Harvey, Irma, Maria: This is the hurricane season scientists expected … and feared

By Eric Holthaus
20 September 2017
(Grist) – After multiple intense hurricane landfalls this month, the scenes from the Caribbean have been horrific — trees stripped bare, houses flattened, million-dollar yachts strewn like toys.
Category 5 hurricanes, like Irma and Maria, are the pinnacle of nature’s fury. There is simply no weather event on Earth that can cause so much destruction so quickly. They are worst-case scenarios.On Wednesday morning, Maria became one of the most intense Atlantic hurricanes ever recorded to make landfall, striking southeastern Puerto Rico with winds of up to 155 mph. Puerto Rican residents rationed basic supplies and hunkered down in fragile infrastructure in anticipation of the storm, which wiped out 100 percent of the island’s power. Recovery could take years.“We have not experienced an event of this magnitude in our modern history,” Puerto Rico Governor Ricardo Rosselló said in an island-wide address Tuesday night.There is evidence that we are emerging from an era of messy meteorological data, where we were blind to warming seas strengthening hurricanes because the really damaging ones were rare. If that’s true, weather historians may look to this year as the beginning of a frightening new phase of superstorms.About 85 percent of all damage done by hurricanes is attributable to “major” storms — those stronger than Category 3, so roughly one-quarter of all storms. While relatively infrequent, they are by far the most destructive — a Category-5 cyclone has 500 times the power of a Category 1. Globally, major hurricanes have become slightly more common in recent decades, even as overall numbers have held steady.Further, there’s nothing in recorded history that resembles what Irma and Maria have inflicted on Caribbean islands in recent days. Since Sept. 6, the two hurricanes have made six separate landfalls at Category-5 strength. Before this month, just 18 such landfalls had happened in the previous 165 years (and never more than three in a single year). Clearly there’s something happening here — and there’s a developing consensus among scientists about what factors are responsible. [more]