Quantifying what works in cities
C40 research does two things:
1. Identifies where and why cities need to act: analysing emissions, climate risks, and future impacts on people and infrastructure to guide action aligned with the goals laid out in the Paris Agreement.
2. Evaluates what works: analysing how specific city actions reduce emissions and enhance quality of life through cleaner air, better health, good green jobs, and economic resilience.
This research develops scenarios that inform climate action priorities and provide mayors with credible data to secure funding and build political support. It helps city teams design programmes that deliver measurable results. It also provides advocates and researchers with evidence from the world’s leading climate cities.
Explore C40’s research
See research that defines the actions cities must take and the pace required.
Explore Impact Research
Use open-access tools to quantify health, economic, and climate gains.
Discover the wider real-world benefits of climate action on jobs, equity, and well-being.
See city-level research quantifying the real-world results of urban climate action.
Understanding city climate impact
Research that answers the question: what actions do cities need to take, and how fast?
Accelerating urban climate action: A city guide to creating positive tipping points – Shows how cities can trigger positive tipping points, where clean technologies cross a threshold of accessibility, affordability, and attractiveness that causes their adoption to grow rapidly on its own. The guide outlines proven, integrated policy strategies for accelerating electric vehicle and heat pump uptake.
Accelerator Progress Reports – Evidence of how C40 cities are delivering on science-based commitments to halve fossil fuel use by 2030. Each report captures progress across key areas, including clean air, construction, transportation, waste, and food systems.
Building a cleaner future – How cities are planning the shift from fossil gas to renewable energy, unlocking clean-energy jobs and cheaper heat for residents.
Climate Emergency, Urban Opportunity – Demonstrates how national governments and cities can work together to unlock the economic benefits of zero-carbon development.
Cities, Climate and Migration – Shows how cities are managing the realities of climate-driven migration through inclusive planning and equitable services.
Coal-free cities – Makes the economic and health case for phasing out coal power and demonstrates how cities are leading the clean-energy transition.
Deadline 2020 – The first city-level roadmap that continues to guide how cities plan, measure, and deliver climate action today.
Effective emergency preparedness for flooding and drought – Five clear steps cities can take to protect vulnerable communities from extreme weather and reduce losses before disasters strike.
Focused Acceleration – Outlines 12 priority actions that enable cities to meet 2030 emissions targets and stay on track to meet goals outlined in the Paris Agreement.
Focused Adaptation – Identifies 15 high-impact actions to help cities adapt to heat, drought, and flooding through nature-based and systemic resilience measures.
Legal interventions – Explains how mayors can use legal reform, litigation, and city powers to accelerate national and corporate climate accountability.
NDC Ambition Handbook – Helps countries and cities identify the most impactful actions across energy, transport, buildings, waste, and urban planning to raise national climate ambition and align with goals laid out in the Paris Agreement.
Past the peak: Accelerating climate action in C40 cities – Documents how 60 C40 cities have passed peak emissions and are now cutting carbon. Stockholm and Copenhagen are leading reductions of over 40% since peaking, proving that urban growth and emissions can be decoupled.
Projecting cooling demand in cities – Explores projected cooling demand in C40 cities up to 2050, and the greenhouse gas and power demand consequences for cities.
The cost of fossil gas – Reveals the health, economic, and climate costs of fossil gas use, showing why cities must move toward renewables.
The Future We Don’t Want – Quantifies the human and economic risks of inaction, showing how climate breakdown could affect billions of urban residents by 2050 and why adaptation and mitigation are essential.
Water Safe Cities – Quantifies how floods and droughts will affect 97 cities by 2050 and offers tools to safeguard hospitals, energy systems, and communities.
Tools for measuring benefits
Open-access tools that quantify the impact of local climate action
Healthy and Efficient Retrofitted Buildings (HERB) – Estimates the health, social, and economic gains from retrofitting city buildings. Cities can use it to make a stronger investment case for large-scale renovation and healthier urban environments.
Healthy Neighbourhood Explorer – An interactive map and a scenario planning tool that shows how urban planning interventions can reduce emissions, increase active mobility and improve community health. It helps architects, planners, developers, and community groups identify how walkable, connected neighbourhoods can improve wellbeing.
Heat Resilient Cities tool – Calculates the environmental, health, and economic benefits of adapting to extreme heat through green corridors, parks, and water features. Cities use it to prioritise and communicate high-impact resilience actions.
Pathways Air Quality – A city-level modelling tool that measures how climate policies affect air quality and public health. It allows cities to integrate air quality management with climate action planning for win-win outcomes.
Benefits for people and economies
Research that answers the question: what difference does climate action make for people and economies?
Benefits of urban climate action – Quantifies the health, air-quality and economic gains when cities decarbonise power, transport and buildings together, helping leaders make the case for ambition.
Clean air, healthy planet – A practical framework for integrating air-quality management with climate planning, including steps to quantify PM2.5 and health outcomes.
Exploring the just transition – Europe – Examines how European cities can drive an equitable shift to net zero, identifying local policies that link climate ambition with social inclusion and decent work.
Exploring the just transition – South Africa – Sets out city actions to reduce emissions and create decent work while addressing historic inequalities.
Exploring the just transition – United States – Identifies policies cities can use to cut emissions while improving job quality and fairness across US communities.
Green job opportunities in clean construction – Analyses how the shift to low-carbon, resource-efficient construction can create millions of decent jobs worldwide, and highlights the city-level policies that make this transition equitable and viable.
Integrating benefits in sustainable infrastructure – Shows how cities can build broader social, environmental and economic goals into infrastructure planning, helping projects attract support, funding and long-term impact.
Sensing change – Highlights how cities are using affordable air quality sensors to map pollution, protect at-risk communities, and design smarter, fairer clean air policies.
The benefits of healthy and efficient buildings – Shows how retrofits improve health, learning, and productivity while cutting bills and emissions, with city examples using the HERB toolkit.
City case studies
Evidence of climate action delivering results in cities
Cities100 – Showcases 100 global examples of bold, replicable city climate actions, highlighting the economic, social and environmental benefits of local leadership.=
The wider benefits of deep building retrofits – Shows how city retrofit projects in New York, Milan and Copenhagen cut emissions, improve health and learning, and make the case for wider investment.
Quezon City: Electrifying the municipal vehicle fleet – Details how switching the city’s government fleet to electric vehicles cuts emissions, lowers operating costs, and supports national clean transport goals.
Related
How C40 helps cities access the evidence and insight they need to accelerate climate action and create local opportunity.
Explore how transforming city systems helps scale up climate action and create more liveable cities.
