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.