Different forces drive storm-induced sea level spikes on U.S. East, Gulf coasts, says CPO-funded study

Different forces drive storm-induced sea level spikes on U.S. East, Gulf coasts, says CPO-funded study

Using a new powerful NOAA global climate model, NOAA and partner researchers show in a new study that the Gulf Coast to the Atlantic coast will experience greater and higher storm surges in the future as warming progresses, but these sea level spikes will be driven by differing forces in the two regions.

Stronger hurricanes will be the primary driver of storm surges along the Gulf Coast while increased sea level will be a primary cause of spikes in sea levels along the East Coast, according to the research funded by the NOAA Climate Program Office’s MAPP Program.

The scientists found that even in the absence of global warming, the Gulf Coast, and especially New Orleans, is particularly vulnerable to storm surge. As the climate warms, the Gulf Coast will be even more susceptible to extreme storm surges, said MAPP-funded lead author of the new study Jianjun Yin, University of Arizona Associate Professor of Geosciences.

“We are entering a period in numerical modeling where global models used to study climate are now able to make meaningful statements about the statistics of extreme weather events,” said Stephen Griffies, a physical scientist at NOAA’s Geophysical Fluid Dynamics Laboratory and co-author of the new research. “This study shows the importance of refined-resolution climate models for providing actionable information that is critical to coastal communities to adapt to life near the ocean in a warming world.”

Researchers studied the coastline from Halifax, Nova Scotia, to Houston, Texas. Using the NOAA model, they simulated how adding more carbon dioxide to the atmosphere at a rate of increase similar to that observed since the mid-20th century would affect sea level rise and storm surge. For both regions, storm surge heights will increase in the future as warming progresses, researchers found.

“For the Gulf of Mexico coast, the extreme sea level is highly sensitive to tropical cyclone characteristics like the storm winds,” said Yin. “But for the East Coast of the U.S., especially the Northeast coast, the story is different -- the maximum storm surge is mainly influenced by the background sea level rise.”

Scientists were able to more accurately predict how the seas along the East Coast and Gulf Coast would rise during tropical cyclones, including hurricanes, and other storms such as nor’easters using NOAA’s newest climate model - the Geophysical Fluid Dynamics Lab model CM4. The model combines information on weather, climate and sea level to produce high confidence predictions.

The modeled climate simulations that added carbon dioxide to the atmosphere year after year as warming progresses found there will be fewer -- but stronger -- tropical cyclones. In addition, the model also showed that increased carbon dioxide in the atmosphere would cause the Atlantic Meridional Overturning Circulation to slow down, increasing sea level rise and storm surge on the East Coast.

The Atlantic Meridional Overturning Circulation is a system of ocean currents that transports heat northward and is responsible for the mild climate in Europe and North America. “If AMOC slows down, it can influence weather and climate over Europe and North America and cause sea level to rise,” said Yin.

Co-authors of the research also included Michael Winton and Ming Zhao of NOAA GFDL, Laura Zanna of the University of Oxford and New York University. The research was funded in part by NOAA’s Climate Program Office Modeling, Analysis, Predictions and Projections Program.

Read the paper »

View the University of Arizona press release »

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Americans’ health, security and economic wellbeing are tied to climate and weather. Every day, we see communities grappling with environmental challenges due to unusual or extreme events related to climate and weather.