Glaciers and the Latest Ice Age

Abstract

The cryosphere consists of glacial ice, sea ice, ice shelves, ice caps, continental glaciers, valley glaciers, permafrost, and ice in rivers and lakes. Some of the cryosphere is temporary, such as sea ice near the North Pole and elsewhere, and it melts in warm months and re-freezes during colder months. Glacial ice on land represents a vast store of fresh water. It also is directly tied to sea level. For example, as glacial ice melts, sea level is raised worldwide. As glaciers expand, sea level is lowered worldwide. The two most important areas on Earth for freshwater storage are Greenland and Antarctica. Greenland’s glaciers are receding faster than Antarctica’s because global warming is affecting the Northern Hemisphere glaciers more so than those in the Southern Hemisphere. Sea ice is disappearing in the Northern Hemisphere and is sometimes expanding in the Southern Hemisphere. The rate of Greenland’s ice loss is accelerating. Ice cores from the cryosphere tell scientists a great deal about the history of the atmosphere from gas bubbles trapped within them. Isotope studies tell us about past atmospheric compositions and temperatures. Glaciers were more extensive in the recent geologic past in what is generally known as the Pleistocene “ice age.” Carbon dioxide and global temperatures have been correlated throughout the past 800,000 years from ice cores.