INSTITUTE OF ATMOSPHERE PHYSICS, CHINESE ACADEMY OF SCIENCES
IMAGE: SUNSET AT BEIHAI PARK Show more CREDIT: KEXIN CHEN
Against the backdrop of global warming, more intense and frequent heat waves have a huge impact on humanity. Hence, the characteristics of extreme temperature changes have become a central concern of the climate change community in the future. Climate models offer a way to study the possible changes in extreme temperatures in the future. To make it easier to compare models from different modeling groups worldwide, the World Climate Research Program (WCRP) has launched the Coupled Model Intercomparison Project (CMIP), which is dedicated to providing standardized climate simulation results for comparison purposes. However, there are still great uncertainties in the simulation results of various models. Especially when simulating temperature extremes in China, an important question is what the differences are between the models of the previous CMIP phase (CMIP5) and their more advanced versions in the current phase (CMIP6).
To remedy this, researchers from Beijing Normal University selected 27 models from CMIP6 and CMIP5 and calculated eight extreme temperature indices as defined by the team of experts for the detection and indices of climate change. The simulation performances of different models in terms of their temporal and spatial distribution of extreme temperatures were compared, and the results were recently published in Atmospheric and Oceanic Science Letters.
According to this study, the CMIP6 models reproduce the spatial distributions of the annual maxima of the daily maximum temperature, the annual minima of the daily minimum temperature and the frost days better than CMIP5. However, the CMIP6 models still have poor capabilities to capture warm days and cold nights and, in particular, create obvious cold or warm prejudices against the Tibetan plateau. It also compared different versions of models from the same model organization and found that the enhanced CMIP6 models for some models did not differ significantly from their CMIP5 counterparts.
Overall, compared to CMIP5 models, CMIP6 offers improved options for simulating extreme temperatures in China. The simulation capabilities of some individual models in CMIP6 are obviously better than most of the other models. We can therefore trust that these CMIP6 models will drive regional models to conduct downscaling studies and project future extreme temperature changes.