1. Emission trajectories of these ozone-depleting substances (ODSs) are not developed by the SRES team, but adopted from WMO/UNEP (1998).

2. During the approval process of the Summary for Policymakers at the 5th Session of Working Group III (WGIII) of the IPCC from 8 to 11 March 2000 in Katmandu, Nepal, it was decided to combine the A1C and A1G groups into one "fossil intensive" group A1FI in contrast to the non-fossil group A1T, and to select two illustrative scenarios from these two A1 groups to facilitate use by modelers and policy makers. This leads to six scenario groups that constitute the four scenario families, three of which are in the A1 family. All scenarios are equally sound.

3. In particular, the IPCC Working Group I (WGI) Second Assessment Report (SAR) GWPs are calculated for constant concentrations. In long-term scenarios, concentrations may change significantly, as do GWP values. It is unclear how to apply GWPs to long-term scenarios in a meaningful manner. In addition, the GWP approach is not applicable to gases such as SO₂ and ozone precursors.

4. Note that unless stated otherwise cumulative emissions reported in this chapter always refer to total carbon, while annual emissions in this section refer to energy and industry emissions only.

5. The IMAGE results for the A2 and B2 scenarios are based on preliminary model experiments carried out in March 1998. As a result of limited resources it has not been possible to re-run these experiments. Hence, unlike for the IMAGE A1 and B1 scenarios, the IMAGE team has not been able to provide background data and details for these scenario calculations and the population and economic growth assumptions are not harmonized fully.

6. The IMAGE results for the A2 and B2 scenarios are based on preliminary model experiments carried out in March 1998. As a result of limited resources it has not been possible to re-run these experiments. Hence, unlike for the IMAGE A1 and B1 scenarios, the IMAGE team has not been able to provide background data and details for these scenario calculations and the population and economic growth assumptions are not harmonized fully.

7. The most comprehensive treatment is embedded in the IMAGE model. For the sake of comparison the IMAGE team has made a tentative estimate of those (net) emissions that are reasonably consistent with what other models reported. These derived values are used in this report.

8. For the A1G-MiniCAM scenario emissions from congruent model runs derived from other models have been estimated.

9. Following UN energy statistics and IPCC inventory practices, international bunker fuels are included in global totals, but not in national/regional subtotals (and their aggregates to global totals). Hence, bunker fuels are reported separately here.

10. To convert into SO₂ , a unit frequently used in the sulfur scenario literature, multiply the MtS numbers by 2.

11. All emissions coefficients were calculated with the MESSAGE model.

12. In this report represented by four macro-regions - OECD90, REF, ASIA, and ALM.

13. The numbers of the two additional illustrative scenarios for the A1FI and A1T scenario groups can be found in Appendix VII.