Abstract
The ecosystem and societal development in arid Central Asia are highly vulnerable to climate change. During the past five decades, significant warming occurs in Central Asia, but whether the influence of anthropogenic forcing is detectable remains unclear. Therefore, we employ the optimal fingerprinting method to address the question in this study. The observed annual mean temperature (°C) over Central Asia significantly increases by 1.33 from 1961 to 2005, which mainly concentrates in summer (0.90), autumn (1.22), and winter (2.48). The influence of anthropogenic forcing, particularly the greenhouse gases (GHG) forcing, on both the annual and seasonal significant warming trends are robustly detected. GHG increases the annual, summer, autumn, and winter mean temperature (°C) by 1.25 (0.52–2.00), 1.11 (0.32–1.92), 1.11 (0.40–1.83), and 2.50 (0.91–4.34), respectively. Attribution results demonstrate an underestimation (overestimation) of CMIP5 models in simulating the annual and winter (summer and autumn) historical warming trend in Central Asia, implying a potential bias of the future temperature projections reported in IPCC AR5. Thus, we adjust the projections based on the attributed scaling factors, showing that the projected annual, summer, autumn, and winter mean temperature would significantly increase at a rate (°C decade−1) of 0.32 (0.16–0.49), 0.20 (0.06–0.35), 0.24 (0.10–0.38) and 0.58 (0.24–0.93) under RCP4.5, while 0.74 (0.36–1.12), 0.48 (0.14–0.84), 0.58 (0.25–0.91), and 1.25 (0.53–2.02) under RCP8.5, respectively, demonstrating large annual variation. To the end of twenty-first century, the annual (winter) mean temperature (°C) over Central Asia would increase by 7.00 (11.75) under RCP8.5, 0.85 (5.17) higher than the unadjusted results.
Highlights
Far from ocean and lying on the north of Tibetan Plateau (Fig. 1a), Central Asia (35°–55°N, 50°–95°E) is one of the most arid regions with an annual precipitation amount less than 350 mm (Fig. 1b) and characterized by cool desert climate with sparse vegetation and Central Asia has experienced a significant warming during the past one hundred years, with an accelerating warming rate in recent five decades which is much higher than the global land average (Hu et al 2014; Zhou et al 2018; IPCC 2013)
In Northwest China which is located at the eastern part of Central Asia, the winter warming rate is larger than the other seasons, and is associated with weakening winter Siberian High and increasing
The results from multi-model ensemble mean of ALL simulations can well capture the observed annual warming trend over Central Asia, with a rate of 0.29 °C decade−1, which is close to the observed value
Summary
Far from ocean and lying on the north of Tibetan Plateau (Fig. 1a), Central Asia (35°–55°N, 50°–95°E) is one of the most arid regions with an annual precipitation amount less than 350 mm (Fig. 1b) and characterized by cool desert climate with sparse vegetation (shrubland and grassland) and Central Asia has experienced a significant warming (about 0.15 °C decade−1) during the past one hundred years, with an accelerating warming rate (about 0.33 °C d ecade−1) in recent five decades which is much higher than the global land average (about 0.19 °C decade−1) (Hu et al 2014; Zhou et al 2018; IPCC 2013). The precipitation in Central Asia shows significant increasing trend during the past five decades, with the largest increasing trend in Northwest China (Shi et al 2007; Chen et al 2011; Zhao et al 2014; Li et al 2016; Hu et al 2017). The significant increasing precipitation in Northwest China is associated with the increased evaporation results from significant warming during the past half-century (Chen et al 2011; Peng and Zhou 2017; Peng et al 2018). Associated with the significant warming over Central Asia during the past five decades, the areas of dry-land expanded acceleratedly, temperature and precipitation extremes increased significantly, and the glacier in Tianshan Mountains retreated markedly (Deng et al 2014; Chen et al 2016; Huang et al 2016a; Wang et al 2017)
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