Foreword 1

Executive summary 2

Introduction 8

  Why this report? 8

  Understanding overshoot pathways 9

  Every fraction of a degree matters, every investment matters 10

01 Entering an era of 1.5°C overshoot 13

  1.1 Global warming approaching 1.5°C 13

  1.2 Futures lost and futures still available 15

  1.3 The climate impacts of entering a 1.5°C world 18

  1.4 Global warming reversal after overshoot 19

  1.6 Adaptation and mitigation must move together in tackling overshoot 25

02 Overshoot risks and impacts: Implications on human and environmental systems 29

  2.1 Framing risk, impacts and implications 29

  2.2 Nature, ecosystems and biodiversity 32

  2.3 Impacts on social and human systems 38

03 Limiting overshoot - mitigation pathways 48

  3.1 Accelerating mitigation to limit climate related risks 48

  3.2 Stringent near-term mitigation to limit peak warming 49

  3.3 Strategies to bring global warming back below 1.5°C 52

  3.4 Feasibility, equity and avoiding over-reliance on a future temperature decline 57

04 Adapting to overshoot realities in the context of development 65

  4.1 Adaptation in an overshoot context 66

  4.2 Contexts matter: The difficulty in aligning adaptation to lived realities, both now and in the future 67

  4.3 Implementation of mitigation and adaptation pathways: Interdependencies and trade-offs 69

  4.4 Systemic and transformational adaptation: What considerations are needed for overshoot risk reduction 81

  4.5 Synthesis and key take aways for adaptation 83

05 Conclusion: Through overshoot and beyond -  Risks, choices and frontiers 89

  5.1 Reading of overshoot pathways 89

  5.2 Decisions under constraint and uncertainty 92

  5.3 Frontiers opened by overshoot 93

  5.4 Navigating the return to a safer future 96

06 Bibliography 97