President Obama shared plans for the controversial Keystone XL pipeline during a speech on climate change at Georgetown University Tuesday. (The Washington Post)

President Obama delivered his most forceful push for action on global warming on Tuesday, declaring that his administration would impose tighter pollution controls on coal- and gas-fired utilities and establish strict conditions for approval of the proposed Keystone XL pipeline.

Obama also announced that the government would take climate change into consideration in its everyday operations. The shift could affect decisions on a range of issues, including bridge heights, flood insurance rates and how the military gets electricity overseas.

The actions make clear that the president will bypass Congress in seeking to reshape the federal government and the nation’s electricity sector. The aggressive posture also sets up major confrontations with the fossil fuel industry and its Republican allies, who immediately vowed to punish Democrats in elections next year for waging a “war on coal” by setting new limits on carbon emissions.

Speaking to college students and environmental activists at Georgetown University, the president mocked those who disclaim any connection between human activity and climate change and suggested that curbing carbon emissions amounted to a moral obligation owed to future Americans.

“I refuse to condemn your generation and future generations to a planet that’s beyond fixing,” he told the crowd, adding later, “We don’t have time for a meeting of the Flat Earth Society.”

Highlights of Obama’s plan to cut carbon

In perhaps the most significant policy unveiled Tuesday, Obama ordered the Environmental Protection Agency to propose limits on carbon dioxide emissions from existing coal- and gas-fired utilities by 2015.

The president also surprised supporters and detractors alike by announcing that he would approve the Keystone XL pipeline — which would carry crude oil from Canada to the Gulf of Mexico — only if “does not significantly exacerbate the climate problem.”

It remains to be seen how much practical effect his declaration will have on the final pipeline decision, however. A draft environmental assessment by the State Department found that blocking the project would not translate into fewer greenhouse gas emissions because the crude oil destined for the pipeline would be transported through other means, such as by rail.

Utilities, conservatives irked

Obama’s bold rhetoric — American Electric Power chief executive Nick Akins called it “fervent” — unsettled many utility executives and some conservative Democrats. Republicans accused him of waging a “war on coal” and sought to link the speech to key Democrats who are up for reelection in states dependent on the fossil-fuel industry.

In Virginia, Attorney General Ken Cuccinelli II issued a statement saying that his Democratic gubernatorial opponent, Terry McAuliffe, and Obama were “inflicting devastating and unnecessary regulatory burdens on Virginia’s coal industry.”

Sen. Mary Landrieu (D-La.), who is up for reelection next year, sought to draw a sharp distinction between herself and Obama, saying that although both back environmental protections, “I believe that overzealous regulations are harmful to our economy.”

Sen. Joe Manchin III (D-W.Va.) also criticized the moves. “It’s clear now that the president has declared a war on coal,” he said in a statement.

Environmentalists said, however, that Obama was simply acknowledging that the United States could not address global warming without targeting power plants, which account for a third of the nation’s greenhouse gas emissions.

Sierra Club executive director Michael Brune, whose group’s “Beyond Coal” campaign has contributed to the closure or scheduled retirement of 147 coal plants in the country, said the speech marks a turning point in the nation’s energy policy.

“The president realizes that you can’t combat climate change without a direct confrontation with the fossil fuel industry,” Brune said in an interview. “What has us most encouraged by the president’s speech is he is lacing up his gloves and getting ready for that fight.”

Many environmentalists were clearly giddy. “I felt like I’d just woken up from 12 years of Bush-Cheney, and today was the first day of the Obama administration,” tweeted Glenn Hurowitz, a managing director at the consulting firm Climate Advisers.

But even as Obama made clear that his administration would target coal-fired power plants, he did not spell out how the EPA would do so or what it would cost.

Earlier this year, the EPA delayed a rule limiting greenhouse gas emissions from new power plants. The agency will revive the rule in September and will establish separate standards for gas- and coal-fired power plants, as the utility industry had sought, according to people familiar with the agency’s plans who spoke on the condition of anonymity because of the sensitivity of the issue.

Both sides prepare for battle

The American Coalition for Clean Coal Electricity, which is funded by utilities, railroad companies and others, announced Tuesday that it would launch a multimillion-dollar advertising and social media campaign to counter the administration’s climate initiatives. Group spokeswoman Lisa Miller said the effort would begin next month inside the Beltway before expanding to other states in August.

Organizing for Action, a nonprofit advocacy group affiliated with Obama, launched a voter-mobilization effort Tuesday in support of the climate-change agenda. “I need to know you’ll fight alongside me,” the president is quoted as saying in a message distributed by the group. “Say you will.”

But in his speech, Obama also cautioned that there may be few immediate political rewards for attempts to curb the nation’s carbon output. He said progress would be measured “in crises averted, in a planet preserved.”

Americans have consistently supported the idea of imposing mandatory limits on greenhouse gas emissions to address global warming. Three out of four people backed this approach in a Washington Post-Kaiser Family Foundation poll last summer, and support has been at 65 percent or higher since 2009.

But climate change has failed to register the same level of intensity among American voters as other high-profile issues. In a Pew Research Center global poll issued Monday, just 40 percent of U.S. respondents identified climate change as a major threat, a number lower than any other region in the world.

Climate-change effects

As part of his pitch for intensifying the government’s action on climate, the president emphasized that the United States and other countries are already facing climate-change effects such as rising sea levels and increasingly frequent severe weather. He said the federal government will “partner with communities seeking help to prepare for droughts and floods, reduce the risk of wildfires, protect the dunes and wetlands that pull double duty as green space and as natural storm barriers.”

Federal agencies, he said, will be required to ensure that projects funded with taxpayer dollars are “built to withstand increased flood risks.” Administration officials said other efforts would include strengthening dune systems and building oyster reefs to limit the wave effect of storms and working to restore the lower Mississippi River delta system.

John Kostyack, vice president for wildlife conservation at the National Wildlife Federation, said Obama’s speech “gives acknowledgment and a push and added thrust to the work to prepare for the worst aspects of climate change. He’s begun to make the case that it’s far less than the cost of doing nothing.”

Lenny Bernstein and Steven Mufson contributed to this report.