Heat and cold wave intensity and spatial extent on the Iberian Peninsula: future climate projections (2050–2095)

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In the current context of global warming, heat waves are extreme climate events that have captured the focused attention of the scientific community due to their increasing impact on public health, energy consumption, fire risk, and agriculture livestock. Although less studied, cold waves remain an extreme climate event to be reckoned with, with implications for transport systems, energy consumption, crops, and human health. This paper presents an analysis of the representative concentration pathway (RCP) 4.5 and RCP 8.5 scenarios under European Coordinated Regional Downscaling Experiment simulations using the excess heat factor (EHF) and excess cold factor indices for the Iberian Peninsula and the Balearic Islands (IPB). The study period is the second half of the 21st Century (2050–2095) with respect to the historical reference period (1971–2000), and the dimensions analysed are intensity and spatial extent. The projected EHF results show a very significant increase on these dimensions. The average change in maximum heat wave intensity for the IPB is projected to be 144%, which is 40% more than in the 2021–2050 period. The largest changes are expected in the east and southeast and will reach 300%. The average spatial extent of heat waves is projected to increase by 1–2.7% per decade, significantly amplifying fire risk, energy demand, and human exposure. For cold waves, both dimensions will decrease. The average change in maximum cold wave intensity will be − 16%, and the maximum extent will decrease much more than the average, with decreases between − 0.7%/decade and − 3.2%/decade, which will imply lower exposure. Despite this, the RCP 8.5 scenario will record a higher maximum intensity of cold waves in the IPB than the RCP 4.5 scenario, demonstrating that such events will continue to exist in the second half of the century, even with high radiative forcing.