Former U.S. Army Captain Jonathan Powers, who served in Iraq, talked about how "Climate change makes the world a more dangerous place."
He spoke of the many studies by US intelligence and defense agencies that have already assessed the growing security threats created by human-induced global warming.
Asked by ABC News what impact climate change had on terrorists such as the Taliban and Al Qaeda, retired Army Major General Donald Edwards responded, "It's a proven fact that when young people are disaffected -- lands flooded, or drought and no food -- they lose respect for the government and become prime targets for recruiting."
Shifting into the jargon of military management, he added that "There will be a significant threat outflow."
Edwards said he did not want to mention specific terrorist groups, but other Department of Defense sources have told ABC News of analyses by military and intelligence teams that have found the effects of long-term drought, worsened by global warming, playing into the hands of the Taliban and their Al Qaeda allies.
Powers said there was a general understanding among military analysts that severe conditions that are expected only to worsen as global warming advances were what the military calls "threat multipliers."
120 heads of state and government are due to arrive before the end of the week.
US President Barak Obama is scheduled to appear on Friday.
Additional metal detectors have started to appear in some halls in preparation for the enormous security problems the leaders bring with them.