## 4 Results  
### Drought Risk Assessment  
Hazard factors, including natural and anthropogenic climate change, determine the probability of risk [42]. Hazard refers to the various characteristics and abnormalities of the main meteorological factors causing the disaster, such as abnormal changes in precipitation and temperature, which are generally considered to affect disaster risks. Figure 2a shows the distribution of hazard risk based on three hazard factors: Precipitation, temperature, and drought-affected areas. After processing the data, a comprehensive hazard index was obtained. The comprehensive hazard index decreased from north to south, and attention should be paid to drought prevention measures in the north. Vulnerability describes a system of vulnerability and lack of ability to adapt to variation and change [43], and it is generally defined as the possibility, degree, or state of a system that is vulnerable to damage under external interference. The greater the vulnerability of the region, the greater the potential for damage and the higher the risk. Figure 2b shows the distribution of vulnerability risk based on three vulnerability indicators: Total agricultural output value, water resources, and forest area. After data processing, a vulnerability model was established, and the composite vulnerability index was obtained. The composite vulnerability index generally showed a decreasing trend from north to south (Figure 2b). Though Guangdong had abundant water vapor, the vulnerability index was relatively high for drought. Therefore, the vulnerability of Guangdong should be given special attention. Exposure degree refers to the infrastructure, resources, environment, society, economy and cultural property that are closely related to human life and production [44]. The greater the exposure is in a region, the greater the potential loss and the higher the risk. Figure 2c shows the distribution of exposure risk based on three exposure indexes, including permanent population, cultivated land area, and gross output value of agriculture, forestry and fisheries. After data processing, the exposure model was established, and a comprehensive exposure index was obtained. The exposure index trend was in contrast to the hazard index trend and generally increased from north to south. It is worth noting that  
Figure 1: Distribution of future (2021–2050) net primary productivity (unit: kg m\({}^{-2}\) s\({}^{-1}\)) changes under different emissions scenarios (**a**) RCP 4.5 (**b**) RCP 8.5 (based on 1988–2017). A greener (or redder) grid indicates an improvement (or worsening) of the ecological environment. although the drought in the south was less than that in the north, the exposure was higher in the south than in the north. Therefore, the exposure in the south should be given more attention. Figure 2: Drought risk assessment during the historical period (1988–2017): (**a**) Hazard, (**b**) vulnerability, and (**c**) exposure. To reduce the drought risk in the study area, we extracted the main risk factors in each area (Table 4) from the drought risk assessment (Figure 2) to provide countermeasures. (1) High hazard and vulnerability risks in disaster-bearing environments are the main risks in Gansu and Ningxia. The high hazard risks in these regions are mainly due to the dry climate, low precipitation and high temperature (relative to the same latitude). However, with industrial development, the impact of anthropogenic aerosols on natural disasters is increasing. In areas with a low moisture content, an increase in aerosols will inhibit precipitation. Some feasible measures to address this risk are to reduce the emission of carbon dioxide and pollutants. The transition from traditional agriculture to irrigated agriculture and the increase in the total number of reservoirs may be able to adequately improve the disaster reduction capacity. Expanding forest areas and reducing industrial water use may reduce vulnerability.