This article presents the synthesis of results from the Stanford Energy Modeling Forum Study 27, an inter-comparison of 18 energy-economy and integrated assessment models. The study investigated the importance of individual mitigation options such as energy intensity improvements, carbon capture and storage (CCS), nuclear power, solar and wind power and bioenergy for climate mitigation. Limiting the atmospheric greenhouse gas concentration

Reducing risks of severe outcomes and improving chances of limiting warming to 2°C

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)

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Increased ambition and implementation are essential

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Stabilizing climate change well below 2 °C and towards 1.5 °C requires comprehensive mitigation of all greenhouse gases (GHG), including both CO2 and non-CO2 GHG emissions. Here we incorporate the latest global non-CO2 emissions and mitigation data into a state-of-the-art integrated assessment model GCAM and examine 90 mitigation scenarios pairing different levels of CO2 and non-CO2 GHG abatement pathways. We estimate that when non-CO2 mitigation contributions are not fully implemented, the timing of net-zero CO2 must occur about two decades earlier. Conversely, comprehensive GHG abatement that fully integrates non-CO2 mitigation measures in addition to a net-zero CO2 commitment can help achieve 1.5 °C stabilization. While decarbonization-driven fuel switching mainly reduces non-CO2 emissions from fuel extraction and end use, targeted non-CO2 mitigation measures can significantly reduce fluorinated gas emissions from industrial processes and cooling sectors. Our integrated modeling provides direct insights in how system-wide all GHG mitigation can affect the timing of net-zero CO2 for 1.5 °C and 2 °C climate change scenarios.

This paper presents an overview of the study design and the results of the EMF 24 U.S. Technology Scenarios. The EMF 24 U.S. Technology Scenarios engaged nine top energy-environment-economy models to examine the implications of technological improvements and technological availability for reducing U.S. greenhouse gas emissions by 50% and 80% by 2050. The study confirms that mitigation at the 50% or 80% level will require a dramatic transformation of the energy system over the next 40 years. The study also corroborates the result of previous studies that there is a large variation among models in terms of which energy strategy is considered most cost-effective. Technology assumptions are found to have a large influence on carbon prices and economic costs of mitigation.