U.N. Secretary-General Ban Ki-moon has urged countries around the world to join efforts to combat climate change.

In opening remarks made to a U.N. climate change summit on Tuesday, Ban said failure to reach a broad agreement this year on climate change would be morally inexcusable, economically short-sighted and politically unwise.

Ban stressed that national leaders must become global leaders to meet the needs of their own people.

Ban’s remarks come as the Kyoto Protocol will expire in 2012. The international treaty under the U.N. Framework Convention on Climate Change aims to slash by 2012 greenhouse gas emission levels by five-point-two percent from levels posted in 1990. Parties of the U.N. Framework Convention on Climate Change will meet in Copenhagen, Denmark, in December to discuss the establishment of a new climate change treaty.