SINGAPORE — As policymakers plan ahead in Tokyo, Osaka-Kobe and other major port cities in Japan, one of the most vexing questions they face is how much will the sea level rise in coming decades?
The stakes are high. By the 2070s, the number of people in the 136 big port cities around the world who are exposed to coastal flooding is projected to grow more than threefold, to around 150 million. If the predictions of scientists advising the United Nations on global warming are correct, port cities will have to endure more intense effects of climate change, including a rise in sea level, increasingly violent storms, and land subsidence as well as flooding, according to a recent study for the OECD, the Paris-based think tank of advanced economies.
The study, published in July, forecast that the value of flood-exposed economic assets in these port cities in the form of buildings, transport networks, utilities and other infrastructure could grow even more dramatically than population exposure, reaching $35 trillion by the 2070s, approximately 9 percent of projected global gross domestic product, up from 5 percent in 2005.
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