Carbon model worksheet 1 answers

A schematic of the organic and inorganic components of the modelled carbon cycle.

http://www.noc.soton.ac.uk/jmodels/images/wiki/cmodel.jpg
The article provides answers to the questions posed in the carbon model worksheet 1.

Worksheet answers

1. Run the model until year 2100, without fossil fuels. What is the atmospheric CO₂ concentration at the end of the run? Now add 4000 Gt C of fossil fuels between 1900 and 2300 AD. How high does atmospheric CO₂ go by year 2100?
   

   Unperturbed value = 282 ppm. With 4000 Gt C it rises to 975 ppm by year 2100.

2. Double the river flux of phosphorus. What impact does this have on year 2100 atm. CO₂?
   

   960 ppm (-15 ppm).

3. Double the river flux of nitrate (this has an impact on alkalinity and therefore on atmospheric CO₂. What difference does this make to the rise in CO₂ by year 2100?
   

   982 ppm (+7 ppm).

4. Halve the mixing strength between: (1) surface and middle boxes, (2) middle and deep boxes, and (3) both simultaneously. What affect do those changes have on atmospheric CO₂?
   

   (1) 966 ppm (-9 ppm); (2) 1007 ppm (+32 ppm); and (3) 996 ppm (+21 ppm).

Other related pages

• Carbon model overview
• Carbon model details
• Carbon model pros
• Carbon model cons
• Carbon model worksheets
• Phosphorus model overview

References

• Chuck, A. et al. (2005). The oceanic response to carbon emissions over the next century: investigation using three ocean carbon cycle models. Tellus B 57, 70-86.
• Tyrrell, T. (1999). The relative influences of nitrogen and phosphorus on oceanic primary production. Nature 400, 525–531.
• Tyrrell, T. et al. (2007). The long-term legacy of fossil fuels. Tellus B 59, 664-672.

External links

• Description of the chemical element carbon, Wikipedia
• Description of the carbon cycle, Wikipedia
• Description of the chemical element phosphorus, Wikipedia
• Description of the phosphorus cycle, Wikipedia