The value of buildings and other assets exposed to the same risks around the world will increase by a factor of more than 10, from $3 trillion, or 5 percent of current global GDP today, to $35 trillion in 2070, or 9 percent of projected global GDP, states the report, published Tuesday.
The report, titled "Ranking of the World's Cities Most Exposed to Coastal Flooding Today and in the Future," was written by experts from the Organization for Economic Cooperation and Development with assistance from British and French academics and insurance risk modeling experts.
Speaking before leaving for the U.N. Climate Change conference in Bali, Indonesia, this week, OECD Secretary-General Angel Gurria said there was a need for swift action to mitigate the risks.
"Climate change is already happening, and concerted action is needed now to prevent its worst impacts," he said, adding that there were a range of policy options available, but "political commitment is needed to implement them."
Its authors call the report "the largest study on urban coastal flood exposure ever undertaken" and say they analyzed more than 130 key port cities worldwide "to investigate the likely impact of climate change alongside subsidence, population growth, and urban economic development."
The study examines the exposure of people and infrastructure to what risk analysts call "a 1-in-100 year flood event" -- in other words, the kind of major disaster likely to happen once every hundred years -- which they state is a commonly accepted benchmark in assessing catastrophic risk.