A comparison of carbon emissions perspectives for a single city and insights for data developers and policymakers

Cities are setting targets for emissions reductions, however a lack of consensus on methodologies has produced a range of metrics. This makes it important for policymakers to understand how policies might impact metrics, and to communicate the impacts of policy choices. We take the municipality of Glasgow (Scotland) as a case study to calculate and compare four emissions accounting metrics. Our results reveal variation across metrics, arising from differences in the coverage and elements included, and large differences in major areas—emissions from housing and transport. Taking specific local policy ambitions to reduce emissions—the development of heat networks and reducing passenger kilometres driven—we describe conceptual and measurement issues in how these will impact on each metric. Our findings suggest a critical pathway forward for development of city-scale emissions data, and lessons for policymakers on the use of metrics and demonstrating the impact of policies.