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has experienced several cold periods (known as ice ages ) and warm periods ( interglacials ) over approximately the last 1 million years. Climate scientists believe that these periods of changing climate can last many thousands of years. The Elements of the Climate System What drives climate? Just as with weather, climate has its own complex system comprised of five elements:

• Atmosphere • Hydrosphere • Cryosphere • Lithosphere • Biosphere

The atmosphere is air that surrounds the surface of the earth. Astronauts in space call it the thin blue line.

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The New Weather: Climate and Weather