and disappearing with the ice are whole colonies of penguins. both are early warning signs that the global warming day of reckoning is upon us. to find out what's happening at the bottom of the world, we stop first at the high mountains of patagonia in chile, where you can actually see firsthand the consequences of a warming planet. >> this massive ice is glacier o'higgins. it's been frozen for tens of thousands of years in the mountains of southern chile. o'higgins is spectacular for its beauty. >> [speaking in spanish] >> but for a scientist like gino casassa, it's breathtaking for its speed. >> this was the glacier front position in 1896. >> now o'higgins is morphing into a lake, retreating more than any glacier in south america. the glacier was sitting where we are sitting right now. >> we would have been covered by ice. i think it's a very clear picture that the world