On the Vulnerability of NATO Installations to Climate Variability and Change: A System-Level Perspective

This task focuses on the understanding of the spatial connections among 91 NATO installations subject to hydroclimatological extremes, including precipitation, surface temperature, and wet bulb temperature, under both historical and future conditions. It allows a system-level view of the vulnerabilities of NATO installations to climate change and the associated extremes. We first perform statistical bias correction and evaluate how well global climate models (GCMs) part of the Sixth Phase of the Coupled Model Intercomparison Project (CMIP6) are able to reproduce the historical trends. Based on these analyses, we select a subset of well-performing models, which we use to examine how the spatial dependence in climate extremes is projected to change. In particular, we consider two future periods (Mid-of-Century: 2015-2048; End-of-Century: 2067-2100) with respect to the 1981-2014 period, under four shared socioeconomic pathway scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5). We show that temperature-based extremes are correlated in space and have a large footprint, impacting more than one base at once. When we focus on precipitation extremes, we find that their spatial correlation is much weaker, with a much smaller chance of impacting more than one installation. Moreover, GCMs can reproduce these observed behaviors. In analyzing the future projections of these hydroclimatic extremes, we show that the spatial correlation in temperature-based extremes across NATO installations is projected to increase, especially toward the end of the 21st century and for higher emission scenarios. These results highlight the current and future susceptibility of the NATO installations to climate extremes in light of climate change when viewed through a system-level perspective.