It should be noted that one of the requirements for IPCC Technical Papers is that they must be based solely on material already in the IPCC assessment reports and special reports. The results presented here are therefore consistent with these earlier reports. It should also be noted that, while all the emissions limitation proposals refer only to Annex I countries as agreed upon in the Berlin Mandate (FCCC/CP/1995/7/Add. 1. Decision 1/CP.1), dated 6 June 1995, in order to be able to carry out an analysis for global CO2 concentrations and climate implications it is necessary to use global emissions. Since there are no formal proposals for limitations on emissions from non-Annex I countries, we derive these global values by combining Annex I country emissions under the various limitation proposals with emissions for non-Annex I countries from the "no-climatepolicy" IS92a, c, and e scenarios (see Box). The emissions limitation proposals used in this Paper are expressed variously in terms of CO2 only or in terms of greenhouse gases. For the purposes of this Paper all the proposals are interpreted as applying to fossil CO2 emissions alone. The reasons for using this approximation are given in Section 3. Implications of Proposed CO2 Emissions Limitations To fully meet the initial request of the SBSTA (i.e., to discuss the temperature and sea level implications of the emissions limitation proposals) in a comprehensive manner, it would be necessary to cover the full range of possible concentrations (taking into account sinks and sources) of other gases such as methane (CH4), nitrous oxide (NO), tropospheric ozone (03) and the halocarbons, along with the full range of possibilities for sulphate aerosols derived from sulphur dioxide (SO2) emissions. Such an analysis is beyond the scope of this Paper. Further discussion of the effects of various scenarios for other gases and sulphate aerosols is given in IPCC Technical Paper 38 (Schimel, et al., 1997). 6 An alternative but equivalent way to derive global emissions is to first determine the emissions reductions for Annex I countries that result from a particular emissions limitation proposal (this will depend on the IS92 scenario that the limitation proposal is compared with), and to subtract this from the global emissions for the same IS92 scenario. 7 Fossil CO2 emissions are those arising from fossil fuel combustion (including gas flaring) and cement production. 8 Hereafter referred to as TP3: similarly, TPI and TP2. IS92 emission scenarios The six IPCC scenarios, IS92a-f. (Leggett, et al., 1992), Supplementary Report to the IPCC Scientific Assessment, hereafter referred to as IPCC92) embody a wide array of assumptions affecting how future greenhouse gas emissions might evolve in the absence of climate policies beyond those already adopted. A summary of the economic growth, energy supply and population projection assumptions made in deriving these scenarios is given in Table 4. The IS92 scenarios take into account: (a) The London Amendments to the Montreal Protocol; (b) Population forecasts of the World Bank and United Nations; (c) The report of the Energy and Industry Subgroup of the IPCC (IPCC-EIS, 1990); (d) Political and economic changes in the former Soviet Union, Eastern Europe and the Middle East; and (e) Data on tropical deforestation and sources and sinks of greenhouse gases. Overall, the scenarios indicate that greenhouse gas emissions could rise substantially over the coming century in the absence of new and explicit control measures. IS92a and IS92b: These scenarios give emission estimates that are intermediate compared with those of the other IS92 scenarios. The major difference between IS92b and IS92a is that IS926 takes into account information available up to 1992 on the commitments of some OECD countries to stabilize their CO2 emissions. IS92c: This scenario assumes the lowest rate of population and economic growth and severe constraints on fossil fuel supplies. As a result, it is the lowest emission scenario and the only one showing a decreasing emission trend. 1592d: This scenario employs the low population growth rate of IS92c but a higher economic growth rate, hence it has the second lowest future emission estimates., IS92e: This scenario assumes intermediate population growth and high economic growth rates with plentiful fossil fuels. Consequently, this scenario has the highest estimates of future emissions. IS92f. This scenario uses the highest population estimates of the IS92 scenarios, but lower economic growth assumptions. It is the second highest emission scenario. Revised versions of these scenarios are currently being produced by IPCC and will be published as a special report. Implications of Proposed CO2 Emissions Limitations The present Technical Paper discusses only the direct effects of the emissions limitation proposals. Therefore, issues such as "carbon leakage”, whereby emissions reductions in Annex I countries may have energy price and trade effects which could result in increased emissions in non-Annex I countries, and technology transfer effects, whereby new technology used in Annex I countries could also be used in non-Annex I countries resulting in possible lower emissions in these countries, are not discussed. 