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CLAIMED LAND: A dike in Doemitz, Germany.
Jens Büttner/Picture-Alliance/DPA/AP
CLAIMED LAND: A dike in Doemitz, Germany.

Waves of the future?

Science | Building dikes to combat sea rise appears cheaper than the alternatives

Imagining what the world will look like when great-grandchildren are adults may be fun or frightening, depending on your perspective. In a new study speculating on the effects of global warming, a group of European scientists imagined the future of coastlines. They calculated the cost of coastal flood damages that could result from sea level rise by the end of the century, and compared it with the cost of building sea walls.

The study, published in February in Proceedings of the National Academy of Sciences, considered these main drivers of sea level rise: thermal expansion of the ocean, melting of glaciers, and melting of ice sheets on Greenland and Antarctica. Using a range of scenarios, they estimated that by 2100 sea levels would rise by 10 to 48 inches. That would put between $17 trillion and $210 trillion in assets at risk of storm surge flooding in coastal communities around the world, depending on how wealthy those communities have become by then.

Huge assumptions are at play here, which is why it’s best to think of these scenarios as exercises in imagination. The ocean is indeed rising—up to 8 inches in the past century. But we can’t say for sure how high it will be 20, 40, or 86 years from now. The sea rise forecast in the study depends on whether temperatures continue to rise and ice sheets continue to melt. (The authors admit Antarctic melting remains “uncertain.”) Right now the world is experiencing a 16-year pause in global warming that hadn’t been predicted by leading climate models.

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Shall we put uncertainty aside and imagine the worst case? The authors of the study say the annual cost of coastal flood damage would be far lower—less than $100 billion—if coastal communities progressively raised the height of dikes to counter the flood risk. Dike construction and maintenance would cost $12 billion to $71 billion a year, globally, they estimate. That’s not a bad deal considering Hurricane Sandy alone produced $66 billion in damage, much due to flooding.

It’s a good deal for another reason, too. Bjørn Lomborg, a Danish researcher who often writes about climate change, has argued that adapting to climate change would be far cheaper and more effective than the carbon-capping schemes politicians like to pitch. One economist estimated Europe’s carbon reduction policies have come at a price tag of up to $250 billion a year—but will ultimately reduce sea rise by less than an inch.

Even granting the uncertain prospect of sea level rise, improving dikes appears far more cost-effective than shutting down fossil fuels.

Science startup

Handout

David W. Snoke is a University of Pittsburgh physics professor, a laser scientist, and the president of a new science organization, the Christian Scientific Society. He hopes the group, launched in 2012, will attract Christian researchers who feel out of place at other scientific organizations. “The distinctive of our group is that we are not, by and large, young-earth creationists,” he says, although members must agree to a statement of faith affirming inerrancy of Scripture and a historical Adam. At an upcoming society meeting in Pittsburgh in May, speakers will debate whether Neanderthals were humans or something more like “orcs.” —D.J.D.

Daniel James Devine
Daniel James Devine

Daniel is a reporter for WORLD who covers science, technology, and other topics in the Midwest from his home base in Indiana. Follow Daniel on Twitter @DanJamDevine.

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