In his staunch defense of multilateralism delivered to the U.S. Congress earlier this week, French President Emmanuel Macron expressed his hope that the United States would not in fact leave the landmark Paris agreement on fighting climate change, as President Donald Trump has declared. Macron’s appeal to the need for active American leadership underscores only one of the obstacles to an effective global response to this urgent environmental threat. Some of these challenges are inherent in the mechanics of a long and overdue transition to lower-carbon forms of energy. Others are due to political decisions made by global economic powers, […]