Research Highlights

Recent highlights of our science

CESM1(BGC) Historical Carbon Cycle Characterized

December 15, 2014

Objective

Characterize the fidelity of the Community Earth System Model (CESM1) carbon cycle with terrestrial carbon--nitrogen dynamics and an ocean biogeochemical model.

Approach

Two sets of preindustrial-control and 20th century experiments were initialized and forced with prescribed CO2 emissions (PROG) and CO2 mole fractions (PRES).

Time series of 20th century (a) 2-m air temperature anomalies and (b) surface net CO2 tracer compared to observations.
Time series of 20th century (a) 2-m air temperature anomalies and (b) surface net CO2 tracer compared to observations.

Results/Impacts

  • CESM1(BGC) configuration used for CMIP5 experiments was introduced and described.
  • Model broadly reproduced observed 20th century carbon cycle, but exhibited notable biases.
  • Model exhibited excessive increase in atmospheric CO2 due to weak land and ocean carbon uptake.
  • Model had a weak seasonal cycle of atmospheric CO2 in the Northern Hemisphere due to seasonal biases in land-to-air CO2 fluxes.
  • Model response of atmospheric CO2 to El Niño Southern Oscillation was too weak.

Lindsay, Keith, Gordon B. Bonan, Scott C. Doney, Forrest M. Hoffman, David M. Lawrence, Matthew C. Long, Natalie M. Mahowald, J. Keith Moore, James T. Randerson, and Peter E. Thornton. December 15, 2014. “Preindustrial-Control and Twentieth-Century Carbon Cycle Experiments with the Earth System Model CESM1(BGC).” J. Clim., 27(24):8981–9005. doi:10.1175/JCLI-D-12-00565.1.

CESM1(BGC) Historical Carbon Cycle Characterized
Click to download this highlight slide