Will the tropical land biosphere dominate the climate–carbon cycle feedback during the twenty-first century?
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Global warming caused by anthropogenic CO2 emissions is expected to reduce the capability of the ocean and the land biosphere to take up carbon. This will enlarge the fraction of the CO2 emissions remaining in the atmosphere, which in turn will reinforce future climate change. Recent model studies agree in the existence of such a positive climate–carbon cycle feedback, but the estimates of its amplitude differ by an order of magnitude, which considerably increases the uncertainty in future climate projections. Therefore we discuss, in how far a particular process or component of the carbon cycle can be identified, that potentially contributes most to the positive feedback. The discussion is based on simulations with a carbon cycle model, which is embedded in the atmosphere/ocean general circulation model ECHAM5/MPI-OM. Two simulations covering the period 1860–2100 are conducted to determine the impact of global warming on the carbon cycle. Forced by historical and future carbon dioxide emissions (following the scenario A2 of the Intergovernmental Panel on Climate Change), they reveal a noticeable positive climate–carbon cycle feedback, which is mainly driven by the tropical land biosphere. The oceans contribute much less to the positive feedback and the temperate/boreal terrestrial biosphere induces a minor negative feedback. The contrasting behavior of the tropical and temperate/boreal land biosphere is mostly attributed to opposite trends in their net primary productivity (NPP) under global warming conditions. As these findings depend on the model employed they are compared with results derived from other climate–carbon cycle models, which participated in the Coupled Climate–Carbon Cycle Model Intercomparison Project (C4MIP).
KeywordsClimate Carbon cycle Feedback Global warming C4MIP NPP
This research was financed by the German Ministry for Education and Research (BMBF) under two DEKLIM projects, grants 01LD0106 and 01LD0024, and by the European Community under the CYCLOPES project. The simulations were performed on the NEC SX-6 supercomputer installed at the German Climate Computing Centre (DKRZ) in Hamburg. We thank all C4MIP participants for contributing their model results and numerous helpful comments.
- Cramer W, Bondeau A, Woodward FI, Prentice IC, Betts RA, Brovkin V, Cox PM, Fisher V, Foley JA, Friend AD, Kucharik C, Lomas MR, Ramankutty N, Sitch S, Smith B, White A, Young-Molling C (2001) Global response of terrestrial ecosystem structure and function to CO2 and climate change: results from six dynamic global vegetation models. Global Change Biol 7:357–373CrossRefGoogle Scholar
- Friedlingstein P, Dufresne J-L, Cox PM, Rayner P (2003) How positive is the feedback between climate change and the carbon cycle? Tellus 55B:692–700Google Scholar
- Friedlingstein P, Cox P, Betts R, Bopp L, von Bloh W, Brovkin V, Cadule P, Doney S, Eby M, Fung I, Bala G, John J, Jones C, Joos F, Kato T, Kawamiya M, Knorr W, Lindsay K, Matthews HD, Raddatz T, Rayner P, Reick C, Roeckner E, Schnitzler K-G, Schnur R, Strassmann K, Weaver AJ, Yoshikawa C, Zeng N (2006) Climate - carbon cycle feedback analysis, results from the C4MIP model intercomparison. J Climate 19:3337–3353 doi:10.1175JCLI3800.1CrossRefGoogle Scholar
- Global Carbon Project (2003) Science framework and implementation. In: Canadell JG, Dickinson R, Hibbard K, Raupach M, Young O (eds) Earth system science partnership (IGBP, IHDP, WCRP, DIVERSITAS) Report No. 1, Global Carbon Project Report No. 1, 69 pp, CanberraGoogle Scholar
- Houghton RA (2003) Revised estimates of the annual net flux of carbon to the atmosphere from changes in land use and land management 1850–2000. Tellus 55B:378–390Google Scholar
- Jones PD, New M, Parker DM, Martin S, Rigor IG (1999) Surface air temperature and its changes over the past 150 years. Rev Geophys 37(2). doi:10.1029/1999RG900002Google Scholar
- Kattge J, Knorr W (2007) The temperature dependence of photosynthetic capacity in a photosynthesis model acclimates to plant growth temperature: a re-analysis of data from 36 species. Plant Cell Environ (accepted)Google Scholar
- Keeling CD, Whorf TP (2005) Atmospheric CO2 records from sites in the SIO air sampling network. In: Trends: a compendium of data on global change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak RidgeGoogle Scholar
- King AW, Gunderson CA, Post WM, Weston DJ, Wullschleger SD (2006) Plant respiration in a warmer world. Science 312. doi:10.1126/Science.1114166 Google Scholar
- Marland G, Boden TA, Andres RJ (2003) Global, regional and national emissions. In: Trends: a compendium of data on global change. Carbon Dioxide Information Center, Oak Ridge National Laboratory, U. S. Department of Energy, Oak RidgeGoogle Scholar
- Peylin P, Bousquet P, Le Quere C, Sitch S, Friedlingstein P, McKinley G, Gruber N, Rayner P, Ciais P (2005) Multiple constraints on regional CO2 flux variations over land and oceans. Global Biogeochem Cycles 19:GB1011. doi:10.1029/2003GB002214Google Scholar
- Prentice IC et al (2001) The carbon cycle and atmospheric CO2. In: Houghton JT, Yihui D (eds) The Intergovernmental Panel on Climate Change (IPCC) Third Assessment Report. Cambridge University Press, New York, chap. 3, pp 185–237Google Scholar
- Roeckner E, Baeuml G, Bonaventura L, Brokopf R, Esch M, Giorgetta M, Hagemann S, Kirchner I, Kornblueh L, Manzini E, Rhodin A, Schlese U, Schulzweida U., Tompkins A (2003) The general circulation model ECHAM5. Part I: Model description. Report 349, Max-Planck-Institut for Meteorology, HamburgGoogle Scholar
- Sitch S, Smith B, Prentice IC, Arneth A, Bondeau A, Cramer W, Kaplan JO, Lewis S, Lucht W, Sykes MT, Thonicke K, Venevsky S (2003) Evaluation of ecosystem dynamics, plant geography and terrestrial carbon cycling in the LPJ dynamic global vegetation model. Global Change Biol 9:161–185CrossRefGoogle Scholar
- Takahashi T, Sutherland SC, Sweeney C, Poisson A, Metzl N, Tilbrook B, Bates N Wanninkhof R, Feely RA, Sabine C, Olafsson J, Nojiri Y (2002) Global sea-air CO2 flux based on climatological surface ocean pCO2 and seasonal biological and temperature effects. Deep-Sea Res 49:1601–1622CrossRefGoogle Scholar
- Tans PP, Conway TJ (2005) Monthly atmospheric CO2 mixing ratios from the NOAA CMDL carbon cycle cooperative global air sampling network, 1968–2002. In: Trends: a compendium of data on global change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak RidgeGoogle Scholar
- Wetzel P, Winguth A, Maier-Reimer E (2005) Sea-to-air CO2 fluxes from 1948 to 2003. Global Biogeochem Cycles 19:GB2005. doi:10.1029/2004GB002339Google Scholar
- Zeng N, Qian H, Munoz E, Iacono R (2004) How strong is carbon cycle-climate feedback under global warming? Geophys Res Lett 31:L20203. doi:10.1029/2004GL020904Google Scholar