Increased losses from Natural Disasters due to Wealth, Population Expansion

In recent decades, the amount of damage wrought by weather-related natural disasters has skyrocketed, much to the chagrin of insurance companies and the millions of people affected by them. Is this the work of human-induced climate change?

Climate models predict that global warming will generate larger, more frequent extreme weather events, from tropical storms to droughts. But climate models look at long-term changes -- putting one's finger on a single event and saying "this was because of global warming" is difficult at best, and more often it's thought of as irresponsible.

Now, a new study that examines decades of disaster data has concluded that climate change isn't to blame for the increase in damages. At least, not yet.

Instead, the author Laurens Bouwer, a Dutch researcher at the Institute for Environmental Studies, concludes that population and economic growth are to blame. His article, which is due to be published in the journal Bulletin of American Meteorological Society, looked at 22 studies from around the world that measured the impacts of natural disasters over a 30-year period.

Global wealth has increased dramatically in the last half-century. People are earning more money, and thus spending more on their homes and their cars. As a result, when a natural disaster strikes, the potential for damage is greater than in the past. 

Additionally, increases in populations are driving people to occupy areas vulnerable to natural disasters. For example, crowding in Bangladesh has spurred expansion into flood plain regions. 

Together these two factors explain the spike in losses produced by natural disasters, Bouwer reported.

Climate change would only be responsible if the natural disasters studied produced more damage than what one would expect for a growing society. In the seven studies that corrected for changes (increases) in population and capital at risk, no trends could be attributed to anthropogenic climate change.

An additional seven studies that accounted for only one or neither of the recommended corrections also showed no trends in increased losses. This leaves eight studies that did show an increase, indicating perhaps climate change did play a part in those increases. Not all these studies correctly accounted for loss increases either, however, so it is difficult to discern climate change's exact influence, according to Dot Earth, where the study was first written up.

Bouwer is adamant about not ruling out climate change as a culprit in future natural disasters (and perhaps even many of the disasters for this year). To prevent further ambiguity, future studies need to consistently account for influential factors, from climate change to population growth, and do this in a standardized way. 

Image: National Institute for Occupational Safety and Health (NIOSH), Flickr