WATCH: Ocasio-Cortez peddles extreme fear over climate change, despite facts from scientists

For freshman Rep. Alexandria Ocasio-Cortez (D-N.Y.), it has become increasingly clear that fighting climate change is the legacy she wants to cement for herself.

During a town hall with MSNBC's Chris Hayes Friday, which centered around Ocasio-Cortez's controversial "Green New Deal," the New York Democrat centered her climate change narrative around fear, warning of what could happen if America doesn't act swiftly in response to alleged man-made climate change.

What did Ocasio-Cortez say?

She said America has once "confronted this type of stagnation and this type of systematic threat," comparing climate change to the Great Depression, World War II, and the Cold War.

"First all of, we've been here before: we've been here before with the Great Depression. We've been here before with World War II, even the Cold War," Ocasio-Cortez said. "And the answer has been an ambitious and directed mobilization of the American economy to direct and solve our problem, our biggest problem."

Ocasio-Cortez later called climate change the "greatest existential threat" to the future of the U.S. As the Washington Free Beacon noted, Ocasio-Cortez has made similar comparisons in the past, saying during her campaign that the U.S. should fight climate change in a manner similar to how Allied powers fought Nazi Germany in World War II.

Ocasio-Cortez Compares Fighting Climate Change to Winning World War IIwww.youtube.com

Later in the town hall, Ocasio-Cortez compared climate change to the 9/11 terrorist attacks.

"On the events of September 11, 2001, thousands of Americans died in the largest terrorist attack on U.S. soil and our national response, whether we agree with it or not, our national response was to go to war in one then eventually two countries," she said. "Three thousand Americans died in Puerto Rico in the aftermath of Hurricane Maria. Where is our response?"

Ocasio-Cortez even doubled down on the widely mocked provision addressing bovine flatulence.

What about her claim about the end of the world?

In January, Ocasio-Cortez was widely mocked for claiming the world would end in 12 years if the U.S. — and humanity in general — does not directly address the significant threat that climate change poses.

Ocasio-Cortez doubled down on her claim Friday, warning that "climate change is different because we have an expiration date," citing a report by the United Nation's Intergovernmental Panel on Climate Change.

"So my concern is that we are going to be the frog in the pot of boiling water," she said, warning that "our kids are doomed" because lawmakers only debate climate change in order to pass "wimpy" solutions.

But scientists heavily pushed back against Ocasio-Cortez's claim, which the media latched onto in an apparent attempt to convey the seriousness of climate change.

"All the time-limited frames are bulls**t," Gavin Schmidt, who leads NASA's Goddard Institute for Space Studies in New York, told Axios. "Nothing special happens when the 'carbon budget' runs out or we pass whatever temperature target you care about, instead the costs of emissions steadily rise."

"Twelve years isn't a deadline, and climate change isn't a cliff we fall off — it's a slope we slide down," Kate Marvel, a climate scientist at NASA, told Axios. "We don't have 12 years to prevent climate change — we have no time. It's already here. And even under a business-as-usual scenario, the world isn't going to end in exactly twelve years."