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

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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)
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Where do we want to go?
Malti-gas emission profiles to mitigate dangerous
climate change.

• Introduction
• Methods
• Limitations
• Results

Malte Meinshausen, malte.meinshausen_at_env.ethz.ch,
17. February 2004, RIVM
Photo courtesy Leila Mead, IISD.ca
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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

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Methods I World per-capita emissions
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Methods II The distribution of possible
emission levels
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Methods III Going along equal percentiles
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Methods IV Overview
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Limitations

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

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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

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Limitations II Ranking Correlations
gt0
0
0
gt0
gt0
gt0
gt0
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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.

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Results / Found again

• Multi-gas CO2 scenarios have substantially less
  overall forcing. ? Comparison CO2-only WRE450 and
  multi-gas S450C.

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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 2C
  requires, atmospheric concentrations to peak
  below
• 420 ppmv CO2 or
• 490 ppmv CO2 equivalence

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Results II Comparison to long-term pledges
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Results II Comparison to long-term pledges
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Results II Comparison to long-term pledges
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Results II Comparison to long-term pledges
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Results II Comparison to long-term pledges
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Results II Comparison to long-term pledges
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Results II Comparison to long-term pledges
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Results II Comparison to long-term pledges
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Results II Comparison to long-term pledges
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Results II Comparison to long-term pledges
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Results II Comparison to long-term pledges
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Results II Comparison to long-term pledges
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Results II Comparison to long-term pledges
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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 2C
  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)

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