Study Estimates Consequences of Flooding, Disaster in World’s Port Cities

A paper recently published by the Organisation for Economic Co-operation and Development (OECD) estimates the exposure of the world’s port cities to coastal flooding due to storm surges, and damages from high winds. The study details the potential financial and human tolls that stand to be impacted — or lost — by the decade of the 2070s, due to climate change, and the cities’ and countries’ levels of ability to cope.

The 63-page study focused on 136 cities around the world, cities with current total population of approximately 40 million, that are considered at risk of a one in 100-year coastal flood event. By the 2070s, the population is expected to be as high as 150 million who will be affected by sea-level rise and storm dangers heightened by climate change.

The total value of assets exposed, as of 2005, is figured to be 3,000 billion USD, as much as five percent of global gross domestic product (GDP). By the 2070s, those numbers are predicted to be 35,000 billion USD and nine percent of global GDP.

Currently, the top 10 cities with greatest amount of exposed population are: Mumbai, Guangzhou, Shanghai, Miami, Ho Chi Minh City, Kolkata, Greater New York, Osaka-Kobe, Alexandria and New Orleans.

In the 2070s, the top 10 cities based on population are anticipated to be: Kolkata, Mumbai, Dhaka, Guangzhou, Ho Chi Minh City, Shanghai, Bangkok, Rangoon, Miami and Hai Phòng.

When considering value of assets, the developed nations of course rate higher — or most in danger. The top 10 cities (2005) based on assets are: Miami, Greater New York, New Orleans, Osaka-Kobe, Tokyo, Amsterdam, Rotterdam, Nagoya, Tampa-St Petersburg and Virginia Beach.

In the 2070s, the assets again re-configure the rankings to be: Miami, Guangdong, Greater New York, Kolkata, Shanghai, Mumbai, Tianjin, Tokyo, Hong Kong, and Bangkok.

The OECD paper points at five steps that need to be taken to manage these potential catastrophes:

To effectively manage each of the key drivers of risk, adaptation strategies must encompass a range of policy options, including, as relevant, a combination of (1) upgraded protection/infrastructure, (2) managing subsidence (in susceptible cities), (3) land use planning to both reduce vulnerability, including focusing new development away from the floodplain, and preserving space for future infrastructure development, (4) selective relocation away from existing city areas, and (5) flood warning and evacuation, particularly as an immediate response in poorer countries.

Source: Nicholls, R. J. et al. (2008), “Ranking Port Cities with High Exposure and Vulnerability to Climate Extremes: Exposure Estimates”, OECD Environment Working Papers, No. 1, OECD publishing, © OECD.
doi:10.1787/011766488208

Photo: Sepperer Markus, everystockphoto.com