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Inter-Agency Climate Change Forum Meeting Date: December 19 2007 Paper: IACCF 2007 Dec/5 Stabilisation wedges – a discussion paper for the UK nature conservation agencies This paper provides a critique of the “7 wedges” approach previously presented to the forum. It concludes that the size of the wedges is highly dependent upon the selection of an appropriate emissions reduction scenario. The deployment of the technologies required to deliver deep cuts in emissions has the potential to give rise to adverse biodiversity impacts. Further work is required to assess the size and potential impacts of the wedges necessary to deliver deep reductions in UK emissions. Given the level of expertise required it is likely that such work would need to be commissioned from outside of the nature conservation agencies. Action by IACCF: That the forum considers the appropriateness of various stabilisation scenarios with the aim of endorsing the adoption by the UK of a minimum emissions reduction target of 80% That the forum considers whether work should be commissioned to assess the energy mix required to deliver such reductions by 2050, thereby assessing the size of the UK wedges. It is suggested that a first step would be to commission an analysis of the WWF/RSPB/IPPR “80% Challenge” document. That the forum considers whether further work is required to assess the impact of UK-based wedges on domestic and overseas biodiversity. Documents: IACCF 2007 Dec-5 Discussion paper IACCF 2007 Dec-6 PDF of WWF/IPPR/RSPB “80% Challenge” publication -1- Inter-Agency Climate Change Forum STABILISATION WEDGES A DISCUSSION PAPER FOR THE UK NATURE CONSERVATION AGENCIES 1. Summary The concept of stabilisation wedges provides a useful solution-orientated approach to illustrate how significant emissions reductions may be practically delivered on a global level. However, the original approach was not without its problems and, as proposed by many advocates, contains weaknesses arising from an inappropriate choice of stabilisation levels and resulting unrealistic pathways to emissions reductions. These weaknesses have to some extent been addressed by other parties. An initial analysis of the “seven wedges” approach to reducing global emissions suggests that there may be significant adverse biodiversity impacts associated with some of the proposed technologies, although many will have neutral or positive effects on nature conservation interests. In particular the levels of production associated with the size of bio-fuels wedges reinforces concerns about tropical deforestation and domestic land use changes arising from fuel crops. There are a number of problems associated with translating the wedges approach to a national (United Kingdom) level because it currently focuses on displacing emissions growth globally to 2050 whereas UK policy is to reduce overall national emissions by a significant amount well before that date. A UK wedges based scenario would, therefore, be based on selecting a portfolio of technologies to deliver emissions reductions and displace existing technologies rather than displacing growth (which in any event on a UK-wide basis will be extremely low compared to global “business as usual” growth predictions). Further analysis on behalf of the nature conservation agencies may be required to assess the size and impact of these wedges, particularly if an 80% emissions reduction target is favoured over the 60% reduction currently proposed in the Climate Change Bill. -2- Inter-Agency Climate Change Forum 2. Introduction The body of evidence in respect of climate change, together with growing assessment of risk levels, is now sufficient1 to give clear and strong guidance to policy makers to shape a response to the challenge posed by human release of greenhouse gases into the atmosphere. However there is confusion concerning options for mitigation with some commentators claiming that emissions reductions can be delivered within the scope of existing technologies while others have claimed that radical new technology is required to deliver a low-carbon economy. Two Princeton researchers, Stephen Pacala and Robert Scolow, published a paper in Science in 20042 advocating an approach which identifies options to “solve the climate problem for the next-half century”. This approach identifies “stabilization wedges”, essentially bundles of existing