The two-fifths of all Americans living in counties on the coast will be the most affected by climate changes, according to a new study. If we would assemble the total surface of these counties on the costal U.S. in just one country for the sake of comparison, it would be housing a population with the third highest GDP in the world. Unfortunately, they are living on a land which is the most in danger of being washed away by devastating floods.
People living in coastal cities already know about the dangers they are exposed to, by being next to an angry ocean. And, as climate changes keep progressing at an increased pace, the ocean seems to become angrier.
Coastal cities are exposed not only to the devastating power of the ocean in case of tsunamis. They are at risk of what experts in infrastructure call a "combined flood." This event can happen when heavy precipitations coincide with the rising sea level powered by a storm, called a "surge." In such unfortunate circumstances the sewers would fill first and possible the ground cannot hold any more water since it gets too saturated. The water issue would overwhelm the city's flood management technology.
This kind of situation was experienced already during Hurricane Katrina in New Orleans and during Super-storm Sandy in New York. One of the first studies to research the issue of combined flooding was published in Nature Climate Change on Monday. The new study reports that, over the past half century, these kind of devastating events have been increasing.
What worries experts in climate change, when the overall sea level will rise, it's going to happen a lot more often. According to other recent studies, including a paper by preeminent climate scientist James Hanson published last week, experts expect the rising in sea levels to happen faster than anyone thought before.
Combined flooding has also happened before when overflowing sewers challenged cities from San Jose to Miami. The cities' storm-water systems could not manage to flush rainwater out fast enough. However, until now scientists have rarely researched the combined effects of precipitations and storm surge. According to the co-author of the new study, a structural engineer at the University of Maine named Shaleen Jain, until now the whole community of hydrologists has focused only on inland processes, while coastal researchers have focused only on storm surges.
The new study has found that the Atlantic and Gulf coast regions are most at risk, mainly because they are often affected by tropical cyclones and hurricanes that may bring significant amounts of rain and lead to large storm surges, according to another co-author of the study, Thomas Wahl, a coastal engineer at the University of South Florida. Areas in the west are also at risk of combined flooding, from Los Angeles to Seattle. California can get affected by the Pineapple Express and in the winter wet and windy storms gallop across the Pacific Northwest.