Study says warming may push more hurricanes toward US coasts

A recent study indicates that the warming of the planet is likely to result in an increased occurrence of more severe hurricanes heading towards the eastern and Gulf coasts of the United States, with a particular focus on Florida. While previous research has mainly focused on how human-driven climate change could influence the frequency, intensity, and moisture content of tropical storms, the current study, featured in the Science Advances journal, shifts attention to the crucial aspect of the hurricanes’ trajectories.

The lead author of the study, Karthik Balaguru, a climate scientist at the Pacific Northwest National Laboratory, emphasizes that the alterations in steering currents are the key factor. According to Balaguru, these currents are gradually shifting storms closer to the U.S. coasts. In the Gulf of Mexico, the steering currents generally move from south to north, while on the East Coast, the usual west-to-east pattern is diminishing, potentially leading to more east-to-west movement.

Taking into account advanced climate and hurricane simulations, including a specially developed system, the study projects that under the most pessimistic warming scenario, the number of U.S. coastal impacts by storms could rise by approximately one-third by the close of the century. Particularly, the central and southern regions of Florida’s Atlantic coastline are predicted to experience an even more notable increase in hurricane hits.

There is some debate among climate scientists regarding the utility of focusing on worst-case scenarios, given that many calculations suggest a slowdown in carbon emissions. Balaguru argues that since his research places greater emphasis on steering changes rather than storm intensity, the extent of warming is not as significant a factor.

The study attributes changes in air currents to warming in the equatorial eastern Pacific Ocean, near the coast of South America. Different regions of the world are warming at varying rates due to climate change, with models indicating faster warming in the eastern Pacific area.

The study also highlights the influence of atmospheric waves, similar to the jet stream or polar vortex events, that travel west to east and are linked to temperature or pressure variations. These wave patterns disturb the atmospheric equilibrium, creating a counterclockwise circulation in the Gulf of Mexico. Consequently, this circulation brings about east-to-west winds in the eastern Atlantic and north-to-south winds in the Gulf of Mexico, ultimately affecting wind shear—a phenomenon where the difference in wind speed and direction at different altitudes impacts hurricane development.

The reduction in wind shear implies that hurricanes could become stronger, a point Balaguru stresses. Overall, the shift in steering currents and wind shear changes raises the risk of hurricane impacts on the United States, according to University of Albany atmospheric scientist Kristen Corbosiero.

While the study is generally regarded as coherent by external scientists, there are noted limitations. The study does not consider the birthplaces of storms, which is a crucial factor, and it assumes a global trend toward more frequent El Niño events, which could dampen Atlantic hurricane activity. However, recent observations suggest a pattern more similar to La Niña events.

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• Study: Changes in air patterns as the world warms may push more hurricanes toward US coasts
• Science Advances Journal
• Pacific Northwest National Laboratory
• University at Albany – Atmospheric and Environmental Sciences
• National Center for Atmospheric Research
• Purdue University Climate Extreme Weather Lab
• AP’s Climate Initiative