Progressive commentator David Burstein defended the progressive movement's concerns surrounding climate change, telling "Fox & Friends" on Saturday that the United States was facing an environmental. "crisis."

Burstein, co-founder of "Run for America,"  spoke to Fox News one day after students in cities around the world ditched school as part of a "climate strike."

Fox News host Jedediah Bila suggested to Burstein that the left kept shifting their predictions and rhetoric surrounding the environment.

TEEN CLIMATE CHANGE ACTIVIST CALLS AOC AN 'ICON,' TELLS CONGRESS URGENT ACTION NEEDED

"Look I think the reality is, and the reason you're seeing people out in the streets fighting on this issue, is because this is a crisis," responded Burstein, who indicated that early warnings about climate change came at a time when the world still had the opportunity to avert its worst effects.

"Now, we're facing a pretty serious set of crises -- and I think people need to focus less on the specific differences and different scientists' predictions about what's going to happen when because there actually is a lot of debate about that," he told Bila. "What we know is that what's happening and what's going to happen is very, very serious and that it requires not just a little bit of incremental approach from the government, it requires real serious stakes from everybody."

More from Media

Democratic presidential candidates have warned about the specter of climate change and pushed aggressive proposals to address the issue.

The issue also received attention from the Defense Department which released a report earlier this year describing "the effects of a changing climate" as a "national security issue with potential impacts to Department of Defense ... missions, operational plans, and installations." Former Defense Secretary James Mattis also warned about the issue this month.

CLICK HERE TO GET THE FOX NEWS APP

Others have mocked the concerns as alarmist while pointing to past warnings that the world would undergo another Ice Age. On Wednesday, the right-leaning Competitive Enterprise Institute released a report detailing decades of apocalyptic predictions about climate change that failed to come to pass.

The dire predictions, often repeated in the media, warned of a variety of impending disasters – famine, drought, a new ice age, and even disappearing nations – if the world failed to act.