Hurricane Science Becomes a Matter of Policy as NOAA Takes Sides

NOTE: The following is one of a series of case studies produced by the Union of Concerned Scientists' Scientific Integrity Program between 2004 and 2010 to document the abuses highlighted in our 2004 report, Scientific Integrity in Policy Making.


The extent to which greenhouse gas emissions from human activity contribute to an increase in hurricane number and intensity in recent years is a matter of active scientific debate. Yet in the fall of 2005, at the end of an extraordinarily strong hurricane season and after the tragedy of Hurricane Katrina, the National Oceanic and Atmospheric Association (NOAA) decided to act as though this debate did not exist and adopt an official position that the cause of Atlantic hurricanes had nothing to do with global warming. The connection between global warming and stronger hurricanes has been politically sensitive because the Bush administration has opposed proposals to restrict the release of greenhouse gases.

On November 29, 2005, NOAA's website featured a news article declaring "NOAA research shows that the tropical multi-decadal signal is causing the increased Atlantic hurricane activity since 1995, and is not related to greenhouse warming."¹ That same day, NOAA held a press conference where chief hurricane forecast scientist Gerry Bell denied that "greenhouse warming" had any effect on hurricanes.² James Hansen, a senior climatologist and director of NASA's Goddard Institute for Space Studies, criticized NOAA's position in a February 2006 speech. "The categorical contention that recent hurricane intensification is due to a natural cycle of Atlantic Ocean temperature…and has nothing to do with global warming is irrational. How could a hurricane distinguish between a natural and greenhouse gas warming?"³ 

The agency's position ignored several recent scientific studies, including some by NOAA scientists, that link global warming to the frequency and intensity of hurricanes. One study published a few months previously in the prestigious journal Science argued that it is "not inconsistent with recent climate model simulations that a doubling of CO2 [in the atmosphere] may increase the frequency of the most intense cyclones."4

Such a definitive statement from a federal science agency on an unsettled scientific issue released just two months after Hurricane Katrina struck many scientists as an inappropriate injection of political spin into what should be a scientific debate. There was also considerable evidence that NOAA was not allowing scientists with differing views on hurricanes and global warming to speak to the media.

Jerry Mahlman, former director of NOAA's Geophysical Fluid Dynamics Laboratory, was quoted as saying "I know a lot of people who would love to talk to you, but they don't dare. They are worried about getting fired."5 Donald Kennedy, editor-in-chief of Science and former president of Stanford University, also added, "There are a lot of scientists there who know it is nonsense, what they are putting up on their website, but they are being discouraged from talking to the press about it."6

Thomas Knutson was one NOAA hurricane expert whose access to the media was curtailed. Dr. Knutson's research differed from the official NOAA position and did indeed show a link between hurricane activity and global warming. Dr. Knutson was twice barred by NOAA public affairs officials from speaking to television reporters about the issue. In one case, media requests for Dr. Knutson were instead transferred to Dr. Chris Landsea, a NOAA climate expert whose views more closely matched the official position.7 

A year later, in September 2006, NOAA was again caught trying to make climate science fit an ideological position when a fact sheet suggesting global warming was contributing to the frequency and strength of hurricanes was blocked from release by officials at NOAA's parent agency, the Department of Commerce. The journal Nature quoted NOAA Administrator Conrad Lautenbacher as saying that the document "could not be released because the agency cannot take an official position on a field of science that is changing so rapidly."8


1. “NOAA attributes recent increase in hurricane activity to naturally occurring multi-decadal climate variability,” NOAA Magazine, November 29, 2005, accessed December 7, 2006.

2. Judis, John B. “NOAA’s Flood,” The New Republic, February 11, 2006, accessed December 7, 2006 (subscription required).

3. James E. Hansen, “Can We Still Avoid Dangerous Human-Made Climate Change?” Presentation on February 10, 2006 at New School University, New York City, derived substantially from an earlier

(6 December 2005) presentation to the American Geophysical Union, in San Francisco, California, accessed December 7, 2006.

4. Webster, P. J., G. J. Holland, J. A. Curry, H.-R. Chang. 2005. Changes in Tropical Cyclone Number, Duration, and Intensity in a Warming Environment. Science, 309:1844.

5. Judis.

6. Ibid.

7. Juliet Eilperin, “IGs Probe Allegations On Global Warming Data,” Washington Post, November 2, 2006, accessed December 7, 2006.

8. Giles, Jim. "Is US hurricane report being quashed?" Nature, September 26, 2006.

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