150-year shift of potential geographical distribution of desertification in China:Past,present and future
Land desertification is a major ecological challenge facing the world,profoundly affecting human life and sustainable development.As one of the countries with the most severe desertification issues across the world,China has a population of 580 million living on 6.6 million square kilometers of dry land.The climate in northern China has changed significantly over the past 20 years.Precipitation,aridity index,and comprehensive humidity index have all shown significant non-linear increasing trends in the northwest region.However,whether the current potential geographical distribution of desertification(PGDD)in China has changed and the changing pattern in the past century is still unclear.Recent research found that it underestimated the impact of increasing CO2 on future potential evapotranspiration.This resulted in an overestimation of changes in potential evapotranspiration when predicting future aridity,thereby exaggerating the prediction of future desertification expansion.Here we investigated the current spatial distribution of PGDD in China and its historical evolution over the past 120 years(1901-2020),and predicted the spatial pattern trend of PGDD in 2050.This analysis considered the impact of increasing CO2 concentrations on future potential evapotranspiration based on the modified Penman-Monteith(PM)equation by using high-resolution gridded meteorological data(CRU TS4.06)and datasets from ten global climate models within the Coupled Model Intercomparison Project Phase 6(CMIP6).The results show that the PGDD area in China is approximately 4.8 million square kilometers,accounting for nearly 50％of the country's land area in the baseline period of 1991-2020.In the past 120 years(1901-2020),the total area of PGDD in China has shown a trend of first decreasing and then increasing,with 1978 as the turning point.The study founded that the smallest area of PGDD in China occurred in the 1970s.During this period of 1901-2020,the changes in aridity of PGDD in China generally showed a trend of"dry in the east and wet in the west".From 1901 to 2020,the area that became wetter in the PGDD was four times the area that became drier.The overall climate became wetter,resulting in a decrease in PGDD area of approximately 35000 square kilometers in 2020.It is projected that by 2050,China's PGDD is expected to decrease by 5.51％,4.70％,and 3.73％respectively compared with the current situation from low emissions to high emissions under three shared socioeconomic pathway scenarios.The lower the emission intensity,the smaller China's PGDD.Compared to the modified PM equation that takes into account changes in CO2 concentration,the traditional PM equation overestimates the area of PGDD in China.To sum up,the total area of PGDD in China has shown a downward trend over the past 120 years.However,nearly half of China's land area remains vulnerable to desertification risks.Keeping the emission intensity low helps reduce the area of PGDD.The climate of PGDD in China will become humid in the future.Current research mainly analyzes changes in PGDD based on natural climate conditions,without quantitatively considering the impact of human activities on desertification.In future studies,more comprehensive approaches are needed to integrate the impact of human activities and natural conditions on PGDD and conduct in-depth analysis and assessment to gain a deeper understanding of the dynamic changes in these regions.Finally,the understanding of current and future situations of PGDD in China will be conducive to its formulation of national key ecological project planning and desertification prevention and control strategy.
万方数据
维普
