title: The carbon balance of Africa: synthesis of recent research studies.
abstract: The African continent contributes one of the largest uncertainties to the global CO(2) budget, because very few long-term measurements are carried out in this region. The contribution of Africa to the global carbon cycle is characterized by its low fossil fuel emissions, a rapidly increasing population causing cropland expansion, and degradation and deforestation risk to extensive dryland and savannah ecosystems and to tropical forests in Central Africa. A synthesis of the carbon balance of African ecosystems is provided at different scales, including observations of land-atmosphere CO(2) flux and soil carbon and biomass carbon stocks. A review of the most recent estimates of the net long-term carbon balance of African ecosystems is provided, including losses from fire disturbance, based upon observations, giving a sink of the order of 0.2 Pg C yr(-1) with a large uncertainty around this number. By comparison, fossil fuel emissions are only of the order of 0.2 Pg C yr(-1) and land-use emissions are of the order of 0.24 Pg C yr(-1). The sources of year-to-year variations in the ecosystem carbon-balance are also discussed. Recommendations for the deployment of a coordinated carbon-monitoring system for African ecosystems are given.
authors.affiliation: Laboratoire des Sciences du Climat et de l'Environnement, CEA-CNRS-UVSQ, CE Orme des Merisiers, 91191 Gif sur Yvette, France. philippe.ciais@cea.fr
authors.forename: P
authors.initials: P
authors.lastname: Ciais
authors.forename: A
authors.initials: A
authors.lastname: Bombelli
authors.forename: M
authors.initials: M
authors.lastname: Williams
authors.forename: S L
authors.initials: SL
authors.lastname: Piao
authors.forename: J
authors.initials: J
authors.lastname: Chave
authors.forename: C M
authors.initials: CM
authors.lastname: Ryan
authors.forename: M
authors.initials: M
authors.lastname: Henry
authors.forename: P
authors.initials: P
authors.lastname: Brender
authors.forename: R
authors.initials: R
authors.lastname: Valentini
mesh_terms: D000349:Africa; D018533:Biomass; D057486:Carbon Cycle; D057231:Climate Change; D017753:Ecosystem; D012987:Soil / Q000032:analysis; D013997:Time Factors; D014197:Trees
chemical_list: D012987:Soil