New study on Pacific windstorms reveals regional patterns but no rising trend of typhoon landfalls

03 July 2007, Asia Pacific

New scientific findings on typhoons in the North West Pacific have been released today by a leading Hong Kong university. The study identified regional cycles of typhoon landfall and associated climate conditions, which will make the determination of typhoon activity for each Asian region far more accurate.

The study traced these cycles, which are alternating periods of higher or lower incidence of typhoons making landfall along the Asian coast, over the past 60 years. Although the cycles are shown to be influenced by climate patterns, there is no evidence of increased typhoon landfall activity due to global warming.

The study and the research team were led by Professor Johnny Chan, Chair of Applied Physics (Atmospheric Science) of the City University of Hong Kong and Director of the Shanghai Typhoon Institute. The study, which was funded by Swiss Re, is the first one to analyse various historical climate records against typhoons making landfall in three distinct regions (Southern, Middle and Northern coastline) in Asia.

The early 1960s and early 1990s saw notable typhoon landfalling activity 'upswings' happening more or less concurrently in the South, Middle and North Asian regions. In recent years, though, there is less concurrence in landfalling activity, with the Northern (Japan, South Korea) and Middle (coast from Taiwan to Shanghai) regions experiencing near average activity while the Southern region (South China coast, Philippines, Vietnam) has seen fewer typhoon landfalls compared to the long-term average.

Prof. Chan believes it is likely that typhoon landfalling activity will generally pick up again over the coming five to 10 years. He stressed that findings indicate a cyclical pattern, not a continuous increase of activity. 'We can now not only measure the lengths of the cycles,' Prof. Chan said, 'we have also found that the cycles operate differently in different parts of Asia, which means we have made a substantial step forward in pinning down which countries or areas are more likely to be hit by typhoons in any given period.'

The pattern of these cycles seems to be governed to a considerable extent by variations in large scale climate phenomena, such as the El Niño/La Niña oscillation. Hence, changes in typhoon activity fluctuate with the periodicities of climate patterns, which typically range between five and 20 years. More research will be needed to better understand how climate will influence typhoons in the future and what effect typhoon activity will have on climate patterns.

Implications for insurers

Peter Zimmerli, a member of Swiss Re's Asian natural perils team, said these new findings will be of great value to insurers covering Asia's typhoon-prone and highly populated areas. He pointed to the North Atlantic where Hurricane Katrina has triggered a heated debate about the potential links between global warming and hurricane activity.

'This ongoing debate is of particular interest to the insurance industry because if cyclone landfalling activity patterns really are changing, this is going to have significant implications for insurers' pricing and management of tropical cyclone risks,' he said. However, insurers in Asia have, until now, had far less information about typhoon activity in their region than their counterparts in America and the Caribbean.

Prof. Chan's study separately analysed all typhoon-intensity cyclones (i.e. with wind speeds over 33 metres per second) versus tropical storms that did not reach typhoon strength. When comparing the two, he found a similar historic typhoon landfalling activity pattern. 'We see the same cyclical pattern emerging, so here we are not seeing any evidence that global warming has made typhoons more severe or caused more severe typhoons to be hitting the coast, ' Prof. Chan concluded.
Mr. Zimmerli said this means good news for Asia's insurers: 'For the time being, there is no need to adjust tropical cyclone risk assessment that is based on long-term historical activity. Having said that, we need to stay alert and monitor developments closely in the years to come.'

Mr. Zimmerli added: 'It has to be borne in mind that even in years with lower cyclone activity, devastating storms can develop. So even if climate patterns that steer typhoon activity become more predictable in the future, I do not foresee reinsurers jumping in and out of markets.'

Swiss Re, which is Asia's leading reinsurer of natural catastrophe risk, is a regular sponsor of original research designed to foster knowledge for the benefit of the industry. In 2005, the company also sponsored a study on the predictability of Tokyo earthquakes, the results of which have already had significant impact on how insurers are assessing these risks.
A full report from the City University of Hong Kong study will be available later in 2007.

Notes to editors

Swiss Re is the world's leading and most diversified global reinsurer. The company operates through offices in more than 25 countries. Founded in Zurich, Switzerland, in 1863, Swiss Re offers financial services products that enable risk-taking essential to enterprise and progress. The company's traditional reinsurance products and related services for property and casualty, as well as the life and health business are complemented by insurance-based corporate finance solutions and supplementary services for comprehensive risk management. Swiss Re is rated "AA-" by Standard, Poor's, "Aa2" by Moody's and "A+" by A.M. Best.

Swiss Re has been associated with Asia since 1913 and now has more than 900 staff in Asia Pacific. The company has been present in China since 1995, and opened its branch in Beijing in 2003 to offer the full range of reinsurance products and services. Swiss Re's Asian headquarters are in Hong Kong.
In 2006, Swiss Re celebrated 50 years since opening its first offices in Asia Pacific.