Climate Change and the Record Breaking 2020 Atlantic Storm Season

This year’s Atlantic hurricane season was the worst on record and it marks the fifth straight year with above-average storm activity. Each year there are an average of around 12 storms in the Atlantic, in 2020 there was a record breaking 31. This includes 13 hurricanes (twice the normal number) with six of them rated as Category 3 or higher (also twice the normal average). There is little doubt among climate scientists that warmer ocean temperatures are at least partly responsible for the growing number of intense storms. The storm season is starting earlier and generating more rapidly intensifying hurricanes. Attribution science is making it increasingly possible to directly link storms and hurricanes to climate change.

“We are seeing more rain, and more precipitation in general,” Richard B. Rood, a professor of meteorology at the University of Michigan’s College of Engineering, told Inside Climate News. “The other thing we have been seeing is individual events that are more extreme and more precipitation in general.” As a result of warming, the atmosphere is holding 7 percent more moisture than it did just five decades ago, Jennifer Francis of Woods Hole Oceanographic Institution told Yale Climate Connections. Heavy precipitation events, fueled by the extra moisture, have increased almost 40 percent across the upper Midwest in recent decades, according to the U.S. Global Change Research Program. Such heavy precipitation events are predicted to keep increasing.

Scientist Kevin Trenberth said the 2020 spike in hurricanes is not surprising. “In general, one expects more activity as the climate warms,” he said. “This can be manifested in multiple ways: more intense storms, bigger storms, longer-lasting storms, and more storms. Also in general there is increased risk of flooding.”

The rate of intensification observed by scientists following hurricane Laura corroborates the evidence connecting storms to climate change, more specifically warming oceans. Laura was the strongest storm to hit Louisiana in a century and a half.  The Category 4 hurricane registered wind speeds of 150 mph and caused 28 deaths and at least $12 billion in economic damage. Like hurricanes Eta and Iota which killed 270 people and caused more than $9 billion in damage, Laura intensified rapidly as it neared the coast increasing its destructive power once it made landfall.  Laura went from being a Category 1 to a Category 4 in less than 24 hours making it one of the fastest transformations on record in the Gulf of Mexico. The trend towards rapidly intensifying storms is supported by hurricane Maria (which increased wind speed by 80 mph in a 24 hour period) and other recent rapid storms (Harvey, Irma, Florence, Michael, and Dorian).

As reported by the Washington Post, the phenomenon of rapid intensification is happening more frequently in the Atlantic due to global warming. Like many of his peers, NOAA researcher Jim Kossin thinks warm ocean waters are contributing to the rapid intensification of storms. “Our confidence continues to grow that storms have become stronger, and it is linked to climate change and they will continue to get stronger as the world continues to warm,” Kossin said. MIT hurricane expert Kerry Emanuel has also warned that we can expect more rapid intensification as the planet warms.

A 2019 study in the journal Nature documented a trend toward more rapidly intensifying hurricanes in the Atlantic Ocean between 1982 and 2009, and according to their model global warming is likely the cause. A 2020 study by Kossin and his colleagues further corroborated this point by showing that storms are now more likely to be more intense because of climate change.

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