10 June 2019

Projected Changes in United States Regional Extreme Heat Days

Bivariate quantile mapping of CMIP5 simulations.

Science

Accurate projections of extreme heat days (EHD, the combined occurrence of high air temperatures and specific humidity) are obtained using bivariate quantile mapping of CMIP5 simulations. For many regions and cities in CONUS, there is no overlap between the frequency of high‐humidity EHDs from the historical and future periods, indicating that increases in extreme heat are robust.

Impact

Projections of multivariate climate extremes require methodological approaches that can maintain relationships among variables. Here we apply a piecewise multivariate quantile mapping approach to temperature and humidity projections from CMIP-5 and analyze the resulting climatology of extreme heat days (EHDs) with explicit consideration of the prevailing humidity.

Summary

Our new approach to piecewise multivariate bias correction method shows good fidelity in reproducing the frequency of different types of extreme heat days (EHD) in the historical period. When applied to output from CMIP-5 GCMs for many regions and cities in CONUS, there is no overlap between the frequency of high‐humidity EHDs from the historical and future periods, indicating that increases in extreme heat are robust and that future extreme heat events are likely to be comprised of both high air temperature and high specific humidity and thus may have greater negative impacts on human health.

Contact
S.C. Pryor
Cornell University
Publications
Schoof, JT, SC Pryor, and TW Ford.  2019.  "Projected Changes in United States Regional Extreme Heat Days Derived From Bivariate Quantile Mapping of CMIP5 Simulations."  Journal of Geophysical Research: Atmospheres 124(10): 5214-5232.  https://doi.org/10.1029/2018JD029599.