Landfalling Typhoons Have Become More Intense Over Last 40 Years

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In the Northwest Pacific, already a hotspot for tropical cyclones, the storms that strike East and Southeast Asia have been intensifying more than those that stay out at sea over the last four decades, a new study finds.

The proportion of landfalling storms that reach Category 4 or 5 strength — the storms that wreak the most damage, as recent examples like 2013’s devastating Super Typhoon Haiyan show — has doubled and even tripled in some areas of the basin, researchers found. The increases seem to be the result of faster intensification linked to warmer ocean waters in coastal areas.

Super Typhoon Haiyan as it headed toward landfall in the Philippines, where it caused enormous destruction in November 2013. (NASA)

The findings, detailed Monday in the journal Nature Geoscience, are in line with the broader increase in the most intense tropical cyclones expected with rising global temperatures, though these trends have not yet specifically been linked to human-caused climate change.

‘Little Doubt’ Typhoons Intensifying

The Northwest Pacific normally sees the most tropical cyclone activity of any ocean basin because of the deep well of ocean heat available to fuel typhoons, as such storms are called there.

The new work is an outgrowth of a previous study by the same researchers that found that typhoon intensity had increasedbasin-wide since the late 1970s and suggested that another 14 percent increase in intensity could be expected by the end of the century, as the ocean takes up most of the excess heat trapped by greenhouse gasses.

Wei Mei, a tropical cyclone and climate researcher at the University of North Carolina at Chapel Hill, said that he and his colleagues were curious if typhoons in some parts of the basin were intensifying more than others. To investigate this, they grouped the typhoons into clusters based on where they formed and the paths they followed.

They found that the clusters that had the most landfalling hurricanes showed much clearer increases in intensity than those where most storms stayed out at sea. The cluster with the biggest trend had a 15 percent increase in intensity and, as part of that trend, saw the number of Category 4 and 5 storms increase from about one per year in the late 1970s to more than four per year recently.