Climate impacts on China's terrestrial carbon cycle: An assessment with the dynamic land ecosystem model

China has very complex geographical and geological environments, and is strongly influenced by monsoon climate, which results in substantial temporal and spatial climate variability. China's climate has experienced enormous changes in the past 40 years (1961-2000). We found air temperature and precipitation increased 0.21°C and 5.88 mm (3.8% increase) per decade, respectively in China from 1961 to 2000. During the same time period, global average temperature and precipitation only increased about 0.1°C and 0.05-1.0% per decade, respectively. To assess climate impacts on China's terrestrial ecosystems, we used the Dynamic Land Ecosystem Model (DLEM), a daily time-step and carbon, nitrogen, and water coupled biogeochemical model, to simulate effects of seasonal, interannual and spatial climate variability on net primary production (NPP) and net carbon exchange (NCE). Based on DLEM model simulation results, we found climate change has caused CO₂ release into the atmosphere, while NPP decreased slightly from 1961 to 2000. In the last 10 years (1990s) climate change has caused about 50% of the total released CO₂ in the 40-year period, while NPP only slightly decreased. From seasonal comparisons, we found summer was the major contributor to CO ₂ release, while spring was the major contributor to CO₂ sink. Mean annual NCE increased greatly with increased monsoon intensity and was higher in the years of El Niño.