The startling new reality we have created by combusting coal, natural gas and releasing other harmful substances was on full display in the tragic aftermath of Hurricane Dorian, which slowly terrorized the Caribbean, the U.S. East Coast and Canada in late August and early September.
The statistics related to the storm were scientifically staggering for several reasons. Dorian became the fifth hurricane to reach Category 5 status over the past four North Atlantic hurricane seasons, a rate unheard of historically for such storms. The other four — Irma, Maria, Matthew and Michael — brought extensive damage to Puerto Rico and other Caribbean Islands, as well as the U.S. Gulf and East Coasts. Dorian also broke the record for the strongest storm so far north in the Atlantic east of Florida. This is part of a trend: large storms are moving further north, while also remaining more powerful than they have historically in these latitudes, largely due to warmer waters. Over the past half century, the ocean has absorbed more than 90 percent of the excess warming humans have generated from the burning of fossil fuels.
Dorian remarkably underwent two rapid intensifications, which occur when a storm’s wind speed increases by more than 35 miles per hour in less than 24 hours. Scientists have found that this rapid intensification of storms has become increasingly prevalent in recent Atlantic hurricane seasons and that this trend could be linked to climate change.
At times, Dorian moved slower than most people could walk along its devastating Category 5 path over the Bahamas. This nightmare for residents and visitors lasted for more than two days over parts of the island nation, likely breaking the record for most powerful prolonged exposure in Atlantic history (previously held by Hurricane Mitch, which hit Honduras in 1998). Recent science points to an increased likelihood of North Atlantic hurricanes stalling when they near our coasts.
The combination of warmer air and stalling storms has also led to record-breaking rainfall in cases like Hurricane Harvey, which made landfall in Texas in 2017. NASA calculated rainfall amounts of more than 36 inches from Dorian over the Bahamas, and 16 to 24 inches over many areas off the U.S. East Coast. The combination of rising seas and powerful winds and rain as hurricanes linger over a region leads to storm surges that reach higher and further inland. A storm surge of 18 to 23 feet inundated Grand Bahama International Airport and submerged the majority of Grand Bahama Island. Devastation and the difficult road to recovery will likely continue long after the water levels recede, possibly for years.
Can we call Hurricane Dorian a 100 percent “natural” disaster? Science says, most likely not.
Climate change is making Atlantic hurricanes more intense than they have been historically. While people in coastal communities often express sentiments to the effect of “we’ve been through this before and know what to do,” the reality is these storms are already more dangerous compared to those they’ve experienced in the past.
The intensification of these storms fueled by climate change leaves people and property at greater risk. Such record-breaking storms are also proving to be increasingly costly with 2017 hurricanes Harvey, Maria and Irma having a combined nominal cost approaching $300 billion, with incalculable loss in terms of lives. We must prepare for these increasingly dangerous storms. For example, better understanding how and when rapid intensification occurs could help forecasters give more lead time for coastal regions confronting hurricane-force winds and associated risks to prepare.
We also need our leaders to take urgent action to address climate change, enacting policies that go the furthest in reducing emissions while also improving ways to keep communities safe.
Brenda Ekwurzel is a senior climate scientist and the director of climate science for the Climate & Energy Program at the Union of Concerned Scientists, as well as a co-author of the fourth National Climate Assessment Volume II.