6. Estimates of Average Annual Carbon Stock Changes/Accounted for ARD Activities and Some Additional Activities

6.1. Afforestation, Reforestation, and Deforestation

55. Different definitions and accounting approaches under Article 3.3 of the Kyoto Protocol produce different estimates of changes in carbon stocks. There are seven Definitional Scenarios described in Chapter 3 of the underlying report. Table 3 illustrates, with data and methods available at the time of the Special Report, the estimated carbon stock changes accounted from ARD activities under the IPCC and FAO Definitional Scenarios, assuming recent area conversion rates remain constant and excluding carbon in soils and wood products. Three different carbon accounting approaches have been applied to the FAO Definitional Scenario to illustrate the effect of different accounting approaches. [3.5.3, 3.5.4, Table 3-4, Table 3-17]

56. The IPCC Definitional Scenario yields estimates of average annual accounted carbon stock changes from afforestation and reforestation in Annex I Parties from 2008 to 2012 of 7 to 46 Mt C yr^-1. This would be offset by annual changes in carbon stocks from deforestation of about -90 Mt C yr^-1, producing a net stock change of -83 to -44 Mt C yr^-1. If hypothetically, for example, afforestation and reforestation rates were to be increased in Annex I Parties by 20% ⁴ for the years 2000 to 2012, estimated annual changes in carbon stocks would increase (from 7 to 46 Mt Cyr^-1) to 7 to 49 Mt C yr^-1. If hypothetically, for example, deforestation rates were to be decreased by 20%, estimated annual losses of carbon stocks due to deforestation would reduce (from -90 Mt C yr^-1) to -72 Mt C yr^-1. [3.5.4]

57. The three accounting approaches under the FAO Definitional Scenario yield different results. Estimated average annual carbon stock changes in Annex I Parties from afforestation and reforestation are -759 to -243 Mt C yr^-1 under the FAO land-based I approach; -190 to 295 Mt C yr^-1 under the FAO land-based II approach; and 87 to 573 Mt C yr^-1 under the FAO activity-based approach. Estimated average annual carbon stock changes from deforestation are about -90 Mt C yr^-1 in all three approaches, as in the IPCC Definitional Scenario. [3.5.4]

58. For comparison, the IPCC Definitional Scenario yields estimates of average annual accounted carbon stock changes from afforestation and reforestation globally from 2008 to 2012 of 197 to 584 Mt C yr^-1. This would be offset by annual changes in carbon stocks from deforestation of about -1788 Mt C yr^-1, producing a net stock change of -1591 to -1204 Mt C yr^-1. If, hypothetically, for example, afforestation and reforestation rates were to be increased globally by 20% for the years 2000 to 2012, estimated annual changes in carbon stocks would increase (from 197 to 584 Mt C yr^-1) to 208 to 629 Mt C yr^-1. [3.5.4]

59. In the IPCC Definitional Scenario and FAO Definitional Scenario with land-based I accounting approach, the accounted carbon stock changes are broadly consistent with the 2008-2012 actual changes in carbon stocks from land under Article 3.3. The IPCC and FAO Definitional Scenarios bring different amounts of land under Article 3.3, hence the estimated carbon stock changes in Table 3 differ.

60. In the FAO Definitional Scenario with land-based II and activity-based accounting approaches, the accounted carbon stock change is not consistent with the 2008-2012 actual changes in carbon stocks on land under Article 3.3, except in the case of short rotation cycles.

61. In neither of the two Definitional Scenarios is the accounted carbon stock change consistent with the 2008-2012 actual carbon stock changes, nor with the net exchanges with the atmosphere, at the national and global levels in part because the land under Article 3.3 is small in comparison with the national and global forest area. [3.3.2, 3.5.4]

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