29 November 2016

Tropical Cyclone Activity under RCP4.5 and RCP8.5 Compared to the Present

Science

This study examines how characteristics of tropical cyclones (TCs) that are explicitly resolved in a global atmospheric model with horizontal resolution of approximately 28 km are projected to change in a warmer climate using bias-corrected sea-surface temperatures (SSTs).  The impact of mitigating from RCP8.5 to RCP4.5 is explicitly considered and is compared with uncertainties arising from SST projections.  We find a reduction in overall global TC activity as climate warms. This reduction is somewhat less pronounced under RCP4.5 than under RCP8.5.  By contrast, the frequency of very intense TCs is projected to increase dramatically in a warmer climate, with most of the increase concentrated in the NW Pacific basin.  Extremes of storm related precipitation are also projected to become more common. Reduction in the frequency of extreme precipitation events is possible through mitigation from RCP8.5 to RCP4.5.  In general more detailed basin-scale projections of future TC activity are subject to large uncertainties due to uncertainties in future SSTs.  In most cases these uncertainties are larger than the effects of mitigating from RCP8.5 to RCP4.5.

Impact

This study examines how characteristics of tropical cyclones (TCs) that are explicitly resolved in a global atmospheric model with horizontal resolution of approximately 28 km are projected to change in a warmer climate using bias-corrected sea-surface temperatures (SSTs).  The impact of mitigating from RCP8.5 to RCP4.5 is explicitly considered and is compared with uncertainties arising from SST projections.  We find a reduction in overall global TC activity as climate warms. This reduction is somewhat less pronounced under RCP4.5 than under RCP8.5.  By contrast, the frequency of very intense TCs is projected to increase dramatically in a warmer climate, with most of the increase concentrated in the NW Pacific basin.  Extremes of storm related precipitation are also projected to become more common. Reduction in the frequency of extreme precipitation events is possible through mitigation from RCP8.5 to RCP4.5.  In general more detailed basin-scale projections of future TC activity are subject to large uncertainties due to uncertainties in future SSTs.  In most cases these uncertainties are larger than the effects of mitigating from RCP8.5 to RCP4.5.

Summary

This study examines how characteristics of tropical cyclones (TCs) that are explicitly resolved in a global atmospheric model with horizontal resolution of approximately 28 km are projected to change in a warmer climate using bias-corrected sea-surface temperatures (SSTs).  The impact of mitigating from RCP8.5 to RCP4.5 is explicitly considered and is compared with uncertainties arising from SST projections.  We find a reduction in overall global TC activity as climate warms. This reduction is somewhat less pronounced under RCP4.5 than under RCP8.5.  By contrast, the frequency of very intense TCs is projected to increase dramatically in a warmer climate, with most of the increase concentrated in the NW Pacific basin.  Extremes of storm related precipitation are also projected to become more common. Reduction in the frequency of extreme precipitation events is possible through mitigation from RCP8.5 to RCP4.5.  In general more detailed basin-scale projections of future TC activity are subject to large uncertainties due to uncertainties in future SSTs.  In most cases these uncertainties are larger than the effects of mitigating from RCP8.5 to RCP4.5.

Contact
Susan Bates
National Center for Atmospheric Research (NCAR)
Publications
Bacmeister, JT, C Hannay, SC Bates, N Rosenbloom, KA Reed, and MF Wehner.  2016.  "Tropical Cyclone Activity under RCP4.5 and RCP8.5 Compared to the Present."  Climatic Change, doi:10.1007/s10584-016-1750-x..