Stabilisation%20of%20GHG%20concentrations%20in%20the%20atmosphere%20Findings%20of%20the%20IPCC

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Stabilisation of GHG concentrations in the
atmosphereFindings of the IPCC

• Bert Metz
• co-chairman IPCC Working Group III

INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE (IPCC)
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Warning

• These are findings from TAR and SRCCS
• AR4 findings may be different
• AR4 approval/ acceptance dates
• January 29- February 1, 2007 WG I
• April 2-5, 2007 WG II
• April 30- May 3, 2007 WG III

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Article 2 of the UNFCCC

• stabilization of greenhouse gas concentrations
  in the atmosphere at a level that would prevent
  dangerous anthropogenic interference with the
  climate system ..

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Climate change risks and global mean temperature
Global mean teamp above 1990
Global mean teamp above 1990
Risks of extreme weather events
Risks to unique and threatened ecosystems
Risks of regional impacts
Risks of Aggregate impacts
Risks of large scale non- linearities
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Global mean temperature and stabilisation level
source IPCC TAR Synthesis Report, 2001
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AR4 look for latest assessment of

• climate sensitivity gtgt relationship between GHG
  concentrations and global mean temperature
• climate change risks

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To stabilise concentrations in the atmosphere
emissions have to go down to very low levels
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The stabilisation challenge depends on the
reference scenario and the stabilisation level
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Emission reductions required for different
stabilisation levels
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Emission reductions required for different
stabilisation levels
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Emission reductions by whom?

• All stabilisation studies ( except B1 baseline)
  assume that industrialised countries reduce their
  GHG emissions first
• Emissions from all regions diverge from baselines
  at some point
• B1 baseline emission reductions through
  sustainable development policies

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Illustrative example of mitigation options
contributing to stabilisation
SRCCS, fig TS12
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Costs of stabilisation go up with lower
stabilisation levels CO2 only
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Projected mitigation costs are sensitive to the
assumed emissions baseline
Costs for some countries/regions/time periods may
be (much) higher
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Decision making

• Step-by-step process towards stabilisation
• Balancing risks of insufficient or excessive
  action
• Portfolio of implementing mitigation and
  adaptation options, policy instruments and
  further technology development and diffusion
• Equity and efficiency are critical elements of
  international regimes
• Integrate climate change mitigation and
  adaptation into sustainable development policies

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AR4 look for latest assessment of

• Multigas stabilisation studies (CO2 and other
  GHGs)
• Stabilisation studies with more mitigation
  options
• Stabilisation studies for lower stabilisation
  levels than in TAR
• New estimates of costs of stabilisation (in
  relation to costs of inaction) and distribution
  of costs depending on international regime modes
• Relation between sustainable development and
  climate change impacts, adaptation and mitigation

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Climate change is not just an environmental
issue, but a development issue
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The long term picture

• Technical potential of known technologies
  adequate for 450 ppm stabilisation or lower
  broad package needed
• Lifestyle/ behaviour change would help, but not
  essential
• Mitigation costs (NOT counting avoided climate
  change damages and co-benefits) depend on
  baseline and stabilisation levels
• Learning makes new technologies attractive over
  time
• Associated socio-economic and institutional
  changes important
• Technology transfer crucial

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