Economic losses from US hurricanes consistent with an influence from climate change

Warming of the climate system and its impacts on biophysical and human systems have been widely documented. The frequency and intensity of extreme weather events have also changed, but the observed increases in natural disaster losses are often thought to result solely from societal change, such as increases in exposure and vulnerability. Here we analyse the economic losses from tropical cyclones in the United States, using a regression-based approach instead of a standard normalization procedure to changes in exposure and vulnerability, to minimize the chance of introducing a spurious trend. Unlike previous studies, we use statistical models to estimate the contributions of socioeconomic factors to the observed trend in losses and we account for non-normal and nonlinear characteristics of loss data. We identify an upward trend in economic losses between 1900 and 2005 that cannot be explained by commonly used socioeconomic variables. Based on records of geophysical data, we identify an upward trend in both the number and intensity of hurricanes in the North Atlantic basin as well as in the number of loss-generating tropical cyclone records in the United States that is consistent with the smoothed global average rise in surface air temperature. We estimate that, in 2005, US$2 to US$14 billion of the recorded annual losses could be attributable to climate change, 2 to 12% of that year’s normalized losses. We suggest that damages from tropical cyclones cannot be dismissed when evaluating the current and future costs of climate change and the expected benefits of mitigation and adaptation strategies.