Hurricane Flossie near Big Island in August 2007. (Photo courtesy of NASA)

A study headed by a team of scientists at the International Pacific Research Center at the University of Hawaiʻi at Mānoa, shows that Hawaiʻi could see a two- or three-fold increase in tropical cyclones by the last quarter of this century. The study appeared in the May 5, 2013, online issue of Nature Climate Change.

To determine whether tropical cyclones will become more frequent in Hawaiʻi with climate change, lead author Hiroyuki Murakami and climate expert Professor Bin Wang joined forces with Akio Kitoh at the Meteorological Research Institute and the University of Tsukuba in Japan. The scientists compared in a state-of-the-art, high-resolution global climate model the recent history of tropical cyclones in the North Pacific with a future (2075–2099) scenario, under which greenhouse gas emissions continue to rise, resulting in temperatures about 2°C higher than today.

“In our study, we looked at all tropical cyclones, which range in intensity from tropical storms to full-blown category 5 hurricanes. From 1979 to 2003, both observational records and our model document that only every four years on average did a tropical cyclone come near Hawaiʻi. Our projections for the end of this century show a two-to-three-fold increase for this region,” explained Murakami.

Surprisingly, even though fewer tropical cyclones will form in the eastern Pacific in Murakami’s future scenario, we can expect more of them to make their way to Hawaiʻi.

“Our finding that more tropical cyclones will approach Hawaiʻi as Earth continues to warm is fairly robust because we ran our experiments with different model versions and under varying conditions. The yearly number we project, however, still remains very low,” reassured Wang.

—Adapted from a UH Mānoa news release