Sustainabite: Coastal Adaptation with Dr. Molly Mitchell

On February 6, 2025, the Office of Sustainability hosted the first Sustain-a-bite of the semester, featuring Dr. Molly Mitchell, assistant professor of ecosystem health at the Batten School of Coastal and Marine Sciences at the Virginia Institute of Marine Science (VIMS). Her research focuses on coastal resource management and shifts in coastal resources due to sea level rise and human activity.

Mitchell began by outlining the history of floods and water level measuring in  Virginia. Norfolk has been measuring water levels for almost a century using a tide gauge, which measures relative sea level rise. Using the records from the water gauge over the past 100 years, it is evident that flooding frequency increased as urbanization increased, with a rapid rise in the mid 90s and the beginning of the 21st century.

The flooding boom is in large part due to climate change. Higher air temperatures result in increasing water temperatures, which have two effects. The first is thermal expansion since molecules are more active as water heats up, extending the ocean. The second is the melting ice sheets that add more volume into the ocean.

The latter result is impacting the Atlantic Meridional Overturning Circulation, a system where ocean currents move warm water north and cold water south towards the tropics. As ice sheets melt and water in the north becomes warmer, the system is slowed and more water moves toward the coast instead of continuing the circulation, and this change is strongly impacting Virginia.

In addition to flooding, warmer water also has ecological effects. An Increase in water temperatures has led to a different distribution of species. For example, shrimp, which prefer warm water, are now found in Virginia’s bay. Changing precipitation patterns and habitat loss are also impacting species survival.

Using satellite altimeter and tide gauges, Mitchell shared that researchers estimate that sea level is going up by 8 to 9 millimeters per year in certain areas. In Norfolk, researchers project an increase in sea level of a foot and a half by 2050.

Other impacts include saltwater intrusion in agricultural fields and decrease of marshes, lost due to asphalt. Researchers estimate that the Chesapeake Bay will see a decline of half its marshes by 2050. Locally, stormwater drainage and coastal septic systems are seeing higher levels of failure with the rising water table.

Mitchell then presented solutions for adaptation, making a point to emphasize that not all solutions will be the best solution in each area based on affordability and geographic necessities. She showed a Dutch storm surge barrier that has been successful in the Netherlands but is not a practical solution due to its high cost. “I want you to move beyond thinking of giant infrastructure when you talk about adapting,” she said.

However, it is difficult to know which methods will be the most effective. “It is this uncertainty on the ground, and how you use your landscape,” Mitchell said. Norfolk has an outlined plan for how they are building to mitigate flood impacts. These projects include seawalls, levees, and establishing a living shoreline with marsh grasses.

“The other thing we do to adapt is we change policies and we change the way we use our landscape,” said Mitchell, introducing what she believes to be the more effective solution. In an effort to aid policy decisions, VIMS manages AdaptVA.com, a website that provides localities and individuals with important information so they may make informed, sustainable decisions.

Sadie McMahon ‘27, a Virginia native who attended the talk, enjoyed hearing about flood mitigation in her home state. “It’s very interesting to see how the landscape’s going to change in the next couple of years, and learning about ways we can prevent too much damage,” she said.

Sarah Herrera ‘25, co-president of the Marine Science Society, was interested in the talk’s focus on adaptation and the number of different solutions. “Sea level rise is not a ‘one size fits all’ solution,” she said.