## 5 Conclusions  
Based on process-based models and multisource satellite-observed LAI, GPP, and SIF, this study comprehensively examined the interannual trend in vegetation greenness and productivity and their significance in global drylands from 1982 to 2018 using the Theil-Sen method and the MK test. Two sets of controlled experiments based on the PLS regression method were designed to detect the sensitivity of vegetation growth to the primary influencing factors, and the relative offsets in the contribution to vegetation growth between CO\({}_{2}\), SW, and VPD were eventually measured. The results showed that vegetation greenness and productivity have substantially increased at an average rate of 1.70 \(\times\) 10\({}^{-3}\) m\({}^{2}\cdot\)m\({}^{-2}\) (LAI, \(p\) < 0.05) and 4.10 \(\times\) 10\({}^{-3}\) gC\(\cdot\)m\({}^{-2}\cdot\)d\({}^{-1}\) (GPP, \(p\) < 0.05) across global drylands since the early 1980s. Additionally, 22 ESMs from the CMIP6 project consistently predicted the sustained greening trend over global drylands in different SSP scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5) from 2019 to 2100. Reducing SW-induced decreases in LAI in dryland ecosystems was larger than that of VPD, and dryland vegetation was restricted more strongly by decreasing SW at the 7-28 cm soil depth. Great offsets existed in the contributions between enhanced water constraints and CO\({}_{2}\) fertilization, in which the former offset approximately 38.49% of the beneficial effects of the latter to vegetation changes. Process-based models supported the satellite-observed finding that increasing water constraints failed to overwhelmingly offset the significant effect of CO\({}_{2}\) fertilization on dryland ecosystems. This work emphasizes the differences in the impact of SW at different soil depths on vegetation dynamics across global drylands and highlights the far-reaching importance of significant CO2 fertilization to greening dryland ecosystems despite increasing atmospheric and SW constraints. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/rs16244733/s1](https://www.mdpi.com/article/10.3390/rs16244733/s1)]([https://www.mdpi.com/article/10.3390/rs16244733/s1](https://www.mdpi.com/article/10.3390/rs16244733/s1)), Figure S1. Spatial distribution of global arid and semiarid areas derived by the Aridity Index (AI); Figure S2. The temporal trend of LAI and GPP derived by 11 state-of-the-art ecosystem models from the TRENDY project under the S0 (no forcing changes), S1 (only varying CO2 concentration), S2 (varying CO2 concentration and climate), and S3 (varying CO2 concentration, climate, and LCC) scenarios across global drylands from 1982 to 2018. (a) LAI and (b) GPP; Figure S3. The interannual trend in climatic factors in global drylands during 1982-2018: (a) CO2; (b) SW at different depths of 0-7, 7-28, 28-100, and 100-289 cm; (c) VPD; (d) P; (e) T; and (f) SRAD; Figure S4. Spatial distribution of the interannual trend in main climatic factors across global drylands over the past four decades of 1982-2018: (a) SW, (b) VPD, (c) P, (d) T, and (e) SRAD. Regions labelled by black dots represent those trends that are statistically significant at a 95% significance interval (Mann-Kendall test; \(p<0.05\)); Figure S5. Spatial distribution of the interannual trend in soil water (SW) across global drylands during 1982-2018 at different soil depths: (a) 0-7 cm, (b) 7-28 cm, (c) 28-100 cm, and (d) 100-289 cm. Regions labelled by black dots represent those trends that are statistically significant at a 95% significance interval (Mann-Kendall test; \(p<0.05\)); Figure S6. The partial correlation between GPP changes and CO2 (a,b) VPD (e,f) and SW (c,d) in global drylands during the period of 1982-2018; Figure S7. The partial correlation between SIR changes and CO2 (a,b) VPD (e,f) and SW (c,d) in global drylands during the period of 2000-2018; Figure S8.