Geography

Document Type

Article

Abstract

This paper, developed under the framework of the RECCAP initiative, aims at providing improved estimates of the carbon and GHG (CO2, CH4 and N2O) balance of continental Africa. The various components and processes of the African carbon and GHG budget are considered, existing data reviewed, and new data from different methodologies (inventories, ecosystem flux measurements, models, and atmospheric inversions) presented. Uncertainties are quantified and current gaps and weaknesses in knowledge and monitoring systems described in order to guide future requirements. The majority of results agree that Africa is a small sink of carbon on an annual scale, with an average value of -0.61 ± 0.58 Pg C yr-1. Nevertheless, the emissions of CH4 and N2O may turn Africa into a net source of radiative forcing in CO2 equivalent terms. At sub-regional level, there is significant spatial variability in both sources and sinks, due to the diversity of biomes represented and differences in the degree of anthropic impacts. Southern Africa is the main source region; while central Africa, with its evergreen tropical forests, is the main sink. Emissions from land-use change in Africa are significant (around 0.32 ± 0.05 Pg C yr-1), even higher than the fossil fuel emissions: this is a unique feature among all the continents. There could be significant carbon losses from forest land even without deforestation, resulting from the impact of selective logging. Fires play a significant role in the African carbon cycle, with 1.03 ± 0.22 Pg C yr-1 of carbon emissions, and 90% originating in savannas and dry woodlands. A large portion of the wild fire emissions are compensated by CO2 uptake during the growing season, but an uncertain fraction of the emission from wood harvested for domestic use is not. Most of these fluxes have large interannual variability, on the order of ±0.5 Pg C yr-1 in standard deviation, accounting for around 25% of the year-to-year variation in the global carbon budget.

Despite the high uncertainty, the estimates provided in this paper show the important role that Africa plays in the global carbon cycle, both in terms of absolute contribution, and as a key source of interannual variability. © Author(s) 2014. CC Attribution 3.0 License.

Publication Title

Biogeosciences

Publication Date

2014

Volume

11

Issue

2

First Page

381

Last Page

407

ISSN

1726-4170

DOI

10.5194/bg-11-381-2014

Keywords

annual variation, anthropogenic effect, biogeochemistry, biome, carbon cycle, carbon dioxide, carbon sink, emission inventory, flux measurement, greenhouse gas, land use change, methane, nitrous oxide, radiative forcing, source-sink dynamics, spatial variation, tropical forest, uncertainty analysis, vulnerability, wildfire

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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