Massive coastal flooding in northern Europe that now occurs once every century could happen every year if greenhouse gas emissions continue to rise, according to a new American Geophysical Union study.
New projections considering changes in sea level rise, tides, waves and storm surge over the 21st century find that global warming could cause extreme sea levels to increase significantly along Europe's coasts by 2100. Extreme sea levels are the maximum levels of the sea that occur during a major storm and produce massive flooding.
The increase in frequency of events that are today considered exceptional is likely to push existing coastal protection structures beyond their design limits, leaving a large part of Europe's coastal zones exposed to flooding, according to the study's authors.
Northern Europe will see the strongest increase in extreme sea levels. In the North Sea region, extreme sea levels could increase by nearly 1m under the worst-case scenario. The Atlantic coasts of the United Kingdom and Ireland could see similar increases in extreme sea levels, while lower but still considerable increases in extreme sea levels are projected for the Norwegian and Baltic seas.
Considering all components
The new research considers how all components that can influence extreme sea levels, including the mean sea level, tides, waves and storm surge, will be affected by climate change. The researchers used information about these different components to project changes in extreme sea levels by 2100 under different greenhouse gas scenarios. Using all of these components provides a more accurate projection of how extreme sea levels will change this century, according to the study's authors.
Under the most extreme scenario, where greenhouse gas emissions continue to rise throughout this century, extreme sea levels along Europe's coastlines could increase by 81cm on average, by 2100. That means 5 million Europeans who are currently under threat of flooding from extreme sea level events that occur every 100 years could face that same risk annually, according to the study.
Even under a more moderate scenario, where greenhouse gas emissions peak in 2040, 100-year extreme sea levels could increase by 57cm on average by the end of the century, with extreme events occurring every few years.
The research will be provided to EU policymakers. The data will also be made public so it can be used by scientists, engineers and coastal managers.