Tracking Urban Carbon: A New Era in Near-Real-Time Emissions Monitoring

Carbon Monitor Cities 2.0 is a cutting-edge system developed by LSCE and Tsinghua University to monitor urban CO2 emissions in near-real-time, using satellite data and machine learning. Piloted in cities across Egypt, South Africa, and Türkiye, it provides policymakers with scalable, actionable insights for climate action.

Carbon Monitor Cities 2.0 is a groundbreaking initiative by researchers from the Laboratoire des Sciences du Climat et de l’Environnement (LSCE) in France and Tsinghua University in China, with support from the City Climate Finance Gap Fund and the World Bank. The project aims to tackle the challenges of tracking urban greenhouse gas emissions in near-real-time, particularly in low- and middle-income countries where traditional data collection methods are often inadequate. By piloting this innovative system in eleven cities across Egypt, South Africa, and Turkiye, the researchers demonstrated how satellite imagery, machine learning, and global datasets could be harnessed to create a scalable, cost-effective solution. This approach enables policymakers and urban planners to access detailed, actionable insights into emissions patterns without relying on local inventories, which are often outdated or inconsistent.

Innovations to Overcome Monitoring Challenges

Traditional methods of city-level emissions monitoring are plagued by gaps and delays. Local greenhouse gas inventories, where they exist, are often inconsistent in methodology and outdated by several years. While global datasets like EDGAR and satellite CO2 measurements offer valuable information, they lack the precision and timeliness required for urban-level climate policies. Carbon Monitor Cities 2.0 overcomes these challenges by delivering emissions estimates with a temporal resolution of ten days and spatial granularity as fine as 500 meters. This allows for detailed tracking of emissions from key urban sectors, such as energy, transportation, and industry, and enables cities to make data-driven decisions about their climate mitigation strategies.

The pilot program covered cities in Egypt, South Africa, and Turkiye, including Cairo, Johannesburg, and Antalya, among others. Emissions from energy generation, road and air transportation, and cement production were the primary focus areas. For instance, in South Africa, emissions from coal-fired power plants were estimated using satellite imagery of cooling towers, combined with machine learning models. Similarly, road transportation emissions were derived from real-time traffic data, which provided insights into vehicle activity and speed patterns. Aviation emissions were calculated using flight data, factoring in aircraft types, load capacities, and distances traveled, while cement industry emissions were monitored through heat signatures detected in satellite imagery.

A Detailed Look at Sectoral Emissions

Energy generation emerged as a key emissions source in the pilot cities. The system used country-specific approaches to estimate emissions based on local fuel mixes. In South Africa, for instance, coal dominates power generation, while Egypt relies heavily on natural gas. Turkiye uses a mix of coal, oil, and gas. Satellite data was instrumental in estimating emissions from power plants and direct fossil fuel combustion in residential and industrial buildings. The system even disaggregated emissions down to individual building blocks, using building height, density, and population as proxies for energy use.

Transportation was another major sector analyzed. Road transport emissions were calculated using traffic flow data from TomTom, while aviation emissions were attributed to city populations based on airport proximity and flight departures. The cement industry, which is a significant contributor to industrial emissions, was monitored through rotary kiln activity captured via satellite heat signatures. Each sector's emissions estimates adhered to the Global Protocol for Community-Scale Greenhouse Gas Inventories (GPC Protocol), ensuring compatibility with international standards.

An Interactive Tool for Policymakers

The project developed a user-friendly online interface that allows city leaders and policymakers to visualize emissions data at different scales, from citywide overviews to detailed district and pixel-level analyses. This interactive tool enables users to track emissions trends over time, compare data across periods, and download information for further analysis. The system is designed to be intuitive and accessible, making it easier for decision-makers to identify emissions hotspots, evaluate the effectiveness of mitigation measures, and plan future actions based on reliable, near-real-time data.

This visualization tool empowers cities to move beyond traditional emissions inventories and adopt a dynamic, data-driven approach to climate action. For instance, the system can help local governments assess the impact of specific policies, such as transportation reforms or building energy efficiency programs, and adjust their strategies accordingly.

Charting a Path for the Future

While the pilot demonstrated the potential of Carbon Monitor Cities 2.0, challenges remain. Satellite data is subject to limitations such as cloud cover, and some assumptions such as proportional fuel usage or constant flight load factors introduce uncertainties. Despite these challenges, the system has proven to be an invaluable tool for monitoring emissions at a level of detail and timeliness that was previously unattainable.

Looking forward, the project envisions scaling up the system to include more cities globally and expanding its sectoral coverage to include emissions from waste and non-cement industries. Incorporating additional data sources, such as satellite-measured CO2 concentrations, could further enhance accuracy and reduce uncertainties. The system also has the potential to monitor other pollutants, such as methane and nitrogen oxides, and to support monitoring, reporting, and verification (MRV) frameworks for carbon credits, enabling cities to monetize their emissions reductions.

Carbon Monitor Cities 2.0 represents a transformative step in urban climate governance, providing cities with the tools needed to address their carbon footprints effectively. As cities around the world face increasing pressure to meet ambitious climate targets, this innovative system offers a scalable, cost-effective solution to drive meaningful change. By combining cutting-edge technology with practical policy applications, it sets a new standard for how urban emissions can be monitored, understood, and mitigated.