Study: Warming oceans intensified 2017 Atlantic hurricane season

WASHINGTON — Harvey, Irma, Maria. These three monster hurricanes, all of which struck U.S. shores at Category 4, likely attained such strength due to Atlantic ocean waters which were abnormally warm, says a new study published in the journal Science Thursday.

And, in future decades, as the ocean warms even more due to rising greenhouse gas concentrations from human activity, the study projects “even higher numbers of major hurricanes.”

Considering the toll of the 2017 hurricane season, which unleashed 10 hurricanes in 10 weeks, and three of the five costliest hurricanes on record in Harvey, Irma, and Maria, it is difficult to imagine the implications of similar circumstances repeating with even greater frequency.

The authors, led by Hiroyuki Murakami of NOAA’s Geophysical Fluid Dynamics Laboratory, conducted high-resolution modeling experiments to draw this ominous conclusion.

Active Atlantic hurricane seasons, like 2017, are often linked to the presence of La Ni?a events in the Pacific Ocean. They’re cyclical, coming around every few years, and are generally hospitable for hurricanes. El Ni?o events, their opposite, introduce hostile winds which tend to suppress hurricane development.

But, based on the results of their modeling experiments, study researchers ruled out La Ni?a was the main driver of the 2017 hurricane onslaught.

The warm Atlantic Ocean, instead, was the more important player.

“We show the increase in the 2017 major hurricanes was not primarily caused by La Ni?a conditions in the Pacific Ocean, but mainly by pronounced warm sea surface conditions in the tropical North Atlantic,” the study said.

Major hurricanes are those rated at least Category 3 on the Saffir-Simpson wind scale.