Are Tropical Storms Becoming More Destructive? Will They?
Lin & Chan, 2015, a study published in Nature Communications, finds that the destructive potential of tropical cyclones (“typhoons”) in the most active and hazardous tropical cyclone basin on Earth, the Western North Pacific Main Development Region, decreased by 35% over the past decade.
Lin and Chan use a metric called the Power Dissipation Index (PDI) to measure the destructive potential of Asia-Pacific typhoons. The PDI is a product of three factors: storm frequency, duration, and intensity. In the past decade, typhoon intensity increased due to increases in ocean heat content. However, typhoon frequency and duration decreased due to stronger vertical wind shear and lower vorticity in the storm genesis region. The declines in frequency and duration overpowered the increase in intensity, producing a net decrease in PDI of approximately 35%.
Based on climate modeling studies, Lin and Chan project that global warming will induce an additional 15% decrease in the Asia-Pacific PDI. In their words, “Although both the intensity and duration increased under global warming, there was an even larger typhoon frequency reduction of 25.7%. As a result, the typhoon PDI decreased by 15.2%.”