Abstract
Under global warming, changes in extreme temperatures will manifest in more complex ways in locations where temperature distribution tails deviate from Gaussian. Confidence in global climate model (GCM) projections of temperature extremes and associated impacts therefore relies on the realism of simulated temperature distribution tail behavior under current climate conditions. This study evaluates the ability of the latest state-of-the-art ensemble of GCMs from the Coupled Model Intercomparison Project phase six (CMIP6), to capture historical global surface temperature distribution tail shape in hemispheric winter and summer seasons. Comparisons with a global reanalysis product reveal strong agreement on coherent spatial patterns of longer- and shorter-than-Gaussian tails for both sides of the temperature distribution, suggesting that CMIP6 GCMs are broadly capturing tail behavior for plausible physical and dynamical reasons. On a global scale, most GCMs are reasonably skilled at capturing historical tail shape, exhibiting high pattern correlations with reanalysis and low values of normalized centered root mean square difference, with multi-model mean values generally outperforming individual GCMs in these metrics. A division of the domain into sub-regions containing robust shift ratio patterns indicates higher performance over Australia and an overestimation of the degree to which tails deviate from Gaussian over southeastern Asia in all cases, whereas model skill over other regions varies depending on season and tail of the temperature distribution. For example, model performance during boreal winter indicates robust agreement (>85% models) with reanalysis for shorter-than-Gaussian warm tails over the Northern Hemisphere, whereas cold-tail shape is generally mischaracterized by GCMs over western Russia. Although there is spatial and model variability, overall, results highlight the capability of the CMIP6 ensemble in capturing seasonal temperature distribution deviations from Gaussianity, boosting confidence in model utility and providing insight into the complexity of future changes in temperature extremes.
Highlights
Extreme warm and cold temperatures are associated with a multitude of impacts on society and the environment, including crop yield reduction, infrastructure damage, and human health concerns (Kunkel et al 1999)
This study evaluates the ability of the latest state-of-the-art ensemble of global climate model (GCM) from the Coupled Model Intercomparison Project phase six (CMIP6), to capture historical global surface temperature distribution tail shape in hemispheric winter and summer seasons
The full ensemble agrees well with reference shift ratio patterns in northern and west-central NAM, the degree of departure from Gaussianity varies among individual GCMs
Summary
Extreme warm and cold temperatures are associated with a multitude of impacts on society and the environment, including crop yield reduction, infrastructure damage, and human health concerns (Kunkel et al 1999). The severity of these impacts may change under future warming, as global projections indicate increases and decreases in the frequency of exceeding current-climate extreme warm and cold thresholds, respectively (IPCC, 2013). (Loikith and Neelin 2019) demonstrated that departures from Gaussianity on the cold side of the temperature distribution in the extratropics are related to the large-scale circulation features that produce extreme temperatures This finding suggests model ability to capture non-Gaussian tails may be linked to realistic representation of circulation dynamics, errors in both of which contribute to uncertainty in simulated extremes. It is essential that climate models adequately resolve tail Gaussianity under current climate conditions to boost confidence in projections of future changes in temperature extremes and associated impacts
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
