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The accelerated global warming and heterogeneous change in precipitation have been resulting in climate system shifts, which plays a key role in the stability of ecosystem and social economic development. Central Asia is account 80% of the temperate desert, characterized by fragile ecosystem; however, it has experienced the fastest warming in recent decades and projected warming in future. The Köppen-Geiger climate classification is a useful tool to assess the potential impacts of climate change on regional ecosystem. The spatial shift and temporal evolution of each climatic zone based on Köppen-Geiger climate classification are analyzed in historical and future period under different scenarios (RCP2.6, RCP4.5 and RCP8.5), high risk regions that might experience more frequent climatic zone shifts are delimited in this study, which could provide the useful information for developing mitigate strategies in coping with the warming threat. The hotter and dryer subtypes of arid climatic zone and warmer subtypes of temperate climatic zone expanded their coverage in Central Asia, corresponding to the tundra climatic, cooler subtype of arid and temperate climatic zone contracted. Based on a method defining the climate-sensitivity, high risk regions are mainly distributed in northern Kazakhstan and Tianshan Mountains region. [ABSTRACT FROM AUTHOR]

Lakes play an important role in regulating the regional climate, especially the large one in the arid region. The Aral Sea located in Central Asia, was once the fourth largest lake in the world, but gradually shrunk and lost more than 80% of its surface. As the Ara Sea dries up in last 60 years, the role of Aral Sea in regulating the regional climate dampens. However, how the Aral Sea regulates the regional climate and its mechanisms remains less understand. The climatic effect of the Aral Sea on regional climate is quantified by comparing two ideal simulations, with the Aral Sea included or excluded, using ALARO-SURFEX regional climate model under 4-km horizontal resolution. The model's performance in reproducing the 2-m temperature, precipitation and surface energy fluxes was evaluated firstly. The Aral Sea decreases (increases) the 2-m temperature in spring-summer (autumn-winter) over the Aral Sea and ambient land, which causes higher (lower) sea level pressure in spring-summer (autumn-winter) corresponding to enhanced the divergence (convergence) in spring-summer (autumn-winter). The lake-effect penetrates to the atmosphere, cools (warms) the daytime air temperature by 2.03 °C (0.07 °C) below (above) the height of 1.4-km during May to September but warming the nighttime air temperature by 0.42 °C below 0.6-km, leads to enhancing descent (ascent) motion in daytime (nighttime), which suppress (trigger) development of local convection in daytime (nighttime). The presence of Aral Sea increases specific humidity below 0.8-km in both daytime and nighttime. As a result, the annual precipitation, especially convective precipitation is increased by 7.08 mm and mainly occurs in nighttime-morning and open water period, but reduced precipitation occurs in 13:00–17:00 and ice frozen period. The presence of Aral Sea substantially reduces the sensible heat, enhances the latent heat, increases ground heat fluxes, but these effects depend season and diurnal variation. The temperature change induced by the Aral Sea is most contributed by the change of latent heat (ground heat) in open water period (ice frozen period), in diurnal timescale, the ground heat contributes most in both daytime and nighttime temperature change. • The regional climate model, ALARO-SURFEX, shows a reliable performance in the Aral Sea region. • Due to the lake-land thermal contrast,climate effect of the Aral Sea remains seasonal and diurnal variation. • Climate effect of the Aral Sea depends on background atmospheric circulation, vegetation condition and topography. [ABSTRACT FROM AUTHOR]