Allen A. Fawcett

Can Paris pledges avert severe climate change

Reducing risks of severe outcomes and improving chances of limiting warming to 2°C Current international climate negotiations seek to catalyze global emissions reductions through a system of nationally determined country-level emissions reduction targets that would be regularly updated. These “Intended Nationally Determined Contributions” (INDCs) would constitute the core of mitigation commitments under any agreement struck at the upcoming Paris Conference of the Parties to the United Nations Framework Convention on Climate Change (UNFCCC) (1). With INDCs now reported from more than 150 countries and covering around 90% of global emissions, we can begin to assess the role of this round of INDCs in facilitating or frustrating achievement of longer-term climate goals. In this context, it is important to understand what these INDCs collectively deliver in terms of two objectives. First, how much do they reduce the probability of the highest levels of global mean surface temperature change? Second, how much do they improve the odds of achieving the international goal of limiting temperature change to under 2°C relative to preindustrial levels (2)? Although much discussion has focused on the latter objective (3–5), the former is equally important when viewing climate mitigation from a risk-management perspective.

The contribution of Paris to limit global warming to 2 °C

The international community has set a goal to limit global warming to 2 °C. Limiting global warming to 2 °C is a challenging goal and will entail a dramatic transformation of the global energy system, largely complete by 2040. As part of the work toward this goal, countries have been submitting their Intended Nationally Determined Contributions (INDCs) to the United Nations Framework Convention on Climate Change, indicating their emissions reduction commitments through 2025 or 2030, in advance of the 21st Conference of the Parties (COP21) in Paris in December 2015. In this paper, we use the Global Change Assessment Model (GCAM) to analyze the near versus long-term energy and economic-cost implications of these INDCs. The INDCs imply near-term actions that reduce the level of mitigation needed in the post-2030 period, particularly when compared with an alternative path in which nations are unable to undertake emissions mitigation until after 2030. We find that the latter case could require up to 2300 GW of premature retirements of fossil fuel power plants and up to 2900 GW of additional low-carbon power capacity installations within a five-year period of 2031–2035. INDCs have the effect of reducing premature retirements and new-capacity installations after 2030 by 50% and 34%, respectively. However, if presently announced INDCs were strengthened to achieve greater near-term emissions mitigation, the 2031–2035 transformation could be tempered to require 84% fewer premature retirements of power generation capacity and 56% fewer new-capacity additions. Our results suggest that the INDCs delivered for COP21 in Paris will have important contributions in reducing the challenges of achieving the goal of limiting global warming to 2 °C.

Technology and U.S. Emissions Reductions Goals: Results of the EMF 24 Modeling Exercise

This paper discusses Technology and U.S. Emissions Reductions Goals: Results of the EMF 24 Modeling Exercise

Representing technology in CGE models: a comparison of SGM and AMIGA for electricity sector CO2 mitigation

The goal of this effort is to compare two climate economic models – the Second Generation Model (SGM) and All Modular Industry Growth Assessment Model (AMIGA) – and highlight the consequences of different modelling approaches and structures on the estimation of climate change policy results. We show that different assumptions about how technology choices are made in the US electricity sector in response to a carbon charge can lead to differences in estimates of environmental, fuel market, and economy-wide impacts. If the differences among models can be better understood, improvements in the models may be made and policy makers will be better informed by the insights provided by the models.

POLICY INSIGHTS FROM THE EMF 32 STUDY ON U.S. CARBON TAX SCENARIOS

The Stanford Energy Modeling Forum exercise 32 (EMF 32) used 11 different models to assess emissions, energy, and economic outcomes from a plausible range of economy-wide carbon price policies to reduce carbon dioxide (CO2) emissions in the United States. Here we discuss the most policy-relevant results of the study, mindful of the strengths and weaknesses of current models. Across all models, carbon prices lead to significant reductions in CO2 emissions and conventional pollutants, with the vast majority of the reductions occurring in the electricity sector. Importantly, emissions reductions do not significantly depend on the rebate or tax cut used to return revenues to the economy. Expected economic costs, as modeled by either GDP or welfare, are modest, but vary across models. These costs are offset by benefits from avoided climate damages and health benefits from reductions in conventional air pollution. Using revenues to reduce preexisting capital or labor taxes reduces costs in most models relative to lump-sum rebates, but the size of the cost reductions varies significantly. Devoting at least some revenue to household rebates can significantly reduce adverse impacts on low income households. Carbon prices at

Will U.S. Forests Continue to Be a Carbon Sink

25/ton or even lower levels cause significant shifts away from coal as an energy source with responses of other energy sources highly dependent upon technology cost assumptions. Beyond 2030, we conclude that model uncertainties are too large to make quantitative results useful for near-term policy design. We close by describing recommendations for policymakers on interacting with model results in the future.

The role of technology for achieving climate policy objectives: overview of the EMF 27 study on global technology and climate policy strategies

This paper develops structural dynamic methods to project future carbon fluxes in forests. These methods account for land management changes on both the intensive and extensive margins, both of which are critical components of future carbon fluxes. When implemented, the model suggests that U.S. forests remain a carbon sink through most of the coming century, sequestering 128 Tg C y−1. Constraining forestland to its current boundaries and constraining management to current levels reduce average sequestration by 25 to 28 Tg C y−1. An increase in demand leads to increased management and greater sequestration in forests. The results are robust to climate change. (JEL Q23, Q54)