This study highlights the underestimation of the impact of vegetation compound droughts (VCDs) on terrestrial carbon uptake. VCDs, defined as periods of low soil moisture (SM) and high vapor pressure deficit (VPD) that severely limit vegetation carbon uptake, are more frequent and severe than previously thought. The widely used quantile-based approach identifies only 11% of VCDs and 26% of global GPP anomalies due to VCDs, leading to an underestimation of their adverse effects. The frequency and intensity of VCDs are projected to increase further, regardless of whether the CO₂ fertilization effect is considered. These findings emphasize the need for improved understanding and adaptation measures to address the risks of VCDs. VCDs are identified based on the impact of SM and VPD on GPP, rather than using extreme quantile thresholds. This approach reveals that VCDs occur more frequently in mid- and low-latitude regions, particularly in drylands, where they cause significant negative GPP anomalies. The impact-based approach also shows that VCDs have a larger effect on GPP than soil droughts or atmospheric aridity alone, especially in dryland ecosystems. The study uses observational data and CMIP6 simulations to analyze the frequency, intensity, and severity of VCDs. Results show that VCDs are more frequent and severe than statistical compound droughts (SCDs), with VCDs causing larger GPP anomalies. The frequency of VCDs is projected to increase in future scenarios, particularly under high-emission scenarios, leading to greater carbon loss. The impact-based approach accounts for regional differences in GPP responses to SM and VPD, providing a more accurate assessment of VCDs and their impacts on terrestrial carbon uptake. The study also highlights the vulnerability of dryland ecosystems to VCDs, which contribute significantly to global carbon sink variability. The underestimation of VCDs using the quantile-based approach has led to an underestimation of their risks, particularly in dryland regions. The findings suggest that future climate change will increase the frequency and severity of VCDs, with significant implications for terrestrial carbon uptake and ecosystem productivity. The study calls for improved mitigation strategies, such as reducing fossil fuel use, improving land management, and restoring forests, to address the increased climate risks.This study highlights the underestimation of the impact of vegetation compound droughts (VCDs) on terrestrial carbon uptake. VCDs, defined as periods of low soil moisture (SM) and high vapor pressure deficit (VPD) that severely limit vegetation carbon uptake, are more frequent and severe than previously thought. The widely used quantile-based approach identifies only 11% of VCDs and 26% of global GPP anomalies due to VCDs, leading to an underestimation of their adverse effects. The frequency and intensity of VCDs are projected to increase further, regardless of whether the CO₂ fertilization effect is considered. These findings emphasize the need for improved understanding and adaptation measures to address the risks of VCDs. VCDs are identified based on the impact of SM and VPD on GPP, rather than using extreme quantile thresholds. This approach reveals that VCDs occur more frequently in mid- and low-latitude regions, particularly in drylands, where they cause significant negative GPP anomalies. The impact-based approach also shows that VCDs have a larger effect on GPP than soil droughts or atmospheric aridity alone, especially in dryland ecosystems. The study uses observational data and CMIP6 simulations to analyze the frequency, intensity, and severity of VCDs. Results show that VCDs are more frequent and severe than statistical compound droughts (SCDs), with VCDs causing larger GPP anomalies. The frequency of VCDs is projected to increase in future scenarios, particularly under high-emission scenarios, leading to greater carbon loss. The impact-based approach accounts for regional differences in GPP responses to SM and VPD, providing a more accurate assessment of VCDs and their impacts on terrestrial carbon uptake. The study also highlights the vulnerability of dryland ecosystems to VCDs, which contribute significantly to global carbon sink variability. The underestimation of VCDs using the quantile-based approach has led to an underestimation of their risks, particularly in dryland regions. The findings suggest that future climate change will increase the frequency and severity of VCDs, with significant implications for terrestrial carbon uptake and ecosystem productivity. The study calls for improved mitigation strategies, such as reducing fossil fuel use, improving land management, and restoring forests, to address the increased climate risks.