Blog ››› ››› KEVIN KALHOEFER
The Washington Post’s weather editor Jason Samenow debunked the claim by climate science deniers and conservative media outlets that the lack of category 3 or higher hurricanes striking the U.S. over the last 11 years is "evidence that global warming is not affecting the storms."
This month marks 11 years since the U.S. mainland was last struck by a “major” hurricane, defined by the National Hurricane Center as a category 3, 4 or 5 storm with sustained wind speeds of at least 111 miles per hour. In response, conservative media have misleadingly cited this fact to wrongly dispute the link between hurricanes and global warming.
For instance, The New American asserted, “The latest report from NOAA that major hurricane activity has subsided for 11 years — despite high levels of CO2 in the atmosphere — provides welcome relief from the assorted predictions made by the ‘global warming’ doomsayers of catastrophic events that supposedly will be caused by human activity.” Similarly, The Daily Caller’s Michael Bastasch wrote that “the hurricane drought sort of runs counter to predictions global warming will make storms more frequent and more intense.” And perhaps most notably, radio host Rush Limbaugh falsely claimed that the lack of a major hurricane making landfall in the U.S. over the past 11 years “bores a hole right through the whole climate change argument.”
But as Samenow explained, researchers believe it is just "dumb luck" that Atlantic storms with sufficient wind speeds to be defined as "major" hurricanes have remained offshore or slowed down before making landfall on the U.S. coastline. Atlantic hurricane activity also accounts for only a small portion of the total storms occurring around the world, as PolitiFact noted when it rated Limbaugh's claim a "Pants on Fire" falsehood.
Samenow, who described the hurricane “drought” as “the most overblown statistic in meteorology,” also pointed out that many hurricanes that had devastating impacts due to extreme rainfall and flooding occurred during this "drought." He noted that because the definition of a “major” hurricane is tied only to wind speeds and not impacts from water, the term “omits some of the most consequential storms in modern history”:
But the criteria for what makes a major hurricane is impossibly restrictive. It is tied to a single hazard, wind, and ignores impacts from water, which causes the lion’s share of fatalities and damage in most hurricanes.
While big wind speeds grab people’s attention and sound scary, precious few people, if any, ever experience a storm’s peak winds. Such high winds are typically confined to a tiny area near the hurricane’s eye.
But tens of thousands of people are exposed to a hurricane’s water, whether it’s freshwater flooding from heavy rainfall or coastal flooding from storm surge, the rise in ocean water as the hurricane comes ashore.
Because the definition of a major hurricane ignores the effects of water, it omits some of the most consequential storms in modern history, which have occurred during the so-called drought.
Consider, in the 11 years since Wilma, two of the three most costly storms in U.S. history occurred: Sandy in 2012, and Hurricane Ike in 2008 — neither of which was classified as “major.”
Moreover, the "impacts from water" that Samenow describes are intensified by climate change. Scientists say that a warming climate is making storms more destructive due to warming air and oceans -- which lead to more rainfall -- and rising sea levels, which worsen storm surges.
Samenow ultimately concluded: “The major-hurricane-landfall drought is an interesting statistic, and that’s about it. It is a fine metric to track and report as a curiosity, but it cannot be used to say anything useful about how hurricanes are affecting society or how their behavior may or may not be changing over time.”