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Emission Pathways and System Transitions Consistent with 1.5°C Global Warming

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Diana Ürge-Vorsatz (WGIII Vice-Chair)

Published in: Environment
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Emission Pathways and System Transitions Consistent with 1.5°C Global Warming

  1. 1. Emission Pathways and System Transitions Consistent with 1.5°C Global Warming 8 Diana Urge-Vorsatz Vice Chair, WGIII Professor, Central European University
  2. 2. Emission pathways - definition • The modelled trajectories of global anthropogenic emissions over the 21st century are termed emission pathways. • Emission pathways are classified by their temperature trajectory over the 21st century: • pathways giving at least 50% probability based on current knowledge of limiting global warming to below 1.5°C are classified as ‘no overshoot’; • those limiting warming to below 1.6°C and returning to 1.5°C by 2100 are classified as ‘1.5°C limited-overshoot’; • while those exceeding 1.6°C but still returning to 1.5°C by 2100 are classified as ‘higher-overshoot’.
  3. 3. Cumulative emissions of CO2 and future non-CO2 radiative forcing determine the probability of limiting warming to 1.5°CSPM1| Faster immediate CO2 emission reductions limit cumulative CO2 emissions Maximum temperature rise is determined by cumulative net CO2 emissions and net non-CO2 radiative forcing due to methane, nitrous oxide, aerosols and other anthropogenic forcing agents.
  4. 4. SPM3a|Global emissions pathway characteristics
  5. 5. SPM3a|Global emissions pathway characteristics
  6. 6. SPM3a|Global emissions pathway characteristics
  7. 7. SPM3a|Global emissions pathway characteristics
  8. 8. SPM3a|Global emissions pathway characteristics
  9. 9. SPM3a|Global emissions pathway characteristics
  10. 10. SPM3b|Characteristics of four illustrative model pathways
  11. 11. SPM3b|Characteristics of four illustrative model pathways
  12. 12. SPM3b|Characteristics of four illustrative model pathways
  13. 13. SPM3b|Characteristics of four illustrative model pathways
  14. 14. SPM3b|Characteristics of four illustrative model pathways
  15. 15. SPM3b|Characteristics of four illustrative model pathways
  16. 16. SPM3b|Characteristics of four illustrative model pathways Temperature and emissions Energy systems Carbon dioxide removal Agriculture
  17. 17. SPM3b|Characteristics of four illustrative model pathways
  18. 18. What can we learn from the pathways? • Capping warming at 1.5C is technologically feasible • There are still choices in the pathways how we can get there • However, each pathway involves virtually all options (except BECCS or CCS), the difference is only in the emphasis on different options • All pathways peak global emissions in the next few years, and radically reduce emissions afterwards • The pathways have markedly different implications on sustainable development
  19. 19. Greenhouse gas emissions pathways • To limit warming to 1.5°C, CO2 emissions fall by about 45% by 2030 (from 2010 levels) • To limit warming to 1.5°C, CO2 emissions would need to reach ‘net zero’ around 2050 • Reducing non-CO2 emissions would have direct and immediate health benefits Compared to 20% for 2°C Compared to around 2075 for 2°C 9 Gerhard Zwerger-Schoner / Aurora Photos
  20. 20. Greenhouse gas emissions pathways • Limiting warming to 1.5°C would require changes on an unprecedented scale Deep emissions cuts in all sectors A range of technologies Behavioural changes Increased investment in low carbon options 10 Peter Essick / Aurora Photos
  21. 21. Greenhouse gas emissions pathways • Progress in renewables would need to be mirrored in other sectors • We would need to start taking carbon dioxide out of the atmosphere • Implications for food security, ecosystems and biodiversity 10 Peter Essick / Aurora Photos
  22. 22. Greenhouse gas emissions pathways • National pledges are not enough to limit warming to 1.5°C • Avoiding warming of more than 1.5°C would require CO2 emissions to decline substantially before 2030 10 Peter Essick / Aurora Photos
  23. 23. Thank you for your attention Vorsatzd@ceu.edu
  24. 24. SPM4|Indicative linkages between mitigation and sustainable development using SDGs (the linkages do not show costs and benefit)
  25. 25. SPM4|Indicative linkages between mitigation and sustainable development using SDGs (the linkages do not show costs and benefit)
  26. 26. SPM4|Indicative linkages between mitigation and sustainable development using SDGs (the linkages do not show costs and benefit)
  27. 27. SPM4|Indicative linkages between mitigation and sustainable development using SDGs (the linkages do not show costs and benefit)
  28. 28. SPM4|Indicative linkages between mitigation and sustainable development using SDGs (the linkages do not show costs and benefit)
  29. 29. SPM4|Indicative linkages between mitigation and sustainable development using SDGs (the linkages do not show costs and benefit)
  30. 30. SPM2| Confidence level for transition: L=Low, M=Medium, H=High and VH=Very high Level of additional impact/risk due to climate change How the level of global warming affects impacts and/or risks associated with the Reasons for Concern (RFCs) and selected natural, managed and human systems
  31. 31. SPM2| Confidence level for transition: L=Low, M=Medium, H=High and VH=Very high How the level of global warming affects impacts and/or risks associated with the Reasons for Concern (RFCs) and selected natural, managed and human systems
  32. 32. SPM2| How the level of global warming affects impacts and/or risks associated with the Reasons for Concern (RFCs) and selected natural, managed and human systems Confidence level for transition: L=Low, M=Medium, H=High and VH=Very high

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