Status of research SB20 21 June 2004 Xiaosu

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Status of research SB-20 21 June 2004 Xiaosu Dai, Michel den Elzen, Niklas Höhne

Status of research SB-20 21 June 2004 Xiaosu Dai, Michel den Elzen, Niklas Höhne

Overview 1. Introduction to the MATCH process Niklas Höhne / Xiaosu Dai 2. Introduction

Overview 1. Introduction to the MATCH process Niklas Höhne / Xiaosu Dai 2. Introduction of first joint paper Michel den Elzen / Niklas Höhne Modelling and assessment of contributions to climate change

SBSTA 17 (Oct 2002) • Work should be continued by the scientific community, in

SBSTA 17 (Oct 2002) • Work should be continued by the scientific community, in particular to improve the robustness of the preliminary results and to explore the uncertainty and sensitivity • Be of a standard consistent with the practices of peer-reviewed published science. • The process should be inclusive, open and transparent. • Capacity building: strongly encouraged Parties and institutions to facilitate capacity-building in developing countries, including by hosting scientists from developing countries • Invited the scientific community, including IGBP, WCRP, IHDP and IPCC to provide information on how they could contribute • Encouraged scientists to undertake further work, to make the results of their work publicly available and to report progress at SBSTA 20, June 2004 (side event). • SBSTA decided to review the progress at its 23 rd session (Nov 2005). Modelling and assessment of contributions to climate change

MATCH process UNFCCC process • • Two expert meetings Coordinated modelling exercise “ACCC” •

MATCH process UNFCCC process • • Two expert meetings Coordinated modelling exercise “ACCC” • • • Ad-hoc group Initiated by Brazil and UK Two expert meetings so far Modelling and assessment of contributions to climate change

MATCH process Objective: • Assess methods for calculating the contribution of different emission sources

MATCH process Objective: • Assess methods for calculating the contribution of different emission sources (e. g. regional, national or sectoral) to climate change and its impacts, taking into account uncertainties, and the sensitivity of the calculations to the use of different methods, models and methodological choices. Outputs: • Provide clear guidance on the implications of the use of the different scientific methods, models, and methodological choices • Where scientific arguments allow, recommend one method/model/choice or several possible methods/models/choices for each step of the calculation of contributions to climate change, taking into account scientific robustness, practicality and data availability • Organization of expert meetings, workshops and a coordinated modelling exercise • Prepare papers to be published in peer reviewed scientific journals Modelling and assessment of contributions to climate change

MATCH process Scientific Coordination Committee Xiaosu Dai National Climate Center, China Michel den Elzen

MATCH process Scientific Coordination Committee Xiaosu Dai National Climate Center, China Michel den Elzen RIVM, Netherlands Jan Fuglestvedt CICERO, Center for International Climate and Environmental Research - Oslo, Norway Jason Lowe Met Office, Hadley Centre for Climate Prediction and Research, UK Joyce Penner University of Michigan, USA Michael Prather (Chair) University of California at Irvine, USA Cathy Trudinger CSIRO Atmospheric Research, Australia Murari Lal IIT, India José Domingos Gonzalez Interministerial Committee on Global Climate Change, Miguez Brazil Niklas Höhne (Secretary) ECOFYS, Germany Modelling and assessment of contributions to climate change

MATCH process Developing country participation: • Fund for travel costs of developing country experts

MATCH process Developing country participation: • Fund for travel costs of developing country experts sponsored by governments of Germany, Norway, UK (currently funds for further 15 developing country expert trips) Support unit: • Ecofys under contract to UK Defra Information: • http: //www. match-info. net Modelling and assessment of contributions to climate change

MATCH-info. net • Background • Organization • Papers • Expert meetings • File exchange

MATCH-info. net • Background • Organization • Papers • Expert meetings • File exchange • Discussion forum Modelling and assessment of contributions to climate change

Participation at last meeting Modelling and assessment of contributions to climate change

Participation at last meeting Modelling and assessment of contributions to climate change

Individual scientific papers • • Pinguelli & Kahn (2001): The present, past, and future

