Multi-Greenhouse Gas Mitigation and Climate Policy

Special Issue of The Energy Journal: "Multi-Greenhouse Gas Mitigation and Climate Policy"

In December 2006 a Special Issue of The Energy Journal, entitled "Multigas Mitigation and Climate Policy", was published. This Special Issue presents the results of the most recently completed study organized by Stanford University’s Energy Modeling Forum (EMF), commonly referred to as EMF-21. Edited by John Weyant, Stanford Univ., and Francisco de la Chesnaye, U.S. EPA, the 520-page volume is the largest and most comprehensive international, coordinated study on greenhouse gas (GHG) scenarios to date.

This Special Issue provides a complete report on a comparative set of analyses of the economic and energy sector impacts of multigas mitigation of anthropogenic GHGs, including carbon dioxide (CO₂) and the more potent non-CO₂ GHGs including methane (CH₄), nitrous oxide (N₂O) and a set of fluorinated gases (PFCs, HFCs and SF6). In 2000, energy-related CO₂ emissions accounted for about three-quarters of global emissions, with the combination of non-CO₂ gases making up the rest on a CO₂-equivalent basis

Objectives of the study

1. Conduct a multigas policy assessment to improve the understanding of the affects of including non-CO₂ GHGs and terrestrial sequestration into short- and long-term mitigation policies;
2. Advance the state-of-the-art in integrated assessment and climate economic modeling. Nineteen energy-economic modeling teams from Asia, Europe, and the U.S. along with international experts on non-CO₂ GHGs and forestry participated in the study. Many of the modelers who participated in EMF-21 have now formed a new international consortium (supported by the new EMF-22 study) to develop the next round of global economy, energy, and GHG scenarios.

Results from EMF-21 study

Results from EMF-21 provide reference projections of all GHGs to 2100 and also estimate the economic effects of meeting a stabilization target of 4.5 Wm-2 (watts per square meter) relative to pre-industrial times, which corresponds to an equilibrium temperature increase of 3.0°C. Although the models project that CO₂ emissions grow throughout the century, the range of reference case projections is quite large, with projections from some models showing slightly more than a doubling and others showing an approximate five-fold increase over the century. The reference emissions for CH₄, the second most important GHG, show about a doubling of emissions over the century. For the climate stabilization case, all models show that climate mitigation under a multigas policy leads to an appreciable reduction in both marginal costs and effects on global GDP.

Insights

The two principal insights from the study are:

1. the range of economic sectors from which non-CO₂ GHGs originate is far larger and more diverse than for CO₂;
2. the mitigation costs for these sectors and their associated gases can be lower than for energy-related CO₂ alone.

Taken together, these two factors result in a more diverse portfolio of potential mitigation options, and thus the potential for reduced costs, for a given climate policy objective.

More information

• to the article: Long-Term Multi-Gas Scenarios to Stabilise Radiative Forcing