More than 4 billion people – half of the world’s population – live in cities. These big, bustling economic hubs bring together people from all backgrounds to share ideas and work together to find ways to thrive.
They’re also the source of two-thirds of greenhouse gas (GHG) emissions, which accelerate global heating.
What would it take to improve goods and services in ways that help us keep global heating below 1.5°C and avoid even more debilitating storms, heat waves and droughts than we’ve seen lately? And how might those changes affect quality of life?
That’s what we set out to answer in 2019, in an area of work that was very new to us then, just as it was for many important stakeholders, from governments to businesses and beyond. The result is a report C40 published with Arup and the University of Leeds, entitled: “The Future of Urban Consumption in a 1.5°C World.”
So what is this report?
 An analysis, not a plan. We analysed consumption-based emissions among our global network of cities within six major categories: buildings and infrastructure, food, clothing and textiles, private transport, aviation, electronics and household appliances. We examined ways to address emissions, considering the potential impact of changes in consumption on emissions and quality of life in cities, and the role mayors and other urban stakeholders might play.
 A possibility, not inevitability. Improving the production, transport and consumption of goods and services can deliver plenty of benefits in addition to reducing emissions, we found. For example:
- London could save more than $11 billion over five years by using existing buildings more efficiently and avoiding new construction.
- 160,000 deaths per year could be prevented in C40 cities if people ate more fruits and vegetables.
- 170 million m2 of on-street parking could be freed up for public use, like 2.5 million trees or 25,000 km of cycle lanes, if there were fewer vehicles in C40 cities.
- C40 city residents could collectively save as much as $93 billion a year by buying fewer new clothes and textiles.
- $70 million in damages from air pollution that impacts human health, buildings, infrastructure and food production could be avoided by reducing flights and adopting sustainable aviation fuels.
 An invitation, not a prescription. Consumption-based emissions are big contributors to global heating, we found; on average, emissions from C40 cities are about two-thirds more than previously understood when these emissions are counted. We examined the factors that influence consumer choice and how cities and businesses can help to reduce the emissions related to the goods and services we use. Mayors, we concluded, are well-positioned to bring together businesses, civil society, national governments and consumers to pursue changes in urban consumption patterns that reduce emissions and improve lives.
 An effort to support all, not just some. We explored ways to make the production of goods and services less carbon-intensive without compromising their function, and provided a scenario for the adoption of low-carbon choices without compromising quality of life. In practice, these ideas aren’t intended for every person, community or city. To successfully transition to a lower-carbon economy, cities must balance their ambition with what’s financially, technologically and culturally feasible. No one city or nation will follow the exact same emissions reduction pathway.
 A beginning, not an end. Since our report was published, cities around the world have begun to map consumption-based emissions and explore ways to reduce them – whether that’s by improving public transport or helping grocery chains improve supply chains. For the first time, in 2022, the UN Intergovernmental Panel on Climate Change (IPCC) included a chapter on emissions from consumer demand in its annual report. The IPCC suggests up to 70% of much-needed emission reductions could be achieved by improving consumption, and has urged cities to look at consumption patterns and supply chains to achieve their net-zero GHG commitments.
The fact is, a wide range of actions could help to drive down emissions. Our analysis shows that a city that consumes more sustainably is also a city where residents are healthier, it is safer to walk and cycle, there is more public space, there is cleaner air and water, land is used effectively and housing is more affordable.
The evidence from our report shows that city leaders, residents, businesses, civil society and national governments have a once-in-a-lifetime opportunity to work together to reimagine urban consumption patterns in ways that reduce emissions and improve lives for millions of people around the world.