Bergen Earth system model (BCM-C): model description and regional climate-carbon cycle feedbacks assessment

Abstract

We developed a complex Earth system model by coupling terrestrial and oceanic carbon cycle components into the Bergen Climate Model. For this study, we have generated two model simulations (one with climate change inclusions and the other without) 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 CO<sub>2</sub> emission scenarios. Globally, a pronounced positive climate-carbon cycle feedback is simulated by the terrestrial carbon cycle model, but smaller 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 CO<sub>2</sub> fertilization effect, in the equatorial and northern hemisphere mid-latitude regions. For the ocean, our analysis indicates that there are substantial temporal and spatial variations in climate impact on the air-sea CO<sub>2</sub> 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 CO<sub>2</sub> gas solubility in seawater and, hence, reduces the strength of positive climate carbon cycle feedback in this region. In most ocean regions, the changes in the Revelle factor is dominated by changes in surface <i>p</i>CO<sub>2</sub>, and not by the warming of SST. Therefore, the solubility-associated positive feedback is more prominent than the buffer capacity feedback. In our climate change simulation, the retreat of Southern Ocean sea ice due to melting allows an additional ~20 Pg C uptake as compared to the simulation without climate change

Role of volcanic forcing on future global carbon cycle

“…Thus, only sulfur aerosols are included in this study. The BCM-C future projection and climatecarbon cycle feedback under the SRES-A2 have been evaluated and is well within the range of other models (Friedlingstein et al, 2006;Tjiputra et al, 2010).…”

“…The LPJ is a large-scale dynamic vegetation model and contains 10 plant functional types. A more detailed description of the BCM-C model and its evaluation are available in Tjiputra et al (2010).…”

“…Earth system models, which contain interactions between the atmospheric and oceanic physics coupled with the global carbon cycle, are useful tools for predicting how future climate would evolve under a given anthropogenic greenhouse gas emission scenario. Recent studies using such models have indicated that future climate change will reduce the efficiency of the Earth system to absorb the emitted anthropogenic carbon, and would hence provide a positive feedback (Friedlingstein et al, 2006;Crueger et al, 2008;Tjiputra et al, 2010). Those studies, however, did not take into account not yet predictable factors such as volcanic eruptions or similar external forcings.…”

Oxygen and indicators of stress for marine life in multi-model global warming projections

“…The Bergen Earth System Model coupled with terrestrial and oceanic carbon cycle models (BCM-C) is described in detail in Tjiputra et al (2010) Model (MICOM) and is documented in Bleck and Smith (1990) and Bleck et al (1992). Updates to the model code are described in Bentsen et al (2004) and Assmann et al (2010).…”

MIROC-ESM 2010: model description and basic results of CMIP5-20c3m experiments

“…Tjiputra et al, 2010;Weaver et al, 2001;Hill et al, 2004;Redler et al, 2010). This work describes the structure and performances of an ESM developed on the basis of the version presented by Kawamiya et al (2005) at the Japan Agency for MarineEarth Science and Technology (JAMSTEC) in collaboration with, among others, the University of Tokyo and the National Institute for Environmental Studies (NIES).…”