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Carbon Cycle

by Systems&Cycles (Submitted: 06/06/2013)

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WHAT IS IT?

Carbon Cycle models the fast carbon cycle. The model is intended to examine the effect of human activities on the amount of Carbon in the atmosphere and the upper ocean. Carbon is reported in gigatons. Upper ocean pH is shown.

The model can be initialized to two settings: One represents conditions in 2010; the other represents pre-industrial conditions. The 2010 setting allows for growth of terrestrial biomass. Terrestrial biomass decreases in the 1710 scenario to simulate deforestation for fuel and agriculture.

HOW IT WORKS

Carbon reservoirs and fluxes, especially for the 2010 scenario, are based on the diagram at http://earthobservatory.nasa.gov/Features/CarbonCycle/ (except that I used a terrrestrial plant biomss of 600). The size of the reservoirs are roughly proportionate to the values given in the diagram, although the Deep ocean is somewhat smaller than it should be.

The pools of Carbon monitored are the atmosphere, the upper ocean, and the deposition of calcium-shelled organisms. The sources of Carbon are: emissions, ocean photosynthesis, and land plant (forest) photosynthesis. Land plant photosynthesis and respiration are proprtional to land plant biomas.
Sinks include ocean respiration, landplant respiration, soil respiration, and tree growth. Soil respiration increases as forest is removed. Calcium-shelled organisms is the long-tern sink of carbon in this model. The amount of calcification can be adjusted, but it is also automatically affected by the concentration of Carbon in the upper ocean. The object that sinks to indicate calcification is a coccolithophore!

The absorption of Carbon by the ocean is affected by the ratio of Carbon in the ocean surface over the ratio of Carbon in the atmsophere. Carbon can go in either direction depending on this ratio. I used 8/10 as a base ratio.

HOW TO USE IT

Use the diagram at http://earthobservatory.nasa.gov/Features/CarbonCycle/ as a reference.
Forest can be added to the initial land plant biomass. Ocean photosynthesis can be increased initially or yearly.
Hints:
If you have difficulty adjusting a slider to an exact value, you can right click it to edit it and type in the value you desire.

THINGS TO NOTICE

You can make the model crash by adjusting the value of a variable higher or lower. What happens to cause the crash?
Output of emissions is given the shape of little factories. Once in the atmosphere, all carbon has the same probability of being removed by photosynthesis or absorption by the ocean. Once in the ocean, it has the same probability of any carbon there of being sequestered by calcification.

THINGS TO TRY

Try to determine what average yearly emissions are necessary to transform the 1710 world to the 2010 world. Also try to develop various scenarios to mitigate the current Carbon problem. Calcification and terrestrial biomass growth can be manipulated for this purpose

EXTENDING THE MODEL

A problem to overcome: under low emissions and high absorption, the ocean becomes depauperate of Carbon. I neede a feedback to return Carbon sequested in biomass and sedimentation.

NETLOGO FEATURES

RELATED MODELS

Watercycle; Global Carbon Cycle; Greenhouse Effect

CREDITS AND REFERENCES

http://earthobservatory.nasa.gov/Features/CarbonCycle/
http://www.climate.gov/#climateWatch
U.S. DOE. 2008. Carbon Cycling and Biosequestration: Report from the March 2008 Workshop, DOE/SC-108, U.S. Department of Energy Office of Science (http://genomicscience.energy.gov/carboncycle/report/).
IPCC, 2000 - Nebojsa Nakicenovic and Rob Swart (Eds.)
Cambridge University Press, UK. pp 570
IPCC, 2007: Climate Change 2007: Synthesis Report. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, Pachauri, R.K and Reisinger, A. (eds.)]. IPCC, Geneva, Switzerland, 104 pp.
Climate Change 2001: The Physical Science Basis, Summary for Policymakers, IPCC
Hall, T/ 2008. Can Ocean Carbon Uptake Keep Pace with Industrial Emissions?
http://www.giss.nasa.gov/research/briefs/hall_03/

http://www.waterencyclopedia.com/Bi-Ca/Carbon-Dioxide-in-the-Ocean-and-Atmosphere.html
Much of the coding was adapted from Watercycle.nlogo, so I thank that anonymous modeler.

Holian, Gary, Andrei P. Sokolov and Ronald G. PrinnUncertainty in Atmospheric CO2 Predictions from a Parametric Uncertainty Analysis of a Global Ocean Carbon Cycle Model
Report No. 80 September 2001
http://web.mit.edu/globalchange/www/MITJPSPGC_Rpt80.pdf

Keith, H., Mackey, B. G. & Lindenmayer, D. B. 2010 Re-evaluation of forest biomass carbon
stocks and lessons from the world’s most carbon-dense forests. Proc. Natl Acad. Sci. USA
106, 11 635–11 640. (doi:10.1073/pnas.0901970106)

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