“Look, I think it is absolutely vital for every country, every leader to send a signal that the viciousness of a handful of killers does not stop the world from doing vital business,†Obama said, when asked on Sunday whether the attacks would have an effect on the mood of the summit. Obama has repeatedly emphasized the damaging effect that climate change has on national security in preparation for the summit. During a Coast Guard graduation speech in May, Obama emphasized that the recruits would be facing the threat global warming. “Climate change constitutes a serious threat to global security,...