Climate changes over time. Twenty thousand years ago, much of Europe and North America was covered with a thick sheet of ice, as Greenland is today. Climate changes take place over years, centuries, millenia, or even millions of years, with changes occurring suddenly or gradually. The record of these changes is preserved in glaciers, in lake and ocean sediments, in corals and trees, and, for the distant past, in rocks. Readings this record is basic to understanding how the climate system works today.
Topic: Earth Science
Subtopic: Climate/Climate Change
Keywords: Climatic changes--Observations, Meteorology--Research, Paleoclimatology