Earth Much Warmer in the Past

Yes, you read that right. The earth was much warmer in the past (hundreds of thousands of years ago) than generally believed. According to Science Magazine, scientists found the oldest plant DNA inside a glacier on Greenland. The glacier was estimated to date to 450,000 to 900,000 years ago.

What is most interesting in the article is that during the last period between ice ages, 116,000-130,000 years ago, when temperatures were on the average 9^o F higher than now, the glaciers on Greenland did not completely melt away. Hmmm. How could the earth be warmer than now? There wasn't anyone driving hydro-carbon cars. So, what caused the warm up? (Maybe it had something to do with the sun. Just a thought.) And yet the glaciers were still there.