low- or zero-carbon technologies, capable of delivering emissions reductions. Each wedge increases in size over time, displacing the growth in carbon emissions arising from increased demand for energy. They advocate that the fifteen technologies, grouped into seven main wedges (forming a “stabilization triangle”), could be scaled up to provide stabilisation of atmospheric CO2 at the level of 500ppm. 3. Critique of the wedges approach - key issues The approach proposed by Pacala and Scolow is attractive because it is solutionorientated; offering a positive message that climate change can be addressed with existing technologies. As a result the approach has been endorsed by a number of organisations; both within the corporate and NGO sectors. The wedges approach is of particular value in testing stakeholder opinion on the deployment of the various technologies and has spawned a number of web-based tools which can be used to explore the effect of various mixtures of technology on carbon emissions. However, as a tool for policy makers to set targets for deployment of low or zero-carbon technology, the use of the “wedges” approach is problematic unless the assumptions underlying the methodology are questioned. Pacala and Scolow acknowledge that the approach is an “idealization”3, however the following issues should be considered: 3.1 Choice of stabilisation level Pacala and Scolow’s approach focuses on limiting atmospheric CO 2 to 500 ± 50 ppm. However, since 2004 (when the paper was published) many commentators have revised their opinion as to what an appropriate stabilisation level should be. Stern Review – “The Science of Climate Change: Scale of the Environment Challenge”, page 2 Pacala, S & Socolow, R (2004), Stabilization Wedges: Solving the Climate Problem for the Next 50 Years with Current Technologies, Science, 305, p968-972 3 Presentation to the Scientific Symposium on the Stabilisation of Greenhouse Gases, Exeter 2005 http://www.stabilisation2005.com/day3/Socolow.pdf 1 2 -3- Inter-Agency Climate Change Forum Much of this commentary has focussed on minimising the risk of exceeding a 2ºC increase in global temperature above pre-industrial levels. This 2ºC approach was adopted by The International Symposium on Greenhouse Gas Concentrations and Avoiding Dangerous Climate Change (ADCC)4 in Exeter in 2005 and in the Stern Review5. For the purposes of this paper it has been assumed that this approach is appropriate although it should be noted that some commentators suggest that even a 1ºC change would constitute “dangerous climate change”6. Generally, while there is some disagreement about what emissions stabilisation level would lead to global temperature change remaining below 2ºC, there is general consensus that it would be considerably lower than the 500ppm CO2 level (around 600ppm CO2 equivalent7) adopted by Pacala and Scolow. Box 1 – Measurements of greenhouse gas levels - CO2 equivalent (CO2e) Carbon dioxide equivalent, CO2eq or CO2e, is used to provide a broader measure of total greenhouse gas contributions than solely that arising from atmospheric carbon dioxide. It expresses the global warming potential of all greenhouse gases in terms of the amount of atmospheric carbon dioxide that would have the same global warming potential. The carbon dioxide equivalent for a gas is derived by multiplying the mass of that gas by the associated Global Warming Potential (“GWP”). For example, the GWP for methane is 21. This means that emissions of 1 million metric tonnes of methane are equivalent to emissions of 21 metric tonnes of carbon dioxide. For the purposes of this paper references will be made to CO2e, which will be used from this point onwards Table 1 (below) provides a summary of global mean temperature increases above pre-industrial levels predicted by the IPCC to occur for given atmospheric greenhouse gas levels. It can be seen from the table that the emissions stabilisation scenario utilised by Pacala and Scolow (WRE500) would probably lead to a temperature increase above pre-industrial levels of around 3.5ºC. It would, therefore be appropriate to consider other emission stabilisation scenarios when assessing the size of stabilisation wedges. Table 1 Co2 concentrations and emissions 4 CO2 concentration (ppm) CO2 – equivalent concentration (ppm) Global mean temperature increase above preindustrial level at equilibrium (ºC) Peaking year for CO2 emissions Global