Environmental and public health advocates are defending the Obama administration’s new climate rules as an important and necessary step to save the planet.

“We have only a few years left to reverse these trends, and the Clean Power Plan will help us do that,” Margie Alt, executive director of Environment America, told reporters Monday.

President Obama unveiled controversial new climate rules Monday that require power plants by 2030 to cut carbon emissions 32 percent from what they were at a decade ago.

The Environmental Protection Agency’s climate rules have come under scrutiny from Republicans and business groups that say they will force coal plants out of business, but environmental activists say that’s a small price to pay for rules that will create new clean energy jobs to replace those lost in other sectors.

Fighting climate change is the “race of our lives,” said Environmental Defense Fund president Fred Krupp.

“Climate change is one of the serious threats facing our nation,” said Neera Tanden, president of the Center for American Progress. “People who attack this rule are really acting out of a vision of the past, not the future.”

“Ten, 20, 50 years down the road, our children won’t be asking why the president took the action he did today,” added Rhea Suh, president of the Natural Resources Defense Council. “They’ll be asking why it took so long.”

Billionaire environmental activist Tom Steyer called the power plant regulation a “major turning point” in the fight against climate change.

“It creates a tremendous opportunity for American business to do what it does best: turn a generational challenge into a story of American ingenuity and foresight,” Steyer said in a statement.

For many environmental activists, the fight is a long time coming.

“In 40 years of environmental advocacy, I’ve never been more proud of any president,” said League of Conservation Voters president Gene Karpinski. “A challenge as great as climate change requires steps as bold as this.”

Public health advocates are also beaming about the benefits of the new climate rules, which will prevent some 3,600 premature deaths and 90,000 asthma attacks in 2030, according to the EPA.

The American Lung Association called climate change a “public health emergency.”

“Breathing healthy air is essential to life,” said American Lung Association president Harold Wimmer. “The evidence is clear that climate change now harms lung health and public safety.

But some environmental activists expressed disappointment that the rules don’t go far enough to protect against climate change.

“Our ambition can’t end here,” said World Wildlife Fund vice president Lou Leonard. “A large gap remains between the carbon-cutting pledges that countries, including the US, are making ahead of the Paris talks and what science says is needed to avoid runaway climate change.”

Friends of the Earth President Erich Pica characterized the rules as a first step.

“While historic, when measured against increasingly dire scientific warnings, it is clear the rule is not enough to address our climate crisis,” Pica said. “This rule is merely a down payment on the U.S.’s historic climate responsibility.”