Unraveling the Role of Vegetation CO2 Physiological Forcing on Climate Zone Shifts in China

Increasing atmospheric CO2 causes substantial spatial and seasonal changes in air temperature and precipitation through its radiative (RAD) and vegetation physiological (PHY) effects. However, it remains poorly understood on how these two effects impact the integrated climate zone shifts over China. Here, we disentangle the RAD and PHY effects on the shifts of Köppen‐Geiger climate zones from pre‐industrial to 4 × CO2 in China using nine Earth system models. We find that climate zone changes over approximately 56.1% of China, and PHY contributes 15.2% of such changes at 4 × CO2. PHY shifts regional climate to warmer and wetter classifications, shrinking (−42.8%) the arid zone distributions and promoting (26.8%) the tropical zone northward extensions. Our findings highlight the critical role of vegetation in reshaping the overall climate zone distributions, yet introduce potential risk to climate mitigation and adaptation. Plain Language Summary Ongoing rise in atmospheric CO2 not only alters the magnitudes of temperature and precipitation, but also shifts their spatial and seasonal variations, reshaping climate zone distributions. Vegetation amplifies global warming and modulates precipitation through its physiological response (PHY) to rising CO2, but how this process affects the local climate zone shifts is understudied, especially in China. Using nine CMIP6 Earth system models, we find that climate zone undergoes shifts across 56.1% of China at 4 × CO2, and PHY contributes 15.2% of such changes. PHY aids the northward expansions of tropical and temperate zones, and generally shifts the regions to warmer and wetter climate from pre‐industrial to 4 × CO2. Importantly, PHY diminishes (−42.8%) the arid zone coverage, indicating an important role of vegetation to alleviate water stress in those regions. Strong PHY contributions to the total climate zone area changes caused by rising CO2 emerges in Shandong, Shanxi, Ningxia, Guangdong and Guangxi at 4 × CO2. Our results clarify the climate zone shifts at 4 × CO2 and unravel the role of vegetation physiological response on shifting future climate zone distributions in China, providing new perspective on the role of vegetation in climate system. Key Points Climate zone shifts across 56.1% of land area in China at 4 × CO2, 15.2% of which is contributed by vegetation CO2 physiological forcing CO2 physiological forcing shifts the regions to a warmer climate through lifting temperature, expanding tropical zone nort