Scientists: Climate Change May Offer Hurricane Help

Could warmer air help push hurricanes into the Atlantic Ocean?

A NASA computer model of Hurricane Sandy. A new study says climate change could make such storms less likely along the Atlantic Coast.

Many scientists have blamed global warming for more intense recent hurricane seasons and for the more destructive storms that are predicted in years to come, but a new study says climate change could eventually help safeguard the U.S. Atlantic coast from hurricanes.

Climate change might alter atmospheric conditions so that future hurricanes may be pushed away from the East Coast, according to a study published Monday by the Proceedings of the National Academy of Science.

The warming caused by greenhouse gases—thought to be the result of human activities such as burning fossil fuels—could redirect atmospheric winds that steer hurricanes.

By the next century, the study's authors report, atmospheric winds over the Atlantic could blow more directly from west to east during hurricane season, pushing storms away from the United States.

The study was conducted by meteorologists Elizabeth Barnes at Colorado State University; Lorenzo M. Polvani of Lamont-Doherty Earth Observatory in Palisades, New York; and Adam H. Sobelband at Columbia University.

The authors used computer simulations to arrive at their theory about climate change and influences on hurricanes' tracks.

Deterring Another Sandy?

The changes they predict could make it less likely that a future hurricane would follow a path similar to the one that Hurricane Sandy took last fall, when it devastated much of the northeastern U.S. coast, particularly New Jersey and New York.

Sandy's unusual track was caused by a rare interaction between atmospheric winds known as the jet stream and a high-pressure weather system known as a "blocking system" to the north of the hurricane. The interaction steered Sandy on a track that took it almost due west as it made landfall in New Jersey last October 29.

The study's authors noted that Sandy's track was the most perpendicular to the Atlantic coast of any storm on record. But the east-blowing winds that the study's authors say could result from climate change could push future such storms toward the Atlantic Ocean.

The authors also suggested that the change in atmospheric winds would reduce the likelihood that a high-pressure blocking system similar to the one that affected Sandy's path would form. That would further increase the likelihood that future Atlantic hurricanes would be steered away from the U.S.

A Longer Hurricane Season

Some meteorologists, however, disagreed with the study's findings.

Jennifer Francis, a meteorologist at Rutgers University, said the study "makes a useful contribution" to the understanding of how climate warming may be affecting weather patterns. But she said that though the computer models used in the study are the best available, their accuracy is uncertain.

"In my view, the analysis and results from this and other recent studies do not support the strong statements made by the authors," she said.

Meteorologist Jeff Masters, director of the private weather forecasting website Weather Underground, said there are indications that hurricane seasons are lasting longer in recent decades. Hurricanes are most likely to occur between June 1 and November 30, but warmer sea water could extend the season, he said.

"A longer season gives the opportunity for more strong hurricanes to penetrate to the Northeast U.S. in late fall," Masters said. "This would potentially offset any decrease in Sandy-like impacts due to fewer blocking highs forming in a future climate."

CSU's Barnes, the lead author of the study, acknowledged that the possible lengthening of the hurricane season is a factor in the tracks of future storms and that the computer programs used in the study are "imperfect."

"We comment on that in this paper," she said. "The point one should take from our paper is just that these are the best climate models we have, and they do not support the notion that the kind of steering flow that occurred in Sandy will become more frequent in a warming climate."

Kerry Emanuel, a professor of meteorology at Massachusetts Institute of Technology who edited the PNAS paper, said that "changing steering patterns are only a part of the whole problem of how and whether hurricane risk may change in a particular place."

"One must also account for changing locations and times of storm formation, and changing storm frequency and intensity," Emanuel said. "These can very much change the landscape of hurricane risk, so one should be careful in drawing overall conclusions about such risk from just one piece of this problem."