Title: Earth's Changing Climate  | National Geographic Society
Headings: Earth's Changing Climate
Earth's Changing Climate
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Earth’s Changing Climate
Natural Causes of Climate Change
Human Causes of Climate Change
Global Warming

Content: As climates change, organisms that live in the area must adapt, relocate, or risk going extinct . Earth’s Changing Climate
Earth’s climate has changed many times. For example, fossils from the Cretaceous period (144 to 65 million years ago) show that Earth was much warmer than it is today. Fossilized plants and animals that normally live in warm environments have been found at much higher latitudes than they could survive at today. For instance, breadfruit trees, now found on tropical islands, grew as far north as Greenland. Earth has also experienced several major ice ages—at least four in the past 500,000 years. During these periods, Earth’s temperature decreased, causing an expansion of ice sheets and glaciers. The most recent Ice Age began about 2 million years ago and peaked about 20,000 years ago. The ice caps began retreating 18,000 years ago. They have not disappeared completely, however.