(Credit: Jacquelyn Martin/AP Photo)

President Obama today pushed back against critics of his plan to dramatically cut U.S. carbon emissions, telling supporters it's necessary to confront a looming threat to "this beautiful blue ball in the middle of space that we're a part of."

"Climate change is real. It has impacts not just in a distant future. It has serious impacts as we speak," the president said during a conference call with public health advocates and other environmental supporters of the new proposed EPA regulations that aim to curb carbon emissions from coal-fired power plants.

More on the Environmental Protection Agency plan HERE , which some advocates are calling the most significant environmental regulations in decades.

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Opponents of the policy - both Republican and Democrat - have variously voiced skepticism of a human role in climate change, the costs of such change and concern about harm to the U.S. economy by unilaterally imposing new restrictions on American energy companies.

House Speaker John Boehner today called Obama's plan "nuts." Senate Minority Leader Mitch McConnell called it a "dagger in the heart of the middle class." Some congressmen of both parties vowed to enact legislation to block the EPA regulations.

The president however was undeterred, asserting his executive authority and arguing that the new standards "are going to help us leave our children a safer and more stable world."

There will always be "naysayers who said this is going to destroy jobs and destroy industry," he said. "You will hear from critics who say the same thing they always say, that these guidelines will kill jobs, or crush the economy. What we've seen every time is that these claims are debunked when you actually give workers and businesses the tools and the incentive they need to innovate. "

With political and legal fights against the EPA on the horizon, Obama told his army of environmental activists to counter opponents whose "spin overwhelms substance, and that PR overwhelms science."