The international climate pact passed Saturday "represents the best chance we have to save the one planet we've got," President Obama said hours after the historic agreement was signed.
"No nation, not even one as powerful as ours, can solve this challenge alone," Obama said of the deal, which the United States and nearly 200 other countries agreed to in Paris Saturday after two weeks of intensive talks. "And no country, no matter how small, can sit on the sidelines. All of us had to solve it together."
Praising "the most ambitious climate change agreement in history," which calls for nations to dramatically cut greenhouse gas emissions, Obama acknowledged that "no agreement is perfect, including this one."
"We cannot be complacent," he said. "The problem's not solved because of this accord."
The Paris agreement is the first time an accord has been adopted that asks all countries to do their part in the fight against climate change, with the long-term goal being to make sure global warming stays "well below" 2 degrees Celsius (3.6 degrees Fahrenheit) and to "pursue efforts" to limit the temperature rise to 1.5 degrees Celsius (2.7 degrees Fahrenheit).
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The U.S. is the second largest climate polluter in the world. Obama has pledged to cut the nation's overall greenhouse gas emissions by 26 to 28 percent by 2030.
"This agreement represents the best chance we have to save the one planet we've got," he said. "I believe this agreement can be a turning point for the world."
Republicans in Congress have already voiced opposition to the climate talks, arguing that Obama's commitment to reducing emissions from power plants would cost thousands of jobs and raise electricity costs.
"We can expect the administration to cite this 'agreement' as their excuse for establishing emission targets for every sector of the U.S. economy not only including utilities, but petroleum refining, all manufacturing, agriculture and others," said Sen. James Inhofe, R-Okla., chairman of the Senate Environment and Public Works Committee.
But Obama, in his late Saturday evening address, dismissed skeptics by pointing out the jobs that have been created in the last seven years, when the U.S. became a "global leader in fighting climate change."
"Together we've shown what's possible when the world stands as one," Obama said.