This hurricane season has been a destructive one for the United States, with five consecutive tropical cyclones making landfall so far, while a sixth storm -- Ike -- now threatens the Gulf Coast. If the recent past is any guide, adding such a remarkable string of tempests to the volatile atmosphere of an election year should result in a high profile debate on global climate change and severe storms.
This happened in the wake of the devastating hurricane seasons of 2004 and 2005, so why isn't it taking place now, when more scientific evidence has come in linking warming seas to stronger hurricanes?
Keep reading for more on the global warming and hurricane debate. For our local weather. see our full forecast.
Strangely, the political leaders and most of the environmental organizations that would ordinarily raise this issue have thus far largely held back. This has happened despite the fact that one of the storms, Hurricane Gustav, disrupted the Republican Party's convention, and despite the publication of a new study last week in the scientific journal Nature that showed that the strongest Atlantic hurricanes have become more powerful in the past 25 years.
It's neither good nor bad, in my view, that a debate on hurricanes and climate change question hasn't fully erupted, but it is intriguing because of what it may indicate about the climate change strategies of environmental groups and the presidential candidates.
First let's consider the new report that could provide political leaders and environmentalists enough justification to engage anew on this issue.
The study showed that, especially in the North Atlantic Ocean basin, the strongest hurricanes grew stronger in the past 25 years, which was consistent with warming ocean temperatures during that period. Past studies have attributed warming seas to increasing atmospheric concentrations of greenhouse gas emissions from human activities.
In order to avoid some of the shortcomings of previous work on the subject, authors James B. Elsner and Thomas H. Jagger of Florida State University and James P. Kossin of the University of Wisconsin relied upon satellite observations of tropical cyclone wind speeds. However, some scientists maintain that even with the new study's revised methods, tropical cyclone records remain too sparse and fraught with inaccuracies to permit the detection of a climate change signal.
Elsner, Kossin and Jagger found that winds in the strongest storms have gotten closer to each storm's "maximum potential intensity," which is the theoretical upper limit on an individual storm's strength given certain ocean and atmospheric conditions. "Our results are qualitatively consistent with the hypothesis that as the seas warm, the ocean has more energy to convert to tropical cyclone wind," the study stated.
Given this study and the occurrence of so many land-falling storms this season, it's surprising that many environmental groups and both of the presidential candidates have held back from discussing a possible link between hurricanes and climate change.
In fact, some green groups have drawn ire from the Left for being too reticent.
The energy smart blog revealed that as Hurricane Gustav headed for Louisiana, Fred Krupp, the president of Environmental Defense Fund, sent an email to other environmental leaders asking them to hold back on the global warming/hurricanes angle.
"Our first concern relates to the fact that any particular hurricane hitting Louisiana is not an example of how global warming is making everything worse," Krupp wrote. "There is recent research showing that warmer seas are increasing the average strength of hurricanes, and we should not shy away from saying that, but we must exercise extreme care in saying that Louisiana has been hit again because of global warming."
Krupp noted concerns that pushing too hard on warming could jeopardize other initiatives that Environmental Defense and others are pursuing in Louisiana, such as restoring that state's wetlands.
As Krupp well knows, environmental groups have been criticized in the past for hyping up climate change concerns by blaming extreme weather events on warming. So, as the leader of Environmental Defense, he may have been justified for being a bit, well, defensive. Furthermore, he was correct that warming may have had nothing to do with Hurricane Gustav's formation or ultimate landfall location.
Nonetheless, Krupp's email drew a harsh rebuke from Joe Romm of the progressive Center for American Progress. Romm said Krupp's message was "illustrative of the catastrophic messaging failure of the environmental community on issues of climate, government action, and energy." In addition, he accused environmentalists and progressive activists of retreating from attempts to link climate change to extreme weather of all kinds, and urged them to change course based on recent scientific studies.
In contrast to Romm's interpretation, perhaps the more accurate explanation is that most environmental groups and the two presidential candidates are focused more this year on engaging people in climate-related energy policy discussions than on global warming itself. Polls have shown that energy concerns are widespread, whereas climate change is not as much of a priority for most voters. The hurricanes/climate change issue could therefore be viewed as a distraction from what voters want leaders to address.
Also, if they use the recent hurricanes as an opportunity to discuss global warming, candidates and activists run the risk of being seen as trying to score political points off of storm victims.
But despite these reasons for holding back, with Hurricane Ike approaching and more than two months left in hurricane season, it's perhaps inevitable that another hurricanes and global warming debate will flare up this year. But who will start that conversation, and where it will lead, are unclear.