Global warming:
Earth's temperature near highest level in a million years

Earth may nearing its warmest level in the last million years according to a paper published by NASA scientists in the Proceedings of the National Academy of Sciences. James Hansen of NASA's Goddard Institute for Space Studies in New York City and colleagues report that "Earth is now reaching and passing through the warmest levels in the current interglacial period" and that global temperature may be within one degree Celsius (1.8°F) of the maximum temperature of the past million years. "That means that further global warming of 1 degree Celsius defines a critical level. If warming is kept less than that, effects of global warming may be relatively manageable," said Hansen. "During the warmest interglacial periods the Earth was reasonably similar to today. But if further global warming reaches 2 or 3 degrees Celsius, we will likely see changes that make Earth a different planet than the one we know. The last time it was that warm was in the middle Pliocene, about three million years ago, when sea level was estimated to have been about 25 meters (80 feet) higher than today."