In his column yesterday, New York Times columnist Nicholas D. Kristof jumps on the bandwagon suggesting that greenhouse gas policies can be used as a tool to modulate future hurricane behavior. We’ve covered this subject in some detail here, but there are two points worth making on this column.

First, Kristof goes out of his way to avoid the obvious issue of societal vulnerability. He quoted Kerry Emanuel as follows: “My results suggest that future warming may lead to … a substantial increase in hurricane-related losses in the 21st century.” Kristof’s ellipses significantly change the meaning of Emanuel’s statement. Here is the full quote from Emanuel’s paper (PDF), including the information replaced by Kristof with ellipses, “My results suggest that future warming may lead to an upward trend in tropical cyclone destructive potential, and-taking into account an increasing coastal population- a substantial increase in hurricane-related losses in the twenty- first century.” This is playing a bit fast and loose with Emanuel’s statement, given that Emanuel says elsewhere, “For U.S.-centric concerns over the next 30-50 years, by far the most important hurricane problem we face is demographic and political.” Of course, as we’ve documented here, for at least the next half century and probably longer, societal vulnerability to hurricanes dominates any projected greenhouse gas effects, so in an essay advocating greenhouse gases as a tool of disaster management, it is obvious why Kristof would want to pretend that this issue doesn’t exist.


Second, Kristof relies on the opinions of scientists rather than what you find in the peer-reviewed scientific literature. Now, the scientists that he cites are surely very intelligent people, and the peer reviewed literature has its own flaws, and of course Kristof is a columnist not an IPCC contributor. But it seems to me that we have the peer-reviewed literature for a reason, and that in general it is likely a more reliable guide to what we know than predictions of smart scientists as to what future research will reveal. Kristof relies on the opinions of smart people whose views are convenient to his argument, and ignores the opinions of smart people whose views are inconvenient. This is called cherry picking. One way to adjudicate among different opinions of scientists is to consult the peer-reviewed scientific literature (this is of course what the IPCC does), and when there are different perspectives in the peer-reviewed literature, then that is a reality of science.

Over the last few weeks it has become apparent to me that the controversy over hurricanes and global warming exists because different scientists have different views as to what future research will reveal, and they have been outspoken in advancing these opinions. Bill Gray, for example, expects future research to reveal no discernible connection between hurricanes and global warming. By contrast, Kevin Trenberth believes that a connection will be found. Future research will help to clarify this dispute. But if one takes a look at the peer-reviewed science available today (and later this week), there is in fact a clear consensus on this subject.

In his column Kristof cites the useful, but non-peer-reviewed Real Climate weblog and Emanuel speculating that, “The large upswing [in the PDI] in the last decade is unprecedented, and probably reflects the effect of global warming.” This last statement is what scientists call a hypothesis. It may in fact be correct. Bill Gray may also be proven correct. To address such divergent views is one reason why we do research in the first place. We could save a lot of money in research funding if we substituted scientific opinions for research. But lets be very clear — as of today, as we documented in our BAMS paper, research has not been conducted that would allow for a definitive conclusion on these different opinions on hurricanes and global warming. And unless there are some surprises in the publication pipeline, it does not look like there will be any peer-reviewed scientific studies available by the end of 2005, and thus available to the next IPCC, that clarify the issue of attribution of greenhouse gas effects on hurricanes.

Scientists would do themselves and decision makers a favor by clearly identifying knowledge that can be supported by the peer-reviewed literature and that which is based on opinions by scientists as to what future research will reveal. Our forthcoming BAMS paper on hurricanes and global warming should be interpreted as an assessment of what statements can be made based on the peer-reviewed literature available today. Some scientists of course want to make stronger statements, on one side or the other, and they of course have every right to, but they should be careful to qualify such statements as hypotheses or statements of expectation and not of findings. Otherwise, if scientists’ opinions are as good a basis of knowledge as peer-reviewed studies, then what is the point of the peer-reviewed literature at all?