Rising Seas Are Set To Cost Earth's Cities $1 Trillion Before 2050

A trillion dollars? Hell, that’s barely the cost of one Iraq war. Though, at the same time, a trillion dollars is also the yearly GDP of the United States 60 times over. So it’s kind of how you look at it. In any case, that’s the figure World Bank economist Stephane Hallegatte and his team came up with for the total cost of coastal damage likely to be incurred by the Earth’s nations before the year 2050 due to flooding if drastic measures aren’t taken. Their report is out in the new issue of Nature Climate Change.

As if it even needs to be said, that huge tab comes thanks to climate change. Or at least climate change combined with ill-prepared cities. Right now, global loses due to flooding run about $6 billion per year, hitting primarily four cities: Miami, New York, and New Orleans in the United States, and Guangzhou in China. Together those four pay out just under half of the yearly global total. The new figures are based on a loss-risk scenario involving four factors: population growth, rising sea levels, planned protection upgrades, and subsidence. That last thing is when cities sink naturally due to the extraction of oil and other resources; fossil fuels manage to catch us from every direction.

The trillion dollar figure breaks down to a yearly hit of between $60 and $63 billion, disproportionately shouldered by poorer countries. The team notes that if even the world goes all-in for increased flood protection—building protective dykes along vulnerable coastlines, mostly—the yearly cost of flooding is still going to shoot up to $50 billion a year. This is simply because no dyke is perfect, and a dramatic increase in population is just going to mean that more and more people are relying on those imperfect dykes. "That means that if we have a dyke rupture, as there are more people behind the dykes, we will have ever bigger catastrophes," Hallegatte says in a press release.

War is actually a good analog for the challenge facing the world’s coasts (and a globally warmed world generally); though defending against rising sea levels is hardly as pointless as some of the planet’s more recent armed endeavors. This threat is real and directly in front of our faces, approaching as visibly as a line of tanks. The report notes bluntly, "Failing to adapt is not a viable option in coastal cities."

Reach this writer at michaelb@motherboard.tv.