High Mountains Becoming Wetter While Deserts Getting Drier in Xinjiang, China since the 1980s

Yong Zhang,Wensheng Zhang,Yanzhen Zhang,Chengbang An,Chao Lu,Luyu Liu

doi:10.3390/land10111131

Abstract

Climate change has been thought to drive the accelerated expansion of global drylands. However, many studies reveal that Arid Central Asia (ACA) has been warming and wetting in recent decades, representing an anomalous response to global climate change. Given that ACA is composed of complex ecosystems and landforms, it is not clear whether or not this trend is uniform in this topographically heterogenous region. Here, we integrate the Google Earth Engine and ERA5-Land reanalysis data to study the trend of changes, since the 1980s, in temperature and precipitation in the Tianshan Mountains and the surrounding deserts, collectively referred to as the Tianshan and Desert Ecozone, which is in Northwest China. Our results show that only 20.4% of this area is becoming both warmer and wetter, which occurs mainly in the altitudes above 2800 m (Tianshan Ecozone). All three alpine ecosystems (coniferous forests, alpine meadow, and nival zone) in the Tianshan Ecozone exhibit similar warming and wetting trends, including of elevation-dependent wetting on the specific altitude range. In contrast, the low-lying oasis where human activities are mostly concentrated is undergoing warming and drying, which will face a greater threat of drought projected under three emissions scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5). These results highlight the importance of considering the differences of climate change in different altitude gradients and different ecosystems when studying climate change in drylands.

Highlights

Arid and semi-arid regions, composed of deserts, shrubs, and savanna, account for 40% of the global terrestrial ecosystem, and they feed approximately 38% of the world’s population [1]
In order to answer these questions, in this paper we focus on Xinjiang, NW China, the core area of Arid Central Asia (ACA), the Tianshan Mountains and Desert Ecozone
The Desert Ecozone had a higher rate of warming than the Tianshan Mountains Ecozone

Summary

Introduction

Arid and semi-arid regions, composed of deserts, shrubs, and savanna, account for 40% of the global terrestrial ecosystem, and they feed approximately 38% of the world’s population [1]. In addition to the socioeconomic values, arid ecosystems are sensitive to global climate change and play an important role in the global carbon cycle [2]. Large warming may lead to increased evaporation, decreased precipitation, prolonged droughts, and the accelerated expansion of drylands [4], which in turn may reduce carbon sequestration and further enhance global warming [5]. There are regional differences in the world’s dryland climate change. Reanalysis datasets show that the global semi-arid and arid regions show a significant warming and drying trend, but there are obvious regional differences in precipitation changes [6]. Based on the above research, we found that the research on climate change in arid regions is mainly focused on large-scale areas, but there is less attention to climate change in different ecological systems and different altitude gradients in arid regions

Results

Discussion

Conclusion