are likely the main driver of climate change.
Perry was asked in a CNBC interview if he believed carbon dioxide was the "primary control knob" for the earth’s temperature.
"No. Most likely the primary control knob is the ocean waters and this environment that we live in," Perry said in the June 19 interview.
We decided to investigate Perry’s claim about climate change’s main cause, which scientists have likened to a "control knob."
Perry’s claim flies in the face of settled science.
The world’s leading authority on climate change, the Intergovernmental Panel on Climate Change, has concluded that human activity is "extremely likely" to be the main driver of warming since the mid 20th century.
While it’s still possible to find dissenters, scientists around the globe generally agree with this conclusion.
The graph below, based on work by NASA's Goddard Institute for Space Studies, shows just how closely human activity syncs with the earth’s rising temperature, especially since 1950.
The blue line shows how human factors (land use, ozone, aerosols and greenhouse gases) have contributed to global warming. The black line is the Earth’s recorded temperature since 1880.
This is not to say natural factors don’t affect the climate. They do. But Perry is wrong to call them the main cause of the earth’s rising temperature.
When you look at how natural causes (orbital and solar changes plus volcanic activity) have contributed to climate change, it’s clear the impact is less than that of human factors.
Perry is also wrong to say ocean waters are responsible for the uptick in temperature.
While oceans are a vital part of the climate system, and variations in their circulation can affect local climates in important ways, they don’t account for global warming, said Gavin Schmidt, climatologist and director of NASA's Goddard Institute for Space Studies.
"We have concluded close to all of the recent trends in global temperature is due to human activity, and CO2 is the dominant factor," Schmidt said, referring to carbon dioxide.
Perry misidentified climate change’s main "control knob," but he’s not the first Trump administration department head to fudge the facts on our warming planet.
We previously issued a False rating to Environmental Protection Agency chief Scott Pruitt’s claim that carbon dioxide is not "a primary contributor to the global warming that we see."
In fact, carbon dioxide is a greenhouse gas that collects in the earth’s atmosphere and traps excess heat. It has functioned like a "primary control knob" that’s been dialed up dramatically since humans began releasing significantly more amounts of CO2 into the air, mostly by burning fossil fuels, at the dawn of the Industrial Revolution.
"A reasonable analogy can be drawn between the way that atmospheric CO2 controls the global temperature of the Earth, and how your house thermostat controls the temperature of your house," said Andrew Lacis, a climatologist at NASA's Goddard Institute for Space Studies.
The NASA graph below shows the influence of greenhouse gas emissions, including a 40 percent increase in atmospheric CO2 since 1750 (green line), on the Earth’s temperature (black line).
Energy Secretary Rick Perry said, "Most likely the primary control knob (for the earth’s temperature) is the ocean waters and this environment that we live in."
Perry’s claim contradicts settled science. While natural factors certainly affect the climate, human factors are the main contributor to global warming, and carbon dioxide has acted as the "primary control knob" governing the earth’s relatively recent uptick in temperature.
We rate Perry’s statement False.