Page:Implications for US National Security of Anticipated Climate Change.pdf/12



Effects of Climate Change on US National Security: Possible Timeframes
The major forces driving climate are understood well enough for models to forecast climate trends for general regions, but complex interactions in the climate system, modeling uncertainties, and human choices make it difficult to project when and where specific weather and climate effects will most significantly affect national security. Most scientists expect that climate change generally will exacerbate current conditions—for example, making hot, dry places hotter and drier.

Future climate conditions could be altered significantly by government policies, industrial practices, or consumer behavior regarding greenhouse gas emissions. That said, IPCC scenario modeling suggests that aggressive environmental policies would not begin to slow the growth of global average surface temperatures for another 15-20 years because of the lag time for complex global climate systems to respond to changes in human behavior (see chart below).



The long time horizon for climate change makes for different assessments of the national security implications for different periods. We make these assessments based on the IPCC’s findings of projected climate change and our understanding of the possible pathways by which climate change affects national security. 12