## 3 Results  
### Future Climate Changes under Different RCP Scenarios  
The downscaled climate data indicate that the climate in Tianshan North Slope will experience a wetter and warmer trend under the three different RCPs (Figure 2a,b). The linear fitting shows that the regional annual precipitation will increase with a predicted maximum rate of 11.8 mm per decade under the RCP8.5 scenario, a medium rate of 9.0 mm per decade under the RCP4.5 scenario, and a minimum rate of 6.5 mm per decade under the RCP2.6 scenario in 2006-2055 (Figure 2a). Similar to the precipitation temporal patterns, the regional annual mean temperature will increase with a predicted maximum rate of 0.49 \({}^{\circ}\)C per decade under the RCP8.5 scenario and minimum rate of 0.22 \({}^{\circ}\)C per decade under the RCP2.6 scenario from 2006 to 2055 (Figure 2b). A noteworthy feature is that the temperature increase rate under RCP4.5 (0.24 \({}^{\circ}\)C per decade) is very close to the one under RCP2.6 during 2006-2055 period (Figure 2b). In addition, there is temporal heterogeneity in the climate patterns. During the first 30 years (2006-2035), the regional annual precipitation and mean temperature increase at a higher rate than in the next 20 years (2036-2055) (Table 2) under the three different RCPs. The climate changes under the three RCPs are positive, except for the precipitation change under RCP4.5 from 2036 to 2055 (Table 2). The CO\({}_{2}\) concentration change from 2006 to 2055 is presented in Figure 2c. It shows that the CO\({}_{2}\) concentration will reach 442.55 ppm, 498.47 ppm, and 570.52 ppm \begin{table}
\begin{tabular}{c c c} \hline \hline
**Inputs** & **Unit** & **Methods and Sources** \\ \hline \multicolumn{3}{c}{_Base maps_} \\ \hline Elevation & m & Aggregated from 30 m Advanced Spaceborne Thermal Emission \\ Aspect & Degree & and Reflection Radiometer (ASTER) Global Digital Elevation \\ Slope & Degree & Model Version 2 data set ([[http://gdem.ersdac.jspacesystems.or.jp/](http://gdem.ersdac.jspacesystems.or.jp/)]([http://gdem.ersdac.jspacesystems.or.jp/](http://gdem.ersdac.jspacesystems.or.jp/))) \\ \hline Soil texture & \% & \\ Soil pH & – & \\ Soil bulk density & g cm\({}^{-3}\) & \\ \hline Vegetation & & \\  & & ([[http://midasia.geodata.cn/Portal/index.jsp](http://midasia.geodata.cn/Portal/index.jsp)]([http://midasia.geodata.cn/Portal/index.jsp](http://midasia.geodata.cn/Portal/index.jsp))) \\ \hline \multicolumn{3}{c}{_Transient data_} \\ \hline Groundwater level & m & Cold and Arid Regions Science Data Center at Lanzhou \\  & & ([[http://westdc.westgis.ac.cn](http://westdc.westgis.ac.cn)]([http://westdc.westgis.ac.cn](http://westdc.westgis.ac.cn))) \\ \hline CO\({}_{2}\) & ppmv & Predefined CO\({}_{2}\) concentration under RCP2.6, RCP4.5, and RCP8.5 [39] \\ \hline Precipitation & mm & \\ Solar radiation & W m\({}^{-2}\) & \\ Relative humidity & \% & \\ Maximum, minimum & \({}^{\circ}\)C & \\ and average temperature & \({}^{\circ}\)C & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Input Data Sets for AEM. under RCP2.6, RCP4.5, and RCP8.5 by 2055, respectively. The CO\({}_{2}\) concentration is predicted to reach the maximum (442.76 ppm) in 2052 under RCP2.6, and keeps almost a linear increasing rate (2.44 ppm year\({}^{-1}\)) under RCP4.5 and has an accelerated increasing rate under RCP8.5 (Figure 2c). Figure 3 presents the spatial pattern of the annual precipitation change between 2006 and 2055. It clearly shows that the largest precipitation increase happens in the mountainous area under all three RCPs. However, the precipitation decreases in the northeastern and eastern part of the study area under RCP2.6 and RCP4.5, respectively. Moreover, the precipitation differences are less than 50 mm in the desert, while they are higher than 100 mm in the mountains. This indicates that the precipitation will increase much more in the mountains than in the basin.