Obama just announced America's most ambitious climate policy to date

U.S. President Barack Obama unveiled a new Clean Power Plan on Monday, calling it the "single most important step America has ever taken in the fight against climate change."

He stressed the importance of cutting carbon emissions immediately to prevent climate instability in the decades to come.

"We're the first generation to feel the impact of climate change, and the last generation that can do something about it," he said.

"I believe there is such a thing as being too late," he said. "This is one of those rare issues, because of its magnitude... that if we don't get it right, we may not be able to reverse. We may not be able to adapt sufficiently."

Obama's Clean Power Plan, which will be released in full over the coming week, aims to to cut greenhouse gas emissions from U.S. power stations by nearly a third within 15 years. Although the U.S. has been steadily decreasing its carbon emissions, the Clean Energy Plan plan sets a target to cut carbon emissions from the power sector by 32 per cent by 2030, compared with 2005 levels. The ambitious targets have some industry critics calling it a "war on coal."

Democratic presidential candidates Hillary Clinton and Bernie Sanders both applauded the plan, and pledged to defend it.

But some environmental groups say Obama's plan doesn't go far enough.

"This plan is a good first step, but not enough for Obama to hang his climate legacy on," 350.org spokesperson Karthik Ganapathy said.

Critics including right-wing pundit Rush Limbaugh have slammed the Clean Power Plan, claiming that the climate has not become warmer in recent years. But NASA reports say 2014 has been the warmest year on record to date, and Arctic sea ice has been melting at a rapid pace, to the point that it could break apart completely by the year 2020.

North of the border, the Harper government pledged in May to cut greenhouse gas emissions by 30 per cent below 2005 levels by 2030. However, the target didn't include plans to reduce emissions from Alberta's oil sands, which are the largest source of Canada's climate pollution.

In the Clean Power Plan video, Obama asks Americans to make climate change an election issue, telling viewers to "remind everyone who represents you that protecting the world we leave to our children is a prerequisite for your vote."