Investigating the relative contribution of anthropogenic increase in greenhouse gas and land use and land cover change to Asian climate: A dynamical downscaling study

Human activity have caused significant increase in greenhouse gas (GHG) concentration and land use and land cover change (LULCC), which can in turn affect regional and global climate. We investigate the relative contributions of increased GHG concentration and LULCC to the precipitation and surface air temperature (SAT) in Asia through three dynamical downscaling simulations with different land cover maps and GHG concentrations. The results suggest that the increased GHG concentration leads to an increase (decrease) in precipitation over East Asia and Southeast Asia (South Asia) in spring and winter. Over Southeast Asia and the Bay of Bengal, LULCC induced a significant decrease in precipitation in autumn and winter, and the change is greater than that induced by GHG. Moreover, the enhanced GHG concentration generally leads to a decrease in dry days or light rain days and an increase in heavy rain days over the land area. However, LULCC-induced changes in extreme precipitation are generally weak. The increased GHG concentration induces a significant increase of 1-3 degrees C in the SAT throughout the year. LULCC plays a more important role than the increased GHG concentration in modulating the SAT over South Asia, Southeast Asia, and East Asia throughout the year. The increased GHG concentration and LULCC cause a broader range of changes in the daily temperature frequency. The anomalous warm event of 8-10 degrees C increases by 1-1.5 days per season in the middle latitude regions in boreal spring due to the increased GHG concentration. LULCC also leads to an increase in high-temperature events except central Asia.

Automated summary

Human activity has led to an increase in greenhouse gas concentration and land use change, which in turn affect precipitation and surface air temperature in Asia. Increased greenhouse gas concentration results in increased precipitation in East Asia and Southeast Asia in spring and winter, while land use change leads to significant precipitation decrease in Southeast Asia and the Bay of Bengal in autumn and winter. Increased greenhouse gas concentration also leads to a decrease in dry days or light rain days and an increase in heavy rain days, but land use change has a weaker impact on extreme precipitation. Throughout the year, increased greenhouse gas concentration causes a significant increase in surface air temperature, while land use change plays a more important role in modulating surface air temperature. These changes also affect the frequency of daily temperature.