## 3 Results
### Temporal and Spatial Patterns of the Regional NPP and ET  
Similar to the temporal patterns of the climate change, the regional annual NPP and ET show an increasing trend from 2006 to 2055 under all three RCPs (Figure 5). The mean NPP for Tianshan North Slope during 2006-2055 is 176.4 g C m\({}^{-2}\) under RCP2.6, 182.4 g C m\({}^{-2}\) under RCP4.5 and 196.9 g C m\({}^{-2}\) under RCP8.5. The regional mean NPP of Tianshan North Slope shows an increasing trend with the rate of 1.16, 1.62, and 2.15 g C m\({}^{-2}\) year\({}^{-1}\) under RCP2.6, RCP4.5, and RCP8.5, respectively (Figure 5a). The regional mean EIs for Tianshan North Slope during 2006-2055 under RCP2.6, RCP4.5, and RCP8.5 are 130.6, 131.7, and 136.3 mm, respectively. The regional mean ET presents an increasing trend with a rate of 0.38 mm year\({}^{-1}\) under RCP2.6, 0.43 mm year\({}^{-1}\) under RCP4.5, and 0.52 mm year\({}^{-1}\) under RCP8.5 (Figure 5b). Moreover, in response to climate change, the NPP and ET dynamics in the first 30 years (2006-2035) are different from those in the next 20 years (2036-2055) (Table 3). The NPP change rates in different periods under the three RCPs share the similar pattern with that of regional precipitation (Tables 2 and 3). It can be seen in Table 3 that the regional mean NPP of Tianshan North Slope shows a decreasing trend during 2036-2055 under the RCP4.5 scenario. In the first 30 years, the ET increases fastest with 0.87 mm year\({}^{-1}\) under RCP4.5 and slowest with 0.77 mm year\({}^{-1}\) under RCP8.5, which is different from the change in precipitation during the same period. In the next 20 years  
Figure 3: The spatial patterns of annual precipitation difference between 2006 and 2055 under RCP2.6 (a), RCP4.5 (b), and RCP8.5 (c). (2036-2055), the ET in Tianshan North Slope presents an increasing trend under RCP2.6 and declining trends under RCP4.5 and RCP8.5 (Table 3). The regional ET increasing rate under the RCP8.5 scenario is less steep compared to the other two RCPs during the first 30 years and during the next 20 years, however, the increasing rates of the corresponding NPP under RCP8.5 are the largest, even the ET shows a decreasing trend during the next 20 years under RCP8.5. This may result from the difference of CO\({}_{2}\) fertilization effects induced by the CO\({}_{2}\) concentration differences under different RCPs. Compared to the first 30 years, as the difference of CO\({}_{2}\) concentration increases, this CO\({}_{2}\) fertilization effect is much clearer during the next 20 years. Figure 4: The spatial patterns of annual mean temperature difference between 2006 and 2055 under RCP2.6 (**a**), RCP4.5 (**b**), and RCP8.5 (**c**). Figure 5: Temporal variation of regional mean annual NPP (**a**) and ET (**b**) from 2006 to 2055 under RCP2.6, RCP4.5 and RCP8.5. The spatial patterns of the NPP differences between 2006 and 2055 under the three RCPs indicate that the annual NPP shows an increasing trend in most parts of Tianshan North Slope, especially in the central and western area, where the CRP is widely distributed (Figures 1b and 6). In response to the climate change, the annual NPP decreases slightly in the northeastern part of Tianshan North Slope under RCP2.6 (Figure 6a). Compared to RCP2.6 and RCP4.5, the increase of NPP under RCP8.5 is the largest both in intensity and area (Figure 6). Similar to the spatial patterns of the NPP differences, the strong ET increase mainly occurs in the central and western part of the Tianshan North Slope (Figure 7). Under RCP2.6, the ET decreases in the northeastern part and the high mountains of Tianshan North Slope, which could be induced by the decline of precipitation in the northeastern part and the decline of the temperature in the high mountains. Moreover, the decline of ET in the high mountains under RCP4.5 and RCP8.5 shares the same pattern of the decline in temperature (Figure 7b,c). SPT is mainly present in the high mountains, and its growth is limited by temperature.