From a Central American cave comes research that has a dire warning for the northeastern US: global warming may be sending more hurricanes your way.
New research shows a long-term northward shift of hurricanes in the Atlantic Ocean. By studying the history of rainfall originating from a stalagmite in a cave in Belize, scientists concluded that storms that once would have made landfall in Central America, the Gulf Coast or Florida are turning north, a trend that puts on the trail major cities in the northeastern US. catastrophic storms.
Superstorm Sandy in 2012 and Hurricane Irene in 2011 are examples of the types of damage that are in store for the region more often as rising greenhouse gas levels affect the primary air currents that drive tropical storms. A team of climate scientists reported this conclusion recently in the journal Scientific Reports.
“It is important to try to protect vulnerable areas and economic centers in the Northeast from the effects of similar storms that could occur more often in the future,” said lead author Lisa Baldini, a U.S. climate researcher at the Durham University in England.
The chemical signature of rainfall derived from the stalagmite helped show that the change was mainly caused by human-made greenhouse gas emissions since the late 19th century. If the build-up of heat-trapping pollution continues, it could lead to more frequent and stronger storms for the region, he said.
Given the potential for catastrophic damage, projecting how global warming will affect hurricanes has been a big goal of climate researchers. This study adds important information, said climate scientist Yang Hu, of Alfred Wegener Institute for Polar and Marine Research in Germany, who was not involved in the study.
“I think the main conclusion is consistent with our research showing that the climate system is expanding poleward,” said Yu, who has studied how changes in basic ocean currents affect storm tracks off the coasts of Africa, Asia and North America. . He said the new findings also support the Intergovernmental Panel on Climate Change's latest global assessment, which suggests tropical storm tracks will shift northward.
How many storms will form and whether they maintain their strength near the Northeast coast is a different question, he said, because one of his recent studies suggests that cooling of the North Atlantic from melting Arctic ice could reduce the frequency of storms. storms in this area.
Kevin Trenberth, head of the Climate Analysis Department at the National Center for Atmospheric Research, said the researchers may have underestimated the effect of the El Niño-La Niña cycle, which can shift tropical storm activity. He said the research is inconclusive when it comes to storm tracks.
“There are no strong expectations for changes in the tracks, and the observational studies are very mixed in conclusion (as they should be) and depend on the data set and the period and parameters being analyzed,” he said via email.
According to Suzana Camargo, an ocean and climate physics researcher with Columbia University's Lamont-Doherty Earth Observatoryexists scientific consensus about the global trend of an increase in the number of more intense storms, but fewer storms overall. Other studies documented a strong poleward shift of tropical storm tracks in the western North Pacific and South Pacific.
The signal isn't as clear in the Atlantic, but Baldini and her co-researchers aimed to bolster those predictions by studying carbon and oxygen isotopes in the annual layers of the Belize stalagmite, which can tell a climate story like tree rings. Rainfall from hurricanes has a unique chemical signature. The rainfall record preserved in the stalagmite is extremely clear dating back 450 years.
“What we saw was a peak in tropical cyclone activity in Belize around 1650, then a gradual decline until today,” he said. “There are two possible explanations, either a decrease in numbers or storms moving away from our site.”
Other data showed no overall decline in the number of Atlantic hurricanes, and researchers found records of more hurricanes making landfall in places further north, such as Jamaica, Florida and Bermuda.
The study concluded that natural warming over the centuries had some effect on hurricane tracks, but a sharp decline in hurricane activity in the western Caribbean in the late 19th century coincided with an increase in carbon dioxide and sulfate aerosol emissions. in the atmosphere.
Co-author Dr Amy Frappier, of the Department of Geosciences at Skidmore Collegesaid the findings show how Atlantic hurricanes are responding to warming.
Based on what is known from global climate models, initial Northern Hemisphere cooling from heat-reflecting aerosol pollution, such as sulfur dioxide from coal burning, should have pushed the hurricane's tracks southward. But that effect was outweighed by rising CO2, which is expanding the world's tropical belts and pushing hurricanes further north, according to Frappier.
The northward shift of the hurricane's track does not mean the Caribbean will be spared.
The 2016 Atlantic hurricane season began with a very unusual mid-Atlantic January storm and ended last week with another unusual storm, Hurricane Otto. This was the southernmost storm on record to hit Central America.
Bob Berwin
Reporter, Austria
Bob Berwyn is an Austria-based reporter who has covered climate science and international climate policy for more than a decade. Previously, he reported on the environment, endangered species and public lands for several Colorado newspapers and also worked as an editor and assistant editor for community newspapers in the Colorado Rockies.
