1CSIRO Marine and Atmospheric Research, P.O. Box 3023, Canberra ACT 2601, Australia
2University of California, Dept. of Earth System Science, Irvine, CA, USA
3CSIRO Marine and Atmospheric Research, PB1, Aspendale, Victoria 3195, Australia
4CICERO, P.O. Box 1129 Blindern, 0318 Oslo, Norway
5CSIRO Land and Water, P.O. Box 1666, Canberra ACT 2600, Australia
Abstract. This paper reports a study of the full carbon (C-CO2) budget of the Australian continent, focussing on 1990–2011 in the context of estimates over two centuries. The work is a contribution to the RECCAP (REgional Carbon Cycle Assessment and Processes) project, as one of numerous regional studies being synthesised in RECCAP. In constructing the budget, we estimate the following component carbon fluxes: Net Primary Production (NPP); Net Ecosystem Production (NEP); fire; Land Use Change (LUC); riverine export; dust export; harvest (wood, crop and livestock) and fossil fuel emissions (both territorial and non-territorial).
The mean NEP reveals that climate variability and rising CO2 contributed 12 ± 29 (1σ error on mean) and 68 ± 35 Tg C yr−1 respectively. However these gains were partially offset by fire and LUC (along with other minor fluxes), which caused net losses of 31 ± 5 Tg C yr−1 and 18 ± 7 Tg C yr−1 respectively. The resultant Net Biome Production (NBP) of 31 ± 35 Tg C yr−1 offset fossil fuel emissions (95 ± 6 Tg C yr−1) by 32 ± 36%. The interannual variability (IAV) in the Australian carbon budget exceeds Australia's total carbon emissions by fossil fuel combustion and is dominated by IAV in NEP. Territorial fossil fuel emissions are significantly smaller than the rapidly growing fossil fuel exports: in 2009–2010, Australia exported 2.5 times more carbon in fossil fuels than it emitted by burning fossil fuels.