change in CO2 emissions in 2050 (% of 2000 emissions) 350-400 400-440 440-485 485-570 445-490 490-535 535-590 590-710 2.0 – 2.4 2.4 – 2.8 2.8 – 3.2 3.2 – 4.0 2000-2015 2000-2020 2010-2030 2020-2060 -50 to -85 -30 to -60 +5 to 30 +10 to +60 Schnellnhuber, H.J (ed)(2006), Avoiding Dangerous Climate Change, Cambridge 2006 5http://www.hm- treasury.gov.uk/independent_reviews/stern_review_economics_climate_change/stern_review_report. cfm 6 e.g. http://pubs.giss.nasa.gov/docs/2006/2006_Hansen_etal_1.pdf 7 See Box 1 -4- Inter-Agency Climate Change Forum 570-660 660-790 710-855 855-1130 4.0 – 4.9 4.9 – 6.1 2050-2080 2060-2090 +25 to +85 +90 to +140 From WEO 20078, based on IPCC 20079 3.2 Scenarios for stabilisation below WRE500 (approx 600ppm CO2e) For the purposes of this paper two emissions stabilisation scenarios are discussed, both published by the International Energy Agency in its World Energy Outlook (WEO) in November 2007. These scenarios have been chosen because they combine the robustness of IPCC climate change scenarios (which include the potential impact of differing atmospheric greenhouse gas concentrations on global mean temperature) with current market-based predictions of emission levels (including those arising from recent increases in economic growth in India and China). The selection of these scenarios is for the purpose of discussing the assessment of wedge size only, rather than representing the endorsement of any particular climate change prediction. The first of these scenarios, the “Alternative Policy Scenario”, is based on a 550ppm CO2e stabilisation level. While this level is lower than that utilised by Pacala and Scolow, such a level would still correspond to an increase in average temperature of around 3ºC above pre-industrial levels10. The second scenario published by the IEA is the “450 Stabilisation Case”. Stabilisation at 450 ppm CO2e offers an even chance of staying below the 2ºC level11. However, as Table 1 highlights, such a scenario requires emissions to peak in the very near future and for large scale cuts in emissions to be delivered by 2050. When it is remembered that Pacala and Scolow propose no requirement for cuts in emissions before 2050 it becomes apparent that, if a 450ppm CO 2e target is desirable, the shape of the “stabilisation triangle” (and the wedges which form it) are likely to be very different than that advocated in their 2004 paper. It should be noted that adoption of a 450ppm CO 2e target would not guarantee that global warming was constrained to below 2ºC. Indeed both Stern and the IPCC express the possibility of limiting increases to 2ºC at not much better than 50% under a 450ppm CO2e target. For this reason many commentators have advocated more ambitious targets. For example WWF International has adopted a 400ppm CO 2e target as the basis for its wedged-based analysis.12 International Energy Agency, World Energy Outlook 2007, Chapter 5 “Global Environmental Repercussions” 9 Intergovernmental Panel on Climate Change, Climate Change 2007: Fourth Assessment Report, IPCC, Geneva 10 WEO 2007, page 207 11 ADCC 2006, page 265 12 WWF International (2007) http://assets.panda.org/downloads/climatesolutionweb.pdf 8 -5- Inter-Agency Climate Change Forum 3.3 Choice of stabilisation scenario determines the size of the wedges Figure 1 at the rear of this paper illustrates how the stabilisation triangle and wedges vary according to which stabilisation target is selected. Figure 1(a) illustrates the triangle selected under the WRE500 scenario chosen by Pacala and Scolow. In this case reductions in carbon emissions below current levels would not be required until after 2050. The resulting triangle (and wedges) therefore focuses only on displacing “business as usual” predictions of emissions growth. The WEO Alternative Policy Scenario, introduced above, would produce a stabilisation triangle similar to that shown in Figure 1(b). Under this 550ppm CO2e stabilisation scenario emissions stabilise in the mid-2020s and fall thereafter to around 30% of 2000 emissions by 205013 with further decreases thereafter (see also Table 1). The WEO 450 Stabilisation Case gives rise to a significantly larger triangle than that proposed by Pacala and Scolow; see Figure 1(c). Under this scenario global energy related CO2 emissions peak in 2012 at around 30Gt and decline to 23 Gt in 2030 with further decreases thereafter to between 50-85% of 2000 emissions by 205014. 