Ice Cores From Greenland

paleoclimatologist James White has made recent discoveries in ice core samples taken from icebergs. it reveals that during ive ages carbon dioxide levels are low, around 180 in the ice samples. where as when its warmer the CO2 levels increase to around 280 parts per million. The second finding is that the changes in the CO2 level happened fast and at that rate means the ocean rose rapidly. right now we stand at 392 ppm which means the earth is rapidly changing  and sea levels could rise soon.

http://www.scientificamerican.com/article.cfm?id=ice-cores-from-greenland-unlock-ancient-climate-secret