Obama: Climate change 'growing and urgent threat'

President Barack Obama told a United Nations meeting on Tuesday that pollution must be contained to address climate change.
Specifically, he called out China, saying that the most populous country on Earth, with the fastest increase in carbon pollution, must join the United States to lead the rest of the world in carbon reduction.
"We have a responsibility to lead," Obama said to applause. "That's what big nations have to do."
Obama was speaking at the U.N. Climate Summit, a one-day meeting hosted by U.N. Sec