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disaster preparedness

Using technology to stay ahead of disaster risk

John Roome's picture
Hurricane Patricia. Photo credit: NASA Earth Observatory

We’re witnessing an unprecedented uptick in record-breaking storms. In October last year, Hurricane Patricia came ashore in Mexico with record breaking 200 miles per hour winds. A few months later on the other side of the world, Cyclone Winston broke records for Pacific basin wind speeds, destroying parts of mainland Fiji with 180 miles per hour winds. More recently, Cyclone Fantala became the most powerful storm in the Indian Ocean ever recorded.
Experts agree that its activities by people which are increasing the severity of storms like these. Climate change isn’t just projected to increase the intensity of hurricanes and cyclones, but a whole other range of other natural hazards, like droughts, floods, storms, and heat waves.

Increasing Flood Risks Create Major Challenges for World's Coastal Cities

Stéphane Hallegatte's picture

 NOAA via Wikimedia
The flooding of New Orleans, caused by Hurricane Katrina in 2005, illustrates the vulnerability of cities that are highly dependent on coastal defenses. Photo: NOAA []

Increasing flood risks create a major political and institutional challenge for the world’s coastal cities, as ambitious and proactive action at the local level over the next decades will be needed to avoid large-scale flood disasters. However, the implementation of flood risk management policies meets many obstacles.

In a recent study written with colleagues Colin Green, Robert Nicholls and Jan Corfee-Morlot as part of an OECD project on urban vulnerability, we estimate how flood risks could change in the future in 136 coastal cities, in response to increasing population and wealth, local environmental change, and climate change. We find that because current flood defenses and urbanization patterns have been designed for past environmental conditions, even a moderate change in sea level is sufficient to make them inadequate, thus magnifying flood losses to catastrophic levels. If no action is taken to reduce flood vulnerability, most coastal cities would become inhospitable and dangerous places to live, with annual losses in excess of US$1 trillion dollars.

What can be done?

Our analysis suggests that upgrading defenses could mitigate these losses and the impacts of rising sea levels. However, these upgrades need to include a package of risk management policies. First, coastal defenses should make use of the protection the environment can offer for free: Marshes, seagrass beds, coastal and kelp forests, and coral reefs provide natural buffers that absorb the energy from waves and storms, making it easier and cheaper to protect urban development. In addition artificial constructions are also required to provide full protection. We are not only talking about dykes: a city surrounded by dykes will need pumping systems to drain rainfall water, and a harbor will need moving barriers to let ships in and out of the port.