Influence of the carbon cycle on the attribution of responsibility for climate change

The carbon cycle is one of the fundamental climate change issues. Its long-term evolution largely affects the amplitude and trend of human-induced climate change, as well as the formulation and implementation of emission reduction policy and technology for stabilizing the atmospheric CO₂ concentration. Two earth system models incorporating the global carbon cycle, the Community Earth System Model and the Beijing Normal University-Earth System Model, were used to investigate the effect of the carbon cycle on the attribution of the historical responsibility for climate change. The simulations show that when compared with the criterion based on cumulative emissions, the developed (developing) countries’ responsibility is reduced (increased) by 6 %–10 % using atmospheric CO₂ concentration as the criterion. This discrepancy is attributed to the fact that the developed world contributed approximately 61 %–68 % (61 %–64 %) to the change in global oceanic (terrestrial) carbon sequestration for the period from 1850 to 2005, whereas the developing world contributed approximately 32 %–49 % (36 %–39 %). Under a developed world emissions scenario, the relatively larger uptake of global carbon sinks reduced the developed countries’ responsibility for carbon emissions but increased their responsibility for global ocean acidification (68 %). In addition, the large emissions from the developed world reduced the efficiency of the global carbon sinks, which may affect the long-term carbon sequestration and exacerbate global warming in the future. Therefore, it is necessary to further consider the interaction between carbon emissions and the carbon cycle when formulating emission reduction policy.