Greenland has the only permanent ice sheet in the Arctic, and its big! With depths of up to 3,400 meters / 11,000 feet thick, the ice at the bottom could be hundreds of thousands of years old.

But its only about one-eighth the size of the Antarctic ice sheet. We're talking about ice down there that's OLD!

Ice cores provide the ultimate record of past environments. Whatever happens on the Earth that changes the atmosphere - the big events - is recorded in the ice and it stays there. Drilling into the ice gives scientists a look back to the days when humans had nothing to do with climate change.

A recent ice core sample recovered in Antarctica goes back 740,000 years (nearly twice as long as any other ice core record) and scientists haven't even reached the bottom of the ice sheet! The possibility of a million-year ice core is out there, and that would be a really BIG step back in climate history.