What causes polar bears to be endangered?

1. n

2. https://www.washingtonpost.com/news/energy-environment/

3. http://news.bbc.co.uk/earth/hi/earth_news/newsid_8700000/8700472.stm

4. http://www.chicagotribune.com/news/nationworld/ct-polar-bears-global-warming-2025-20150701-story.html

5. How they are endangered and on their way to extiction.

6. http://weblogs.chicagotribune.com/news/politics/blog/2008/05/its_official_polar_bears_endan.html

7. http://www.bbc.co.uk/blogs/climatechange/2009/05/how_endangered_is_the_polar_bear.html

8. http://www.latimes.com/nation/la-na-polar-bear-decline-20141117-story.html