2. SUMMARY OF MAIN RESULTS The key results of this study are as follows: Emissions Emissions by Annex I countries under the French (FR) or Netherlands (NL) emissions limitation proposals are substantially less than emissions under the IS92 scenarios IS92a, b, e and ƒ throughout the twenty-first century. Compared with the IS92c and d scenarios, the differences are small. Relative to the IS92a scenario, Annex I country emissions under the limitation proposals represent reductions of 30-90 per cent by the year 2100. ⚫ Even if Annex I countries were to follow the FR or NL limitation proposals, global emissions in 2100 would be two to three times the 1990 level, if non-Annex I country emissions were to grow during 1990-2100 according to the IS92a scenario. Concentration . When the FR or NL emissions limitation proposals for Annex I countries are combined with IS92 scenarios for nonAnnex I countries, projected CO2 concentrations are less than under any of the IS92 scenarios. The concentration reductions relative to the IS92 scenarios (with the exception of IS92c) eventually become substantial, of the order of 100 ppmv by 2100 for IS92a and 200 ppmv by 2100 for IS92e. The effects of emissions limitation proposals accrue only Temperature and Sea Level • Future CO2 concentration projections are subject to uncertainties arising from our incomplete understanding of the carbon cycle. However, uncertainties in the reductions in radiative forcings arising from the emissions limitation proposals are smaller. This is because the cumulative emissions reductions due to the limitation proposals are small relative to the total cumulative emissions, and because of the non-linear relationship between CO2 concentration and radiative forcing. • The emissions limitations proposals considered here affect future changes in global mean temperature and sea level. By 2100, relative to the no-limitation cases, the reduction in global mean temperature increase resulting from the NL-2% limitation proposal ranges between 0.1°C (i.e., from 0.7°C down to 0.6°C for IS92c and a climate sensitivity of 1.5°C) and 0.9°C (i.e., from 3.9°C down to 3.0°C for IS92e and a climate sensitivity of 4.5°C), while the reduction in sea level rise ranges between 2 cm (i.e., from 12 cm down to 10 cm for IS92c and a climate sensitivity of 1.5°C) and 15 cm (i.e., from 100 cm down to 85 cm for IS92e and a climate sensitivity of 4.5°C). 3. DESCRIPTION AND QUANTIFICATION OF EMISSIONS LIMITATION PROPOSALS As noted in the Introduction, the emissions limitation proposals for Annex I countries examined in this Technical Paper are documented in the 31 January 1997 report of the AGBM entitled "Framework Compilation of Proposals from Parties for the Elements of a Protocol or Another Legal Instrument" (FCCC/AGBM/1997/2, pp. 34-39). The details (for those suggestions that may be fully defined in quantitative terms) are summarized in Table 1 and expressed in terms of absolute CO2 emissions in Table 2. In producing Table 2, emissions limitation suggestions expressed in terms of greenhouse gases (rather than CO2 specifically) have been interpreted as applying to fossil CO2 emissions alone. If such limitations were achieved through emissions reductions of nonCO2 greenhouse gases in addition to, or in place of, CO2 emissions reductions (i.e., in accordance with the so-called "comprehensive" approach noted in Article 3.3 of the FCCC), then higher CO2 emissions than those assumed here would be possible. However, if the emissions limitation proposals were expressed in CO2-equivalent terms (e.g., see TP3, Section 2.2) in an appropriate way, then the temperature and sea level results produced here would apply equally to the CO2-alone and greenhouse gas (CO2-equivalent) cases. In the absence of any suggestions for the breakdown between CO2 and non-CO2 emissions reductions, and because there is no agreed method of satisfactorily quantifying the effects of non-CO2 emissions reductions in CO2-equivalent terms, it is not possible to easily quantify the additional CO2 emissions that a comprehensive approach might allow. The emissions limitation proposals listed in Table 2 assume that Annex I country emissions levels in the year 2000 are the same as in 1990. This is in accordance with Article 4.2(a) and (b) of the FCCC. It is also assumed in all cases that CO2 emissions for Annex I countries remain constant over 1990-2000. If the limitation proposals remain unchanged after the year 2000, the effects of these simplifications on the calculated CO2 concentrations are very small. Should emissions for Annex I countries rise during the 1990s, then fall to the 1990 level in the year 2000, the increase in concentration in the year 2000 would be approximately 0.4 ppmv for every additional GtC of CO2 emissions accumulated over 1990-2000 declining to 0.2 ppmv per additional GtC by 210010. Within the range of possible emissions for the 1990s, this effect on concentration is negligible. 