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www.geosci-model-dev-discuss.net/2/845/2009/
doi:10.5194/gmdd-2-845-2009
© Author(s) 2009. This work is distributed
under the Creative Commons Attribution 3.0 License.
Bergen earth system model (BCM-C): model description and regional climate-carbon cycle feedbacks assessment
1University of Bergen, Department of Geophysics, Allégaten 70, 5007 Bergen, Norway
2Bjerknes Centre for Climate Research, Allégaten 55, 5007 Bergen, Norway
3Nansen Environmental and Remote Sensing Center, Thormølensgate 47, 5006 Bergen, Norway
4Bert Bolin Centre for Climate Research, Svante Arrhenius väg 8 C, 106 91 Stockholm, Sweden
Abstract. A complex earth system model is developed by coupling terrestrial and oceanic carbon cycle models into the Bergen Climate Model. Two model simulations (one with climate change inclusions and the other without) are generated to study the large scale climate and carbon cycle variability as well as its feedback for the period 1850–2100. The simulations are performed based on historical and future IPCC CO2 emission scenarios. Globally, a pronounced positive climate-carbon cycle feedback is simulated by the terrestrial carbon cycle model, but less significant signals are shown by the oceanic counterpart. Over land, the regional climate-carbon cycle feedback is highlighted by increased soil respiration, which exceeds the enhanced production due to the atmospheric CO2 fertilization effect, in the equatorial and northern hemisphere mid-latitude regions. Although the model generates nearly identical global oceanic carbon uptake between the coupled and uncoupled simulations, our analysis indicates that there are substantial temporal and spatial variations in air-sea CO2 fluxes. This implies feedback mechanisms act inhomogeneously in different ocean regions. In the North Atlantic subpolar gyre, the simulated future cooling of SST improves the CO2 gas solubility in seawater, and hence reduces the strength of positive climate-carbon cycle feedback in this region. In most of the ocean regions, the changes in Revelle factor is dominated by changes in surface pCO2, and not by the warming of SST. Therefore, the solubility feedback is more prominent than the buffer capacity feedback. In our climate change simulation, the opening of Southern Ocean sea ice due to melting allows an additional ~20 Pg C uptake as compared to the simulation without climate change.
Discussion Paper (PDF, 3120 KB) Supplement (306 KB) Interactive Discussion (Closed, 6 Comments) Final Revised Paper (GMD)
Citation: Tjiputra, J. F., Assmann, K., Bentsen, M., Bethke, I., Otterå, O. H., Sturm, C., and Heinze, C.: Bergen earth system model (BCM-C): model description and regional climate-carbon cycle feedbacks assessment, Geosci. Model Dev. Discuss., 2, 845-887, doi:10.5194/gmdd-2-845-2009, 2009. Bibtex EndNote Reference Manager XML
