Future Nearshore Wave Climate Projection for the Northwestern Atlantic

Adrean Webb1, Tomoya Shimura1 and Nobuhito Mori2, (1)Kyoto University, Kyoto, Japan, (2)Disaster Prevention Research Institute, Kyoto University, Kyoto, Japan
Recent research suggests approximately 50% of the world’s coastlines are at risk of future climate-driven changes in nearshore wind-wave conditions. These changes can reshape the coastal zone and exacerbate flooding through wave overtopping and wave setup. Here, a high-resolution (7 km) wave climate projection for the Northwestern Atlantic has been conducted to help assess possible end-of-century regional impacts under an RCP8.5 climate forcing scenario. NOAA WAVEWATCH III is utilized with a CMIP5 AGCM (to help quantify uncertainty) to simulate three regions of interest: Eastern Seaboard (7 km), Gulf of Mexico (7 km), and Caribbean Sea (21 km). Hourly wind field forcings are provided by MRI-AGCM 3.2S (21 km) and the increased temporal frequency and spatial resolution allow for better modeling of large storm events.

Climatological (25-year) significant wave height differences between future and historical periods indicate that a seesaw effect will occur, with decreases occurring in the Northwest Atlantic and Gulf of Mexico and increases occurring in the Caribbean Sea. These differences coincide with similar changes in surface winds and there are sharp decreases (~20%) in incident shoreline energy along the Eastern Seaboard. Changes in extreme wave statistics do not follow the same pattern and there are increases in extreme wave heights along the northern Eastern Seaboard and parts of the Caribbean. Further details of the projection will be discussed, including underlying changes, model uncertainty, and extreme wave height analysis.