Nancy Benac

The declaration was a boost to climate negotiators seeking a tough accord and a challenge to Republican senators, many of whom don’t believe that global warming is real.

Pushing for a powerful climate deal, President Barack Obama called the global talks opening Monday outside Paris an "act of defiance" against terrorism that proves the world stands undeterred by Islamic State-linked attacks in Europe and beyond.

Jumping into the issues of the day, Pope Francis opened his visit to the United States with a strong call Wednesday for action to combat climate change, calling it a problem that "can no longer be left to a future generation."