Whether you rely on network, print, or electronic media for your news, headlines have been dominated by high impact weather events such as the late winter and spring tornado outbreaks, as well as one of our warmest winters on record. Inevitably, questions arise: Are these weather extremes caused by climate change and how can we plan our infrastructure for future weather impacts?

Incorporating Climate Change Variables in Infrastructure Planning

Energy, water, and transportation systems are in need of serious upgrades throughout the U.S. Climate change and variability is a well-recognized planning concern for development and rehabilitation of this infrastructure. Typical questions that arise during infrastructure planning focus on:

• Long-range availability of water and the occurrence of droughts and floods
• Changes in temperature that impact heating and cooling decisions
• Consequences of sea level rise on our coastal communities

Narrowing Down Global Climate Change Forecasts to Answer Your Concerns

The Intergovernmental Panel on Climate Change (IPCC) has been studying weather impacts of our changing climate for more than two decades. Global circulation models (GCM) provide needed insights into expected changes in sea level rise, seasonal temperature and precipitation patterns, and the frequency of extreme weather events. These broad scale model outlooks have put many nations, including the U.S., on notice that adaptation to climate change and variability isn’t a question of “if,” but “when” it’ll become necessary.

At Dewberry, we continue to develop ways to “downscale” the GCM global forecasts of climate change and make them relevant to the watershed basin and community levels.

Primary Tools and Processes for “Downscaling” GCM Global Forecasts

Statistical downscaling

Use statistics to give local meaning to GCM outlooks, relating changes in local average temperature to changes in precipitation, cloud cover, and winds.

• Pro: Relatively inexpensive to develop and quick to calculate
• Con: Answers have roughly a 25 percent chance of being right

Dynamic downscaling

Link the GCM model outlooks to a regional scale atmospheric model, producing 50 to 100-year outlooks for cities, coastal areas, and river basin size areas.

• Pro: Preserves naturally observed cause-effect relationships
• Con: More costly and roughly 45 percent right

Dynamic Trend Analyses (DTA)

Use to prepare one to 50-year climate outlooks of estimated temperature, precipitation, runoff, and weather hazard trends on all local to national scales. This technique relies on the strong relationships between sea surface temperature oscillations, atmospheric circulation periodicity, and other atmospheric-ocean connections to precipitation, temperature, drought and hurricane frequency, energy usage, and severe weather occurrences.

• Pros: Outlooks are usually more than 65 percent right but only for 50-year periods
• Cons: Relies on historic relationships being projected into the future

At Dewberry, we use these tools and processes to re-imagine scenario-based and realistic solutions to adapt to the climate impacts and challenges our infrastructure clients’ face.