Anthropogenic CO 2 emissions in Africa

Anthropogenic CO2 emissions in Africa J. G. Canadell, M. R. Raupach, and R. A. Houghton Global Carbon Project, CSIRO Marine and Atmospheric Research, Canberra, ACT 2601, Australia Woods Hole Research Center, Falmouth, MA 02540, USA Received: 1 September 2008 – Accepted: 25 September 2008 – Published: 19 November 2008 Correspondence to: J. G. Canadell (pep.canadell@csiro.au) Published by Copernicus Publications on behalf of the European Geosciences Union.


Introduction
The wide acceptance of the existence of human-induced climate change, together with the dominant role of CO 2 as an anthropogenic greenhouse gas, has led to increasing interest in characterizing the regional contributions of anthropogenic CO 2 emissions, their underlying drivers, and their historical trends.The two main anthropogenic CO 2 fluxes are emissions from the combustion of fossil fuels and net emissions from land use change, the latter being largely driven by deforestation in tropical regions (Canadell et al., 2007;Houghton, 2007).Knowledge of these fluxes and their characteristics is Figures

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Printer-friendly Version Interactive Discussion essential for the design of regional and global agreements aimed to stabilize greenhouse gas emissions over the coming decades.Much of the focus on anthropogenic CO 2 emissions has been on the developed world and emerging economies in Asia which together account for over 80% of the cumulative CO 2 emissions and growth (Raupach et al., 2007).
With a population of 943M (UNSD, 2008), Africa's economy is dominated by Least Developed Countries (LDCs) and Developing Countries (DCs), and accordingly its contribution to global fossil fuel emissions (8.2 PgC y −1 in 2005; Canadell et al., 2007) are smaller than the global per-capita average.However, there is an upward trend to African emissions as national economies undergo rapid development.In addition, CO 2 emissions from land use change (e.g.deforestation, reforestation) globally contribute approximately 1.5 PgC y −1 (Canadell et al., 2007), with a contribution coming from Africa still poorly constrained.With the fastest population growth in the world, some rapidly developing economies, and new pressures on land to meet food and bioenergy demands, Africa is set for a growing influence on the global CO 2 balance.
Here we report a regional and temporal analysis for the continent of Africa on i) CO 2 emissions from the combustion of fossil fuels, and their underlying drivers and trends; and ii) the net CO 2 emissions from land use change and forestry, with historical trends.We place the findings in the global context and compare Africa with other major regions in the world.

Emissions and drivers from fossil fuel
We analyze CO 2 emissions from the combustion of fossil fuel for all countries in Africa for the period 1980-2005, using emissions data from the Energy Information Administration (EIA, 2008).In this data set, total fossil fuel emissions includes the consumption of solid, liquid and gas fuels, together with flaring of natural gas.al., 2007) to analyze the drivers and trends of fossil fuel emissions: where F is fossil fuel emissions, P is population, g is per-capita Gross Domestic Product, GDP/population, and h is the C intensity of the economy, as F /GDP.Population data was obtained from the United Nations Statistics Division (UNSD, 2008) and GDP from the International Monetary Fund (IMF, 2008) based on Purchasing Power Parity.All GDPs are expressed in 2000 US dollars.The C intensity of the economy is the C emitted in order to produce 1 US $ of GDP.This measure is the product of the energy consumed per dollar of economic activity (the energy intensity of the economy) and the C emitted per unit of energy (the C intensity of the energy).We acknowledge that a significant economic activity in Africa might rely on traditional and non-market energies such as biomass.
A more extensive description of the datasets and an extended Kaya identity can be found at Raupach et al. (2007).

