Rising temperatures on Earth have caused concern about how glacial ice sheets, accumulated over millions of years, will react if the warming trend continues. And there's one ice sheet in particular that dwarfs all others in terms of its current size and its potential impact if the planet were to significantly heat up.
The Antarctic ice sheet covers about 98 percent of that continent, making it the largest single mass of ice on Earth. On average, the ice layer there is about 7,000 feet (2,134 m) thick – approximately the length of 23 football fields. It holds around 61 percent of the fresh water on Earth.
Keeping an eye on the ice:
- If all of Antarctica's ice melted, sea levels around the world would rise about 200 feet (61 m). Since most of the continent stays well below freezing for the entire year, this seems a highly unlikely possibility. However, the danger is that Antarctica is one of the world's "tipping points" – rising temperatures resulting in ice melt and sea-level rise could trigger a feedback loop that is difficult to reverse.
- At the North Pole, the ice is not nearly as thick, and it floats on the Arctic Ocean. If it melts, sea levels are not expected to be affected.
- The ice covering Greenland is a more immediate concern. Because Greenland is relatively closer to the equator, the ice is more likely to melt if current climate trends continue, and could result in sea levels rising up to 20 feet (7 m) if all of it melted.