On the September 25 broadcast of ABC's This Week, George Will asserted in a panel discussion that no scientific evidence supports a correlation between global warming and recent intense hurricane activity, stating that such claims are as baseless as blaming the hurricanes on the “prescription drug entitlement.” As host George Stephanopoulos and guest David Gergen attempted to point out, Will's comments on hurricane frequency ignored the heart of the current scientific debate that postulates a link between hurricane intensity -- not frequency -- and warming trends.

Will's attempt to downplay any relationship between warming and hurricane activity relied on a chart documenting the frequency of hurricanes striking the mainland United States. National Weather Service data show that the number of hurricanes striking the United States has not increased in recent decades but rather has fluctuated from decade to decade.

The main question for scientists in investigating links between global warming and hurricanes, however, has not been “How often?” but instead “How intense?” By presenting data on hurricane frequency relative to the mainland United States, Will showed only that hurricanes originating in the Atlantic Ocean are not occurring any more frequently than in past decades. Although this observation is accurate, it does not address the fact that hurricanes are becoming increasingly powerful, a trend identified in research on hurricanes worldwide.

A recent study by the Georgia Institute of Technology and the National Center for Atmospheric Research, which appears in the September 16 issue of Science magazine, revealed that "[t]he number of Category 4 and 5 hurricanes worldwide has nearly doubled over the past 35 years" and that "[t]he shift occurred as global sea surface temperatures have increased over the same period." Kerry Emanuel of the Massachusetts Institute of Technology has conducted similar research, suggesting in the August issue of Nature magazine that current and future global warming may well increase the destructiveness of hurricanes. According to Emanuel, “The energy released by the average hurricane (again considering all hurricanes worldwide) seems to have increased by around 70% in the past 30 years or so, corresponding to about a 15% increase in the maximum wind speed and a 60% increase in storm lifetime.”

Further, Emanuel stated: "[E]verywhere we have looked, the change in hurricane energy consumption follows very closely the change in tropical sea surface temperature. When the sea surface temperature falls, the energy consumption falls, and conversely, when it rises, so too does the energy consumption." He continued: "[R]ecords strongly suggest that the 0.5 degree centigrade (1 degree Fahrenheit) warming of the tropical oceans we have seen in the past 50 years is unprecedented for perhaps as long as a few thousand years. Scientists who work on these records therefore believe that the recent increase is anthropogenic." Will's research therefore omits the kinds of changes in hurricane activity that may indeed be linked to global climate change.

From a panel discussion that included Stephanopoulos, Will, Gergen, and political strategist Donna Brazile on the September 25 broadcast of ABC's of This Week:

STEPHANOPOULOS: But it comes, and I wanted to pick up on something that [National Hurricane Center director] Max Mayfield said there. It looks like this is just the beginning of what could be a long stretch of hurricanes. And the big debate is we know that the oceans are warming, we know that we're in for this era of hurricanes, but the big debate, George Will, is how much of that is caused by global warming? I think I know what you think about this, and I think you've got some backup from Max Mayfield.

WILL: I do. We have a graphic here that will really underscore what he told you, which is, “This is just a normal cycle.” If you could put the graphic up of U.S. hurricane strikes by decades. The bar graphs are the white bars show the total number of hurricanes per decade. The red graph shows the severe category 3, 4, and 5 ones, and what they show is it was particularly bad in the 1910s, 1930s, and 1940s -- before someone had decided that global warming was the cause of this.

STEPHANOPOULOS: Yes, but if you look at -- we're only halfway through the decade barely, we've had six very intense hurricanes this decade, and we do know, David Gergen, that the ocean is warming and a lot of scientists have looked at this -- Science magazine, Nature magazine -- and say we don't know for sure, but global warming could be playing a part in this.

GERGEN: We certainly know that ocean temperatures have increased in temperature by about a degree in the last 30 years. We know that in the Gulf [of Mexico] it's about five degrees above normal. We know that warmer waters produce more severe hurricanes, and we know that in the last 30 years or so we've had an increase of 80 percent in the intensity of hurricanes. In other words, we've had 80 percent more Category 4 and Category 5 hurricanes in the last 30 years. Now, that is not conclusive proof of global warming causing hurricanes. George is absolutely right about that -- there is a natural cycle here. The question, though, it does seem to be under these circumstances this is a wake-up call to take global warming and climate change more seriously and to investigate this more seriously not to sigh and to treat dismissively.

STEPHANOPOULOS: Donna's nodding, and George is sighing.

WILL: I have an alternative theory. I think these two hurricanes were caused by the prescription drug entitlement. You will say, “How can you say that? The entitlement hasn't even started.” There's no conclusive evidence that global warming, that is to say, an unprecedented, irreversible, and radical change has started. You will say, “There's no scientific proof.” Same answer. You will say, “Aren't you embarrassed, Mr. Will, to be attaching your political agenda to a national disaster?” Yeah, I'm embarrassed, but everyone else is doing it.