Harvey and Irma were both powerful Category 4 hurricanes that wrought devastation after hitting the U.S. coast, but they weren’t unprecedented, ranking seventh and 18th in terms of landfall air pressure.
An analysis by Colorado State University meteorologist Philip Klotzbach found that Hurricane Irma made landfall in Florida at 929 mb, or millibars, tying it for the seventh most powerful storm to hit the mainland since recordkeeping began in the 1850s.
Hurricane Harvey, which hit Texas on Aug. 25, ranked 18th at 938 mb, placing it in a three-way tie with an 1898 Georgia hurricane and Hurricane Hazel in 1954.
His chart comes with the two recent hurricanes fueling the debate over whether climate change driven by human greenhouse-gas emissions has resulted in more extreme weather events.
Among those pushing the climate-change narrative was billionaire Richard Branson, owner of Virgin Airlines, who rode out Irma on his private island in the British Virgin Islands.
Photos posted Sunday showed buildings and vegetation on his property suffered extensive damage.
“Man-made climate change is contributing to increasingly strong hurricanes causing unprecedented damage,” Mr. Branson said in a Friday statement. “The whole world should be scrambling to get on top of the climate change issue before it is too late for this generation, let alone the generations to come.”
Anthony Watts, who runs the skeptics’ website Watts Up With That, said the air-pressure graphic should prompt global-warming activists to take a deep breath.
“With Irma ranked 7th, and Harvey ranked 18th, it’s going to be tough for climate alarmists to try connecting these two storms to being driven by CO2/global warming,” Mr. Watts said in a post. “But they’ll do it anyway.”
The two storms come as the first major hurricanes to hit the U.S. coast in 12 years.
Hurricane Irma was downgraded to a tropical storm Monday as it moved north toward Georgia after slamming the Florida Keys on Sunday with winds measured at 115 kt, or knots.
The record for the strongest landfall winds was set by the 1935 Labor Day hurricane at 160 kt, followed by Hurricane Camille in 1969 at 150 kt, according to the Klotzbach chart.