PARIS, FRANCE - DECEMBER 04: Bill McKibben speaks during Pathway to Paris at Le Trianon on December 4, 2015 in Paris, France. (Photo by David Wolff - Patrick/Redferns)
PARIS, FRANCE - DECEMBER 04: Bill McKibben speaks during Pathway to Paris at Le Trianon on December 4, 2015 in Paris, France. (Photo by David Wolff - Patrick/Redferns)