Climate Change and the 2005 and 2006 Hurricane Seasons

Global warming contributed to 2005's brutal hurricanes

Posted: 20-Jun-2007; Updated: 08-Jul-2007

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Rita was one of three 2005 storms to rank among the top six fiercest hurricanes on record. (Photo: Courtesy NOAA)

Hurricane Katrina is this generation’s Hurricane Camille. But the big difference between the memorable storms in 2005 and 1969 is that Camille was an unusually strong storm. Katrina is a sign of what's ahead: fiercer hurricanes.

The 2005 hurricane season was the worst ever. The final tally included:

• the most named storms (27),
• the most hurricanes (15),
• the most intense hurricane ever recorded (Wilma, a Category 5 that ravaged Mexico's Yucatan Peninsula), and
• an estimated $100 billion in damages from all hurricanes that hit the U.S. including Katrina.

Did global warming play a role in 2005’s raucous season? Recent research strongly indicates that the answer is "Yes."

Extraordinarily warm ocean waters fueled the 2005 hurricanes

New evidence published in Geophysical Research Letters in June 2006 shows that global warming was responsible for about half of 2005’s unusual warmth in the Atlantic.

The paper's lead scientists, Kevin Trenberth and Dennis Shea (of the National Center for Atmospheric Research), concluded that climate change has enhanced the threat of severe storms. Specifically, "the global warming influence provides a new background level that increases the risk of future enhanced [hurricane] activity." (See Trenberth and Shea.)

Warm ocean waters are a hurricane's engine. In fact, for a hurricane to occur, ocean temperatures must be at least 80 degrees Fahrenheit. This is why the U.S. hurricane season runs from June through November, when ocean waters in the North Atlantic are warmest. (See more about the scientific link between hurricanes and climate change.) A torrent of recent research has clarified the link between global warming and stronger hurricanes. (See more about recent studies.)

If storms are getting worse, why was 2006 so quiet?

Does the wonderfully quiet 2006 Atlantic hurricane season mean global warming is not happening? Unfortunately, no.

Global warming refers to long-term increases in global temperatures. Year-to-year and day-to-day temperatures will still vary, even if the overall trend is up. The same holds true for trends that are influenced by global warming, such as hurricane intensity.

And we are talking about a global trend, not a regional one. Although no 2006 hurricanes made landfall in the U.S., other parts of the world, like Southeast Asia, were slammed with fierce storms. We in this country thankfully had a quiet year; many others did not.

Global warming is heating up the oceans. Because warm waters fuel hurricanes, our warmer climate means storms like Katrina are more likely.