WASHINGTON — Taking aim at global warming, President Barack Obama introduced a politically charged plan Monday to order big and lasting cuts in the pollution discharged by America’s power plants. But the plan, though ambitious in scope, wouldn’t be fully realized until long after Obama’s successor took office and would generate only modest progress worldwide.

Obama’s proposal to force a 30 percent cut in carbon dioxide emissions, by the year 2030 from 2005 levels, drew immediate scorn from Republicans, industry groups and even a few Democrats who are facing fraught re-election campaigns in energy-dependent states. Environmental activists were split, with some hailing the plan and others calling it insufficiently strict to prevent the worst effects of global warming.

In all likelihood, the plan marks one of the most significant steps Obama will take to shape the country he governs during his final years in office. Stymied by Congress on nearly every front, Obama has turned to actions he can take on his own, but has found limited means to effect the type of sweeping change he has envisioned in his two campaigns.

The effort would cost up to $8.8 billion annually in 2030, the EPA projected. But the actual price is impossible to predict until states decide how to reach their targets — a process that will take years.

Obama, in a conference call with public health leaders, sought to head off critics who have argued the plan will kill jobs, drive up power bills and crush the economy in regions of the U.S.

“What we’ve seen every time is that these claims are debunked when you actually give workers and businesses the tools and the incentives they need to innovate,” Obama said.

Never before has the U.S. sought to restrict carbon dioxide from existing power plants, although Obama’s administration is also pursuing the first limits on newly built plants. While the plan would push the nation closer to achieving Obama’s pledge to reduce total U.S. emissions by 17 percent by 2020, it still would fall short of the global reductions scientists say are needed to stabilize the planet’s temperature.

Connie Hedegard, the European Union’s commissioner for climate change, called the rule “the strongest action ever taken by the U.S. government to fight climate change.” But she also said, “All countries, including the United States, must do even more than what this reduction trajectory indicates.”

Fossil-fueled U.S. power plants account for 6 percent of global carbon dioxide emissions, so even a steep domestic cut affects just a portion worldwide. And even with the new limits, coal plants that churn out carbon dioxide will still provide about 30 percent of U.S. energy, according to predictions by the Environmental Protection Agency, down from about 40 percent today. Power plants are America’s largest source of greenhouse gases, accounting for 38 percent of annual emissions. Plants have already reduced carbon emissions nearly 13 percent since 2005, meaning they are about halfway to meeting the administration’s goal.

The 645-page proposal forms the linchpin of Obama’s campaign to deal with climate change, and aims to give the U.S. leverage to prod other countries to act when climate negotiations resume in Paris next year. At home, however, the power plant limits won’t cut as big a chunk out of greenhouse gas emissions as Obama’s move to tackle pollution from cars and trucks. That separate effort is to double fuel economy for vehicles made in model years 2012-25. And the drawn-out timeline for the power plant plan, coupled with threats by opponents to block it, infused Monday’s announcement with uncertainty.

“I know people are wondering: Can we cut pollution while keeping our energy affordable and reliable? We can, and we will,” said EPA Administrator Gina McCarthy.