Julian Ryall, National Geographic News 25 Sep 09;
Increasingly powerful "supertyphoons" will strike Japan if global warming continues to affect weather patterns in the western Pacific Ocean, scientists say.
Supercomputer simulations show there will be more typhoons with winds of 179 miles (288 kilometers) per hour—considered an F3 on the five-level Fujita Scale—by 2074.
By definition, supertyphoons carry winds of at least 150 miles (241 kilometers) per hour.
Such storms would be more destructive than Hurricane Katrina, which slammed into U.S. states along the Gulf of Mexico in August 2005.
"The most important factor in the creation of these typhoons is the warming of sea-surface temperatures in the western Pacific," said researcher Kazuhisa Tsuboki of Nagoya University.
Small but Severe
If global warming continues at its present pace, by 2080 the western Pacific Ocean will be 3.6 degrees Fahrenheit (2 degrees Celsius) warmer, according to Tsuboki, who worked with a team from Japan's Meteorological Research Institute.
"That sounds like a small difference, but it will have a very big impact on a typhoon," Tsuboki said.
That's because even a relatively minor increase in seawater temperature adds an exponentially larger amount of energy to a storm, he said.
A rise in air temperature will also increase the amount of water vapor in the lower atmosphere, adding yet more fuel to the system.
Typhoons generally cover an area of between 311 and 497 miles (500 and 800 kilometers), Tsuboki said.
But to the researchers' surprise, the predicted supertyphoons will be smaller, stretching only 249 miles (400 kilometers).
However the storms will pack a far higher concentration of energy, wind speed, and overall destructive power.
Widespread Damage
The tempests would cause a great deal of damage across Japan, which is unprepared for such violent weather systems, Tsuboki said.
Ferocious winds would level homes and damage infrastructure such as bridges and power lines. Severe floods would also inundate low-lying areas.
The most destructive typhoon to strike Japan to date was Typhoon Vera, which barreled across the country in September 1959.
Known in Japan as the Isewan Typhoon, the storm came ashore in Ise Bay near Nagoya and killed 5,238 people.
