Polar Bears on Thin Ice

We've all seen the pictures of polar bears clinging to tiny ice chunks in the Arctic Ocean.  Most people, scientists and laypersons alike, can connect the dots between melting ice caps and global warming.  The U.S. Department of Interior finally made the connection when it classified the polar bear as a threatened species under the Endangered Species Act.   It's the first time any species has been explicitly protected as a result of climate change habitat destruction.