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."