Starting climate policies early in order to reach long-term climate targets is... as cumbersome

1. Starting climate policies early in order to reach long-term climate targets is... • as cumbersome • yet as neccessary ...as getting out of bed early enough to climb a mountain following C. Schär (2003)

2. Where do we want to go? Malti-gas emission profiles to mitigate dangerous climate change. • Introduction • Methods • Limitations • Results Malte Meinshausen, malte.meinshausen@env.ethz.ch, 17. February 2004, RIVM Photo courtesy Leila Mead, IISD.ca;

3. Introduction • A work-in-progress report • Objective: Multi-gas emission profiles to limit global mean temperatures, radiative forcing, CO2 concentrations etc. • Possible methods for non-CO2: • ‚one size fits all‘ • scaling to (fossil) CO2 • source-specific reduction potentials for all gases (IMAGE) • cost-optimisations (TIMER/FAIR) • and ... • The ‘multi-gas meta approach’ motivation: • ‘Peaking’ and ‘temperature’ related profiles • Dealing ‘consistently’ with non-CO2 gases • Building on pluralism of existing work to derive a continuous set of mitigation profiles

4. Methods I: World per-capita emissions

5. Methods II: The ‚distribution of possible emission levels‘

6. Methods III: Going along equal percentiles

7. Methods IV: Overview

8. Limitations • Throwing garbage in a blender? • Underestimation of non-CO2 / landuse reduction potentials?

17. Limitations • Throwing garbage in a blender? • Underestimation of non-CO2 / landuse reduction potentials? • Comparison with IMAGE EMF21 profiles shows rough consistency for non-CO2 gases – despite lack of fully elaborated scenarios in the underlying pool of scenarios. • Or blending everything into garbage? • Not respecting anti-correlations in scenarios? Ranking correlation analysis

18. Limitations II: Ranking Correlations >0 ~0 ~0 >0 >0 >0 >0

19. Limitations • Throwing garbage in a blender? • Or blending everything into garbage? • Not respecting anti-correlations in scenarios? Ranking correlation analysis • Does the methodology assume a certain probability of the underlying SRES scenarios?  Yes, but robust to different probabilities.

23. Results / ‚Found again‘ • Multi-gas CO2 scenarios have substantially less overall forcing.  Comparison CO2-only WRE450 and multi-gas S450C.

28. Results / ‚Found again‘ • Multi-gas CO2 scenarios have substantially less overall forcing.  Comparison CO2-only WRE450 and multi-gas S450C. • Under default assumptions, to stay below 2°C requires, atmospheric concentrations to peak below • 420 ppmv CO2 or • 490 ppmv CO2 equivalence

29. Results II: Comparison to long-term pledges

30. Results II: Comparison to long-term pledges

31. Results II: Comparison to long-term pledges

32. Results II: Comparison to long-term pledges

33. Results II: Comparison to long-term pledges

34. Results II: Comparison to long-term pledges

35. Results II: Comparison to long-term pledges

36. Results II: Comparison to long-term pledges

37. Results II: Comparison to long-term pledges

38. Results II: Comparison to long-term pledges

39. Results II: Comparison to long-term pledges

40. Results II: Comparison to long-term pledges

41. Results II: Comparison to long-term pledges

42. Results / ‚Found again‘ • Multi-gas CO2 scenarios have substantially less overall forcing.  Comparison CO2-only WRE450 and multi-gas S450C. • Under default assumptions, to stay below 2°C requires, atmospheric concentrations to peak below • 420 ppmv CO2 or • 490 ppmv CO2 equivalence • Long-term pledges of EU countries roughly consistent with derived emission reduction necessities for Annex I countries (Sweden/UK pledges for 2050 on the higher end, though)

43. Looking forward to another 3 ½ months here... Thanks!