3. The Carbon Cycle and Atmospheric Carbon Dioxide

Content

3.2.1 Overview of the Carbon Cycle
3.2.2 Terrestrial Carbon Processes
3.2.2.1 Background
3.2.2.2 Effects of changes in land use and land management
3.2.2.3 Effects of climate
3.2.2.4 Effects of increasing atmospheric CO₂
3.2.2.5 Effects of anthropogenic nitrogen deposition
3.2.2.6 Additional impacts of changing atmospheric chemistry
3.2.2.7 Additional constraints on terrestrial CO₂ uptake
3.2.3 Ocean Carbon Processes
3.2.3.1 Background
3.2.3.2 Uptake of anthropogenic CO₂
3.2.3.3 Future changes in ocean CO₂ uptake

3.3 Palaeo CO₂ and Natural Changes in the Carbon Cycle

3.3.1 Geological History of Atmospheric CO₂
3.3.2 Variations in Atmospheric CO₂ during Glacial/inter-glacial Cycles
3.3.3 Variations in Atmospheric CO₂ during the Past 11,000 Years
3.3.4 Implications

3.4 Anthropogenic Sources of CO₂

3.4.1 Emissions from Fossil Fuel Burning and Cement Production
3.4.2 Consequences of Land-use Change

3.5 Observations, Trends and Budgets

3.5.1 Atmospheric Measurements and Global CO₂ Budgets
3.5.2 Interannual Variability in the Rate of Atmospheric CO₂ Increase
3.5.3 Inverse Modelling of Carbon Sources and Sinks
3.5.4 Terrestrial Biomass Inventories

3.6 Carbon Cycle Model Evaluation

3.6.1 Terrestrial and Ocean Biogeochemistry Models
3.6.2 Evaluation of Terrestrial Models
3.6.2.1 Natural carbon cycling on land
3.6.2.2 Uptake and release of anthropogenic CO₂ by the land
3.6.3 Evaluation of Ocean Models
3.6.3.1 Natural carbon cycling in the ocean
3.6.3.2 Uptake of anthropogenic CO₂ by the ocean

3.7 Projections of CO₂ Concentration and their Implications

3.7.1 Terrestrial Carbon Model Responses to Scenarios of Change in CO₂ and Climate
3.7.2 Ocean Carbon Model Responses to Scenarios of Change in CO₂ and Climate
3.7.3 Coupled Model Responses and Implications for Future CO₂ Concentrations
3.7.3.1 Methods for assessing the response of atmospheric CO₂ to different emissions athways and model sensitivities
3.7.3.2 Concentration projections based on IS92a, for comparison with previous studies
3.7.3.3 SRES scenarios and their implications for future CO₂ concentration
3.7.3.4 Stabilisation scenarios and their implications for future CO₂ emissions
3.7.4 Conclusions

References

Co-ordinating Lead Author
I.C. Prentice

Lead Authors
G.D. Farquhar, M.J.R. Fasham, M.L. Goulden, M. Heimann, V.J. Jaramillo, H.S. Kheshgi, C. Le Quéré,
R.J. Scholes, D.W.R. Wallace

Contributing Authors
D. Archer, M.R. Ashmore, O. Aumont, D. Baker, M. Battle, M. Bender, L.P. Bopp, P. Bousquet, K. Caldeira, P. Ciais, P.M. Cox, W. Cramer, F. Dentener, I.G. Enting, C.B. Field, P. Friedlingstein, E.A. Holland, R.A. Houghton, J.I. House, A. Ishida, A.K. Jain, I.A. Janssens, F. Joos, T. Kaminski, C.D. Keeling, R.F. Keeling, D.W. Kicklighter, K.E. Kohfeld, W. Knorr, R. Law, T. Lenton, K. Lindsay, E. Maier-Reimer, A.C. Manning, R.J. Matear, A.D. McGuire, J.M. Melillo, R. Meyer, M. Mund, J.C. Orr, S. Piper, K. Plattner, P.J. Rayner, S. Sitch, R. Slater, S. Taguchi, P.P. Tans, H.Q. Tian, M.F. Weirig, T. Whorf, A. Yool

Review Editors
L. Pitelka, A. Ramirez Rojas

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