Modeling Post-2012 Climate Policy Scenarios

The Pew Center on Global Climate Change, in collaboration with the Battelle Memorial Institute, is modeling a range of post-2012 global climate policy scenarios. Interim results from this innovative modeling exercise were presented at a side event at the UN climate change talks in Bonn, Germany, in June 2008.

The aim of this initiative is to visualize and to assess alternative post-2012 architectures incorporating different types of climate commitments, including absolute economy-wide emission targets, policy-based commitments, and sectoral agreements. The scenarios are not intended as “proposals” for a future framework. Rather, they are meant to illustrate a range of possible approaches in order to better understand their relative merits.

The modeling is the latest in a series of analyses building on the core finding of the Pew Center’s Climate Dialogue at Pocantico: engaging all the major economies in an effective post-2012 climate effort requires a flexible framework allowing countries to take on different types of commitments. The six policy scenarios modeled represent different combinations of:

• Economy-wide emissions targets (absolute, intensity-based, and “no lose”);
• Policy-based commitments (national policy packages including measures such as efficiency standards or sectoral intensity targets);
• Sectoral agreements (uniform or differentiated standards applied to a given sector in all countries); and
• Funding commitments to support adaptation and technology deployment in developing countries.

The specific configurations of the six scenarios are described in the presentation.

The analysis compares the projected emissions, economic, and technology impacts of the six scenarios to a “business-as-usual” reference scenario, and to idealized “economically efficient” emission pathways for achieving CO₂ concentrations of 450, 550, and 650 ppmv. (There is no prescribed environmental outcome in the six policy scenarios; the aim was for all to achieve outcomes in the range of 450-600 ppmv.)

Preliminary insights from the analysis include the following:

• Environmental Effectiveness – A range of policy mixes can deliver near- and medium-term emission reductions consistent with achieving a reasonable long-term environment outcome – provided they are stringent enough. The particular policy sets prescribed in these scenarios result in CO₂ concentrations in 2100 in the range of 550 ppm. However, if the policies described were to be made more stringent, any of these architectural frameworks could produce stronger environmental outcomes.
• Equity – A range of policy mixes can produce a reasonable distribution of costs. In scenarios with full global emissions trading, mitigation costs are redistributed through trading, and targets can be differentiated to achieve a desired distribution of costs. However, a reasonable distribution of costs also can be achieved in scenarios in which only some regions have economy-wide targets and others participate through other types of commitments.
• Economic Efficiency – Over the long term, emission reduction efforts will be more economically efficient if a regime transitions to full coverage of emissions and to full global emissions trading. In the nearer term, scenarios employing policies other than economy-wide targets diverge from the idealized “efficient” emissions pathway to a greater or lesser degree, depending on the specific policies assumed. One question that emerges is whether allowing a range of commitment types at this stage – and, in so doing, sacrificing some economic efficiency – is a reasonable tradeoff to deliver the effort, equity, and broad participation needed to put economies on track toward meeting the long-term objective of preventing dangerous climate change.

Another round of modeling based on revised policy scenarios is planned, with a final report expected in late 2008.

Previous work building on the Climate Dialogue at Pocantico includes:

Adaptation to Climate Change: International Policy Options
Policy-Based Commitments in a Post-2012 Climate Framework
International Sectoral Agreements in a Post-2012 Climate Framework
Towards an Integrated Multi-track Climate Framework