9 Global Warming Potentials (GWPs) provide a means of comparing the effect of different greenhouse gases with that of CO2. However, the values of the GWPS for a given gas differ greatly depending on the time horizon which is chosen. Therefore GWPs can only be used to provide an approximate measure of CO2 equivalence associated with a specific choice of time horizon. 10 The same sensitivity to emissions "errors" over 1990-2000 applies to global emissions. In other words, if global emissions over 1990-2000 differ from the values assumed here, then the effect would be a change in concentration of 0.4 ppmv for each cumulative GtC of emissions "error" in the year 2000, declining to 0.2 ppmv by the year 2100. Emissions limitation proposals for Annex I countries Reduce CO2 emissions by at least 20 per cent by 2005 Reduce CO2 emissions by 10 per cent by 2005, and by 15-20 per cent by 2010 Reduce CO2 emissions by 10-20 per cent by 2010 Reduce CO2 emissions by 20 per cent by 2005, and by 50 per cent by 2030 Reduce ghg emissions by 5-10 per cent by 2010 Return ghg emissions to 1990 level by 2000, reduce emissions by 10 per Reduce ghg emissions by an average of 1-2 per cent per year (from 2000) Table 1. Description of emissions limitation proposals for Annex I countries (FCCC/AGBM/1997/2, dated 31 January 1997). All reductions are relative to the 1990 level. Some proposals apply to CO, alone, others to CO2 plus other greenhouse gases (ghg) presumably in some equivalent CO2 emissions sense. Note that, in general, FCCC usage of the term ghg excludes gases controlled by the Montreal Protocol. Table 2. Fossil CO2 emissions (GtC/yr) for Annex I countries under the emissions limitation proposals, based on Table I and converted to GtC/yr using 1990 emissions of 4.59 GtC/yr, as given in IPCC92 (Leggett, et al., 1992) and Pepper, et al. (1992) and assuming that the 1900 level is equal to the 2000 value. Gaps in this Table indicate that nothing specific was prescribed for that year. More than one value indicates that a range was specified. If emissions from Annex I countries rose over the 1990s so that their level in the year 2000 exceeded that in 1990 and the higher 2000 level (or some other level) was used as a baseline for future reductions in Annex I country emissions, this would also affect future concentrations. The sensitivity of the concentration projections to such an increase and to the assumed baseline level is, however, relatively small. The emissions limitation proposals considered here may be divided into two groups (Table 3): (a) Proposals up to 2030 or earlier (AOSIS, AT/DE, BE, DK, CH, UK and ZR). This group contains 10 cases when the low (1) and high (h) cases for the AT/DE, BE and UK proposals are considered individually. However, only five of these are unique (viz. [AOSIS, DK]; [AT/DE-I, BE-1]; [AT/DE-h, ZR]; [BE-h, CH, UK-1] and [UK-h]); (b) Proposals up to 2100 (FR and NL). The FR suggestion is based on per capita emissions. Since conversion to actual emissions requires population estimates, the resulting emissions span a range of possibilities. From these we derive low (FR-Low), central (FR-Central) and high (FR-High) emissions cases that span the range. The NL proposal specifies two extremes, corresponding to 1 per cent and 2 per cent per year compound fossil CO2 emissions reductions after 2000, identified as NL-1% and NL-2%, respectively. Appendix 2 gives a more detailed description of the FR and NL emissions limitation proposals. In terms of emissions reductions, the effect of any limitation proposal depends on the baseline from which it is measured. Here we use, to give a range of baselines, the IS92 fossil CO2 emissions scenarios for Annex I countries. Figure 1 compares these with the FR and NL emissions limitation proposals. The IS92 emission scenarios illustrated here, IS92a, c and e, bracket results for the other three scenarios, IS92b, d and f. Table 4 gives a summary of the economic growth, energy supply and population projection assumptions made in deriving these scenarios. Relative to IS92a and IS92e, the proposals represent substantial emissions reductions. Relative to IS92c the FR-Central and FR-High proposals actually have higher emissions. It should be noted, however, that it is difficult to make a direct comparison between IS92c and the FR-Central and FR-High cases because the latter use mid and high (Annex I) population projections, while IS92c uses the low (global) population projection (see Table 4). A more consistent comparison is FR-Low and IS92c, here the emissions reduction proposal represents a relatively small reduction below the IS92c case in terms of cumulative CO2 emissions. Both NL-1% and NL-2% correspond to reductions below IS92c. These are quite substantial (in percentage terms for cumulative emissions) for the NL-2% case. 1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100 Year Figure 1. Fossil CO2 emissions (GtC/yr) for Annex I countries under the French (FR) and Netherlands (NL) emissions limitation proposals compared with those under the IS92a, c and e scenarios. FR-Low, FR-Central and FR-High are derived from a range of possibilities based on per capita emissions. NL-1% and NL-2% refer to 1 per cent and 2 per cent per year compound CO2 emissions reductions after 2000. |