We’ve all heard jokes about how the weatherman is the only person who’s allowed to be wrong 90% of the time and still keep their job. Perhaps this is one of the reasons we as engineers, planners, and architects have so much trouble admitting that WE DON’T KNOW to what extent sea level rise or extreme weather events will affect our communities and projects in the future. We’ve been trained to believe ours is the industry where we can solve a problem and put a box around the answer, but as Bob Dylan first alerted us in 1964, “The Times They Are A-Changin’.”
Even though we can’t always know exactly what will happen, there is still plenty we can do to help communities make responsible, resilient, and adaptable decisions. The National Oceanic and Atmospheric Administration (NOAA) continuously analyzes the effects of global climate change. They are the lead administrative agency for the National Climate Assessment (NCA) reported to Congress every four years.
Based on this report, six scenarios for sea level rise were developed: Low, Intermediate-Low, Intermediate, Intermediate-High, High, and Extreme. Regional climate change and resiliency coalitions are advised to use NCA as a basis for their guidelines and policy and adapt it to local factors, in some cases by paring down the probable scenarios. For example, in the Recommended Projections of Sea Level Rise in the Tampa Bay Region (April 2019), the Low scenario (with a linear rate of rise and no projected acceleration) is excluded based on the observed local conditions.
After paring down scenarios for your region (if this has taken place), three common considerations to help guide the design parameters are:
- Project life cycle. How long is the roadway, pipeline, building, seawall, parking lot, or runway expected to last? Let’s make sure we’re not looking out too far in the future, since uncertainty increases with time.
- Adaptation potential. How easy or difficult would it be to design the project so it could be re-evaluated throughout its life and adjusted if necessary? Perhaps this is where a unique engineering solution could come into play.
- Risk tolerance. How critical is this project for keeping the community safe and functioning? A water plant needs to be fail-safe or restored to operation as quickly as possible. A community park can be closed for a while if needed.
Even though it seems ideal to play it safe and always plan for the Extreme condition, budgets and sustainability considerations likely don’t make this a responsible option. Over-hardening infrastructure could deplete natural resources and remove greenspace, which can exacerbate climate change effects. Working through the questions above and using NCA tools will help guide communities toward the most resilient decisions.
It can be uncomfortable to admit we won’t always know the exact answer but admitting this helps us keep an open mind and figure out the best options as we go. Perhaps the most important part of acknowledging professional uncertainty is creating a feedback loop to keep checking in every few years. This way, we can see if the data is lining up with the selected design conditions. If it’s not, then it’s time to see if adaptive measures are needed. It’s not perfect, but it’s a great framework given the reality of our world today. And of that, I am not uncertain.