Coastal flooding threatens to cost trillions in damage unless protective measures put in place

Rising sea-levels will increase the risk of coastal flooding from storm surges.
Rising sea-levels will increase the risk of coastal flooding from storm surges. Rising sea-levels will leave coastlines throughout the world vulnerable to huge losses from flooding every year, but the damage can be massively reduced if communities are willing to adapt to the increasing flood risk. 

Most coastal regions around the world are well aware of the dangers posed by flooding from the sea. Even now, parts of Europe continue to be battered by a succession of winter storms which have already wreaked havoc along the coastlines of Ireland and Britain. And now researchers are warning that the situation is only likely to get worse as sea-levels continue to rise inexorably over the 21st century.

This study, led by scientists from the Global Climate Forum (GCF), anticipates that global sea-levels could rise by as much as 123 cm by 2100. Even under the best possible scenario, which sees water levels rising by 25 cm, the damage caused by coastal flooding will soar throughout the world. And this will be exacerbated by the huge expansion in population and economic development that is predicted to occur in many coastal areas during the next century.

If no adaptation measures are put in place, up to 600 million people (around 5% of the world’s population) could be directly affected by flooding every single year, while damages to buildings and infrastructure could exceed trillions of US dollars.

But if coastal protection measures are put in place, then the situation appears far brighter. Although some coastal flooding will still occur, the damage will be greatly reduced, possibly costing as little as 80 million US$ each year. While the global price of protecting coastlines with dikes may reach up to US$ 71 billion by 2100, the authors argue that this would be a shrewd investment, particularly in countries with large coastal cities. And more affordable alternatives to dike-building also exist, such as the restoration of wetlands, mangroves and sand dunes, which may be better suited to certain regions.

Given the catastrophic losses that have already arisen from coastal flooding in recent years, the authors are hopeful that communities throughout the world will now begin to implement long-term adaptation strategies to rising sea-levels. Already in New York discussions have begun on the most appropriate protection measures against future storms, while the Thames barrier in London has proved invaluable this year in protecting the city against flooding from high tides. Although costly and challenging, such developments will be essential if we are to defend our towns and cities from rising seas.

Reference: Jochen Hinkel, Daniel Lincke, Athanasios T. Vafeidis, Mahé Perrette, Robert James Nicholls, Richard S. J. Tol, Ben Marzeion, Xavier Fettweis, Cezar Ionescu, & Anders Levermann (2014). Coastal flood damage and adaptation costs under 21st century sea-level rise PNAS, 1222469111 DOI: 10.1073/pnas.1222469111

Image: George Karbus


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