Information related to climate change often is provided as a long-term response of the climate system to different levels of anthropogenic forcing. In addition, emission scenario-dependent projections via General Circulation Models (GCM) generally are provided as time slices and usually for mid-twenty-first century and end of century. Moreover, because of natural variation in the climate system and its predominance in characterizing the uncertainty of climate projections even up to mid-century, projections show little divergence up until that time.
Although understanding the long-term implications of climate change is critical, scientific studies and synthesis reports such as the Third National Climate Assessment have documented that climate is already changing and is not just a long-term issue. As a result, decision-makers, including those within the DoD, are now aware they must prepare for and respond to climate change. They require information about how it affects their decisions not just mid- and end of century, but within the more near-term timeframes in which they typically operate.
The focus of this SON is on the two- to 20-year time horizon. The two-year lower bound avoids overlap with those efforts attempting to extend weather prediction capabilities into at least the seasonal realm in which an underlying climate trend signal is not a focus. The 20-year upper bound 3 reflects the decision horizon for those that are not interested in long-term infrastructure planning or facility siting issues, but for which infrastructure maintenance and operational decisions may still be significantly affected. These decisions explicitly involve infrastructure with a planned performance of less than 20 years, changes in flood risk that may change operational performance or response action relative to extant infrastructure, and or narrowing of operational opportunities. This upper bound still falls well short of the time when divergence in driving emission or concentration pathway scenarios becomes important.
Some research efforts are underway in this space and proposals in response to this SON should not duplicate those efforts. For example, Coupled Model Intercomparison Project, Phase 5 (CMIP5) experiments include research related to decadal prediction using the GCMs with a focus on better representing model initial conditions that may persist over time. The National Earth System Prediction Capability project is focused currently on research questions in the near-term (i.e., less than two years). This SON is intended to explore other approaches that may inform decisions in the two- to 20-year timeframe.
Complementary SERDP-Funded Projects: SERDP is supporting several projects relating to potential non-stationary changes in the hydrologic cycle and coastal water level extremes that in part are investigating moderate time scales.