Keeping warming below 2°C: link and consistency between INDC assessments and long-term goals Joeri Rogelj Side Event COP21 - Paris 1 December 2015

Science facts recap

IPCC AR5 WGI

Science facts recap Any global temperature target 1.5°C 2°C 3.25°C ? See: Knutti & Rogelj, Climatic Change, 2015

Science facts recap Any global temperature target Limited amount of carbon emissions 1.5°C 2°C 3.25°C ? carbon budget See: Knutti & Rogelj, Climatic Change, 2015

Science facts recap Any global temperature target Limited amount of carbon emissions Net zero global carbon emissions = geophysical requirement for any temperature stabilization level 1.5°C 2°C 3.25°C ? carbon budget See: Knutti & Rogelj, Climatic Change, 2015

Science facts recap Higher near-term emissions: steeper and deeper long-term reductions 1.5°C 2°C 3.25°C ? carbon budget

Science facts recap Higher near-term emissions: steeper and deeper long-term reductions 1.5°C 2°C 3.25°C ? carbon budget

Science facts recap Higher near-term emissions: steeper and deeper long-term reductions 1.5°C 2°C 3.25°C ? carbon budget

Science facts recap Higher near-term emissions: steeper and deeper long-term reductions If budget is exceeded: CO 2 removal requirement 1.5°C 2°C 3.25°C ? carbon budget

Operationalization of these facts? Consistent sets near and long-term goals Depend on policy choices: –Time of peak –Height of peak –Near-term evolution of global emissions (next years) –Portfolio of technologies –… 1.5° C 2°C 3.25°C ? carbon budget

Question What do current assessments for near-term emissions imply for global long-term targets?

Some definitions Global net zero CO 2 emissions = Zero CO 2 emissions at a global scale = Carbon neutrality Global net zero CO 2 emissions of energy and industrial processes = Zero CO 2 emissions of energy and industrial processes at a global scale = Full decarbonisation Global net zero Kyoto-GHG emissions = Zero Kyoto-GHG emissions at a global scale = (NOT?) Climate neutrality

A quantitative look Influence of timing of the peak

A quantitative look Influence of timing of the peak Rogelj et al. Environ. Research Letters 2015 Scenarios from IPCC AR5

A quantitative look Influence of timing of the peak Rogelj et al. Environ. Research Letters 2015 Scenarios from IPCC AR5 -peaking around 2010

A quantitative look Influence of timing of the peak Rogelj et al. Environ. Research Letters 2015 Scenarios from IPCC AR5 -peaking around peaking around 2020

A quantitative look Influence of timing of the peak Rogelj et al. Environ. Research Letters 2015 Scenarios from IPCC AR5 -peaking around peaking around peaking around 2030

A quantitative look Influence of timing of the peak Rogelj et al. Environ. Research Letters 2015 Scenarios from IPCC AR5 -peaking around peaking around peaking around 2030 Conclusion: Later peaking drives earlier net zero global CO 2 emissions

A quantitative look Influence of height of the peak Rogelj et al. Environ. Research Letters 2015 For a given CO 2 budget

A quantitative look Influence of height of the peak Rogelj et al. Environ. Research Letters 2015 For a given CO 2 budget -Higher 2020 and 2030 emissions -Earlier global net zero CO 2 emissions

Implications for 1.5 and 2°C and a long-term zero emissions goal Rogelj et al. Environ. Research Letters 2015

Implications for 1.5 and 2°C and a long-term zero emissions goal Rogelj et al. Environ. Research Letters 2015

What do INDCs tell us? UNFCCC Synthesis report on the aggregate effect of the intended nationally determined contributions UNEP 2015 UNEP Emissions Gap Report A UNEP Synthesis Report

Differences between assessments UNFCCCUNEP GAP Assessment type Single elaborated INDC estimate Assessment of other published studies Countries covered 119Varies with underlying studies Uncertainty Structured exploration with statistical methods Variation between studies Treatment of conditionality Part of structured uncertainty analysis Defined by contributing modelling groups Treatment of non-covered countries Use regional projections of Cancun pledges. Part of structured uncertainty analysis Defined by contributing modelling groups 2030 estimate (SAR GWP) 55 (52-57) GtCO 2 -eq/yr54-56 (52-59) GtCO 2 -eq/yr

Differences between assessments UNFCCCUNEP GAP Assessment type Single elaborated INDC estimate Assessment of other published studies 2030 estimate (SAR GWP) 55 (52-57) GtCO 2 -eq/yr54-56 (52-59) GtCO 2 -eq/yr 2°C pathways comparison IPCC database Starting in 2010 or 2020 >66% during 21 century IPCC database Starting mitigation in 2020 >66% in 2100

What do INDCs tell us for the timing of zero global CO 2 emissions Rogelj et al. Environ. Research Letters % 2°C in 2100

What do INDCs tell us for the timing of zero global CO 2 emissions Rogelj et al. Environ. Research Letters % 2°C in 2100

What do INDCs tell us for the timing of zero global CO 2 emissions Rogelj et al. Environ. Research Letters % 2°C in 2100

Is this a sufficient condition? Rogelj et al. Environ. Research Letters 2015

Outlook Why a clearly defined goal matters –Sense of global direction –Warranting science-based policy –Environmental integrity