Fig. 1. The Belt and Road sub-regions: 1. Central-Eastern Europe; 2. West Siberia; 3. Central-Eastern Siberia; 4. West Asia; 5. Central Asia; 6. South Asia; 7. Non-monsoon region of East Asia; 8. Monsoon region of East Asia; 9. Southeast Asia

Fig. 2. Comparison of GCM ensemble mean with observation in the Belt and Road region for 1961-2005: multi-year averaged monthly precipitation (a) and potential evapotranspiration (b)Note: The upper and lower limits represent the range of climate models. The same applies to Figures 4 and 6.

Fig. 3. Spatial distributions of annual precipitation and potential evapotranspiration for 1961-2005: observed and simulated precipitation (a-b); observed and simulated potential evapotranspiration (c-d)

Fig. 4. Comparison of precipitation (a) and potential evapotranspiration (b) in 1986-2005, 1.5℃ and 2.0℃ global warming levels over the Belt and Road region

Fig. 5. Changes in precipitation (a-b) and potential evapotranspiration (c-d) under the 1.5℃ and 2.0℃ global warming scenarios relative to the reference period over the Belt and Road region: (a) and (c) show the changes in precipitation and potential evapotranspiration under the 1.5℃ scenario compared to the reference period; (b) and (d) show the changes in precipitation and potential evapotranspiration under the 2.0℃ scenario compared to the reference period

Fig. 6. Annual aridity index changes in the Belt and Road region under the 1.5℃ and 2.0℃ global warming scenariosNote: Numbers (1-9) denote different areas of the Belt and Road region marked in Figure 1. The same applies to Figure 8.

Fig. 7. Spatial distribution of the aridity index in the Belt and Road region: (a) in 1986-2005; (b) changes in the 1.5℃ with relative to the reference period; (c) changes in the 2.0℃ with relative to the reference period; (d) changes in the 2.0℃ with relative to the 1.5℃ Note: Dashes in the figures represent areas with significant changes at p<0.1. This also applies to Figure 9.

Fig. 8. Seasonal aridity index changes in the Belt and Road region under the 1.5℃ and 2.0℃ global warming scenarios: (a) spring, (b) summer, (c) autumn, and (d) winter Note: The black mark (×) above the bars represents the multi-model ensemble mean in 1986-2005.

Fig. 9. Relative changes of the seasonal aridity index under the 1.5℃ and 2.0℃ warming scenarios: (a) spring, (b) summer, (c) autumn, (d) and winter. (1-3) denote the 1.5℃ scenario relative to the reference period, the 2.0℃ scenario relative to the reference period, and the 2.0℃ scenario relative to the 1.5℃ scenario, respectively.

Fig. 10. Changes in the aridity index attributable to precipitation (a, c) and potential evapotranspiration (b, d) under the 1.5℃ scenario (a, b) and 2.0℃ scenario (c, d) relative to 1986-2005