Stabilisation of GHG concentrations in the atmosphere Findings of the IPCC Bert Metz co-chairman IPCC Working Group III INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE (IPCC)

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 IPCC

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..” IPCC

Climate change risks and global mean temperature Global mean teamp above 1990 Risks of large scale non- linearities Risks of Aggregate impacts Risks of regional impacts Risks of extreme weather events Risks to unique and threatened ecosystems Global mean teamp above 1990 IPCC

source: IPCC TAR Synthesis Report, 2001 Global mean temperature and stabilisation level IPCC

AR4: look for latest assessment of climate sensitivity >> relationship between GHG concentrations and global mean temperature climate change risks IPCC

To stabilise concentrations in the atmosphere emissions have to go down to very low levels IPCC

IPCC SRES A2 Scenario ref IPCC SRES A1B Scenario Global Anthropogenic Carboon Dioxide Emissions (GtC) ref IPCC SRES B1 Scenario ref IPCC SRES A1T Scenario ref IPCC SRES B2 Scenario ref IPCC SRES A1FI Scenario ref The stabilisation challenge depends on the reference scenario and the stabilisation level IPCC

Emission reductions required for different stabilisation levels

IPCC

Emission reductions required for different stabilisation levels

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

Illustrative example of mitigation options contributing to stabilisation SRCCS, fig TS12 IPCC

Costs of stabilisation go up with lower stabilisation levels CO 2 only IPCC

Projected mitigation costs are sensitive to the assumed emissions baseline Costs for some countries/regions/time periods may be (much) higher IPCC

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 IPCC

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 IPCC

Climate change is not just an environmental issue, but a development issue IPCC

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 IPCC