William Brangham:

For as far as the eye can see, Antarctica is covered by thick sheets of ice. In some places, that ice is several miles deep.

This massive continent, as big as the U.S. and Mexico combined, has, for millions of years, been home to some of the most breathtaking landscapes of ice on the planet.

What you can see behind me here is a very good cross-section of a glacier in Antarctica. And what you can see, with all those different layers that is hundreds and thousands of years of snowfall and precipitation stacking up, one on top of the other, and slowly exerting pressure downward on those layers of snow. And that's basically how a glacier is formed.

But Antarctica's ice is now increasingly being threatened, and most researchers believe it's because of climate change. According to one recent study, the continent's ice is slipping away six times faster than it was 40 years ago.