The Leonard Lopate Show Edit this Published in The Leonard Lopate Show On Thin Ice Listen 17 min Queue Download this audio Want to embed this player? Use the code below. More info. <iframe frameborder="0" scrolling="no" height="130" width="100%" src="https://www.wnyc.org/widgets/ondemand_player/wnyc/#file=/audio/json/59784/&share=1"></iframe> Share on Facebook Share on Twitter Email a Friend Science writer Richard Ellis talks about how the polar bear has become a symbol of how climate change threatens life on the planet. In On Thin Ice: The Changing World of the Polar Bear, he looks at why the world population of polar bears has shrunk by half in the last 20 years.