Responses of soil moisture to climate change based on projections by the end of the 21st century under the high emission scenario in the 'Huang-Huai-Hai Plain' region of China

Based on the future potential projections in the late 21st century under the Representative Concentration Pathway (RCP) 8.5 scenario, the maximal responses of surface soil moisture (SSM) to an extreme climate change are exhibited in the 'Huang-Huai-Hai Plain' ('3H') region of China. The Common Land Model (CoLM) and the approach of conditional nonlinear optimal perturbation related to parameters (CNOP-P) are employed to explore the above issue. Three climate change scenarios, associated with temperature change, precipitation change and changes in both temperature and precipitation, are provided by applying the CNOP-P approach and denoted as the CNOP-P-type temperature change scenario, the CNOP-P-type precipitation change scenario and the CNOP-P-type climate change scenario, respectively. For the CNOP-P-type scenarios, the changes in both climatology and climate variability relative to the reference climate condition are included. To explore the different responses of SSM to different types of climate scenarios, the hypothesized climate change scenarios are examined as well, in which only the change in climatology is considered. Numerical results have suggested that the CNOP-P-type scenario induces greater SSM responses in terms of variation magnitudes than the hypothesized climate change does, especially in the semi-arid regions north of 35°N. For the two types of climate change scenarios, the differences about precipitation and soil ice changes result in the difference about SSM changes in the northern region, though the difference about evapotranspiration variations helps to narrow the difference about SSM. The above results imply that climate variability is important to SSM in the semi-arid region.