Katrina, Rita, Wilma – and more
The degree to which climate change may be intensifying tropical cyclones across the world is a topic of spirited scientific discussion, but there's no debating the impacts seen in recent years. Five hurricanes struck or sideswiped the United States in 2004, with four of those slapping woebegone Florida. Meanwhile, a record 10 typhoons raked Japan. Things got even worse in 2005, at least for North America. Based on measurements of their lowest pressure, the year brought three of the six most powerful Atlantic hurricanes ever observed: Wilma (the strongest), Rita (fourth strongest) and Katrina (sixth strongest). All three made devastating landfalls. Wilma slammed Canciin and south Florida, Rita pounded the Texas/Louisiana border, and Katrina swept through Miami before bringing mind-boggling misery and over 1300 deaths to the New Orleans area and the Mississippi coast. All told, there were 27 names assigned to Atlantic hurricanes and tropical storms in 2006 – so many that the National Hurricane Centre reverted to its backup naming list (the Greek alphabet) for the first time ever.
Other parts of the world haven't been spared. Japan endured an unprecedented string of ten landfalling typhoons in 2004 (the previous record was four). Australia was hammered in early 2006 by a trio of cyclones, each packing winds of over 250 kph (155 mph). It's the first time the region has seen three storms of that calibre in a single season. The central Pacific saw its strongest-ever cyclone, loke, in 2006. And Supertyphoon Saomai ripped into the east coast of China that same year – the most intense typhoon to strike the nation in more than half a century.
The damage and misery wrought by 2005's Hurricane Katrina topped anything produced by a single US storm for many decades. The storm's toll in property damage cost tens of billions of dollars, and that doesn't include the cost of restoring the New Orleans levee system to its previous condition – much less the billions more needed to make the system able to withstand a direct hit from a Category 5 hurricane. Some observers linked the Katrina debacle to climate change from the outset, while others denied any connection. Certainly a storm like Katrina doesn't require global warming in order to flex its muscle.Though they're quite rare, hurricanes on a par with Katrina have developed in the Atlantic since records began. However, the gradual warming of tropical waters over the last several decades has made it easier for storms like Katrina to intensify. As for Katrina's landfall in New Orleans, that was simply the luck (albeit the bad luck) of the meteorological draw. Several near-misses had grazed the city since 1965, when Hurricane Betsy produced flooding that killed dozens. Betsy prompted the US Corps of Engineers to build the city-girdling levee system that was in place when Katrina struck. That system was built to withstand only a Category 3 storm, a fateful move sure to be analyzed by critics for years to come – especially since Katrina itself had weakened to Category 3 strength by the time it made landfall.