Satellite: NOAA-17, one of NOAA's 850km-high (530 mile-high) Polar Orbiting satellites.
Image acquired Friday, August 13, 2004; flyover beginning 3:32pm EDT
The Greenland Ice Sheet
Average ice thickness: approximately 2 kilometers
75% of the world's freshwater is locked up in ice sheets such as this one on Greenland, the great ice sheet over the Antarctic, and in glaciers.
As Earth warms due to human and other factors, these great ice sheets will melt and cause not only rising sea levels, but also changing salinity of the oceans' waters.
This in turn will cause changes in ocean circulation patterns, finally leading to changes in weather patterns such as abrupt ice ages, etc.
Fortunately, what you see in the image below is mostly covered with ice...at the present time.