Simulating the Response of the Ocean for a Doubling of Carbon Dioxide in the Atmosphere

Abstract: The uptake of carbon in the ocean may change with global warming, which can have significant feedback effects on the climate. To investigate the change, a two box ocean model has been used to simulate the temperature and carbon content in the atmosphere, in a shallow and deep layer of the ocean, when doubling the amount of carbon dioxide in the atmosphere. The results were compared with a low-resolution Earth system model called cGENIE, which is a more complex model. The two box ocean model showed an increase of temperature in the ocean by 1.2°C. A similar response was simulated in cGENIE where the shallow ocean (0-80 meters depth) increased by 0.22°C. The deep ocean (down to 3600 meters) warmed by 0.48°C. The carbon content followed the same behavior in both models. Carbon dioxide in the atmosphere was absorbed by the ocean after the initial doubling. As the ocean absorbed carbon dioxide the radiative forcing decreased again, reducing the warming effect. The two box model is a conceptual model of the carbon cycle in the ocean that can provide a useful illustration of the key balance of carbon in the climate system, despite the many simplifications.