Brazil's president Dilma Rousseff, first row center, Ivory Coast's president Alassane Ouattara, first row right, Palestine's President Mahmud Abbas, 2nd row center left, Vietnam's Prime Minister Nguyen Tan Dung, 2nd row center right, and Canada's Prime Minister Justin Trudeau, 3rd row center, pose for a group photo during the COP21, United Nations Climate Change Conference, in Le Bourget, outside Paris, Monday, Nov. 30, 2015. More than 150 world leaders are meeting under heightened security, for the 21st Session of the Conference of the Parties to the United Nations Framework Convention on Climate Change (COP21/CMP11), also known as "Paris 2015" from November 30 to December 11. (Martin Bureau/Pool Photo via AP)

8 things to know about the climate talks

The United Nations Climate Conference in Paris is playing host to thousands of representatives from hundreds of countries around the world.