3.4 Other factors may affect the size of the wedges The shape of the stabilisation triangle is also affected by the selection of “Business as Usual” (BAU) scenario. The World Energy Outlook 2007 Reference Scenario provides a very recent forecast of emission levels. While Pacala and Scolow utilise an average growth rate of 1.5% per year, the WEO work suggests an average growth of 1.8%, giving rise to a 57% increase in world emissions between 2005 and 203015. In particular, the report stresses the importance of the contribution of recent strong economic growth in India and China towards these increases in emissions. Again, this suggests that the real size of the stabilisation triangle and component wedges will be significantly higher if such growth is to be displaced by zero-carbon or carbon-neutral technologies at the same time as delivering cuts in emissions. The shape of the wedges may also be affected by other issues. Valuing the contribution of wedges may be problematic (particularly in respect of sinks and the contribution of deforestation to atmospheric CO2 levels). Additionally, technical constraints may not allow the wedges to develop uniformly. Supply chain bottlenecks (as already experienced in the wind energy industry), shortage of capital, regulatory barriers and environmental constraints may all restrict the full potential of all the wedges from being developed16. 13 WEO 2007, Chapter 5 ibid 15 WEO 2007, page 192 16 Wellington et al “Scaling Up: Global Technology Deployment to Stabilize Emissions”, World Resources Institute. http://pdf.wri.org/scalingup.pdf 14 -6- Inter-Agency Climate Change Forum 3.5 Reassessment of the size of the global wedges It is clear from the above that a re-assessment of the size of the wedges from those proposed in the 2004 paper is required. The gap between the WEO Reference Scenario (i.e. BAU) and the 450 Stabilisation Case amounts to 19 Gt in 2030, compared to the 7 Gt “gap” in 2054 (approximately 3.3Gt in 2030) envisaged by Pacala and Scolow. The World Energy Outlook 2007 suggests that the 450 Stabilisation Case is realisable with existing technology but that “exceptionally strong and immediate” policy action would be essential for this to happen and the associated costs would be “very high” (partly because existing plant would need to be replaced immediately rather than at the end of its lifespan). Figure 2 (to rear of this paper), taken from WEO2007, illustrate how such reductions might be delivered. It should be noted that Figure 2 details the “wedges” required to deliver the reduction difference between the Alternative Policy Scenario (550ppm CO2e) and the 450 Stabilisation Case, not the entire portfolio of wedges required to deliver to 450ppm CO 2e target. Additionally the WEO work does not focus on issues such as sinks, deforestation or agricultural practices, rather it focuses solely on energy use. WWF International has calculated climate solution wedges based on a 400ppm CO2e target17 (see Figure ). Such an approach (which is likely to be desirable from a nature conservation viewpoint) stresses the key themes of energy efficiency, deforestation, carbon capture and storage and renewables discussed by Pacala and Scolow. However, as the paper acknowledges, the difficulties with delivering such a programme are exceptional, resulting in an “ominous” outlook. For that reason this paper has discussed the more “realistic” (although still challenging) 450ppm CO 2e scenario. Additionally it should be noted that the WWF International model does not adopt an economic approach – rather it considers wedge-size based on carbon reduction capacity. 4. Biodiversity impacts of the global wedges Pacala and Socolow identify 15 wedges (grouped into 7 larger wedges), each contributing towards reducing carbon emissions from 2004 to 2054 by 25 GtC. The increased deployment of novel technologies may have adverse impacts on biodiversity. An assessment of the potential impact of each of the 15 wedges is set out at Table 2 (at the rear of this paper). Of the 15 wedges, the majority would probably not give rise to adverse biodiversity impacts, particularly as many focus on energy efficiency. However one wedge, relating to biofuels, has the potential to give rise to adverse biodiversity impacts. Such impacts may occur domestically (for example from changes in agricultural 17 http://assets.panda.org/downloads/climatesolutionweb.pdf - this paper also provides in the technical appendices a useful analysis of the problems associated with calculating wedge sizes -7- Inter-Agency Climate Change Forum cropping) or overseas. The current risks are summarised in the JNCC position statement on transport biofuels and biodiversity18. A further five wedges (shaded yellow in Table 2) could give rise to adverse impacts depending on how they were implemented. This may be of particular concern if, as appears likely, extremely large cuts in emissions are required over a relatively short timescale leading to rapid deployment of technologies. Two wedges (reforestation and conservation tillage) could give rise to positive biodiversity effects. It is unlikely, therefore, that a wedges based approach would significantly alter the nature conservation agencies’ current policy advice on the potential adverse effects of emissions reduction technology, namely: Robust certification of biofuels Reduction of deforestation Careful siting of development by utilising Strategic Environmental Assessment and Environmental Impact Assessment Continued stress on the importance of energy efficiency Larger wedges which, as discussed above, will be necessitated by the requirement for urgent cuts in emissions, could give rise to increased biodiversity impacts, particularly in respect of inappropriately sited development. It is not currently possible to assess the impacts of such larger wedges although some work has been carried out in individual sectors. For example, WWF International have estimated that biomass with an energy content of between 110 and 250 exajoules could be achieved from sustainable production by 205019. This level of production, which it is calculated, can be delivered without prejudicing nature conservation interests or food production, would amount to between 9 and 21% of global energy demand in 2050. 5. Identification of “threat wedges” The concept of threat wedges was introduced in a World Resources Institute Paper in April 200720. Threat wedges relate to technologies which increase global carbon emissions. The WRI identify three technologies which, driven by energy security concerns (particularly in North America), could contribute to growing emissions. BAU scenarios could be increased by production of synthetic liquid fuels from coal (CTL), heavy oil production from tar sands and production of oil from shale rock-types. To be available from www.jncc.gov.uk – also attached to this paper http://assets.panda.org/downloads/climatesolutionweb.pdf 20 Wellington et al “Scaling Up: Global Technology Deployment to Stabilize Emissions”, World Resources Institute. http://pdf.wri.org/scalingup.pdf 18 19 -8- Inter-Agency Climate Change Forum 6. Developing a UK based wedges approach The wedges approach could be applied to UK emissions reductions targets to provide an illustration of how those targets could be delivered. A UK-based wedged approach would have a different shaped stabilisation triangle than that applying to the global scenarios described above. UK greenhouse gas emissions under a business as usual scenario are predicted to be relatively flat, falling to the mid 2020s and then rising thereafter 21. The UK government has already committed to a 60% reduction in emissions from 1990 levels by 2050 in the draft Climate Change Bill. The shape of the stabilisation triangle required to deliver this level of reduction is shown at Figure 4(a). However, many commentators have suggested that a 60% emissions reduction target would be incompatible with a goal of stabilisation at 450ppm CO 2e. For example, Höhne et al (2007)22 suggest that the UK should be aiming to reduce greenhouse gas emissions from 1990 levels by 35-45% by 2020 and by 80-95% by 2050. Calls for an 80% reduction target for the UK has been supported by a number of NGOs including WWF, RPSB and the IPPR in the publication “80% Challenge – Delivering a low-carbon UK”23. An 80% reduction target would give rise to a significantly larger stabilisation triangle, as illustrated at Figure 4(b). Calculation of the size of the UK stabilisation triangle (and its component wedges) would need to take account of the following issues. 