Regional contrasts of ecosystem productivity sensitivity to atmospheric CO ₂ growth across East Asia

Elevated global atmospheric CO ₂ intensifies the complexity of climate variability and ecosystem productivity, and its impact on the terrestrial 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 CO ₂ growth rate-in East Asia from 1959 to 2023. Most DGVMs showed net ecosystem production sensitivity as negative, implying an intensification of the inverse relationship with atmospheric CO ₂ growth. By separating East Asia into the 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 the non-monsoon region, whereas photosynthetically active radiation emerged as the key factor in the monsoon region. Furthermore, differences in vegetation structure between the monsoon and non-monsoon regions may contribute to regional differences in the mechanisms associated with vegetation productivity responses to atmospheric CO ₂ growth. By considering regional climate systems and vegetation characteristics, this study highlights that environmental and structural differences influence the ecosystem response to atmospheric CO ₂ 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.