The 2011 Brisbane flood.

19 August 2013 — New research has found that the cost of flooding in coastal cities is set to surpass $1 trillion a year globally unless significant investment in adaptation is made.

The research, reported in Nature Climate Change, said that with investments in adaptation, the costs due to subsidence and sea-level rise could be reduced, but at around $60 billion were still significant.

“Failing to adapt is not a viable option in coastal cities,” the study authors said.

The authors of Future flood losses in major coastal cities quantified the losses by looking at data from 136 of the largest coastal cities in the world.

They found that socio-economic changes alone would raise the cost of damages from US$6 billion in 2005 to US$52 billion in 2050. Adding sea-level rise and subsidence to the analysis increased losses even if barriers were upgraded, and if they weren’t the costs blew out to over $1 trillion.

Around 43 per cent of these costs were incurred in just four cities – Miami, New York and New Orleans in the United States, and Guangzhou in China – and that the US had the largest number of highly exposed urban areas.

Flood reduction actions in these locations could be highly cost effective, the study authors said.

The study found that adaptation alone would not bring damages to an acceptable level, as the magnitude of losses when floods did breach adaptation measures would increase under climate change, and that other measures would be necessary.

“As illustrated by the recent landfall of hurricane Sandy on the east coast of the United States, there is a need to prepare at the local, national and international level for larger floods and the disasters that ensue,” the authors said.

“Such preparations can include strengthening disaster planning measures, including early warning and evacuation systems, more comprehensive insurance schemes and other forms of post-disaster response to quickly rebuild affected communities.”

See the full paper.