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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). Where do we want to go?. Malti-gas emission profiles to mitigate dangerous climate change.
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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)
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;
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
Limitations • Throwing garbage in a blender? • Underestimation of non-CO2 / landuse reduction potentials?
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
Limitations II: Ranking Correlations >0 ~0 ~0 >0 >0 >0 >0
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.
Results / ‚Found again‘ • Multi-gas CO2 scenarios have substantially less overall forcing. Comparison CO2-only WRE450 and multi-gas S450C.
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
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)