New warnings of a global warming-driven increase in the most deadly and destructive tropical storms are especially scary in regions already hit hard, including the Southeastern U.S., where Hurricane Michael damaged 60,000 homes in 2018, and the Caribbean, where Hurricane Maria killed nearly 3,000 people in Puerto Rico and crippled the island’s infrastructure.
There’s more of the same ahead, recent federal research suggests. One study found that the chances of major tropical storms forming increased globally by 6 percent in each of the last four decades. A second shows the biggest increase in frequency in already storm-battered areas, including Florida, the Bahamas, eastern Africa, Japan, China and the Philippine Islands.
The results bolster “projections of increased (tropical cyclone) intensity under continued warming,” the authors of the first study wrote. Those researchers focused on storms with winds greater than 115 mph (category 3 or above), because those cause the most damage.
The findings landed as residents are warily watching Tropical Storm Arthur spin toward the Carolina coast well ahead of the official start of the hurricane season, and with projections for above-average hurricane activity in the Atlantic this summer.
In the Bay of Bengal, Tropical Cyclone Amphan is projected to drive a deadly surge of flooding toward Bangladesh this week, with winds of more than 170 mph. Emergency responders are struggling to evacuate up to a million people, and provide them with emergency shelter during the global coronavirus pandemic, which requires evacuees maintain physical distancing to prevent the spread of the disease.
New tropical storm data from 2010 to 2017 showed that “the probability of a hurricane having wind speeds of at least 100 knots increased by approximately 15 percent between the early and latter halves of the 39-year record.”
Overheated oceans caused by global warming are super-charging tropical storms, but year-to-year variations are also affected by short-term climate cycles like El Niño. The new study helps sort out the different influences, making it “95 percent certain” that oceans heated by global warming are brewing up bigger storms more often, according to National Oceanic and Atmospheric Administration (NOAA) hurricane scientist Jim Kossin, who led the study.
“This shows us there is a global trend of more stronger hurricanes,” Kossin said. “It’s consistent with our expectations, based on physics.” Warmer oceans supply more energy for storms and the warmer atmosphere holds more moisture. Several recent studies show how those combine to cause more damage worldwide, and pin down the role of global warming.
Increasingly, such projections help city planners and coastal developers consider if they should abandon some areas, build seawalls or floodgates, or discourage development on the most vulnerable beaches and bluffs in the next few decades.
Tropical storm frequency has increased in the warm waters of the Atlantic hurricane belt, where dangerous storms often spin toward the Southeastern U.S. and the Caribbean, while decreasing in the southern Indian Ocean and Western North Pacific, according to the second study.
Hiroyuki Murakami, a climate scientist with the NOAA’s Geophysical Fluid Dynamics Laboratory, led that research, which was published May 4 in PNAS. Murakami said the average annual number of tropical storms globally had held steady at 86 since 1980. The frequency increased in hotspots like the Arabian Peninsula and East Africa, Southeast Asia, around the Hawaiian Islands and especially in the eastern Atlantic.Insideclimate News