Individual scientific papers • • Pinguelli & Kahn (2001): The present, past, and future contributions to global warming of CO 2 emissions from fuels, Climatic Change den Elzen and Schaeffer (2002): Responsibility for past and future global warming: Uncertainties in attributing anthropogenic climate change, Climatic Change Trudinger & Enting (2004): Comparison of formalisms for attributing responsibility for climate change: Non-linearities in the Brazilian Proposal approach, Climatic Change Andronova and Schlesinger (2004): Importance of sulfate aerosol in evaluating the relative contributions of regional emissions to the historical global temperature change attribution methods, Mitigation and Adaptation Strategies for Global Change den Elzen, Schaeffer and Lucas (2004): Differentiating future commitments on the basis of countries' relative historical responsibility for climate change: uncertainties in the 'Brazilian Proposal' in the context of a policy implementation, Climatic Change Pinguelli, Kahn, Muylaert and Pires de Campos (2004): Comments on the Brazilian Proposal and contributions to global temperature increase with different climate responses—CO 2 emissions due to fossil fuels, CO 2 emissions due to land use change, Energy Policy Höhne and Harnisch (2004): Calculating historical contributions to climate change – discussing the ‘Brazilian Proposal’, Climatic Change Modelling and assessment of contributions to climate change

Anticipated papers Paper #1 Analysing countries’ contribution to climate change: Scientific choices and methodological

Anticipated papers Paper #1 Analysing countries’ contribution to climate change: Scientific choices and methodological issues: status of the work and first results Paper #2 Demonstration of credible alternative scientific choices and their effect on the emissions, concentration and climate change Paper #3 Formal assessment of uncertainties and clarify parameter space Paper #4 Additional attribution calculations discussed in paper #1 by including the outputs from paper #2 and paper #3 Modelling and assessment of contributions to climate change

Schedule Meeting September 2003: • Formation of the ad-hoc group MATCH • Agreement on

Schedule Meeting September 2003: • Formation of the ad-hoc group MATCH • Agreement on terms of reference, scientific coordination committee, research questions Meeting May 2004: • Discussion of draft paper #1 • Discussion of development of further papers June 2004: SB 20 side event Meeting December 2004 (tentatively 2/3 December in Brazil): • Discussion of draft paper #2 • Discussion of development of further papers Meeting May 2005: Discussion of draft paper #3 Meeting September 2005: Discussion of draft paper #4 SB 23 November 2005: Presentation of results Modelling and assessment of contributions to climate change

Remarks Challenges • New research • Resource requirements for contributing experts • Links to

Remarks Challenges • New research • Resource requirements for contributing experts • Links to other organizations and programmes • Ambitious schedule Strong points of MATCH • Participation of leading experts on the topic • Joint research effort • Results are peer-reviewed publications Modelling and assessment of contributions to climate change

2. First joint paper Analysing countries’ contribution to climate change: Scientific choices and methodological

2. First joint paper Analysing countries’ contribution to climate change: Scientific choices and methodological issues Modelling and assessment of contributions to climate change

Main objective of paper #1 • to summarise the studies and results so far

Main objective of paper #1 • to summarise the studies and results so far (i. e. the contributions to the UNFCCC initiated process) • to present new attribution calculations with non-linear carbon cycle and climate models using non-linear attribution methodologies and updated historical emissions datasets • to investigate the effect of a range of scientific, methodological and policy-related choices on the attribution, but not the full range by all uncertainties. Modelling and assessment of contributions to climate change

Policy choices • Policy choices refer: to parameters of which the values can not

Policy choices • Policy choices refer: to parameters of which the values can not be based on objective ‘scientific’ arguments alone. For example, 100 year time horizon of GWPs. The choices have to be made largely within the policy context. • Policy choices analysed here: – Indicator – Timeframes – Emission scenarios – Mixture of Greenhouse gases – Attribution method Modelling and assessment of contributions to climate change

Scientific uncertainties • Choice of the dataset on historical emissions • Choice of the

Scientific uncertainties • Choice of the dataset on historical emissions • Choice of the representation of the climate system (different models) Modelling and assessment of contributions to climate change

Models used Modelling and assessment of contributions to climate change

Models used Modelling and assessment of contributions to climate change

Model show similar outcomes Source: UNFCCC Modelling and assessment of contributions to climate change

