page 98 note 2 Indeed, the diplomatic conference on climate in Bali appeared to be one of the most undiplomatic of proceedings with reports of acrimony, boos, and crying by diplomats on the way to the outcome. See Bali Forum Backs Climate ‘ ‘Road Map'', Washington Post, Sunday, Dec. 16, 2007, p. A01; Climate Plan Looks Beyond Bush's Tenure, N. Y. Times, Sunday, Dec. 16, 2007, p. 1.

page 98 note 3 31 I.L.M. 849 (1992).

page 98 note 4 Also called the “Bali Roadmap”. Decision -/CP.13, FCCC/ CP/2007/L.7/Rev.l (14 Dec, 2007)(decision numbers have yet to be issued for Decisions taken at COP 13), available at: <http://unfccc.int/files/meetings/cop_13/application/pdf/cp_bali_action.pdf>.

page 98 note 5 37I.L.M. 22 (1998).

page 98 note 6 available at <http://www.ipcc.ch/ipccreports/assessments-reports.htm>.

page 98 note 7 For a detailed account of the 13^th COP to the UNFCCC, see Summary of the Thirteenth Conference of the Parties to the UN Framework Convention on Climate Change and Third Meeting of the Parties to the Kyoto Protocol, 12 Earth Negotiations Bull. (No. 354, 18 Dec. 2007), available at <http://www.iisd.ca/climate/cop13/>.

page 98 note 8 See <http://www.ipcc.ch/ipccreports/assessments-reports.htm>.

page 98 note 9 Rachmat Witoelar, The Bali Roadmap, Address to Closing Plenary by President of the U.N. Climate Conference, Bali (Dec. 15,2007), available at: <http://unfccc.int/files/meetings/cop_13/application/pdf/close_stat_copl3_president.pdf>.

page 120 note 1 Numbers in square brackets indicate a 90% uncertainty interval around a best estimate, i.e. there is an estimated 5% likelihood that the value could be above the range given in square brackets and 5% likelihood that the value could be below that range. Uncertainty intervals are not necessarily symmetric around the corresponding best estimate.

page 120 note 2 Words in italics represent calibrated expressions of uncertainty and confidence. Relevant terms are explained in the Box ‘Treatment of uncertainty’ in the Introduction of this Synthesis Report.

page 120 note 3 Excluding tsunamis, which are not due to climate change. Extreme high sea level depends on average sea level and on regional weather systems. It is defined here as the highest 1% of hourly values of observed sea level at a station for a given reference period.

page 120 note 4 Based largely on data sets that cover the period since 1970.

page 120 note 5 Includes only CO2, CH4, N2O, HFCs, PFCs and SF6 whose emissions are covered by the UNFCCC. These GHGs are weighted by their lOOyear Global Warming Potentials, using values consistent with reporting under the UNFCCC.

page 120 note 6 Increases in GHGs tend to warm the surface while the net effect of increases in aerosols tends to cool it. The net effect due to human activities since the pre-industrial era is one of warming (+1.6 [+0.6 to +2.4]W/m). In comparison, changes in solar irradiance are estimated to have caused a small warming effect (+0.12 [+0.06 to +0.30]W/m).

page 120 note 7 Consideration of remaining uncertainty is based on current methodologies.

page 120 note 8 For an explanation of SRES emission scenarios, see Box 'SRES scenarios’ in Topic 3 of this Synthesis Report. These scenarios do not include additional climate policy above cur rent ones; more recent studies differ with respect to UNFCCC and Kyoto Protocol inclusion.

page 120 note 9 Emission pathways of mitigation scenarios are discussed in Section 5.

page 120 note 10 TAR projections were made for 2100, whereas the projections for this report are for 2090-2099. The TAR would have had similar ranges to those in Table SPM. 1 if it had treated uncertainties in the same way.

page 120 note 11 For discussion of the longer term see material below.

page 120 note 12 Identified on the basis of expert judgement of the assessed literature and considering the magnitude, timing and projected rate of climate change, sensitivity and adaptive capacity.

page 120 note 13 Including arid and semi-arid regions.

page 120 note 14 While this section deals with adaptation and mitigation separately, these responses can be complementary. This theme is discussed in section 5.

page 121 note 15 The concept of “mitigation potential” has been developed to assess the scale of GHG reductions that could be made, relative to emission baselines, for a given level of carbon price (expressed in cost per unit of carbon dioxide equivalent emissions avoided or reduced). Mitigation potential is further differentiated in terms of “market mitigation potential” and “economic mitigation potential”.Market mitigation potential is the mitigation potential based on private costs and private discount rates (reflecting the perspective of private consumers and companies), which might be expected to occur under forecast market conditions, including policies and measures currently in place, noting that barriers limit actual uptake.Economic mitigation potential is the mitigation potential that takes into account social costs and benefits and social discount rates (reflecting the perspective of society; social discount rates are lower than those used by private investors), assuming that market efficiency is improved by policies and measures and barriers are removed. Mitigation potential is estimated using different types of approaches. Bottom-up studies are based on assessment of mitigation options, emphasizing specific technologies and regulations. They are typically sectoral studies taking the macro-economy as unchanged. Top-down studies assess the economy-wide potential of mitigation options. They use globally consistent frameworks and aggregated information about mitigation options and capture macro-economic and market feedbacks.

page 121 note 16 20 trillion = 20,000 billion = 20xl0¹²

page 121 note 17 Studies on mitigation portfolios and macro-economic costs assessed in this report are based on top-down modelling. Most models use a global least cost approach to mitigation portfolios, with universal emissions trading, assuming transparent markets, no transaction cost, and thus perfect implementation of mitigation measures throughout the 21^st century. Costs are given for a specific point in time. Global modelled costs will increase if some regions, sectors (e.g. land-use), options or gases are excluded. Global modelled costs will decrease with lower baselines, use of revenues from carbon taxes and auctioned permits, and if induced technological learning is included. These models do not consider climate benefits and generally also co-benefits of mitigation measures, or equity issues. Significant progress has been achieved in applying approaches based on induced technological change to stabilisation studies; however, conceptual issues remain. In the models that consider induced technological change, projected costs for a given stabilisation level are reduced; the reductions are greater at lower stabilisation level.

page 121 note 18 Further details may be found in Topic 4 of this Synthesis Report.

page 121 note 19 Key Vulnerabilities can be identified based on a number of criteria in the literature, including magnitude, timing, persistence/reversibility, the potential for adaptation, distributional aspects, likelihood and ‘importance’ of the impacts.

page 121 note 20 For the lowest mitigation scenario category assessed, emissions would need to peak by 2015 and for the highest by 2090 (see Table SPM.6). Scenarios that use alternative emission pathways show substantial differences in the rate of global climate change.

page 121 note 21 Estimates for the evolution of temperature over the course of this century are not available in the AR4 for the stabilisation scenarios. For most stabilisation levels global average temperature is approaching the equilibrium level over a few centuries. For the much lower stabilisation scenarios (category I and II, Figure SPM. 11), the equilibrium temperature may be reached earlier.

page 121 note 22 See footnote 17 for more detail on cost estimates and model assumptions.

page 121 note 23 Net economic costs of damages from climate change aggregated across the globe and discounted to the specified year.