Is climate change affecting hurricanes?
Hurricane Harvey placed Houston and much of Southeastern Texas under water. Irma ravaged the Florida Keys. Maria devastated Puerto Rico, and just this month, Dorian decimated the Abaco Islands in the Bahamas.
Recently, Tropical Storm Karen formed east of the Windward Islands. This gives the 2019 Atlantic Hurricane season its eleventh named storm, four of which have been hurricanes, two of those intense. The ACE (accumulated cyclone energy) for the season is currently an 80.
ACE represents the potential destruction and activity during a cyclone season. The average season has eight named storms, four hurricanes, two of them intense, with an ACE score of 72 by September 22.
Is climate change a factor in the series of harsh tropical weather facing the American and Caribbean people? Is it going to get worse? Several climatologists from around the country shared the facts on what, if anything, is happening.
It’s important to recognize the powerful impact behind tropical systems like hurricanes that appear every year. James Hurrell, a professor at Colorado State University’s Department of Atmospheric Science explained the process.
“One of the key factors where hurricanes get their energy is from warm ocean temperatures, greater than 79, 80 degrees Fahrenheit or 26 degrees Celsius. As the oceans warm, there’s more energy to drive those hurricanes,” Hurrell said. “We know that a warmer atmosphere holds more moisture. That can help intensify hurricanes. It also means it’s going to rain more.”
Another facet is a concerning trend among hurricanes in recent years. The storm’s speed, or lack thereof, is a factor that does not have any known correlation with climate change.
“There is a study that the forward speed of hurricanes has slowed down a little bit. We saw that with Dorian, with Harvey flooding Houston, with Florence in South Carolina,” David Zierden, a state climatologist at the Florida Climate Center, said. “Looking at the historical trends, there is a trend for slower forward movement. That is certainly a concern going forward because the slower the storm moves, the longer it impacts an area like The Bahamas.”
If speed and warming temperatures are symptoms of hurricanes nowadays, what could the future hold? Thomas Knutson works for the National Oceanic and Atmospheric Administration’s Geophysical Fluid Dynamics Laboratory. Knutson and those at NOAA project the climate will increase by at least two degrees. That is a 5 % increase in maximum surface temperatures.
“Global temperatures have been rising since the 1970s,” Knutson said, indicating the increase as an ongoing process.
According to Hurrell, it’s not just the likely increasing strength of hurricanes that is a danger, but there are other factors, some with no relation to climate change.
“Hurricanes push water towards the coast, storm surge. Sea levels are higher, so storm surges are going to be more damaging, surging farther inland than before,” Hurrell said. “Couple that with the increasing numbers of people living in coastal areas, that means more and more trouble.”
Despite what Hurrell, Knutson and Zierden have said on the matter, none confirmed a connection between climate change having a direct impact on hurricane systems.
“Hurricanes are still relatively rare events,” Zierden said. “The simple theory is that the oceans are warming and that it is these warm temperatures that provides fuel to drive the strong hurricanes, which is very true. But it also takes the right conditions such as atmospheric moisture, low wind shear and the Saharan Desert acting as an inhibitor.”
By Benjamin Wainer