Articles | Volume 9, issue 12
Biogeosciences, 9, 5407–5430, 2012

Special issue: REgional Carbon Cycle Assessment and Processes (RECCAP)

Biogeosciences, 9, 5407–5430, 2012
Reviews and syntheses
21 Dec 2012
Reviews and syntheses | 21 Dec 2012

The carbon balance of South America: a review of the status, decadal trends and main determinants

M. Gloor1, L. Gatti2, R. Brienen1, T. R. Feldpausch1, O. L. Phillips1, J. Miller3, J. P. Ometto4, H. Rocha5, T. Baker1, B. de Jong18, R. A. Houghton7, Y. Malhi6, L. E. O. C. Aragão8, J.-L. Guyot9, K. Zhao10, R. Jackson10, P. Peylin11, S. Sitch13, B. Poulter12, M. Lomas14, S. Zaehle15, C. Huntingford16, P. Levy16, and J. Lloyd1,17 M. Gloor et al.
  • 1University of Leeds, School of Geography, Woodhouse Lane, LS9 2JT, Leeds, UK
  • 2CNEN-IPEN-Lab., Quimica Atmosferica, Av. Prof. Lineu Prestes, 2242, Cidade Universitaria, Sao Paulo, Brazil
  • 3NOAA/ESRL R/GMD1 325 Broadway, Boulder, CO 80305, USA
  • 4Earth System Science Centre (CCST) National Institute for Space Research (INPE) Av. dos Astronautas, 1758 12227-010. São Jose dos Campos, Brazil
  • 5Departamento de Ciências Atmosféricas/IAG/Universidade de São Paulo, Rua do Matão, 1226 - Cidade Universitária – São Paulo, Brazil
  • 6University of Oxford, Environmental Change Institute, School of Geography and the Environment, South Parks Road, Oxford OX1 3QY, UK
  • 7Woods Hole Research Center, 149 Woods Hole Road, Falmouth, MA 02540-1644, USA
  • 8School of Geography, University of Exeter, Amory Building (room 385), Rennes Drive, Devon, EX4 4RJ, UK
  • 9IRD, CP 7091 Lago Sul, 71635-971 Brasília DF, Brazil
  • 10Nicholas School of the Environment, Duke University, Box 90338/rm 3311 French FSC-124 Science Drive, Durham, NC 27708-0338, USA
  • 11CEA centre de Saclay, Orme des Merisiers, LSCE, Point courrier 129, 91191 Gif Sur Yvette, France
  • 12Laboratoire des Sciences du Climat et l'Environnement (LSCE) Orme des Merisiers, Point courrier 129, 91191 Gif Sur Yvette, France
  • 13College of Life and Environmental Sciences, University of Exeter, Rennes Drive, Exeter EX4 4RJ, UK
  • 14Centre for Terrestrial Carbon Dynamics CTCD, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH, UK
  • 15Max-Planck-Institute for Biogeochemistry- Biogeochemical Systems Department, P.O. Box 10 01 64, D-07701 Jena, Germany
  • 16Centre for Ecology and Hydrology, Bush Estate, Penicuik, Midlothian, EH26 0QB, UK
  • 17School of Earth and Environmental Studies, James Cook University, Cairns, Queensland 4878, Australia
  • 18El Colegio de la Frontera Sur (ECOSUR), Carr, Panamericana-Periferico Sur s/n, San Cristóbal de las Casas, 29290 Chiapas, México

Abstract. We summarise the contemporary carbon budget of South America and relate it to its dominant controls: population and economic growth, changes in land use practices and a changing atmospheric environment and climate. Component flux estimate methods we consider sufficiently reliable for this purpose encompass fossil fuel emission inventories, biometric analysis of old-growth rainforests, estimation of carbon release associated with deforestation based on remote sensing and inventories, and agricultural export data. Alternative methods for the estimation of the continental-scale net land to atmosphere CO2 flux, such as atmospheric transport inverse modelling and terrestrial biosphere model predictions, are, we find, hampered by the data paucity, and improved parameterisation and validation exercises are required before reliable estimates can be obtained. From our analysis of available data, we suggest that South America was a net source to the atmosphere during the 1980s (~ 0.3–0.4 Pg C a−1) and close to neutral (~ 0.1 Pg C a−1) in the 1990s. During the latter period, carbon uptake in old-growth forests nearly compensated for the carbon release associated with fossil fuel burning and deforestation.

Annual mean precipitation over tropical South America as inferred from Amazon River discharge shows a long-term upward trend. Although, over the last decade dry seasons have tended to be drier, with the years 2005 and 2010 in particular experiencing strong droughts. On the other hand, precipitation during the wet seasons also shows an increasing trend. Air temperatures have also increased slightly. Also with increases in atmospheric CO2 concentrations, it is currently unclear what effect these climate changes are having on the forest carbon balance of the region. Current indications are that the forests of the Amazon Basin have acted as a substantial long-term carbon sink, but with the most recent measurements suggesting that this sink may be weakening. Economic development of the tropical regions of the continent is advancing steadily, with exports of agricultural products being an important driver and witnessing a strong upturn over the last decade.

Final-revised paper