THE IMPACT OF CO2 FERTILIZATION ON THE GLOBAL TERRESTRIAL CARBON CYCLE AND INTERANNUAL CHANGES IN CO2 STUDIED THROUGH A CARBON CYCLE DATA ASSIMILATION SYSTEM

• Main Authors: T. Kato, M. Scholze, W. Knorr
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Tundra
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.586.35; http://www.fastopt.com/papers/katoal09.pdf

Based on precise ground measurement of atmospheric CO2 concentration and satellite remote sensing, it is claimed that terrestrial vegetation has increased their activities gradually, and their significance is becoming larger in interannual and seasonal changes of atmospheric CO2 during the last several decades. Among many possible causes, the fertilization effect of CO2 rising on photosynthesis is known to be one of the most possible factors, which could be induced by enhanced terrestrial ecosystem productivity, affecting those atmospheric CO2 changes. This study compares two different model simulations, which are calculated by the Carbon Cycle Data Assimilation System (CCDAS) using constant CO2 concentration and transient CO2 concentration respectively. The result of the CO2 fertilization is a large enhancement of net ecosystem productivity in forests and large decrease of that in tundra and savanna. Difference in global averaged net ecosystem productivity among the two results fluctuate largely. However, there is only little difference in the long-term trend of the growth rate and the amplitude of CO2 seasonality among them. These indicate that CO2 fertilization has affected ecosystem carbon fluxes largely, but did not impact interannual changes in the atmospheric CO2 concentration seasonality.