Description
Projects what share of fossil fuel and land use emissions of CO2 will be aborbed by the biosphere/ocean and what share will remain in the atmosphere.
Input variables
- Global fossil fuel emissions of CO2 (from Regional CO2 emissions module)
- Global CO2 emissions from deforesation (from Land use module)
- Global CO2 sequestration from aforestation (from Land use module)
Key assumptions
The carbon cycle module is based on the Feedback Rich Energy Economy (FREE) model developed by Tom Fiddaman, one of the co-developers of C-LEARN/C-ROADS. For more on FREE, see Fiddaman's MIT doctoral dissertation (1997).
The C-ROADS/C-Learn climate cycle assumes that all global emissions initially go into the atmosphere, where they are then aborbed by three systems:
- biosphere
- mixed ocean layer
- deep ocean layers
Biosphere
The module's biosphere assumptions are a simplified versions of those used in the Integrated Model to Assess the Global Environment IMAGE developed by Rotmans (1990) and the earlier model developed by Goudrian and Ketner (1984).
In C-LEARN/C-ROADS, the biosphere is divided into two sub-systems, biomass and humus.
CO2 uptake by the biosphere, which occurs through plant growth and absorption into soil, is assumed to increase logarithmically with atmospheric concentrations of CO2.
Mixed ocean layer
This module's assumptions about CO2 absorption by the mixed ocean layer (which is assumed to be 75 meters deep) are also based on the IMAGE model developed by Rotmans (1990) and the earlier model developed by Goudrian and Ketner (1984).
The ocean's capacity to absorb CO2 decreases as atmospheric concentration of CO2 rises.
Deep ocean layers
The module's assumptions about CO2 absorption by the deep ocean are similar to those in Oeschger et al., but with fewer layers.
C-LEARN/C-ROADS employs five 200 meter middle layers, and five 560 meter deep ocean layers.
Absorption time increases with depth.
For more detail
The assumptions concerning CO2 absorption by the biosphere, mixed ocean layer, and deep ocean layers are described in greater detail in C-ROADS Simulator Reference Guide pp. 49-61.
Output variables
- Future CO2 removals by biosphere
- Future CO2 removals by ocean
- Future atmospheric concentrations of CO2 (feeds into Climate module)
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