President Barack Obama says there are very few global challenges that can be solved unless the U.S. and China cooperate.

Obama says climate change is one of the most critical challenges. As nations prepare for next month's climate change conference in Copenhagen, Obama says leaders will be watching what the U.S. and China do. He says "that is the burden of leadership that both of our countries now carry."

Obama answered questions from Chinese students during a town hall-style event. He is making his first visit to China since taking office.