As much as 20% of global gross domestic product could be threatened by coastal flooding by the end of the century if no action is taken, according to a new report published Thursday in Springer Nature.
The research, conducted by scientists at the University of Melbourne, found that by 2100 an additional 287 million people, or 4.1% of the world's population, could be at risk of coastal flooding. Based on the areas impacted, this translates to $14.2 trillion worldwide, which is approximately one-fifth of global GDP.
According to the study, areas in Northwestern Europe as well as Southeast and East Asia are the most at risk, with areas in the Northeast of the U.S. and Northern Australia also likely to be impacted.
To arrive at their conclusion, the researchers analyzed sea levels during extreme weather events, and then compared these findings with rising sea level projections. They then looked at topographic data to determine the areas that are at the most risk, and analyzed these regions' population levels and contribution to global GDP.
"Projected sea level rise will significantly increase the frequency of coastal flooding by 2100, with results herein showing that for most of the world, flooding associated with a present day 1 in 100-year event could occur as frequently as once in 10 years, primarily as a result of sea level rise," the report said.
The scientists, led by Ebru Kirezci, found that if no changes are made, 48% more of the world's land area will be exposed to coastal flooding, which translates to a 52% jump in the exposed population. Of the coastal area at risk of flooding, 68% will be from tide and storms, with 32% from projected sea level rise.
"As approximately 600 million people live in low elevation coastal zones ... both the environmental and socio-economic impacts associated with episodic coastal flooding can be massive," the report said.
The total assets exposed to coastal flooding is set to increase from 9% to 13% of global GDP today, to between 12% and 20% by 2100.
The researchers were quick to note, however, that these results assume no action is taken, which means their projections could be overstated. The report also did not account for changing GDP levels, or future population projections.
"In many locations, coastal defences are commonly deployed and by 2100, it is expected that adaptation and specifically hard protection will be widespread, hence these estimates need to be seen as illustrations of the scale of adaptation needed to offset risk," the researchers wrote.
Of course, these measures do not always end up working, such as when New Orleans was devastated by Hurricane Katrina in 2005.
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