TO GO WITH CLIMA 09 GROENLANDIA-GLACIARES - This Aug. 23, 2009 file photo shows University of Maine glaciologist Gordon Hamilton, left, and graduate student Kristin Schild waiting for a helicopter after placing GPS receivers on Helheim Glacier in southeast Greenland. Like Greenland's other major glaciers, it accelerated earlier this decade, contributing to the melt of the ice sheet and sea level rise. (AP Photo/Karl Ritter, File)
COPENHAGEN (AP) - The largest and most important U.N. climate change conference in history has opened with a warning that this could be the best, last chance for a deal to control global warming.
Diplomats from 192 nations are gathered in Copenhagen for what's seen as the climax of two years of contentious negotiations.
The mood today is upbeat after a series of promises by rich and emerging economies to curb their greenhouse gases, but major issues have yet to be resolved.
At stake is a deal that aims to wean the world away from fossil fuels and other pollutants to greener sources of energy, and help poor countries adapt.
Scientists say the consequences of failure include ever-rising temperatures, extinction of species, the flooding of coastal cities, more extreme weather events, drought and the spread of diseases.