Earth System Models provide a valuable tool for investigating the interactions of the climate system with the carbon cycle - referred to as carbon-climate feedbacks. Carbon-climate feedbacks have the potential to impact climate by altering atmospheric CO2 concentrations. In my talk, I will present a couple of examples using Earth System Model simulations to investigate carbon-climate interactions and the implications for future global warming and ocean acidification.
In the first example, we use the CO2 emissions scenarios from 4 Representative Concentration Pathways (RCPs) with an Earth System Model to project the future trajectories of ocean acidification with the inclusion of carbon-climate feedbacks. We show that simulated carbon-climate feedbacks can significantly impact the onset of ocean acidification. The impact of the carbon-climate feedback is most significant for the medium (RCP4.5) and low emission (RCP2.6) scenarios. The high sensitivity of the impact of ocean acidification to the carbon-climate feedbacks in the low to medium emissions scenarios is important because our recent commitments to reduce CO2 emissions are trying to move us on to such an emissions scenario.
In the second example, we investigate the potential of Additional Ocean Alkalization to reduce global warming and ocean acidification. For this study, we consider the high (RCP8.5) and low (RCP2.6) emissions scenarios and compare the sensitivity of the system to both global and regional additions of alkalinity. We show the simulated low emissions scenario is more responsive to alkalinity addition than the high emission scenario with a significantly greater reduction in global warming and ocean acidification. It appears the low emissions scenario is more amenable to "geo-engineering" than the high emission scenario.
Earth System Models provide a valuable tool for assessing the consequences of increasing atmospheric CO2 levels and for determining the efficacy of options to mitigate the increased CO2 levels.