23 August 2010

Disaster Losses and Climate Change

[UPDATE: The NYT's Andy Revkin covers the new article here.]

The Bulletin of the American Meteorological Society has just put online a review paper (peer reviewed) by Laurens Bouwer, of the Institute for Environmental Studies at  Vrije Universiteit in Amsterdam, titled, "Have disaster losses increased due to anthropogenic climate change?".  

Readers of this blog already know the answer to this question, and here is Bouwers' conclusion:
The analysis of twenty-two disaster loss studies shows that economic losses from various weather related natural hazards, such as storms, tropical cyclones, floods, and small-scale weather events such as wildfires and hailstorms, have increased around the globe. The studies show no trends in losses, corrected for changes (increases) in population and capital at risk, that could be attributed to anthropogenic climate change. Therefore it can be concluded that anthropogenic climate change so far has not had a significant impact on losses from natural disasters.
Bouwers rightly acknowledges that there are uncertainties in such studies, and in particular, there will be a need to refine efforts to evaluate changing vulnerability and exposure in future such work, especially as the signal of greenhouse gas driven climate change is expected to become larger.  However, such uncertainties are not presently so large as to undercut Bouwers' conclusion, e.g.,
A rigorous check on the potential introduction of bias from a failure to consider vulnerability reduction in normalization methods is to compare trends in geophysical variables with those in the normalized data. Normalized hurricane losses for instance match with variability in hurricane landfalls (Pielke et al. 2008). If vulnerability reduction would have resulted in a bias, it would show itself as a divergence between the geophysical and normalized loss data. In this case, the effects of vulnerability reduction apparently are not so large as to introduce a bias.
A pre-publication version of the paper is available here in PDF.

Bouwer, L.M. (in press). Have disaster losses increased due to anthropogenic climate change? Bulletin of the American Meteorological Society, doi:10.1175/2010BAMS3092.1.