Turkish President Recep Tayyip Erdogan reacts as he attends the COP 21 United Nations conference on climate change, on November 30, 2015 at Le Bourget, on the outskirts of the French capital Paris. 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. Russian President Vladimir Putin has rejected a meeting with Turkish counterpart Recep Tayyip Erdogan at the climate conference in Paris on Monday, the Kremlin said, as a dispute rages over Ankara's downing of a Russian warplane. AFP PHOTO / JACQUES DEMARTHON