evidence: Global temperatures have risen an average of 1.4˚ F since 1880. Sea ice in the Arctic has thinned and decreased in the last few decades; the Greenland and Antarctic ice sheets are decreasing in mass. The North and South Poles are warming faster than anywhere else on Earth. Glaciers are retreating on mountains all over the world. Spring snow cover in the Northern Hemisphere has decreased over the last 50 years. [...] Evidence from ocean sediments, ice cores, tree rings, sedimentary rocks and coral reefs show that the current warming is occurring 10 times faster than it did in the past when Earth emerged from the ice ages, at a rate unprecedented in the last 1,300 years. [...] Findings from NASA’s Goddard Institute for Space Studies show clearly how much natural and manmade factors contribute to global warming.