VALENCIA, Spain -- The Earth is hurtling toward a warmer climate at a quickening pace, a Nobel-winning U.N. scientific panel said in a landmark report released Saturday, warning of inevitable human suffering and the threat of extinction for some species.

U.N. Secretary-General Ban Ki-Moon said climate change imperils "the most precious treasures of our planet" and called on the United States and China _ the world's two biggest polluters _ to do more to fight it.

As early as 2020, 75 million to 250 million people in Africa will suffer water shortages, residents of Asia's megacities will be at great risk of river and coastal flooding, Europeans can expect extensive species loss, and North Americans will experience longer and hotter heat waves and greater competition for water, the report from the Intergovernmental Panel on Climate Change says. ...   more »