Emissions from land use change
C emissions from land use change and forestry were determined with data and a C tracking model as described in an earlier analysis of Sub-Saharan Africa (Houghton and Hackler, 2006) but were updated in three ways.First, this analysis updates the earlier one to 2005 with data from the UN Food and Agriculture Organization's (FAO) 2005 Forest Resource Assessment (FRA) (FAO, 2006).Second, rates of deforestation for the 1990s were revised downward by 18% (FAO, 2006).Third, 16 countries in north africa were also included in this analysis.For recent years  the approach used rates of deforestation and average biomass values reported by repeated FRAs by the UN (FAO, 1995(FAO, , 2001b(FAO, , 2006) )  The rate of deforestation for shifting cultivation was obtained by the difference between the total deforestation rate of natural forests  and rate of increase in area of croplands.Rates of wood harvest were obtained from FAOStat (FAO, 2001a).Before 1960 rates of land-use change were assumed to have increased linearly from zero in 1900 to the rates given by FAOStat (FAO, 2001a).Rates of change were variable before ∼1900, as lands abandoned from agriculture during periods of wars, epidemics, and famines were cleared again in subsequent years.In contrast to these variable changes, after 1900 both demographic and global economic incentives combined to increase the production of agricultural commodities (Kimble, 1962).
The net flux of C from industrial wood harvest, including C emissions from the decay of harvested products and C uptake from the recovery of harvested forests, were included in this analysis.Industrial wood accounted for ∼10% of total harvests; fuelwood, for 90%.We did not explicitly include fuelwood in the analysis because most of the emissions would be offset by C accumulation in forests recovering from harvest.
Only in regions where fuelwood harvest exceeded regrowth, or vice versa, would there be a net C flux.Furthermore, more wood was burned annually as a result of conversion of forests to croplands and to shifting cultivation than as a result of fuelwood production, and some of this burned material would have been used for fuel.Thus, the net flux of C determined in this analysis includes most of the C emitted from use of fuelwood.

Emissions and drivers from fossil fuel
Africa was responsible for 2. for 93% of total African emissions (240 TgC y −1 ) and 33 LDCs were responsible for the remaining 7% (19 TgC y −1 ).South Africa was the highest emitter in Africa with an average of 110.1 TgC y −1 for the period 2000-2005 followed by Egypt (38.2 TgC y −1 ), Nigeria (25.1 TgC y −1 ) and Algeria (22.4 TgC y − 1) (Fig. 1).For the last year reported in this study, 2005, Africa emitted 285 TgC accounting for 3.7% of the global emissions and 3.6% of global emissions growth (Fig. 2).Emissions per capita in African countries are among the lowest in the world.In 2005, emissions per capita were 0.32 tC y −1 averaged for the whole of Africa, 2.43 tC y −1 for South Africa and 0.02 tC y −1 for Ethiopia.For comparison, the global average was 1.2, USA was 5.5 and Europe was 2.5 (Fig. 2).The C intensity of the African economy in 2005 (or the amount of C emitted as CO 2 to produce 1 US $ of GDP) was 187 gC/$ close to the world average of 199 gC/$.South Africa and Ethiopia had C intensities of 321 and 31 respectively.For comparison, the C intensity of the Former Soviet Union was 464 gC/$, USA was 210 gC/$, Europe was 143 gC/$ and Japan 136 gC/$ (Fig. 2).
Figure 3 shows the trends of fossil fuel emissions and the drivers of those emissions for the period 1980-2005 as per the Kaya identity: population, per capita GDP (US $), and C intensity of the economy (gC/US $).Emissions from Africa have grown at a faster pace than global average and tightly followed population growth.The coupling between emissions and population was strong for DCs and weaker for LDCs where C emissions outpaced population growth due to a simultaneous strong growth in per capita GDP.
The C intensity of the economy in most African countries increased (worsened) between 1980 and the early 1990s and declined (improved) thereafter, with most of the improvement driven by DCs.
South Africa showed a rapid growth in emission tightly coupled with population growth and more recently also with increased per capita GDP.In contrast, Ethiopia's rapid growth in emissions was driven largely by the growth in per capita GDP while Figures Individual regions within Africa show small differences in both the historical pattern and the magnitude of emissions (Fig. 4).Only in North Africa, where the establishment of plantations has recently exceeded deforestation, has the flux of C been a net sink recently (3 TgC y −1 ), small in comparison to the sources from the other regions (40-72 TgC y −1 ).
The regional net C emissions determined in this work were divided among countries based on (1) rates of deforestation (FAO, 2006) and (2) average forest biomass for each country (FAO, 2001).Countries with higher rates of deforestation and/or higher average biomass were assigned a greater proportion of the regional emissions than countries with low rates of deforestation and low average biomass.According to these calculations, 15 countries accounted for about 90% of the emissions from land-use change (Fig. 1).

