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Book, 2008
Current format, Book, 2008, , No Longer Available.
Book, 2008
Current format, Book, 2008, , No Longer Available. Offered in 0 more formats
In the Arctic, the summer ice is melting, making it hard for polar bears to survive. Why is the world getting warmer? The heat of the sun is trapped by the "greenhouse" gases that surround Earth--carbon dioxide, methane, nitrous oxide, and water vapor.
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