Regional contrasts of ecosystem productivity sensitivity to atmospheric CO₂ growth across East Asia

Abstract. Elevated global atmospheric CO₂ intensifies the complexity of climate variability and ecosystem productivity, and its impact on terrestrial ecosystems carbon cycle remains unclear. Using twelve Dynamic Global Vegetation Models (DGVMs) in Trends in land carbon cycle datasets and Global Carbon Budget dataset, we quantified the sensitivity of ecosystem productivity-defined as the rate of change in productivity with global atmospheric CO₂ growth rate-in East Asia from 1959 to 2023. Most DGVMs showed net ecosystem production sensitivity as negative, implying a weakening of terrestrial carbon absorption capacity in response to elevated atmospheric CO₂. By separating East Asia into monsoon and non-monsoon regions, we examined the temporal changes in gross primary productivity sensitivity, which has been decreasing in both regions since the late 1990s. These productivity responses were primarily controlled by soil moisture sensitivity in non-monsoon region, whereas photosynthetically active radiation emerged as the key factor in monsoon region. Furthermore, the dominance of croplands and woody savannas in monsoon region contributes to regional difference in the mechanism associated with vegetation productivity to atmospheric CO₂ growth. By considering regional climate systems and vegetation characteristics, this study highlights that environmental and structural differences influence the ecosystem response to atmospheric CO₂ growth. Ultimately, our findings suggest that considering regionally distinct climate-vegetation feedbacks is essential for improving the accuracy of global carbon cycle projections under future climate change.