In the Intelligence Community's (IC) analysis of the possible impacts of climate change on national security over the next 20 years, the IC takes as a scientific baseline the reports produced by the Intergovernmental Panel on Climate Change (IPCC), the international body responsible for assessing the science related to climate change. This memorandum does not assess effects on the homeland, nor does it evaluate the science of the IPCC reports. [...] Long-term changes in climate will produce more extreme weather events and put greater stress on critical Earth systems like oceans, freshwater, and biodiversity. These in turn will almost certainly have significant effects, both direct and indirect, across social, economic, political, and security realms during the next 20 years. These effects will be all the more pronounced as people continue to concentrate in climate-vulnerable locations, such as coastal areas, water-stressed regions, and ever-growing cities. [...]Climate change and its resulting effects are likely to pose wide-ranging national security challenges for the United States and other countries over the next 20 years through the following pathways:  Threats to the stability of countries.  Heightened social and political tensions.  Adverse effects on food prices and availability.  Increased risks to human health.  Negative impacts on investments and economic competitiveness.  Potential climate discontinuities and secondary surprises.
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