Cost of coastal flooding expected to surge

"If we ignore this problem, the consequences will be dramatic," says Jochen Hinkel. If no adaptation measures are put in place, up to 600 million people (around five percent of the global population) could be affected by coastal flooding in the year 2100. (Credit: Roberto Trm/Flickr)

Coastal regions around the world may face massive increases in damages from storm surge flooding over the course of the 21st century if no action is taken, researchers say.

A new study shows that average damages could increase from about $10 to $40 billion per year today to up to $100,000 billion per year by the end of century.


Published in the Proceedings of the National Academy of Sciences, the study presents one of the first comprehensive global simulation results on future flood damages to buildings and infrastructure in coastal flood plains.

Drastic increases in these damages are expected due to both rising sea levels and population and economic growth in the coastal zone. Asia and Africa may be particularly hard hit because of their rapidly growing coastal mega-cities, such as Shanghai, Manila, and Lagos.

“If we ignore this problem, the consequences will be dramatic,” says Jochen Hinkel from the Global Climate Forum and the study’s lead author.

600 million people affected

In 2100, up to 600 million people (around five percent of the global population) could be affected by coastal flooding if no adaptation measures are put in place.

“Countries need to take action and invest in coastal protection measures, such as building or raising dikes, amongst other options,” Hinkel says. With such protection measures, the projected damages could be reduced to below $80 billion per year during the 21st century.

The researchers say an investment level of $10 to $70 billion per year could achieve such a reduction. Prompt action is needed most in Asia and Africa where, today, large parts of the coastal population are already affected by storm surge flooding.

However, investment must also occur in Europe as shown by the recent coastal floods in South West England.

“If we ignore sea-level rise, flood damages will progressively rise and presently good defenses will be degraded and ultimately overwhelmed,” says co-author Robert Nicholls, professor of coastal engineering at the University of Southampton. “Hence we must start to adapt now, be that planning higher defenses, flood proofing buildings, and strategically planning coastal land use.”

Short-term interests

Meeting the challenge of adapting to rising sea levels will not be easy, Hinkel says.”Poor countries and heavily impacted small-island states are not able to make the necessary investments alone, they need international support.”

Adding to the challenge, international finance mechanisms have thus far proved sluggish in mobilizing funds for adapting to climate change, as the debate on adaptation funding at the recent climate conference in Warsaw once again confirmed.

“If we do not reduce greenhouse gases swiftly and substantially, some regions will have to seriously consider relocating significant numbers of people in the longer run,” Hinkel says.

Yet regardless of how much sea-level rise climate change brings, careful long-term strategic planning can ensure that development in high-risk flood zones is appropriately designed or avoided, Nicholls says.

“This long-term perspective is however a challenge to bring about, as coastal development tends to be dominated by short-term interests of, for example, real-estate and tourism companies, which prefer to build directly at the waterfront with little thought about the future.”

Source: University of Southampton