Second Order Draft Chapter 2 IPCC SR1.5 1 2 Chapter 2: Mitigation pathways compatible with 1.5°C in the context of sustainable 3 development 4 5 6 Coordinating Lead Authors: Kejun Jiang (China), Joeri Rogelj (Belgium/Austria), Drew Shindell (USA) 7 8 Lead Authors: Solomone Fifita (Fiji), Piers Forster (UK), Veronika Ginzburg (Russia), Collins Handa 9 (Kenya), Haroon Kheshgi (USA), Shigeki Kobayashi (Japan), Elmar Kriegler (Germany), Luis Mundaca 10 (Chile/Sweden), Roland Séférian (France), Maria Virginia Vilariño (Argentina) 11 12 Contributing Authors: Katherine Calvin (USA), Oreane Edelenbosch (Netherlands), Johannes Emmerling 13 (Germany/Italy), Sabine Fuss (Germany), Thomas Gasser (France/Austria), Chenmin He (China), Edgar 14 Hertwich (Austria/USA), Lena Höglund-Isaksson (Sweden/Austria), Daniel Huppmann (Austria), Gunnar 15 Luderer (Germany), Anil Markandya (UK/Spain), David L. McCollum (USA/Austria), Richard Millar (UK), 16 Malte Meinshausen (Germany/Australia), Alexander Popp (Germany), Joana Correia de Oliveira de Portugal 17 Pereira (Brazil/UK),Pallav Purohit (India/Austria), Keywan Riahi (Austria), Harry Saunders (Canada/USA), 18 Christina Schädel (Switzerland/USA), Pete Smith (UK), Evelina Trutnevyte (Lithuania/Switzerland), Yang 19 Xiu (China), Kirsten Zickfeld (Germany/Canada), Wenji Zhou (China/Austria) 20 21 Review Editors: Greg Flato (Canada), Jan Fuglestvedt (Norway), Rachid Mrabet (Morocco), Roberto 22 Schaeffer (Brazil) 23 24 Date of Draft: 22 December 2017 25 26 Notes: TSU compiled version 27 28 Do Not Cite, Quote or Distribute 2-1 Total pages: 143 Second Order Draft Chapter 2 IPCC SR1.5 1 Table of Contents 2 3 Executive Summary ......................................................................................................................................... 4 4 5 Introduction to Mitigation Pathways and the Sustainable Development Context .................... 9 6 Mitigation Pathways compatible with 1.5°C ............................................................................. 9 7 The Use of Scenarios to Answer Particular Questions ............................................................ 10 8 New scenario information since AR5 ...................................................................................... 11 9 10 Geophysical relationships and constraints .................................................................................. 13 11 Linking geophysical characteristics to mitigation pathways ................................................... 13 12 The 1.5°C and 2°C carbon budget ........................................................................................... 13 13 Carbon budget computations ............................................................................................... 13 14 Remaining carbon budget and related uncertainties ............................................................ 16 15 2.2.2.2.1 Methodological choices ................................................................................................. 16 16 2.2.2.2.2 Physical uncertainties .................................................................................................... 17 17 2.2.2.2.3 Reversibility and Earth system feedbacks ..................................................................... 17 18 Role of non-CO2 GHGs and aerosols .................................................................................. 19 19 Geophysical characteristics of mitigation pathways ................................................................ 21 20 Near-term to 2050 ................................................................................................................ 21 21 Post–2050 ............................................................................................................................ 25 22 23 Overview of 1.5°C mitigation pathways ...................................................................................... 26 24 Pathways keeping warming below 1.5°C or temporarily overshooting it ............................... 28 25 Factors determining overshoot ............................................................................................ 28 26 Emissions evolution ............................................................................................................. 30 27 2.3.1.2.1 Emissions of long-lived climate forcers ........................................................................ 31 28 2.3.1.2.2 Emissions of short-lived climate forcers and fluorinated gases..................................... 35 29 Key elements and variations of 1.5°C pathways ..................................................................... 38 30 Socio-economic drivers and the demand for energy and land in 1.5°C pathways .............. 38 31 Mitigation options in 1.5°C pathways ................................................................................. 39 32 Policy assumptions in 1.5°C pathways ................................................................................ 45 33 Whole-system transformation .................................................................................................. 45 34 Energy systems transformation............................................................................................ 45 35 2.3.3.1.1 Energy demand .............................................................................................................. 46 36 2.3.3.1.2 Energy Supply ............................................................................................................... 48 37 Land transformation ............................................................................................................ 50 38 Different portfolios of measures .......................................................................................... 51 39 Visions of carbon neutral energy systems ........................................................................... 53 40 Carbon dioxide removal in 1.5°C pathways ............................................................................ 53 41 CDR technologies and deployment levels in 1.5°C pathways............................................. 54 Do Not Cite, Quote or Distribute 2-2 Total pages: 143 Second Order Draft Chapter 2 IPCC SR1.5 1 Sustainability implications of CDR deployment in 1.5°C pathways ................................... 57 2 Implications of near term action in 1.5°C pathways ................................................................ 60 3 4 Disentangling the whole-system transformation ........................................................................ 61 5 Key characteristics of transitions in 1.5°C pathways from today until mid-century ............... 61 6 Energy supply .......................................................................................................................... 62 7 Evolution of primary energy contributions over time ......................................................... 62 8 Deployment of Carbon Capture and Storage ....................................................................... 64 9 Pace of change ..................................................................................................................... 65 10 Energy end-use sectors ............................................................................................................ 66 11 Industry ................................................................................................................................ 67 12 2.4.3.1.1 Reductions in the demand of industrial products and material efficiency ..................... 70 13 2.4.3.1.2 Energy efficiency improvements in industrial production ............................................ 70 14 2.4.3.1.3 Electrification of industry energy demand .................................................................... 70 15 2.4.3.1.4 Reducing the carbon content of non-electric fuels ........................................................ 71 16 2.4.3.1.5 Deployment of innovative technologies and application of carbon capture and storage71 17 Buildings .............................................................................................................................. 72 18 Transport .............................................................................................................................. 74 19 Land-use transitions and changes in the agricultural sector .................................................... 78 20 National pathway literature ...................................................................................................... 83 21 22 Challenges, opportunities and co-impacts of transformative mitigation pathways ................ 85 23 Policy narratives, enabling conditions and potential implications .......................................... 85 24 Policy regimes in line with 1.5°C scenarios ........................................................................ 90 25 Limitations of Integrated Assessment Models in examining policy options ....................... 92 26 Cross-Chapter Box 2.1: Economics of 1.5°C Pathways and the Social Cost of Carbon ...................... 96 27 Economic and financial implications of 1.5°C Scenarios ....................................................... 98 28 Carbon prices ....................................................................................................................... 98 29 Macro-economic impacts of mitigation ................................................................................