A group of scientists at the Bjerknes Centre for Climate Research presented the results concerning future reduction of anthropogenic carbon taken up by ocean and land in a recent article in Geoscientific Model Development. Jerry Tjiputra and co-workers have developed the fully coupled climate-carbon cycle model, which was achieved by implementing terrestrial and oceanic carbon cycle model components into the Bergen Climate Model. They have used this model to simulate future carbon uptake based on one of the Intergovernmental Panel for Climate Change (IPCC)’s future carbon emission scenarios (Figure 1a).
Reduced carbon uptake
The simulation reveals that future warming over land will increase the respiration rate of plants, which will release more CO2 to the atmosphere. This leads to an overall reduction in the simulated terrestrial carbon uptake as compared to a simulation without anthropogenic climate change (Figure 1c).
Over the ocean, increasing surface temperatures, especially at high latitudes, reduces the solubility of CO2 gas in seawater, and hence slows down the oceanic uptake rate of carbon (Figure 1b).
The results contradict the conservative assumption that the ocean-uptake-rate will continue to intensify as the atmospheric CO2 continues to increase. The decreasing amount of anthropogenic carbon taken up by ocean and land implies that more carbon will remain in the atmosphere, and therefore intensify future climate change.
A new generation earth system models
The creation of a new generation of climate models, the so-called earth system models, is under way. The Norwegian contribution is the Norwegian Earth System Model (NorESM) that is now being developed at the Bjerknes Centre in collaboration with the University of Oslo and the National Center for Atmospheric Research (NCAR) in the United States. The improved model will include more realistic processes such as the nitrogen cycle and aerosol feedbacks. In the near future, the scientists will apply the model to explore the relevant mitigation scenarios, such as aiming to stabilize climate change to below 2 degree Celsius warming.