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Keywords:

  • terrestrial carbon balance;
  • terrestrial biosphere modeling;
  • carbon cycle;
  • nitrogen cycle;
  • nitrogen deposition

[1] Global-scale results of the new O-CN terrestrial biosphere model coupling the carbon (C) and nitrogen (N) cycles show that the model produces realistic estimates of present-day C and N stocks and fluxes, despite some regional biases. N availability strongly affects high-latitude foliage area and foliage N, limiting vegetation productivity and present-day high-latitude net C uptake. Anthropogenic N deposition is predicted to have increased net primary productivity due to increases in foliage area and foliage N, contributing 0.2–0.5 Pg C yr−1 to the 1990s global net C uptake. While O-CN's modeled global 1990s terrestrial net C uptake (2.4 Pg C yr−1) is similar to the estimate not accounting for anthropogenic N inputs and N dynamics (2.6 Pg C yr−1), its latitudinal distribution and the sensitivity of the terrestrial C balance to its driving factors are substantially altered by N dynamics, with important implications for future trajectories of the global carbon cycle.