Carbon-nitrogen interactions regulate climate-carbon cycle feedbacks: results from an atmosphere-ocean general circulation model

作者：PETER E. THORNTON, Scott C. Doney, Keith Lindsay, Jefferson Keith Moore, N. M. Mahowald, James T. Randerson, INEZ Y. FUNG, Jean‐François Lamarque, Johannes J. Feddema, Y.-H. Lee · 发表于：Biogeosciences · 年份：2009 · DOI：10.5194/bg-6-2099-2009 · 被引用次数：489 · 研究领域：Atmospheric and Environmental Gas Dynamics、Climate variability and models、Soil Carbon and Nitrogen Dynamics

Abstract. Inclusion of fundamental ecological interactions between carbon and nitrogen cycles in the land component of an atmosphere-ocean general circulation model (AOGCM) leads to decreased carbon uptake associated with CO2 fertilization, and increased carbon uptake associated with warming of the climate system. The balance of these two opposing effects is to reduce the fraction of anthropogenic CO2 predicted to be sequestered in land ecosystems. The primary mechanism responsible for increased land carbon storage under radiatively forced climate change is shown to be fertilization of plant growth by increased mineralization of nitrogen directly associated with increased decomposition of soil organic matter under a warming climate, which in this particular model results in a negative gain for the climate-carbon feedback. Estimates for the land and ocean sink fractions of recent anthropogenic emissions are individually within the range of observational estimates, but the combined land plus ocean sink fractions produce an airborne fraction which is too high compared to observations. This bias is likely due in part to an underestimation of the ocean sink fraction. Our results show a significant growth in the airborne fraction of anthropogenic CO2 emissions over the coming century, attributable in part to a steady decline in the ocean sink fraction. Comparison to experimental studies on the fate of radio-labeled nitrogen tracers in temperate forests indicates that the model repr...