I have a letter in Science this week reacting to an article by Evan Mills in the 12 August 2005 issue of Science, which I comprehensively critiqued here. My letter is accompanied by a lengthy response from Mills. You can find both my letter and the response here in PDF.

I wrote the letter is in response to claims made by Mills (2005) about the role of climate change in the increasing losses related do disasters. Mills stated in the August paper that “climate change has played a role in the rising costs of natural disasters,” and on the “relative weights of anthropogenic climate change and increased exposure” in the loss trend Mills concludes “quantification is premature.” My letter concludes, “Presently, there is simply no scientific basis for claims that the escalating cost of disasters is the result of anything other than increasing societal vulnerability.” Mills response does nothing to question this statement about the current state of the science.

Mills’ lengthy and rambling response to my letter essentially confirms this assertion by discussing many things, but avoids engaging the points that I raised in my letter. Here are a few reactions.

1. First, Science for some reason did not include my page proof changes to the letter. This is not a terribly big deal. But I did update the letter to reflect some more recent literature on hurricanes, and a citation that was “in press” but is now published. I’ve emailed to see where things broke down. You’d think they wouldn’t at Science.


2. Mills writes, “The disaster attribution literature upon which such assertions are based is fraught with data and measurement uncertainties and is decidedly incomplete, especially concerning events outside the United States (1).” To support this claim, he once again cites a paper that has no relevance to the point being made, referencing a study that does not discuss trends in disasters or their attribution (here). Mills seems unaware of actual work that seeks to quantify measurement uncertainties in disaster loss data, like this paper: Downton, M. and R. A. Pielke, Jr., 2005. How Accurate are Disaster Loss Data? The Case of U.S. Flood Damage, Natural Hazards, Vol. 35, No. 2, pp. 211-228. (PDF). He doesn’t seem to realize that if the data are really as bad as he suggests they are, that this doesn’t support his claim to be able to identify a greenhouse gas signal in the loss record.

3. Mills goes on an on about issues that are far removed from his original claims about natural disasters or my reaction to those claims. He discusses “noncatastrophic processes such as small storms, lightning, soil subsidence, permafrost melt, the effects of mold and airborne aeroallergens on human health, coral reef decline, coastal erosion, or crop diseases.” He also mentions “energy prices” and “changes in temperature and precipitation extremes, continental drying, and a range of associated impacts on physical and biological systems.” He also discusses “atmospheric and ocean circulation and elevated ocean heat content, as well as sea-level rise and associated coastal erosion.” Wow, neat stuff. But what do these things have to do with natural disasters or the clear focus of my letter? Nothing.

4. Mills raises some questions, “Why are losses from weather-related events rising faster than those from nonweather events? What are the offsetting effects of human efforts to curb losses (building codes, early warning systems, f ire protection, flood defenses, land-use planning, crop irrigation, etc.)? How do we explain rising economic losses (e.g., those to crops in the heartland or physical infrastructure built on melting permafrost) that are only weakly linked to oft-cited demographic factors such as populations clustering around coastlines? Lastly, why would rising numbers of events not translate into rising costs?” My reaction to this laundry list of uncertainties is to wonder how it can be that in the face of such unanswered questions Mills can so confidently conclude that greenhouse gases are responsible for some part of the historical trend in economic losses from disasters.

5. Mills mischaracterizes one of my papers when he cites a paper of ours to support the following, “Assuming that only socioeconomic factors-rather than rising emissions-influence losses may yield ill-founded policy recommendations that focus exclusively on adapting to climate change while dismissing energy policy as a legitimate part of the toolkit for responding (11).” Here is what our paper (PDF) actually said about energy policy, “Recognizing that climate impacts are best address through adaptation rather than prevention need not undercut he goals of increased energy efficiency and reduced greenhouse emissions.” Dismissing energy policy? Hardly.

I could go on (but I won’t!). Mills concludes with a line that I might have written, “Rather than “proof ” by vigorous assertion, the constructive approach is to better understand the compounding roles of increasing vulnerability and climate change, and take affordable precautionary steps to reduce greenhouse gas emissions and adapt to the changes rather than waiting for unaffordable consequences.” Given that Mills cites essentially none of the relevant literature and once again engages in unfounded assertions, misdirected citations and far-reaching distractions, I am confident that for the thoughtful reader this exchange will go a long way toward clarifying where the state of science lies on this issue.