Some of them are likely to be felt in regions remote from where the actual climate events take place. It is prudent to expect that some of these events will create or exacerbate conditions affecting U.S. national security.

It makes sense for the intelligence community to apply a scenario approach in thinking about potentially disruptive events that are expectable but not truly predictable. For example, when climate models disagree about the direction of a climate trend even when the fundamental science strongly suggests that change is likely, it may make sense to consider the security implications of two or more plausible trends as a way to anticipate risks.

Conclusion 4.1: The overall risk of disruption to a society from a climate event is determined by the interplay among several factors: event severity, exposure of people or valued things, and the vulnerability of those people or things, including susceptibility to harm and the effectiveness of coping, response, and recovery. Exposure and vulnerability may pertain to the direct effects of a climate event or to effects mediated by globalized systems that support the well-being of the society.

The security risks are unlikely to be anticipated by looking only at climate trends and projections. Each of the factors affecting disruption is changing, and several are changing in ways that can be projected with some confidence for a decade or more at the country level or below. Because risk reflects the interactions among these factors and not only the magnitude of climate events, events of a magnitude that has not been disruptive in the past can cause major social and political disruption if exposure and susceptibility are sufficiently great and response is inadequate or widely seen as such. The other side of this coin is that unprecedentedly large climate events do not necessarily lead to security threats if actions have been taken to reduce exposure or susceptibility or increase coping capacity and if authorities are seen to be actively responding to events.

Conclusion 4.2: To understand how climate change may create social and political stresses with implications for U.S. national security, it is essential for the intelligence community to understand adaptation and changes in vulnerability to climate events and their consequences in places and systems of concern, including susceptibility to harm and the potential for effective coping, response, and recovery. This understanding must be integrated with understanding of changes in the likelihoods of occurrence of climate events.

Knowledge from several scientific fields provides useful general insights about the components of vulnerability and how they shape the effects of cli-



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