The technical note describes the methodologies used in the model for estimating collective greenhouse gas impacts of Compact of Mayors cities.

Executive Summary

The Compact of Mayors is an international coalition of cities committed to addressing the challenges of climate change. Since its launch in September 2014, hundreds of cities have joined. To improve understanding of the col-lective impact of cities, World Resources Institute and the Compact of Mayors jointly developed a model to estimate its cities collective emission trajectories. This technical note outlines the methodology used in the model.

The model provides methodologies to aggregate the green-house gas (GHG) reduction targets reported by cities and to estimate the likely GHG reduction of cities that have signed up but not yet formally reported their GHG reduction targets to the Compact of Mayors.

This robust model produces results in different formats, timeframes, and for different categories of cities, such as business-as-usual (BAU) scenario emissions and avoided emissions for Compact-compliant cities, cities with reported targets, cities without targets, and so on. The quality and accuracy of the results depend on the choice of input data and the purpose of analysis.

The model’s main limitation is that it estimates the emis-sion reductions based solely on top-down emission- reduction targets without considering the emission-reduc-tions potential of cities’ financial, technology, renewable energy, and other resources. A focus of future research is to estimate the emission reductions of these cities based on bottom-up approaches.