President Barack Obama addresses the United Nations climate change conference in Paris, Nov. 30, 2015. As global temperature increase shoots past 1.5 degrees Celsius, the vulnerable countries that fought for that Paris Agreement target face a brutal new reality. (Stephen Crowley/The New York Times) By CHICO HARLAN The most ambitious part of the 2015 Paris climate agreement, to limit global warming to 1.5 degrees Celsius, only came about because of a campaign by some of the world’s poorest and…
