China's terrestrial ecosystem carbon budget in the past and future

China is the world's largest emitter of CO2 and aims to reach carbon neutrality by 2060. However, China's terrestrial ecosystem carbon budget (CB), which is crucial to accelerating the realization of the Paris Agreement goals, has not been accurately quantified. Therefore, we analyzed the spatiotemporal pattern, influencing factors, and future evolution trend of China's CB since the end of the 20th century. The results show that from 1997 to 2020, China emitted about 7.57 Pg of CO2 to the atmosphere annually, however, only about 13.4% (or 1.02 Pg) was offset by the total carbon sinks of the ecosystem (CS). China's carbon neutrality capacity (the ratio of CS to CO2 emissions) in 2020 was only 0.14, which presents a massive challenge in realizing carbon neutrality. The spatial distribution of carbon surplus or deficit areas is significantly controlled by economic development and population. Under the global sustainable development scenario, China's carbon neutrality capacity will increase by 16% from 2025 to 2060, and will peak at around 2032. Our findings provide a scientific basis for CO2 reduction and carbon neutrality strategies, helping formulate effective regional sustainable development strategies.