The study, prepared by Harvard University, was conducted to explore the forces driving extreme weather events, their impacts over the next decade and their implications for national security planning.
Such events will affect water and food availability, energy decisions, the design of critical infrastructure and critical ecosystem resources, the report's authors said.
"Lessons from the past are no longer of great value as a guide to the future," environment studies Professor Michael McElroy said. "Unexpected changes in regional weather are likely to define the new climate normal, and we are not prepared."
That holds for both underdeveloped and industrialized countries with large costs in terms of economic and human security, the study found, and specific regional climate impacts -- droughts and desertification in Mexico, Southwest Asia, and the Eastern Mediterranean, and increased flooding in South Asia -- were singled out as being of particular strategic importance to the United States.
Extreme weather require the U.S. to improve its scientific and technical capacity to observe key indicators, monitor unfolding events, and forewarn of impending security threats as nations around the world adapt to a changing climate, the report authors said.