Model show similar outcomes Source: UNFCCC Modelling and assessment of contributions to climate change

Policy choices 1. Indicator 2. Timeframes 3. Attribution method 4. Mixture of greenhouse gases

Policy choices 1. Indicator 2. Timeframes 3. Attribution method 4. Mixture of greenhouse gases Modelling and assessment of contributions to climate change

1. Indicators Source: Ecofys-ACCC Modelling and assessment of contributions to climate change

1. Indicators Source: Ecofys-ACCC Modelling and assessment of contributions to climate change

1. Indicators *: Also discounting most recent emissions +: Can be made forward looking,

1. Indicators *: Also discounting most recent emissions +: Can be made forward looking, when evaluating at a date after attributed emissions end. In such case also a time horizon is required Modelling and assessment of contributions to climate change

1. Indicators ry na i m li e r P Relative contributions using different

1. Indicators ry na i m li e r P Relative contributions using different indicators Modelling and assessment of contributions to climate change

1. Indicators Conclusions • Two main factors influence results • Whether a source emitted

1. Indicators Conclusions • Two main factors influence results • Whether a source emitted ‘early’ versus ‘late’ • The share of emissions of short-lived / long-lived gases. • Choosing the right indicator is ultimately a policy choice that also depends on the purpose of use of the results. • Temperate increase: use evaluation date after the attribution end date • ‘Backward discounting’ and ‘forward looking’: ‘weighted concentrations’ or ‘integrated temperature’ • Not ‘backward discounting’: GWP-weighted cumulative emissions could be an option, which is simple and approximately represents the integrated impact on temperature. Modelling and assessment of contributions to climate change

2. Timeframe • Start date emissions 1890, 1950 and 1990 • End date emissions

2. Timeframe • Start date emissions 1890, 1950 and 1990 • End date emissions 1990, 2000, 2050 and 2100 • Evaluation date of attribution 2000, 2050, 2100, 2500 Modelling and assessment of contributions to climate change

Start-date Source: RIVM-ACCC • Choosing a shorter time horizon (e. g. 1950 or 1990

Start-date Source: RIVM-ACCC • Choosing a shorter time horizon (e. g. 1950 or 1990 instead of 1890) reduces the contributions of OECD 90 countries ('early emitters') to temperature increase. Modelling and assessment of contributions to climate change

End-date Source: RIVM-ACCC • A late end-date increases non-Annex-I contributions, because it gives more

End-date Source: RIVM-ACCC • A late end-date increases non-Annex-I contributions, because it gives more weight to their larger future emissions. • Impact of emissions scenarios (error bars) can be large Modelling and assessment of contributions to climate change

Evaluation-date Source: RIVM-ACCC • A later evaluation-date raises OECD contributions due to: (1) their

Evaluation-date Source: RIVM-ACCC • A later evaluation-date raises OECD contributions due to: (1) their large share in historical CO 2 emissions (long residence time) (2) and their small share of methane emissions (short residence time) Modelling and assessment of contributions to climate change

3. Attribution methods • Normalised marginal method - Attributes responsibility using total sensitivities determined

3. Attribution methods • Normalised marginal method - Attributes responsibility using total sensitivities determined "at the margin". • Residual (all-but-one) method - Attributes responsibility by leaving out the emissions of each region in turn. • Time-sliced - determines the effect of emissions from each time as if there were no subsequent emissions. Modelling and assessment of contributions to climate change

3. Attribution methods • The Residual method, although simple to implement and explain, can

3. Attribution methods • The Residual method, although simple to implement and explain, can be rejected on scientific grounds (not additive). • The Normalised marginal and Timesliced methods are harder to implement and explain. These methods differ in how they treat early vs. late emissions. Modelling and assessment of contributions to climate change

3. Attribution methods Source: CSIRO-SCM • The differences between methods are fairly small compared

3. Attribution methods Source: CSIRO-SCM • The differences between methods are fairly small compared to the effects of many of the other choices already considered. Modelling and assessment of contributions to climate change

