keeping warming below 2°c: link and consistency between indc assessments and long-term goals joeri...
DESCRIPTION
IPCC AR5 WGITRANSCRIPT
Keeping warming below 2°C:link and consistency between INDC assessments and long-term goals
Joeri RogeljSide Event COP21 - Paris
1 December 2015
Science facts recap
Science facts recap
IPCC AR5 WGI
Science facts recap
• Any global temperature target1.5°C
2°C3.25°C?
See: Knutti & Rogelj, Climatic Change, 2015
Science facts recap
• Any global temperature target
• Limited amount of carbon emissions
1.5°C2°C3.25°
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 requirementfor any temperature stabilization level
1.5°C2°C3.25°
C?carbon budget
See: Knutti & Rogelj, Climatic Change, 2015
Science facts recap
• Higher near-term emissions:steeper and deeper long-term reductions
1.5°C2°C3.25°
C?
carbon
budget
Science facts recap
• Higher near-term emissions:steeper and deeper long-term reductions
1.5°C2°C3.25°
C?
carbon
budget
Science facts recap
• Higher near-term emissions:steeper and deeper long-term reductions
1.5°C2°C3.25°
C?
carbon
budget
Science facts recap
• Higher near-term emissions:steeper and deeper long-term reductions
• If budget is exceeded: CO2 removal requirement
1.5°C2°C3.25°
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 10-20 years)– Portfolio of technologies– …
1.5°C2°C3.25°
C?
carbonbudget
Question
What do current assessments for near-term emissionsimply for global long-term targets?
Some definitions
Global net zero CO2 emissions = Zero CO2 emissions at a global scale = Carbon neutrality
Global net zero CO2 emissions of energy and industrial processes = Zero CO2 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 2010-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 2010-peaking around 2020-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 2010-peaking around 2020-peaking around 2030
Conclusion: Later peaking drives earliernet zero global CO2 emissions
A quantitative look
Influence of height of the peak
Rogelj et al. Environ. Research Letters 2015
For a given CO2 budget
A quantitative look
Influence of height of the peak
Rogelj et al. Environ. Research Letters 2015
For a given CO2 budget
-Higher 2020 and 2030 emissions-Earlier global net zero CO2 emissions
Implications for 1.5 and 2°Cand a long-term zero emissions goal
Rogelj et al. Environ. Research Letters 2015
Implications for 1.5 and 2°Cand 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
• UNEP2015 UNEP Emissions Gap ReportA UNEP Synthesis Report
Differences between assessmentsUNFCCC UNEP GAP
Assessment type Single elaborated INDC estimate
Assessment of other published studies
Countries covered 119 Varies 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) GtCO2-eq/yr 54-56 (52-59) GtCO2-eq/yr
Differences between assessments
UNFCCC UNEP GAPAssessment type Single elaborated INDC
estimateAssessment of other published studies
2030 estimate (SAR GWP) 55 (52-57) GtCO2-eq/yr 54-56 (52-59) GtCO2-eq/yr
2°C pathways comparison IPCC databaseStarting in 2010 or 2020>66% during 21 century
IPCC databaseStarting mitigation in 2020>66% in 2100
What do INDCs tell us for the timingof zero global CO2 emissions
Rogelj et al. Environ. Research Letters 2015
50-66% 2°C in 2100
What do INDCs tell us for the timingof zero global CO2 emissions
Rogelj et al. Environ. Research Letters 2015
50-66% 2°C in 2100
What do INDCs tell us for the timingof zero global CO2 emissions
Rogelj et al. Environ. Research Letters 2015
50-66% 2°C in 2100
Is this a sufficient condition?
Rogelj et al. Environ. Research Letters 2015
OutlookWhy a clearly defined goal matters
– Sense of global direction– Warranting science-based policy– Environmental integrity