Population exposure to heat waves in Russian regions according to climate change scenarios for the mid-21 century

Heat waves, such as the one that struck European Russia in 2010, are among the major dangers of climate change. The population shift to large cities and southern regions observed in Russia, together with warming, increases the risks from heat waves. In this paper, we provide estimates of current and future population exposure to heat waves in Russian regions under the projection scenarios introduced by IPCC for the mid-21 century. We aim at identifying regions most at risk and in need of adaptation strategies and at assessing the contribution of climate change and population dynamics to future changes in population exposure. We use both absolute and relative measures to detect extreme summer daily temperatures and the high-resolution population data for the current period and 2050. Our results show an increase in the aggregate exposure from 4.76 billion person-days in the current period to 5.86 and 7.52 billion person-days under the soft and hard scenarios, respectively, notably in the areas where absolute maximum summer temperatures exceed 30 degrees C and 35 degrees C. Against the overall population decline, the increase in exposure is mainly driven by the climatic factor: by the widespread increase in the number of relatively very warm days, up to most of the season in the coastal areas of the Black and Caspian Seas and in the Caucuses, and by the geographical expansion of the zone of absolute high temperatures above 30 degrees C into the densely populated regions of Russia's Main Settlement Belt in Middle Russia, the southern Urals and Siberia. The projected more extreme climate put at risk the regions with large urban agglomerations and a relatively high population density making heat waves to increasingly become a metropolis-related risk, and the few regions that are projected to grow in population size, both through migration inflows, such as Krasnodar Krai, Moscow region, and Tyumen region, and through natural increase, such as the republics of the Caucasus.