FILE - In this Nov. 14, 2007 file photo, the 6,010-meter Huayna Potosi is seen above La Paz. El Alto and its sister city of La Paz, the world's highest capital, depend on glaciers for at least a third of their water, more than any other urban sprawl. But that supply is in peril. Global warming has doomed the world's tropical glaciers. Negotiators from more than 190 countries will meet Dec. 1, 2014, in the Peruvian capital, for two weeks to work on drafts for a global climate deal that is supposed to be adopted next year in Paris. (AP Photo/Dado Galdieri, File)LIMA, Peru (AP) — Energized by new targets set by China and the United States, the world’s top climate polluters, U.N. global warming talks resume Monday with unusual optimism despite evidence that human-generated climate change is already happening and bound to get worse.