Accelerated drying trends over Northeast Asia by anthropogenic forcing during 1948–2010

Abstract

Northeast Asia has experienced a significant drying trend since the 1950s. Attribution of this drying trend is important for understanding drying and its response to anthropogenic forcing. Despite increasing evidence of human influence on surface air temperature and precipitation, how human-induced climate change is affecting the observed aridity change is poorly understood. Here, by employing a “dynamical adjustment” methodology, we present an alternative estimation of the anthropogenic influence on drying trends over Northeast Asia during 1948–2010 from the observational records. Decomposition analysis revealed that the exacerbation of drying trends over Northeast Asia is largely driven by evapotranspiration forcing, which contributed to approximately 64 % of the drying trend and almost doubled that attributed to precipitation deficit. The acceleration of the drying trend by evapotranspiration forcing was mainly attributable to anthropogenic warming effect on potential evapotranspiration (PET). Considering the integrated effect of anthropogenic forcing on both PET and precipitation, the results showed that anthropogenic forcing has increased the extent of the drying trend area by ∼21 % over Northeast Asia during 1948–2010. In particular, the magnitudes of drying trends were significantly amplified by anthropogenic forcing, resulting in an expansion of the areas with enhanced drying trend by ∼43 %. These findings provide compelling evidence of a human influence on half century-scale drying trends over Northeast Asia, implying the overall likelihood of drought events increasing in this region due to anthropogenic forcing.