Despite the lack so far of any hurricanes hitting America this hurricane season (at time of writing), environmental activists are using the memories of last year’s intense season to argue for tough policies on global warming. For example, on August 20, in an emotional Washington Post op-ed, Mike Tidwell of the self-styled “U.S. Climate Emergency Council” asserted that, “Barring a rapid change in our nation’s relationship to fossil fuels, every American within shouting distance of an ocean…will become de facto New Orleanians.”
Tidwell’s is an extreme example, but other activists like Environmental Defense are playing the same game, calling for “meaningful legislation to cap our greenhouse gas emissions.” In doing so, they use fear to overstate the science, and they advance policy goals that will do little to protect vulnerable populations. In doing so, they represent an immoral exploitation of the victims of Katrina.
Hurricanes draw their energy from the sea, and require warm sea surface temperatures (SSTs) to form. Some hurricanes may get stronger, and the area of hurricane formation may expand, as the oceans warm. However, once SSTs reach about 83°F, as routinely happens in the Gulf of Mexico every summer, any hurricane has the potential to become a major — Category 3, 4, or 5 — storm, if other conditions are present. Such conditions include high humidity (dry air dissipates the hurricane’s thunderstorm core) and low wind shear (strong winds in the upper troposphere rip hurricanes apart). Whether, or to what extent, global warming is actually increasing the strength or frequency — or both — of hurricanes is an empirical question.
Alarmists assert that there is a “scientific consensus” that global warming has been linked to an increase in the duration and intensity of hurricanes (Al Gore says as much in his movie An Inconvenient Truth). But the scientific jury is still out on these matters. The alarmists’ Exhibit A is a study by Kerry Emanuel of MIT, which found that hurricane strength, a combination of wind speed and storm duration, which he calls the “power dissipation index” (PDI), increased by 50 percent since the mid-1970s, and that the increase is highly correlated with rising SSTs. However, other experts question these results.
The University of Colorado’s Roger Pielke Jr. finds that once hurricane damage is normalized for changes in population, wealth, and inflation, there is no long-term change in hurricane damage — which runs counter to the hypothesis that hurricanes are becoming more destructive. Christopher Landsea of the National Oceanic and Atmospheric Administration (NOAA), noting no trend in the PDI for land-falling U.S. hurricanes, suggests that Emanuel’s finding may be an “artifact of the data” — a consequence of advances in satellite technology, which have improved detection, monitoring, and analysis of non-land-falling hurricanes.
Philip Klotzbach of Colorado State University found “a large increasing trend in tropical cyclone intensity and longevity for the North Atlantic basin and a considerable decreasing trend for the North Pacific,” but essentially no trend in other tropical cyclone-producing ocean basins. Klotzbach also found a slight downward trend during 1990-2005, even though tropical sea surface temperatures increased by approximately 0.2°C to 0.3°C during this period.
University of Virginia climatologist Patrick Michaels found that, in the Atlantic basin, the hurricane formation area with the best data over the longest period, the “trend” observed by the Webster team disappears once data going back to 1940 are included. The number and percentage of intense storms from 1940 to 1970 were about equal to the number and percentage of intense storms from 1970 to 2004.
In refusing to recognize this very real scientific disagreement, alarmists are using scare tactics and overstatements of the science to promote specific policies, specifically mandated reduction in fossil fuel use. The Kyoto Protocol, which the United States has rejected, is the flagship for such policies. However, since Kyoto would avert an immeasurably small amount of global warming by 2050 (0.07°C), Kyoto-style approaches can provide no protection from hurricanes in the policy-relevant future. It is disingenuous for activists to claim that a hurricane-warming link justifies changes in U.S. energy policy. Indeed, hyping such a link can be counterproductive — if people seek protection from hurricanes via climate change policy, they are apt to neglect the practical preparedness measures that can actually save lives.
The scientific community recognizes this. Ten hurricane scientists, including Kerry Emanuel and Peter Webster, recently issued a “Statement on the U.S. Hurricane Problem” in which they urge policy makers not to let the debate about the “possible influence” of global warming on hurricane activity “detract from the main hurricane problem facing the United States: the ever-growing concentration of population and wealth in vulnerable coastal regions.” Contributing to that problem, they argue, are federal and state insurance and disaster-relief programs that “subsidize” development in high-risk areas.
Although optimistic that “continued research will eventually resolve much of the current controversy over the effect of climate change on hurricanes,” the hurricane experts emphasize that, “the more urgent problem of our lemming-like march to the sea requires immediate and sustained attention.” Consequently, they “call upon leaders of government and industry to undertake a comprehensive evaluation of building practices, and insurance, land use, and disaster relief policies that currently serve to promote an ever-increasing vulnerability to hurricanes.”
United States hurricane policy must not be dictated by global-warming concerns. Diverting resources that would otherwise be spent on protecting vulnerable communities into climate-change policies would unnecessarily increase those communities’ hurricane vulnerability. In preparing for hurricanes, global-warming policies constitute both a red herring and a white elephant.
– Marlo Lewis and Iain Murray are senior fellows at the Competitive Enterprise Institute. A more detailed version of this analysis can be found at http://www.cei.org/.