Storm surge

A storm surge is large change in sea level generated by low atmospheric pressure and strong winds associated with an extreme meteorological event. Storm surges can last from hours to days and can elevate sea level over an area of hundreds to thousands of square kilometres. Low atmospheric pressure allows sea level to rise and gale force winds, combined with the Earth’s rotation, force water towards the coastline. Storm surges can raise sea levels by more than 8m in tropical areas and by over 3m in the North Sea.

Storm surges affect low lying coastlines around the globe and are responsible for significant damage and loss of life. The most devastating coastal floods occur when surges coincide with high spring tides. Mean sea level rise and subsidence (sinking land) also slowly leads to higher floods.

In 1970 a devastating storm surge resulted in at least 300,000 deaths in Bangladesh. In the USA, Hurricane Katrina and Superstorm Sandy are the two most costly natural disasters in US history. They are recent reminders of this global hazard causing major flood damage in New Orleans and New York, respectively. In 2013 Typhoon Haiyan was the most intense storm to ever make landfall. Typhoon Haiyan generated a very large storm surge which impacted the islands of the central Philippines and caused immense damage, leaving nearly 8,000 people dead.