Quantifying the Contributions of Regional Human Activities and Global Climate Change to the Regional Climate in a Typical Mountain-Oasis-Desert System of Arid Central Asia From 1979 to 2018

Many studies have examined the influence of global climate change and regional human activities on the climate of arid Central Asia, but their separate contributions have rarely been reported due to lack of a comprehensive description of regional human activities, especially the irrigation process, in the model. In this study, we conducted two sets of 40-year continuous simulations with and without human activities to distinguish the effects of regional human activities and global climate change on the surface air temperature (T2), humidity (Q2) and precipitation of a typical mountain-oasis-desert system in northern Tianshan by using a modified WRF-Noah model with irrigation processes. The results indicated that the annual average T2, Q2 and convective precipitation during the past 40 years increased by 0.393 & DEG;C, 0.063 g/kg and 0.014 mm/d, respectively, and the annual average large-scale precipitation and total annual average precipitation decreased by approximately -0.017 and -0.003 mm/d, respectively. Regional human activities contributed 52.63% and 50.38% of the change in large-scale precipitation and total precipitation, respectively, while global climate change accounted for more than 80% of the change in temperature and humidity. Among the human activities, irrigation had the largest impact on T2/Q2 over the local irrigation region and on precipitation in the upstream Tianshan mountainous area. However, for the whole region, the increase in the green vegetation fraction was the core factor that impacted the regional climate. Our results can deepen the understanding of the attribution and mechanism of climate change and provide water and heat change references for other mountain-oasis-desert systems in arid endorheic regions.

Automated summary

In this study, two sets of 40-year continuous simulations were conducted to distinguish the effects of regional human activities and global climate change on the climate of arid Central Asia. The results showed that regional human activities contributed significantly to changes in precipitation, while global climate change had a larger impact on temperature and humidity. Irrigation had the greatest influence on local temperature/humidity and precipitation in the upstream mountainous area, while the increase in green vegetation was the key factor affecting the regional climate.