LAUSR

Central Asia covers a large land area of 5 × 106 km2 and has unique temperate dryland ecosystems, with over 80% of the world's temperate deserts, which has been experiencing dramatic warming and drought in the recent decades. How the temperate dryland responds to complex climate change, however, is still far from clear. This study quantitatively investigates terrestrial net primary productivity (NPP) in responses to temperature, precipitation, and atmospheric CO2 during 1980–2014, by using the Arid Ecosystem Model, which can realistically predict ecosystems' responses to changes in climate and atmospheric CO2 according to model evaluation against 28 field experiments/observations. The simulation results show that unlike other middle-/high-latitude regions, NPP in central Asia declined by 10% (0.12 × 1015 g C) since the 1980s in response to a warmer and drier climate. The dryland's response to warming was weak, while its cropland was sensitive to the CO2 fertilization effect (CFE). However, the CFE was inhibited by the long-term drought from 1998 to 2008 and the positive effect of warming on photosynthesis was largely offset by the enhanced water deficit. The complex interactive effects among climate drivers, unique responses from diverse ecosystem types, and intensive and heterogeneous climatic changes led to highly complex NPP changing patterns in central Asia, of which 69% was dominated by precipitation variation and 20% and 9% was dominated by CO2 and temperature, respectively. The Turgay Plateau in northern Kazakhstan and southern Xinjiang in China are hot spots of NPP degradation in response to climate change during the past three decades and in the future.