Someone explain this to me.
A little research on the geography and climate of Greenland shows that in years past our planet was much warmer than today. Scientists who probed two kilometers (1.2 miles) through a Greenland glacier to recover the oldest plant DNA on record said that the planet was far warmer hundreds of thousands of years ago than is generally believed. DNA of trees, plants and insects including butterflies and spiders from beneath the southern Greenland glacier was estimated to date to 450,000 to 900,000 years ago, according to the remnants retrieved from this long-vanished boreal forest.
So…how did man do that? He didn't. Global warming, how can that be thought of today, since science has proved we are colder now than in the certain times in the past.