Ensia: Editors note: 2015 is shaping up to be a pivotal year with respect to climate change as growing concern about impacts converges with a critical stage in the decades-long process of shaping an international agreement to change our trajectory. To help us all prepare for the potentially game-changing 21st gathering of the Conference of the Parties to the United Nations Framework Convention on Climate Change (COP 21) in Paris beginning Nov. 30, Ensia is publishing a series of context pieces from longtime...