Super typhoons becoming more powerful and more frequent, new study finds

Since the late 1970s, typhoons making land in a region stretching from Vietnam and the Philippines to Korea and Japan have become 12 per cent to 15 per cent more intense.

Those hitting south-east Asia with a category 4 or 5 strength have more than doubled in number, with the increase even more for China and Taiwan and regions north, the paper published in Nature Geoscience on Tuesday found.

The increase in sea-surface temperature is key to providing extra energy to tropical storms, with the outcome for the megacities of the region looking grimmer.

For eastern Asia, the strongest storms are now as many as four or more a year compared with about one a year three decades ago, the researchers found.

"The intensification is strongest for typhoons that tend to make landfall because of the stronger warming of the coastal waters near east and south-east Asia," said Wei Mei, a researcher in the department of marine sciences at the University of South Carolina and co-author of the paper.

Additional warming is expected to intensify the storms, particularly in some of east Asia's main economic centres, Dr Mei said: "The typhoons striking mainland China, Taiwan, Japan, and Korea will intensify further because of the faster warming of waters of 20 degrees north."

The paper's release comes just days after China and the United States used the backdrop of the G20 leaders summit in east China's Hangzhou city to announce the world's two biggest carbon emitters would formally ratify the Paris climate agreement.

"Our response to climate change bears on the future of our people and the wellbeing of mankind," Xi Jinping, China's president, said.

This year is well on course to becoming the hottest year on record with preliminary data for August revealing yet another month with record-breaking warmth in a row.

The north-west Pacific basin has both the largest data set of super typhoon-strength storms and the clearest trend towards intensification as the planet warms, Steve Turton, an adjunct professor at the Central Queensland University, said.

This year has also been an active one for the region:

By contrast, the trends are not being replicated so far in the south-west Pacific, such as off north-eastern Australia.

"In the Australian region, it's pretty flat," Professor Turton said. "We are not seeing any trends at all."

That outcome, though, is expected to change.

"With global warming of the oceans and atmosphere, we can expect tropical cyclones to increase in frequency and intensity in all the basins," Professor Turton said.

Damage from winds rise rapidly - as much as to the power of 4 of any increase in speed, he said.

Apart from the social and economic consequences of more intense storms, ecosystems such as forests are likely to suffer more destruction and take longer to recover or favour species more able to cope with disruption.

For hilly regions, such as Hong Kong or elsewhere in the storm tracks, populated areas may become more exposed to landslides from the intensifying storms, Professor Turton said.

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