Obama Ties Keystone Approval to Climate Impact

President Barack Obama said Tuesday the controversial Keystone XL pipeline should be approved only if it doesn't "exacerbate" carbon pollution, as he unveiled a sweeping new plan to tackle climate change.

In a closely watched speech at Georgetown University in Washington, D.C., Mr. Obama also said he would direct the Environmental Protection Agency to create carbon standards for both new and existing power plants, one of the largest sources of greenhouse gas emissions in the U.S.

"The planet is warming and human activity is contributing to it," Mr. Obama said. He continued that "the question now is whether we will have the courage to act before it's too late."

On Keystone, Mr. Obama said the pipeline's climate impact would critical to determining if it goes forward. Environmentalists oppose the pipeline because they fear it could lead to damaging spills of heavy crude, and because they fear it would drive the full development of Canada's oil sands, which produce more greenhouse gases than regular crude during extraction.

Mr. Obama called climate change a pressing issue that "demands our attention now."

The announcement on power plants was immediately embraced by environmental groups, which have pressed the Obama administration to regulate coal-fired power plants that are already in operation, some of which are decades old.

EPA proposed a rule in 2012 to reduce carbon dioxide emissions from new power plants that virtually eliminated the possibility that new coal-fired plants would be built. The EPA has not yet finalized that rule and some in the power sector believe the agency will have to make significant changes to the rule before doing so.

New rules from the EPA to address existing power plants will serve as a key component of Mr. Obama's climate-change plan but are likely to face both legal and political challenges. Republicans argue that the Clean Air Act was not designed to regulate carbon dioxide, but rather other harmful emissions.

In 2009, the EPA determined that greenhouse gases were harmful to human health and the environment--a finding that now serves as the bedrock for future action on addressing carbon-dioxide emissions.

Mr. Obama said critics of his plan may warn of his lost jobs and economic damages. He said these were "tired excuses for inaction."

Keith Johnson contributed to this article.