Population and climate raise tropical cyclone risks

A boy at the site of his family's damaged house in the Bangladeshi coastal district Cox’s Bazar that was damaged by a tropical storm. When a tropical storm becomes a hurricane-speed cyclone, such houses are just washed away. Casualties are higher when the population is not aware of the coming of a cyclone. Tropical cyclones are expected to become less frequent but more intense with future climate change. Credit: amioascension/Flickr

A boy at the site of his family's damaged house in the Bangladeshi coastal district Cox’s Bazar that was damaged by a tropical storm. When a tropical storm becomes a hurricane-speed cyclone, such houses are just washed away. Casualties are higher when the population is not aware of the coming of a cyclone. Tropical cyclones are expected to become less frequent but more intense with future climate change. Credit: amioascension/Flickr

The number of people threatened by tropical cyclones and the disasters they can cause will “greatly increase” over the next 20 years. And though climate change is predicted to increase tropical cyclones’ intensity, the world’s rapidly increasing population will play an even larger part in raising that risk. “Higher intensity will increase the number of people exposed,” explained Bruno Chatenoux from the Global Change and Vulnerability Unit at the United Nations Environment Program in Geneva, Switzerland. “However, we also show that the increase in population is the main trigger that will increase exposure. This finding is key because some governments may be tempted to delay actions to protect their population over uncertainties in climate change’s impact on tropical cyclones.”

This message is what Bruno and seven other Europe and US-based scientists have learnt while developing a new approach for determining the risks from such cyclones. Currently that risk is calculated from databases of reported past events in which the number of disasters caused by tropical cyclones has increased steadily over the past 40 years. However, the deaths those disasters cause has fluctuated up and down, falling from 357,000 in the 1970s to 174,000 in the 2000s. Perhaps more common disasters have been balanced out by people becoming much less vulnerable, the scientists suggest in a paper published in research journal Nature Climate Change. Or perhaps the increased number of disasters is just due to better recording, as TV and the internet becomes more widespread. Read the rest of this entry »

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