Politics & Policy

Global Warming Saps Hurricane Strength

Reduce emissions, save the 'canes!

In June, as the 2007 hurricane season began, the predictions were dire. There were to be 16 named storms. Nine hurricanes. Five “intense hurricanes.” A 74 percent-chance of a storm hitting the U.S. coastline — all above the historical average. And numerous news stories cited Global Warming as the culprit for what was about to happen.

Hurricane season just ended over the weekend. The results? There have been six hurricanes (the historic average), two of them “intense hurricanes” (below average). Not one hit the United States (below average). Floridian business owners are so upset over the inaccurate forecasts that they are considering a lawsuit. Not only has “hurricane hype” cut back on their tourism industry, it has also sent their insurance rates skyrocketing.

Although there were 14 named storms this year, there is some doubt over whether six of them should ever have been named. This discrepancy in naming storms isn’t just a random complaint, it actually shows up in the more objective statistics.

The most wildly incorrect predictions of the season were the number of “Named Storm Days” (NSDs) and “Hurricane Days” (HDs). Forecasters expected 85 NSDs and got just 33.5. They predicted 40 hurricane days and instead got just 11.25. In each case, the observed number is far lower than the historical average between 1950 and 2000 — 49.1 NSDs and 24.5 HDs. This indicates that many of the storms were extremely short-lived or relatively weak.

And sure enough, this year’s Accumulated Cyclone Energy (ACE) — the measure of the square of the wind-strength of all the year’s storms over the time they lasted — was just 68, far below the historic average of 96.2 or the prediction of 170.

So this year’s storm season was an incredible bust. We had fewer serious storms, less wind strength, and more “borderline” storms that just barely and briefly flirted with “named status” before dissipating. The previous year’s hurricane season was a little better — just ten storms, five hurricanes, and an ACE of 78.5. Many of the numbers are falling so far below the historical average, one might conclude that something is radically different from the past.

Normally, when we reach that point, we ask a big, important question like this one: Is global warming sapping the world’s supply of Accumulated Cyclone Energy?

We know the possible consequences of tinkering with our environment, causing unprecedented changes. This is how we approach the subject of man-made global warming. Wherever there is change, we turn immediately to global warming to explain it. Heat and cold, drought and downpour, famine and plenty — all can be caused by global warming. It can cause more foliage and less foliage; a slower-spinning earth and a faster one; more snow and less snow; a sun-scarred desert world, or a new ice age. Climate change makes mountains grow and it makes mountains shrink.

It is not impossible that all (or at least most) of these theories are simultaneously true. But they also have the advantage of making global warming an unfalsifiable theory. Not only can no possible event disprove it, but it can actually serve as an explanation for any natural event worthy of note.

Back to the weak hurricane season, then. According to a new study, this year’s drop in Accumulated Cyclone Energy may be caused by global warming. Higher temperatures cause more evaporation. Water conducts heat more efficiently than air, and so higher levels of atmospheric moisture cause a relative evening out of global air temperatures by region. This results in fewer and weaker cyclones, because wind is the result of variations in air temperature.

Am I making this last bit up? Hard to tell, isn’t it?

But yes, I am. And if some scientist comes along and debunks my shameless, ad hoc abuse of basic scientific concepts, then at least we will have discovered one weather event — perhaps the first in thirty years — that global warming definitely did not cause.

 – David Freddoso is an NRO staff reporter.

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