City emissions inventories count only what happens inside the city boundary, so they miss the reductions cities make possible for residents, businesses and other cities. Carbon handprint thinking measures this impact, and cities can start mapping it without specialist expertise.
Cities were responsible for over 70% of global greenhouse gas emissions in 2020, but their direct control over these emissions is limited. The residual emissions in city-owned operations are also often the most expensive to cut. In our recent webinar, Laura Lakanen, postdoctoral researcher at LUT University, explained how cities may have even greater potential to reduce emissions by helping others cut theirs. We’ve summarised the key takeaways from the session in this article.
In 2021, the city of Espoo installed 18 public electric vehicle charging stations running on wind power on city-owned land. While this had little effect on the city’s own carbon footprint, it gave many residents the opportunity to reduce their emissions.
Research from LUT University estimates that the stations could serve 180 vehicles, based on the EU’s suggested ratio of one public charging point per ten cars. If those vehicles did all their charging there, they would emit up to 110 tonnes of CO2e a year less than when charging at home on Finland’s average grid mix. This equals a 91% reduction. In practice, drivers split their charging between home and public points, so the actual reduction lies between zero and this maximum.
Because reductions like these fall outside a city’s own inventory, they are easy to overlook. Measuring them provides potential for cities to increase their climate impact while prioritising cost-effective actions.
A carbon handprint measures the emissions a city helps others avoid. It is calculated as the difference between two life-cycle footprints: a baseline representing the situation without the city’s action, and the solution the city offers.
The framework developed at LUT University identifies three ways cities create handprints:
A carbon handprint cannot be subtracted from a carbon footprint. The two are measured separately, and cities need both: reducing their own emissions and increasing the reductions they enable for others.
Calculating an actual handprint follows life-cycle assessment (LCA) standards and requires specialist skills, which many climate teams with limited staff and budgets do not have. Assessing handprint potential before an action is implemented, however, requires no LCA expertise.
Cities can start by reviewing their existing climate action plan and identifying which actions already help residents, businesses or other organisations reduce their emissions. Working through stakeholder groups or sectors such as transport and energy produces a shortlist that can be tracked in a spreadsheet or climate action tracking platform. Once usage data is available, the actual handprint of each action can be calculated.
Early research on the transport sector shows how this mapping supports prioritisation. Plotting handprint actions by cost and emission reduction potential places support for EV charging, such as providing land and advising housing co-operatives on low-cost charging, among the high-priority actions. Improved public transport services, lower fares and safer walking and cycling infrastructure offer high reduction potential but require strategic investment. Information campaigns and digital mobility tools play a supporting role.
A handprint lets climate teams show elected officials how much the city has helped residents and businesses reduce their emissions, and at what cost. This can strengthen the case for continued investment in climate work. Because a city’s handprint grows when other cities replicate its solutions, knowledge sharing between cities also becomes part of its measurable climate impact.
Interested in how your city’s climate action plan could capture the full impact of its work? Get in touch with the Kausal team.