From the Executive Summary: "Climate change, current and future alike, is expected to affect the severity, frequency, or duration of extreme weather events, droughts, floods, sea-level rise, precipitation patterns, and the spread of life-threatening diseases. The projected impacts of climate change pose both direct and indirect security and resiliency risks to the Nation, core homeland security missions, and Department of Homeland Security (DHS) infrastructure and operations. The direct effects of climate change--particularly from intensifying hurricanes and other extreme weather events--threaten the economic and physical security of the United States. However, the most significant homeland security impact will be indirect, resulting from climate-driven effects on many countries and their potential to seriously affect U.S. national security interests. In this way, climate change may act as a 'threat multiplier,' aggravating stressors such as poverty, environmental degradation, economic growth, and social tensions that can destabilize human systems and institutions."