Hurricanes have gradually moved northwards from the western Caribbean towards northern North America over the past few hundred years, the study led by Durham University, UK, found.
The researchers suggest that this change in hurricane track was caused by the expansion of atmospheric circulation belts driven by increasing carbon dioxide emissions.
New York and other major cities along the Northeast coast of the U.S. could come under increased threat from these severe storms and need to be better prepared for their potential impact, the researchers said.
The findings are published in the journal Scientific Reports.
Researchers reconstructed hurricane rainfall for the western Caribbean dating back 450 years by analyzing the chemical composition of a stalagmite collected from a cave in southern Belize, Central America.
They found that the average number of hurricanes at the Belize site decreased over time. “At first, that sounded like good news,” said co-author Amy Frappier, Associate Professor and Chair of Skidmore College’s Geosciences Department.
“But, after we compared the hurricane history in Belize with other hurricane records from places such as Bermuda and Florida, we found that Atlantic hurricanes have been moving to the north rather than decreasing in total numbers.”
Although natural warming over the centuries has had some impact on shifting hurricane tracks, the researchers found a marked decrease in hurricane activity in the western Caribbean coinciding with the late 19th Century industrial boom associated with increasing carbon dioxide and sulphate aerosol emissions to the atmosphere.
The researchers said that regional cooling of the Northern Hemisphere due to increased industrial aerosol emissions should have pushed the hurricane tracks southward since Industrialization.
Co-author Amy Frappier, of Skidmore College’s Geosciences Department said “Aerosols from volcanoes and industrialization in the Northern Hemisphere have a cooling effect, which tends to shift moisture belts and hurricane tracks southward, closer to the equator.”
“On the other hand, warming from more carbon dioxide in the air tends to expand the Earth’s tropical belt, - pushing hurricane tracks further north, away from the western Caribbean and towards the Northeastern U.S. We found that the tracks of Atlantic hurricanes have responded more to warming than to regional cooling.”This suggests that from the late 19th Century manmade emissions have become the main driver behind shifting hurricane tracks by altering the position of global weather systems, the researchers said.
If future trends in carbon dioxide and industrial aerosol emissions continue to follow business-as-usual, hurricanes could shift even further northward, exacerbating the risk to the Northeast coast of the USA, they added.
In 2012, Hurricane Sandy struck the Caribbean and much of the eastern seaboard of the United States, stretching as far north as Canada. At least 233 people died as a result of the storm.
A large number of U.S. states were affected by Hurricane Sandy with New York and New Jersey suffering the greatest impacts. The estimated cost of the damage caused by Hurricane Sandy in the USA is said to have run into tens of billions of dollars. “Other notable recent Northeast hurricanes include Irene, Kyle, Floyd, Bob, and Gloria,” said Frappier.
The study’s lead author Dr. Lisa Baldini, in the Department of Geography, Durham University, said, “Our research shows that the hurricane risk to the Northeastern coast of the United States is increasing as hurricanes track further north.“Since the 19th Century this shift was largely driven by man-made emissions and if emissions continue as expected this will result in more frequent and powerful storms affecting the financial and population centers of the Northeastern United States.“Given the devastation caused by Hurricane Sandy it is important that plans are put in place to protect against the effects of similarly destructive storms which could potentially occur more often in the future.”
The researchers added that the northward shift in hurricane tracks may not reduce the risk of tropical cyclones in the Caribbean.
Co-author Dr. James Baldini, in Durham University’s Department of Earth Sciences, said, “Although hurricane tracks have gradually moved northwards away from the western Caribbean, rising sea surface temperatures could promote the development of cyclonic storms within the western Caribbean.
“Consequently tropical cyclone activity across the western Caribbean may remain essentially stable over the current century. However, increased sea surface temperatures also provide extra energy, potentially fueling larger storms. We therefore need to prepare for the effects of more frequent landfalls of larger storms along the Northeast coast of the United States and stronger storms impacting the Caribbean.”
The research was funded by the European Research Council; the National Science Foundation; the Alphawood Foundation; the Schweizer National Fund, Sinergia; and the Inter-American Institute for Global Change Research.
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