6.1 Mix of UK wedges is likely to be different from global counterparts The wedges of technology making up the UK stabilisation triangle are likely to be different from those making up the global stabilisation triangle. The selection of technologies for the UK wedges will therefore need to take account of the nature of the UK economy and environment. For example, the UK’s wind, wave and tidal resources are high compared to the global average, whereas capacity for photovoltaic (solar) energy is probably more limited. The legacy of North Sea oil extraction suggests that there may be more potential for carbon capture and sequestration (CCS). In 2000 the Royal Commission on Environmental Pollution (RCEP) published an assessment of how a 60% reduction in emissions might be delivered 24. The work provides four scenarios for achieving a 60% reduction from 1997 levels by 2050. Details of these scenarios are attached at Tables 3 and 4. Table 3 details four 21 UK CO2 Emissions Projections, Annex C, The Energy Challenge, Department of Trade and Industry (2006) 22 Höhne, N. Phylipsen, D. and Moltmann, S (2007) Factors underpinning future action – 2007 update. Report for DEFRA http://unfccc.int/resource/docs/2007/smsn/ngo/026c.pdf 23 http://www.ippr.org/publicationsandreports/publication.asp?id=573 24 The Royal Commission On Environmental Pollution's 22 nd Report, 2000 http://www.rcep.org.uk/newenergy.htm -9- Inter-Agency Climate Change Forum reduction scenarios and Table 4 details how the resulting energy mix could be delivered. Scenarios for 80% scenarios are less well developed. The “80% challenge” document referred to above provides some limited scenarios based on two models, suggesting that such a target is achievable within the scope of existing technologies and without recourse to nuclear power (the same case as adopted in the 2 nd and 4th RCEP scenarios). Figure 5 shows a potential energy mix under one of the 80% challenge scenarios. However, it should be noted that many of the assumptions, for example those relating to large market penetration of wind power or the use of carbon capture and storage (CCS), rely upon technologies only at a very early stage of development. Furthermore the work’s reliance on market demand based models does not take into account potential barriers to deployment such as the planning system, grid constraint or potential conflicts with other land- and sea- users (for example protected areas, housing and agriculture). Two particularly contentious issues would need to be addressed as part of the selection of appropriate wedges; the role of nuclear power and the contribution of aviation to CO2 levels. The role of nuclear power is problematic, partly because the environmental safety issues associated with long term waste storage have not been solved. In the context of large emission cuts in other sectors the projected rapid growth in aviation related greenhouse gas emissions could be seen as anomalous. Indeed modelling carried out by the Tyndall Centre for Climate Change Research 25 has suggested that at an annual growth rate of only half of that experienced by UK aviation in 2004, the UK’s aviation sector would account for 50% of permissible emissions under a 550ppm scenario and would consume the entire UK carbon budget under the 450ppm model. 6.2 Assessing the biodiversity impacts of the UK wedges It would be essential to assess the biodiversity impact of the UK stabilisation triangle. Such an assessment should also assess the overseas impact of UK energy consumption, particularly in respect of bio-fuel production and hydrocarbon extraction. The “80% challenge” document constrains the amount of bio-fuel use and wind generation within the UK to provide environmental safeguards to limit biodiversity impacts26. Three of the four RCEP scenarios detailed in Table 4 incorporate the use of tidal barrage technologies. Such projects could give rise to significant adverse impacts on biodiversity 25 Bows et al (2006), Contraction & Convergence: UK carbon emissions and the implications for UK air traffic, Tyndall Centre Technical Report No.40 26 http://www.ippr.org/publicationsandreports/publication.asp?id=573 – page 12 - 10 - Inter-Agency Climate Change Forum 6.3 Delivery of wedges on a country basis – sharing the burden It would also be important to assess the impact of each of the UK wedges on the constituent countries of the United Kingdom. For example, the vast majority of wind power is situated in Wales and Scotland rather than England. Scottish waters would provide most of the UK’s tidal and wave power resource. The delivery of UK based wedges could therefore have greater implications for individual country agencies than for the national environment as a whole. It should also be noted that the Scottish Government has is about to start consultation on a climate change bill which would include provisions to reduce Scottish emissions by 80% by 205027. 