Democratic Sen. John Kerry of Massachusetts says global warming is as dangerous as the possibility of war over Iran's nuclear activities.
Kerry made the statement Wednesday, in what's being billed a "major" address to the Senate on climate change.
He compared global warming skeptics to "flat-earthers" and said climate change has become "an unusable word in American politics."
"I believe that the situation we face, Mr. President, is as dangerous as any of the sort of real crises that we talk about," Kerry claimed. "Today, we had a hearing in the Foreign Relations Committee on the subject of Syria, and we all know what's happening with respect to Iran, and nuclear weapons and the possibility even of a war."
"Well, this issue [global warming] actually is of as significant a level of importance, because it affects life itself on the planet," he added.
Later in his comments, Kerry said, "Climate change, over the last few years, has regrettably lost credibility in the eyes and ears of the American people."
Meanwhile, a recent study by a group of U.S. scientists revealed the earth itself is helping to slow global warming.
Researchers found that the oceans and land plants are absorbing excess greenhouse gasses at twice the rate they did in 1960.
Ashley Ballantyne, lead author of the study, said the earth is "pretty resilient."
"Even though we have done very little to decrease our emissions, the Earth continues to lend us a helping hand," he said.
The study is published in the journal Nature.