Prince Albert II of Monaco (R) and his wife Princess Charlene of Monaco (C) with their twins Prince Jacques and Princess Gabriella participate in a climate march in Monaco, November 29, 2015 ahead of the World Climate Change Conference 2015 (COP21) held in Le Bourget near Paris. REUTERS/Jean-Pierre AmetATTENTION EDITORS : FRENCH LAW REQUIRES THAT THE FACES OF MINORS ARE MASKED IN PUBLICATIONS