Developing a full-scale climate projections report is a big undertaking. Estimating current and future conditions for Fairfax County required information from many sources and the use of several sophisticated analytical tools. Here are some of the most important elements of the report methodology.
- Two types of climate conditions were considered for this report: chronic hazards that demonstrate historic and future trends (sea level rise, for example) and acute hazards, or events that may increase or decrease over time (severe storms, for instance)
- The analyses generally used 30-year planning horizons. Time periods shorter than 20 years are not considered representative of climate change. The 30-year horizon was chosen to provide a more robust analysis of heavy precipitation and extreme heat events.
- The report compares future projections to a baseline period (data from 1976-2005) and a current period (data from 1991-2020).
- The projections primarily focus on a mid-century timeframe (2035-2064) centered at the year 2050, and an end-of-century time period (2070-2099) centered at the year 2085.
- To investigate future changes in climate, models were used to simulate a range of climate futures that represent, in part, how global society may evolve over the coming century.
- For this report, two scenarios developed by the Intergovernmental Panel on Climate Change were used. The first assumes a continued increase in greenhouse gas emissions until 2040 and then a decline, with stabilization achieved by the end of the century. The second assumes significant increases in emissions through the end of the century. This scenario aligns with our current trajectory.
- The analyses written up in the report relied on publicly available statistically downscaled climate model data developed by the Scripps Institute of Oceanography at the University of California, San Diego.
- The projections also draw on data from three observation stations: Washington Reagan National Airport, Washington Dulles International Airport, and Vienna, Virginia.
For more information on the report methodology, please see page 10 of the full report.