A Very Long Time

There must be something wrong with this study. After all, the Preznit told us global warming isn't a problem. HealthCentral:

Tiny air bubbles preserved in Antarctic ice going back millennia suggest levels of atmospheric carbon dioxide are higher now than at any time over the past 650,000 years, researchers say.

Increasing levels of carbon dioxide and other "greenhouse gases" that trap the sun's heat are thought to be caused by human activity and are the main cause of global warming.

"There's no natural condition that we know about in a really long time where the greenhouse gas levels were anywhere near what they are now," geosciences expert Edward Brook, of Oregon State University, told the Associated Press.

The new data was conducted by the European Project for Ice Coring in Antarctica and published Friday in the journal Science.

While skeptics have dismissed recent warming as part of the "natural cycle," the ice samples suggest today's warming trend is "over a factor of a hundred faster than anything we are seeing in the natural cycles," researcher Thomas Stocker of the University of Bern, Switzerland, told the AP.