Carbon module
Calculates the change in atmospheric CO2 concentration,
which is the sum of fossil and land-use emissions,
minus ocean and biosphere sinks. The sinks respond dynamically to concentration and temperature.
Java Source Code
Interactions
Affected by: Mitigation or Sres, Climate (biogeochemical feedback), Load-data
Affects: Radiative forcing, Responsibility,
Mitigation (if stabilise concentration)
Carbon Cycle Plot, Carbon Storage Plot
Adjustable parameters
Biosphere sink fertilisation factor
Ocean mixing: vertical diffusivity, sideways mixing, upwelling, high-latitude mixing, gas exchange rate
Ocean chemistry: temperature feedback option, calculation method menu
Historical deforestation by mass balance (expert)
How it works
The carbon cycle is based on the Bern model, as used by IPCC.
This was originally calibrated using chemical tracer and isotope data, and its predictions fall in the mid-range of model intercomparisons.
Emissions
Historical fossil CO2 emissions are from CDIAC (add ref!) and land use change CO2 emissions data is from Houghton et al (add ref!),
(unless you select the option to calculate historical land-use by mass-balance, fixing the atmospheric CO2 using the measured data from Mauna Loa).
Future emissions are determined either by the mitigation module (with a fixed fossil:landuse ratio) or by SRES scenarios.
Ocean sink: HILDA model
(HILDA = High-Latitude Diffusion Advection)
low-latitude (84% surface) divided into 36 layers
depth-dependent vertical diffusion between layers
high-latitude box, well-mixed
horizontal advection between HL & LL
slow upwelling loop (down in HL, up in LL)
surface layer (HL and LL) exchanging with atmosphere
non-linear carbonate chemistry with feedback from temperature
Terrestrial Biosphere sink
4-box biosphere :
green, wood, soil, humus boxes,
linear fluxes between boxes and to atmosphere
non-linear "CO2 fertilisation" factor b
(note further development below)
Calculation method
The entire system is solved using an efficient eigenvector calculation method with a ramp function for non-linear fluxes.
See also:
Eigenvector Calculation Method
Correspondence with IPCC predictions
Carbon Cycle plot , Discussion
Carbon Stoarge plot , See contents of each box
Joos et al 2001
IPCC-TAR WG1 Chapter 3
Future development
The simple 4-box biosphere is based on Bern model as used in IPCC-SAR.
The Bern-CC biosphere as used for IPCC-TAR
This will include a gridded dynamic vegetation model with many plant functional types,
dependent on temperature an precipitation within each gridcell.
A java implementation of this is under development,
however the older model gives similar results.
Plots to show the concentration with ocean depth may also be useful.