US Hurricane Activity Projected into the 2030s

Atlantic hurricane activity has large natural interannual variation. However, there’s evidence that on top of that variation are trends driven by climate change. There’s been considerable work estimating these hurricane trends over the full North Atlantic. But what about regional activity on the US coast? NASA scientist Tim Hall and colleagues have recently projected the hurricane climate-change signal into the 2030s along the US coastline. Their analysis combines a statistical hurricane track model trained on historical data with sea-surface temperature (SST) projections from a suite of global climate models.

Hall and company forecast a complex signal on the US coast. Some regions will experience reduced hurricane landfall rates (the western Gulf, and the mid-Atlantic coast), while other regions will experience increases rates (Florida’s panhandle and Gulf coasts). Summed over the full US coast, there is only modest change in hurricane landfall. An increase in overall North Atlantic activity is partially offset by an eastward shift in tracks, reducing the odds of US landfall. This eastward track shift is also responsible for the regional signals. Tracks that would have hit the western Gulf shift to the eastern Gulf, and tracks that would have hit the US Atlantic coast shift off the coast. Superposed on this geographic pattern is an increased fraction of storms reaching Cat4 and 5 status. Fig 1 summarizes some of these changes on four US regions: Galveston, Tampa, Miami, and Cape Hatteras.

Hall, T. M., J. P. Kossin, T. Thompson, and J. McMahon, US tropical cyclone activity projected into the 2030s, Journal of Climate, submitted, May, 2020.

 

 
Fig 1: Annual occurrence rates in 50km-radius circles surrounding four locations: Galveston TX, Tampa FL, Miami FL, and Cape Hatteras NC. The top panel represents Cat1+, the middle panel Cat3+, and the bottom panel Cat4+. Dark blue represents the period 1950-1980, light blue the period 2010-2019, and red the RCP85 projected rates for 2030 (identical to the RCP45 projected rates for 2038).

Dr Hall is a climate scientist at the NASA Goddard Institute for Space Studies in New York City. He specialises in hurricanes and their relationship to climate. He develops statistical hurricane and weather hazard models, and has worked as a consultant to RMS and reinsurance companies. Dr. Hall can be reached at www.linkedin.com/pub/timothy-hall/a2/709/b27/.

Posted: Monday, May 18th, 2020