Carbon cycle modelling

For the interpretation of atmospheric CO2 measured in ice cores various different carbon cycle models are used depending on the timescale and question of interest. They are all used to test various hypothesis how changes in the climate system might have affected the global carbon cycle.

1. For long-term changes (10 kyr to 2 Myr) we use the Box model of the Isotopic Carbon cYCLE (BICYCLE)  consisting of a modified version of a globally averaged box model of the terrestrial biosphere coupled to an updated version of a multibox model of the ocean/atmosphere subsystem.
While the atmosphere consists of one well mixed box only, the global oceans are resolved by 10 homogeneous reservoirs (five surface, two intermediate, three deep). The ocean model is comparable to well tested models such as PANDORA (10 ocean boxes) or CYCLOPS (14 ocean boxes). The terrestrial biosphere is considered globally averaged by seven compartments representing C3 and C4 ground vegetation, trees, and soil carbon with different turnover times. The model includes mass balance equations for the carbon stocks of the biospheric compartments, for DIC, total alkalinity, phosphate (chosen as the limiting macro-nutrient) and oxygen in the 10 oceanic reservoirs, for CO2 in the atmospheric reservoir, and the 13C and 14C isotopic signatures in all of them.