关键词: 阿富汗, 暖湿化, 干湿指数, 锡斯坦盆地, 瓦罕走廊

Abstract:

The fragile ecosystems of Afghanistan, in the southern arid region of Central Asia, are greatly affected by climate change. In this study, we systematically analyzed the change in the average climate of Afghanistan from 1951 to 2020, in terms of both temporal and spatial patterns, using updated CRU TS V4.05 high-resolution gridded data. Results indicate that the extremely arid, arid, semihumid, and humid climate zones of Afghanistan are distributed from the southwest to the northeast. The annual average air temperature and potential evapotranspiration decreased from the Sistan Basin in the southwest to the Wakhan Corridor in the northeast. By contrast, the annual average precipitation increased. The annual and seasonal average temperature increased consistently, with the most substantial warming over the past 70 years occurring in the western part of Afghanistan; the greatest increase in the seasonal average temperature was in the spring. The data indicated strong spatial heterogeneity in precipitation as well as large seasonal differences. There was a slight decrease in the annual precipitation [-0.43 mm·(10a)^-1] over the study period and a “decrease-increase-decrease” trend in the spatial distribution changes, from the southwest to the northeast. The precipitation was concentrated in winter and spring. From 1951 to 2020, the trend in the potential evapotranspiration in Afghanistan was a significantly upward trend, with a rate of 5.59 mm·(10a)^-1. Annual potential evapotranspiration was found to have decreased over the central region of Afghanistan. Although there were seasonal differences, potential evapotranspiration tended to increase in the spring, summer, and autumn and decrease in the winter. Analysis of the aridity index (AI) revealed interannual variations in the climate of Afghanistan. Drought had intensified in the extremely arid Sistan Basin in the southwest, whereas warmer and wetter weather occurred in the central Hindu Kush region, and the Wahan Corridor area was generally warmer and dryer. The average AI decreased substantially in the spring, leading to the risk of staged drought. Generally, since the beginning of the 21st century, Afghanistan has experienced a slight increase in temperature, a sharp increase in precipitation, and a significant decrease in annual potential evapotranspiration. The region experienced warming and wetting stages, most notably in the spring. In conclusion, all of these changes pose risks and challenges to agricultural production, the cryosphere, and water management.

Key words: Afghanistan, warming-wetting, aridity index, Sistan Basin, Wakhan Corridor