7. Conclusions and recommendations As discussed above the wedges approach to stabilisation is a useful tool to explore how emissions reductions will be delivered. However, further work may be required to assess the sizes of the wedges necessary to deliver lower stabilisation levels of atmospheric greenhouse gases than those assumed under the WRE500 scenario adopted in the 2004 paper. In particular it may be useful to commission an independent assessment of the scenarios adopted for the UK under the “80% Challenge” document which, while providing robust evidence for delivery in the power and transport sectors, does not fully take into account supply constraints. Should such work be commissioned, agreement would first be required between the country agencies on the following issues: Selection of appropriate stabilisation for temperature (e.g. 2ºC) Selection of appropriate emissions stabilisation scenario to meet this target (e.g. 450ppm CO2e). This will need to take into account the risks associated with overshoot and the probabilities of achieving the target. Selection of appropriate “business as usual” scenario (e.g. WEO 2007) Agreement on appropriate UK-wide emissions reduction target (e.g. 80%), noting that Scotland is already likely to adopt an 80% target. Discussion of status of various technologies, most notably nuclear power Further work would probably be required to assess the potential biodiversity impacts of the technologies involved although it may be possible to rely upon a precautionary approach similar to that adopted in the 80% Challenge document. Any analysis of potential biodiversity impacts would need to consider both the domestic and overseas footprint of the resulting technical solutions including, most notably, the use of bio-fuels. Andrew Prior Renewable Energy Advisor Joint Nature Conservation Committee 5th December, 2007 27http://www.scotland.gov.uk/Topics/Environment/Climate-Change/16327/Climate-Change- Bill/Proposals-Timescales - 11 - Inter-Agency Climate Change Forum Figures & tables Figure 1 The shape and size of the stabilisation wedges is highly dependent upon the choice of stabilisation level. In scenarios (b) and (c) wedges must deliver emissions reductions rather than solely displacing growth as is the case with Pacala & Socolow’s proposals. Within scenario (c) reductions might be delivered within the scope of the technologies reviewed by Pacala & Socolow, but delivery will be extremely challenging. (a) Pacala & Socolow stabilisation triangle based on WRE500 scenario BAU 2000 Reductions only after 2054 2050 (b) Stabilisation “triangle” based on a 550ppm CO2 equivalence stabilisation scenario28 Reductions required before 2054 (c) Stabilisation “triangle” based on a 450ppm CO2 equivalence stabilisation scenario29 28 29 WEO 2007 – Alternative Policy Scenario WEO 2007 – 450 Stabilisation Case - 12 - Inter-Agency Climate Change Forum Substantial reductions required before 2054 Note: above figures are illustrative only, not to scale. The choice of scenarios is indicative only and does not endorse a particular approach Figure 2 From WEO (2007) CO2 emissions in the 450 Stabilisation Case Reduction in emissions from Alternative Policy Scenario to 450 Stabilisation Case by 2030 delivered by: Carbon capture and storage (industry and power) Renewables in power sector Nuclear Generation Second generation bio-fuels in transport Fossil fuel efficiency (buildings and industry) Lower electricity use from energy efficient buildings - 13 - 21% 19% 16% 4% 27% 13% Inter-Agency Climate Change Forum Figure 3 From WWF International (2007) Energy wedges in 2050 under a 400 ppm CO2e stabilisation scenario - 14 - Inter-Agency Climate Change Forum Figure 4 Calculating the size of the UK wedges UK business as usual30 and Climate Change Bill 2050 target (60%) (a) 1990 level 2000 2050 ` (b) UK business as usual and increased Climate Change Bill 2050 target (80%) Note: above figures are illustrative only, not to scale. 