Climate change is altering rainfall patterns around the world, which could also cause typhoons and other tropical storms to intensify, scientists said in a paper published Friday.
The year’s most powerful typhoon lashed Taiwan, the Philippines and then China this week, closing schools, businesses and financial markets as wind speeds rose to 227 kilometers per hour (141 miles per hour). On China’s east coast, hundreds of thousands of people were evacuated ahead of landfall on Thursday.
Scientists say more powerful tropical storms are part of a broader phenomenon of weather extremes driven by higher temperatures.
Researchers led by Zhang Wenxia at the Chinese Academy of Sciences studied historical meteorological data and found that about 75% of the world’s land area has seen an increase in “precipitation variability,” or wide fluctuations between wet and dry seasons.
In a paper published in the journal Science, researchers said that rising temperatures have increased the atmosphere’s ability to hold moisture, leading to wide fluctuations in rainfall.
“(Variability) has increased in most places, including Australia, which means there will be more wet periods and more dry periods,” said Steven Sherwood, a scientist at the University of New South Wales’ Climate Change Research Centre, who was not involved in the study.
“This will increase as global temperatures rise, increasing the likelihood of droughts and/or floods.”
Fewer, but more intense, storms
Scientists believe climate change is also altering the behaviour of tropical storms, including typhoons, reducing their frequency but making them more powerful.
“I believe high water vapor in the atmosphere is the ultimate cause of all the trends leading to extreme hydrological events,” Sherwood told Reuters.
Typhoon Gaemi, which made first landfall in Taiwan on Wednesday, was the most powerful storm to hit the island in eight years.
While it is hard to blame climate change for individual weather events, models predict that typhoons become more powerful as a result of global warming, said researcher Sachi Kanada of Nagoya University in Japan.
“In general, warm sea surface temperatures are favorable conditions for tropical cyclone development,” he said.
In its “blue paper” on climate change published this month, China said the number of typhoons in the northwest Pacific and South China Sea has declined significantly since the 1990s, but they are becoming more powerful.
Taiwan also said in its climate change report published in May that climate change is likely to decrease the overall number of typhoons in the region, while each typhoon will become more intense.
Feng Xiangbo, a tropical cyclone research scientist at the University of Reading, said the decrease in the number of storms was due to the uneven pattern of ocean warming, with temperatures rising faster in the western Pacific than in the east.
They said that every 1 degree Celsius increase in temperature was expected to increase the capacity of water vapor to be held in the lower atmosphere by 7%, and that rainfall from tropical cyclones in the United States was expected to increase by 40% for every one degree increase.
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