3. Attribution methods • Differences between methods are greater Source: CSIRO-SCM Source: for later

3. Attribution methods • Differences between methods are greater Source: CSIRO-SCM Source: for later evaluation date (2100) • In general, the results of the different methods vary most for regions with emissions that differ most from the average in terms of early versus late emissions, i. e. India and EU. Modelling and assessment of contributions to climate change

4. Greenhouse gas mixture Which gases are attributed to the regions? 1. Fossil CO

4. Greenhouse gas mixture Which gases are attributed to the regions? 1. Fossil CO 2 2. All anthropogenic CO 2 3. CO 2, CH 4, N 2 O 4. Kyoto basket (CO 2, CH 4, N 2 O, HFCs, PFCs, SF 6) 5. Kyoto basket + more O 3 precursors (NOx, CO and VOC) Modelling and assessment of contributions to climate change

4. Greenhouse gas mixture Source: CICERO-SCM • Two main effects i) Going from fossil

4. Greenhouse gas mixture Source: CICERO-SCM • Two main effects i) Going from fossil fuel CO 2 emissions only to total anthropogenic CO 2 emissions, ii) Inclusion of CH 4 and N 2 O. • The effect is less pronounced on longer time scales (except for the shift from fossil CO 2 to total CO 2). Modelling and assessment of contributions to climate change

Scientific uncertainties 1. 2. Choice of the dataset on historical emissions Choice of the

Scientific uncertainties 1. 2. Choice of the dataset on historical emissions Choice of the representation of the climate system: carbon cycle and climate model and feedbacks Modelling and assessment of contributions to climate change

1. Historical datasets Source: RIVM-ACCC • Fossil CO 2 emissions: small differences in relative

1. Historical datasets Source: RIVM-ACCC • Fossil CO 2 emissions: small differences in relative attribution • CO 2 emissions from land-use changes: differences in estimates leading to large differences. Data sets need to be compared and improved. • CH 4 and N 2 O: Only one dataset is available (EDGAR) Modelling and assessment of contributions to climate change

2. Other scientific uncertainties • The influence of other climate model parameters (e. g.

2. Other scientific uncertainties • The influence of other climate model parameters (e. g. IRFs), based on simulation experiments with nine GCMs and climate models is limited • Including additional non-linearities in calculations of methane-concentrations (IPCC-TAR atmospheric chemistry model ) has a negligible effect on the relative contributions • . . . Modelling and assessment of contributions to climate change

Overall conclusions • First summary of the work undertaken to date. • Not a

Overall conclusions • First summary of the work undertaken to date. • Not a full assessment of the uncertainty range, but an evaluation of the influence of different policy-related and scientific choices. • The influence of scientific choices is notable. Therefore research is ongoing (see papers #2 and #3) • However, the current work suggests, that the impact of policy choices, such as time horizon of emissions, climate change indicator and greenhouse-gas mix is larger than the impact of scientific uncertainties • Impact of uncertainties on the relative contributions is smaller than impact of uncertainties on the absolute changes in temperature. • Research needs: Historical emission datasets Modelling and assessment of contributions to climate change

Backup slides

Backup slides

Policy choices Modelling and assessment of contributions to climate change

Policy choices Modelling and assessment of contributions to climate change

Models are calibrated Modelling and assessment of contributions to climate change

Models are calibrated Modelling and assessment of contributions to climate change

Table 3

Table 3

Contribution to radiative forcing Modelling and assessment of contributions to climate change

Contribution to radiative forcing Modelling and assessment of contributions to climate change

Aerosol forcing Source: CICERO-SCM • Inclusion of SO 2 emissions reduces the contributions from

Aerosol forcing Source: CICERO-SCM • Inclusion of SO 2 emissions reduces the contributions from ASIA and REF, but the effect disappear when there is a gap between attribution end date and evaluation date. • Again effect is less pronounced on longer time scales Modelling and assessment of contributions to climate change

Policy choices vs. scientific choices Source: RIVM-ACCC • Policy choices (start-date, indicators) are more

Policy choices vs. scientific choices Source: RIVM-ACCC • Policy choices (start-date, indicators) are more important than scientific uncertainties (attribution method, climate model) Modelling and assessment of contributions to climate change