Carbon model worksheet 1 answers

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).