Atlantic hurricanes rapidly churning into intense storms over warming water, study finds


CBC
Sat, October 21, 2023 


The list of destructive post-tropical storms and hurricanes which have tracked through Atlantic Canada over the past few decades is an increasingly lengthy list.

From Juan in 2003, Igor in 2010, Dorian in 2019 and Fiona in 2022, plus the many other damaging storms that have moved through, this region is certainly in a period of high tropical-storm activity.

In the cases of Igor, Dorian and Fiona, these are storms that "rapidly intensified" from Category 1 hurricanes into major Category 3 or 4 hurricanes as they tracked through the Atlantic Ocean.

This rapid intensification of hurricanes and how it relates to climate change and our warming oceans has been a topic of much discussion over the past few years. Now, new research shows that swift acceleration in the power of storms is indeed on the rise in the Atlantic Ocean.

The study published this week in the journal Scientific Reports shows that tropical storms or Category 1 hurricanes are now more than twice as likely to rapidly intensify to major hurricanes within a 24-hour period.



The study's author, Andra Garner, a climate scientist at Rowan University in New Jersey, looked at 830 tropical cyclones in the Atlantic Ocean dating back to 1971.

Garner found that from 2001 to 2020, there was an eight per cent chance of storms strengthening from a Category 1 to a Category 3 or higher within just 24 hours.

By comparison, from 1971 to 1990 there was only a three per cent chance storms would rapidly strengthen within that time frame.

This rapid intensification is most problematic when the storms are near land. Even a few days from landfall, however, it can make forecasting more difficult for meteorologists and make planning more challenging for emergency management officials.

Garner's study also found that hurricanes are now more likely to strengthen rapidly off the east coast of the U.S., the Caribbean Sea and tropical eastern Atlantic, compared to the historical 1971-1990 timeframe.


A chart of monthly sea surface temperatures (SST) in the North Atlantic. Normal temperatures are indicated by the 0 line. Red lines mark above-average temperatures. (University of Maine)

The study notes that warm sea surface temperatures are "a vital energy source for intensifying tropical cyclones."

This suggests that human-caused warming is already leading to storms that strengthen much faster than earlier, it conclude