Discussion
Average total anthropogenic C emissions in Africa were 500 TgC y −1 for the period 2000-2005: 260 TgC y −1 from the combustion of fossil fuels and 240 TgC y −1 from land use change.Emissions from land use change thus accounted for 48% of total anthropogenic emissions, giving Africa a unique emission profile in the global context: significant emissions from deforestation and relatively low emissions from fossil fuel burning given the size of its population.
Emissions varied among countries: 10 countries were responsible for 90% of all fossil fuel emissions while 15 countries accounted for 90% of all emissions from land use change (of 55 African countries and dependencies reported in this study) (Fig. 1).
Six countries are in both lists of top emitters: Nigeria, Angola, Zimbabwe, Sudan, Cameroon, and Ghana.Nigeria ranks within the top three in both lists with a total combined emissions of 67.7 PgC y −1 , second in total anthropogenic CO 2 emissions after South Africa.
Fossil fuel emissions were dominated by South Africa and Northern African countries, while emissions from land use change were dominated by the central African countries such as Nigeria, the Democratic Republic of Congo and Zambia (Fig. 1).
The African share of global emissions from fossil fuel was 2.3% and per capita emissions were among the lowest in the world.However, the observed growth rate of emissions (above the world average), caused by rapid growth in per capita GDP and the fastest population growth in the world, will likely lead to increased emission over the next decades.Nevertheless, emissions per capita will remain low by comparison with other continents.
Improvements in the C intensity (decline) remain a challenge for African countries particularly for LDCs whose C intensity has stalled or worsened (increased) since 2000.This latter trend was also found at the global level driven largely by China's strong economic performance coupled with increased C intensity of its energy sector (Raupach et al., 2007).Improvements in the C intensity of the economy results in decreased pollution and increased energy efficiency, characteristics to which all nations aspire.Although rates of deforestation in Africa were higher than those in tropical Asia and nearly as high as those in Latin America, the resulting net annual CO 2 emissions from Africa were lower than from the other regions (Fig. 6).Africa accounted for a third of tropical deforestation between 2000and 2005(FAO, 2006) ) but only 17% of the CO 2 emissions from land-use change (0.24 PgC y −1 out of a total of 1.47 PgC y −1 ) (Canadell et al., 2007).The difference suggests that a greater proportion of deforestation in Africa is of dry forests with low biomass.A recent study of deforestation in humid tropical forests supports this observation.Hansen et al. (2008) reported that the rate of deforestation of humid forests in Africa accounted for only 5.4% of the total rate for humid forests.The much higher rates reported by FAO (2006), in contrast, include dry (lower C stocks) as well humid forests.
Anthropogenic CO 2 emissions of 0.5 PgC y −1 (500 TgC y −1 ) in Africa are the smallest of all inhabited continents but not insignificant compared to global emissions of 8 PgC y −1 .The rate of growth in emissions, however, is above the world average, and Africa's share of global emissions is likely to increase in the coming decades.On the other hand, opportunities exist to leverage regional and international support for development pathways that reduce deforestation and embrace cleaner and more efficient energy systems consistent with regional and global sustainability goals (Canadell and Raupach, 2008;Gullison et al., 2007;IPCC, 2007) and annual changes in land use reported since 1960 by FAOStat (FAO, 2001a) to determine annual net changes in the areas of forests, plantations, croplands, pastures, and shifting cultivation.
5% of the global cumulative CO 2 emissions from fossil fuel for the period 1980-2005, while accounting for 13.8% of the global population in 2005.Average annual emissions were 260 TgC for the period 2000-2005 of which 77 TgC y −1 occurred in Northern Africa (7 countries) and 183 TgC y −1 in Sub-Saharan countries (48 countries).Categorized by economic status, 22 DCs were responsible intensity remained steady.Notice that in Fig.3all quantities were normalized to 1 in 1990 for the purpose of trend comparison, therefore the figures provide no information on the absolute values, which are indicated in Figs.1 and 2. 3.1.1Emissions from land use change Rates of deforestation in most parts of Africa increased between 1900 and 1990 (Fig. 4), and thereafter have leveled off (average of 4the first half decade of the 2000s).The establishment of plantations (∼0.067×10 6 ha yr −1 over the period 1990-2005) has offset little of this forest loss.Net C emissions from deforestation and afforestation, together, averaged 240 TgC y −1 over the period 1990-2005.The emissions from industrial wood harvest (included in the estimate of net flux above) were only 10% of the total net flux.
Analyses were done Figures African countries together, for Northern African and Sub-Saharan countries as separate groups, and for DCs and LDCs also as separate groups (according to the United Nationals Statistics Division).We single out South Africa and Ethiopia as examples of a DC and LDC respectively.