The Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report (AR6) states that the global surface temperature has risen markedly since the pre-industrial era. This warming has led to more frequent and intense extreme heat events over most continents. In summer 2010, western Russia was hit by a record-breaking heatwave, with the region experiencing the warmest summer since at least 1880 and numerous cities recording all-time high temperatures. Furthermore, in the context of global warming, future midlatitude heatwaves analogous to the 2010 event will become even more extreme, with the heatwave intensity increasing by about 8.4°C in western Russia. Thus, unraveling the physical processes involved in the 2010 western Russian heatwave is a matter of considerable concern within the scientific community.
Previous studies have elucidated that this extraordinary event in 2010 mainly resulted from internal natural variability, which includes but is not limited to the processes associated with El Niño to La Niña transition, the intensified Arctic dipole mode, the enhanced moisture–temperature coupling strength, high-latitude land warming, and increased aerosol concentrations. However, there is still some debate regarding the respective roles of dynamical and radiative processes in driving the 2010 western Russian heatwave.
A new study published in Atmospheric and Oceanic Science Letters by a research team led by Professor Song Yang at Sun Yat-sen University, China, reveals that surface dynamics and aerosol processes were the key drivers behind the extraordinary 2010 heatwave. This study provides a new quantitative perspective on the record-breaking western Russian heatwave.
"To date, attribution studies have relied primarily on sensitivity experiments conducted with climate models, which often lead to large uncertainties in quantitative results due to considerable model biases. The coupled atmosphere–surface climate feedback response analysis method with the effects of aerosols incorporated (CFRAM-A) is an efficient, model-free approach for quantitative attributions of extreme temperature events. We applied this method to break down the surface warming in western Russia in 2010 into contributions from individual radiative and dynamical processes," says the first author, Dr. Lianlian Xu.
"Understanding the physical and dynamical origin of regional climate extremes remains a major challenge in our effort to anticipate the occurrences and mitigate the adverse impacts of these extremes," adds the corresponding author, Prof. Song Yang.
According to this study, the surface warming over western Russia in 2010 can be primarily attributed to the effects of surface dynamics (95%), followed by atmospheric dynamics (49%), clouds (19%), and water vapor (6%), which are partially counterbalanced by aerosol-induced cooling (−64%). Further analysis revealed that the total aerosol cooling was predominantly governed by organic carbon (78%), black carbon (36%), and sulfate (−21%).
This research offers a new perspective for understanding the mechanisms of heatwaves globally and is crucial for improving the predictive capability of such extreme events. The framework presented in this paper not only advances understanding of extreme weather event mechanisms but also underscores the complex interplay between dynamical and radiative factors in driving record-breaking heatwaves.
