PARIS: The world’s 136 largest coastal cities could risk combined annual losses of $1 trillion (750 billion euros) from floods by 2050 unless they drastically raise their defences, a study warned on Sunday (Monday in Manila).
Current losses are about $6 billion per year, with four cities—Miami, New York and New Orleans in the United States and Guangzhou in China—incurring 43 percent of the costs, according to a report in the journal Nature Climate Change.
World Bank economist Stephane Hallegatte and colleagues composed a loss risk scenario based on city population growth as well as different levels of sea level rise, protection upgrades and subsidence—the sinking of surface areas often linked to the extraction of oil or other ground resources.
Assuming cities improve their protection to contain the flood risk to current levels, and based purely on the projected growth of city populations and the assets accumulated there, the team warned of a nine-fold increase in losses to $52 billion per year by 2050.
When the team adds the effects of climate change-induced sea level rise and subsidence, the figure increases to between $60 and $63 billion per year.
“With no adaptation (of flood protection), the projected increase in average losses by 2050 is huge, with aggregate losses increasing to more than $1 trillion a year,” said the study—a worst-case-scenario outcome that would roughly equate to the 2012 Gross Domestic Product of Iran.
But even the best protection in the world won’t eliminate the risk, said the study.