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Although there is mounting concern about how high vapor pressure deficit (VPD) and low soil moisture (SM) affect ecosystem productivity, their relative importance is still under debate. Here, we comprehensively quantified the relative impacts of these two factors on ecosystem gross primary production (GPP) using observations from a global network of eddy‐covariance towers and two approaches (sensitivity analysis and linear regression model). Both approaches agree that a higher percentage of sites experience GPP reduction from high VPD than from low SM over the growing season. However, the constraint of high VPD and low SM on GPP reduction is tightly linked with climates and plant functional types. Humid and mesic ecosystems including forests and grasslands are dominated by VPD, while the semi‐arid and arid ecosystems including shrublands and savannas are dominated by SM. The varying dominant role of these two factors on GPP is closely related to plant stomatal behavior, as predicted by a stomatal conductance model. Additionally, we highlight the non‐linear impact of SM on GPP during droughts and the possible underestimation of the SM effects for deep‐rooted plants when only using surface‐layer SM. Our results shed light on a better understanding of the impacts of VPD and SM on vegetation productivity, with important implications for modeling the response and feedback of ecosystem dynamics to current and future climates. Plain Language Summary: Vapor pressure deficit (VPD) has increased over recent decades and is expected to continue to rise in the future with climate change. Projected changes in precipitation and soil moisture (SM) are more uncertain with higher spatial variability and larger projected intermodel spread. Given the global environmental changes underway, it is of paramount importance to independently assess the effects of high VPD and low SM on ecosystem productivity. Here, we assessed the relative impacts of these two factors on ecosystem gross primary production (GPP) using observations from a global network of eddy‐covariance towers. We find that reductions in GPP are more attributable to high VPD rather than low SM, on average. The constraint of these two factors on GPP reduction is tightly linked with climates and plant functional types. We further emphasize the amplified impact of SM on GPP during droughts and the need to consider using deep SM. Overall, our findings provide a more comprehensive and quantitative attribution of the impact of increasing atmospheric dryness and changes in soil water deficit on ecosystem productivity in a changing climate. Key Points: Reductions in gross primary production (GPP) are more attributable to high vapor pressure deficit (VPD) rather than low soil moisture (SM) across all sitesThe constraint of high VPD and low SM on GPP reduction is tightly linked with climates and plant functional typesOur results highlight that the relative and non‐linear impacts of VPD and SM on GPP should be adequately considered [ABSTRACT FROM AUTHOR]

This study calibrated and downscaled data from four scenarios in the Coupled Model Intercomparison Project Phase 6 (CMIP6) to drive the distributed hydrological model soil and water assessment tool (SWAT). Hereafter, this study systematically quantified the changes in streamflow under future climatic conditions in the middle-upper reaches of the Weihe River Basin. The results show that, compared with the base period (1991–2000), the low-emission SSP1-2.6 scenarios resulted in future streamflow reductions to values less than those recorded in the baseline period. Furthermore, the same is true for medium and high-emission SSP3-7.0 scenarios. Under the SSP1-2.6 emission scenarios, streamflow in the 2030s, 2040s, 2050s and 2060s will be reduced by 40%, 50%, 31%, and 38%, respectively. Under the SSP3-7.0 emission 12 scenarios, streamflow will decrease by 44%, 20%, 34%, and 7% in the 2023s, 2040s, 2050s and 2060s, separately. These results supply support for water resource management and water use in the Kuan-chung Plain in the future climate change. [ABSTRACT FROM AUTHOR]

• Quantified future thaw trends of frozen carbon on the TP based on 15 GCMs. • Compared frozen carbon thaw under two schemes with and without permafrost area shrinkage. • Underscored the pivotal role of permafrost area shrinkage in quantifying frozen carbon thaw. • Emphasized the tremendous potential for future carbon emissions from the TP permafrost area. Permafrost degradation on the Tibetan Plateau (TP) is anticipated to result in the thaw of permafrost carbon. Existing studies have been conducted to assess the future thaw of frozen carbon on the TP, primarily focusing on the deepening of the active layer while neglecting the impact of permafrost area shrinkage. This oversight may lead to a significant underestimation of the potential thaw of frozen carbon. Our research underscores the pivotal role of permafrost area shrinkage in estimating the future thaw of frozen carbon. Our findings reveal that when the combined effects of permafrost area shrinkage and active layer deepening are considered, the thaw rates of frozen carbon in various radiative forcing scenarios are nearly four times those based on active layer deepening alone. Notably, our results demonstrate substantial thaw of frozen organic carbon in the TP permafrost area under all four future scenarios: In the low radiative forcing scenario SSP1-2.6, it is predicted that 55.4 % of the organic carbon in the permafrost area 0–10 m soils will be in a state of thaw by 2100, and more than 90 % in the high radiative forcing scenario SSP5-8.5. This substantial thaw is poised to diminish the TP's current carbon sink function significantly. Our study emphasizes that as global warming persists, frozen carbon in permafrost areas will play a more active role in global carbon cycle processes in the future. Furthermore, we stress the importance of considering permafrost area shrinkage in understanding the thaw of frozen carbon, providing valuable insights for carbon balance studies on the TP. [ABSTRACT FROM AUTHOR]