Hurricanes shifting south of North Atlantic: Study warns of growing risks for coastal regions

A new study led by Dr. Cao Xi, Associate Professor at the Institute of Atmospheric Physics, Chinese Academy of Sciences, has uncovered a significant southward shift in the formation of hurricanes over the North Atlantic Ocean. This shift, observed since 1979, is linked to changes in wind patterns and warming trends, raising concerns about increased disaster risks for low-latitude island nations and North American coastal areas. The research is published in the journal npj Climate and Atmospheric Science.

Tropical cyclones, including hurricanes, are among the most destructive natural disasters, causing severe economic losses and casualties due to their strong winds, heavy rainfall, and storm surges. As global temperatures rise, understanding how these storms form and evolve is critical for improving disaster preparedness and climate adaptation strategies. However, the impact of climate change on tropical cyclone activity remains uncertain, as highlighted in the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report.

The study focused on the North Atlantic region, where previous research had noted a slight southward shift in the location of maximum hurricane intensity. By analyzing data from 1979 onwards, the research team discovered a clear southward migration in the formation of hurricanes—tropical cyclones with maximum sustained winds of around 33 meters per second. This shift coincides with an increase in hurricane frequency in the southern part of the North Atlantic (between 10° and 20°N).

The study attributes this trend to a decrease in vertical wind shear, a key factor in hurricane formation, caused by a weakening north-south temperature gradient. This gradient has diminished due to faster warming in the subtropical troposphere, driven by increased atmospheric stability. Using 39 climate models from the CMIP6 project, the team confirmed that external forcing factors, such as greenhouse gas emissions, are the primary drivers of these changes, with natural variability playing a smaller role.

"Our findings suggest that the southward shift in hurricane formation is closely tied to changes in atmospheric conditions under global warming," said Cao, lead author of the study. "This shift could heighten the risk of hurricanes in low-latitude regions, posing greater threats to vulnerable island nations and coastal communities in North America."

The study underscores the need for enhanced monitoring and preparedness in regions likely to face increased hurricane activity. As global warming continues, understanding these trends will be crucial for mitigating the impacts of future storms.

The study is in collaboration with scientists from Zhejiang University, Shanghai Jiao Tong University, the University of New South Wales in Australia, National Climate Center of China, the Chinese Academy of Meteorological Sciences, Key Laboratory of South China Sea Meteorological Disaster Prevention and Mitigation of Hainan Province, Tongji Zhejiang College, and Chengdu Meteorological Bureau.