Impact of Climate Change on Gulf of Mexico Hurricanes

By Cindy L. Bruyère, C3WE Deputy Director

A state of the art modeling study was undertaken by the National Center for Atmospheric Research (NCAR) to estimate the most likely impacts of climate change on Gulf of Mexico hurricane intensity and frequency.  The modeling study entailed the use of two state of the art sets of future climate change simulations.  The first simulation was conducted using a Climate Ensemble approach over a large domain and at relatively high resolution compared to global climate models, and the second simulation was conducted at 4km resolution, over a limited domain covering a smaller sub-set of North America.  Both simulations are based on the Weather Research and Forecasting (WRF: Skamarock et al., 2008) model.  The first simulation addresses frequency changes of hurricanes, and to a lesser extent the change in intensity (due to its coarser resolution 36 km horizontal grid spacing), while the second, addressed changes in intensity of hurricanes in a future climate. A unique aspect of the first simulation is the extensive use of multiple physics ensembles to account for the uncertainty of future climate projections, and a unique aspect of the second simulation is that 28 named hurricanes are simulated in both current and future climates.

The initial concern regarding future hurricanes was that the warmer and moister environment would fuel the formation of significantly strong hurricanes.  While we found that the largest storms intensified based on our named hurricane approach, the level of intensification was not as great as initially anticipated. We hypothesize that the stronger stability in the future climate due to convective heating in the tropic is limiting the intensification as put forward by Hill and Lackmann (2011). He and others have shown that the lapse rate stabilization due to convective heating can reduce the intensification of hurricanes by up to 50%.  The other possible limiting factor is due to reaching the limits of the efficiency of the hurricane heat engine (Holland, 1997). 

The combination of the two independent approaches provides a robust and comprehensive view of the likely future changes to hurricanes in the Gulf of Mexico. 

The combined results of these two simulations show:

  • A tendency towards fewer hurricanes in the Gulf of Mexico and a slight reduction in the proportion of Atlantic hurricanes entering the Gulf.
  • An increased proportion of category 3, 4, and 5 storms in the Gulf of Mexico.
  • Increased precipitation for all cyclones in the Gulf of Mexico (on the order of 30-40%).
  • The characteristics of hurricanes in the Gulf of Mexico in the future are projected to be similar in size and track speed to current hurricanes.
  • These simulations predict a ~10% increase in cyclone damage potential for the most intense hurricanes.

It is important to note that the results for changes in wind speed and precipitation are for 22 named hurricanes subject to the thermodynamics of a future climate. While most of the storms exhibited the behavior indicated, a few of them had reduced winds and precipitation based on the exact trajectory and SST (Sea Surface Temperature) they passed over.

The prediction for fewer but more damaging hurricanes suggests the potential for substantial impacts on infrastructure and operations in the Gulf of Mexico in the future. 

The full report is available as an NCAR Technical Note:
Bruyère, C. L., and Coauthors, 2017: Impact of Climate Change on Gulf of Mexico Hurricanes. NCAR Technical Note NCAR/TN-535+STR, 165 pp, doi:10.5065/D6RN36J3