30 UK CO2 Emissions Projections, Annex C, The Energy Challenge, Department of Trade and Industry (2006) - 15 - Inter-Agency Climate Change Forum Table 2 Pacala & Socolow’s Stablisation Wedges and their potential impacts on biodiversity Option Effort required Potential biodiversity impact 1 Efficient vehicles Increase fuel economy for 2 billion cars from 30 to 60 mpg Neutral 2. Reduced use of vehicles Decrease car travel for 2 billion 30-mpg cars from 10,000 to 5,000 miles per year Neutral / positive (assuming reduced road-building etc) 3. Efficient buildings Cut carbon emissions by one-fourth in buildings and appliances projected for 2054 Neutral 4. Efficient baseload coal plants Produce twice today’s coal power output at 60% instead of 40% efficiency (compared with 32% today) Neutral 5. Gas baseload power for coal baseload power Replace 1400 GW 50%-efficient coal plants with gas plants (four times the current production of gas-based power) Neutral (assuming based on existing sites) 6. Capture CO2 at baseload power plant Introduce CCS at 800 GW coal or 1600 GW natural gas (compared with 1060 GW coal in 1999) See below 7 Capture CO2 at H2 plant Introduce CCS at plants producing 250 MtH2/year from coal or 500 MtH2/year from natural gas (compared with 40 MtH2/ year today from all sources) See below 8. Capture CO2 at coal-to-synfuels plant Introduce CCS at synfuels plants producing 30 million barrels a day from coal (200 times Sasol), if half of feedstock carbon is available for capture See below Geologic storage Create 3500 Sleipners Potentially negative (infrastructure development, particularly in marine environment) 9. Nuclear power for coal power Add 700 GW (twice current capacity) Potentially negative – longterm storage solutions remain unresolved 10. Wind power for coal power Add 2 million 1-MW-peak windmills (50 times the current capacity) “occupying” 30x106 ha, on land or offshore Neutral if appropriate siting (avoiding sensitive habitats, migratory routes etc). Offshore capacity limited by water depth 11. PV power for coal power Add 2,000 GW-peak PV (700 times the current capacity) on 2x106 ha Neutral if assume much is sited on existing structures or can be appropriately sited elsewhere 12. Wind H2 in fuel-cell car for gasoline in hybrid car Add 4 million 1-MW-peak windmills (100 times the current capacity) Neutral but see above in respect of siting of wind turbines 13. Biomass fuel for fossil fuel Add 100 times the current Brazil or U.S. ethanol production, with the use of 250x106 ha (one-sixth of world cropland) Current rates of deforestation to provide biofuels etc suggest that this could only be delivered at expense of biodiversity 14. Reduced deforestation, plus reforestation, afforestation, and new plantations Decrease tropical deforestation to zero instead of 0.5 GtC/year, and establish 300 Mha of new tree plantations (twice the current rate) Positive 15. Conservation tillage Apply to all cropland (10 times the current usage) Neutral (although may be mildly positive) - 16 - Inter-Agency Climate Change Forum Table 3 RCEP scenarios for reducing UK CO2 emissions by 60% by 2050 From RCEP (2000)31 Four scenarios were constructed to illustrate the options available for balancing demand and supply for energy in the middle of the 21st century if the UK has to reduce carbon dioxide emissions from the burning of fossil fuels by 60%: scenario 1: no increase on 1998 demand, combination of renewables and either nuclear power stations or large fossil fuel power stations at which carbon dioxide is recovered and disposed of scenario 2: demand reductions, renewables (no nuclear power stations or routine use of large fossil fuel power stations) scenario 3: demand reductions, combination of renewables and either nuclear power stations or large fossil fuel power stations at which carbon dioxide is recovered and disposed of scenario 4: very large demand reductions, renewables (no nuclear power stations or routine use of large fossil fuel power stations). The key parameters for these four scenarios are as follows: 31 RCEP(2000), Chapter 9 – “Possible UK Energy Balances in 2050”, page 173 - 17 - Inter-Agency Climate Change Forum Table 4 Number of generating plants required under RCEP scenarios to deliver 60% target From RCEP(2000)32 Figure 5 Electricity generation mix to 2050 under MARKAL-MACRO model From “80% Challenge – delivering a low-carbon UK”33 32 33 RCEP(2000), Appendix E – “Illustrative Energy Balances for the UK in 2050”, page 225 http://www.ippr.org/publicationsandreports/publication.asp?id=573 – page 16 - 18 - Inter-Agency Climate Change Forum - 19 -