How urban consumption drives global GHG emissions

June 14th, 2019, Published in Articles: Energize


Cities drive the global economy, and urban decisions have an impact well beyond city boundaries. A new report by C40, Arup and the University of Leeds assesses the impact of urban consumption on climate breakdown and explores the type and scale of changes needed to ensure that C40 cities reduce their GHG emissions in line with internationally agreed, climate-safe limits.

In this case, the impact the report considers is the greenhouse gas (GHG) emissions resulting from urban consumption of building materials, food, clothing and textiles, private transport, electronics and household appliances, as well as private aviation travel. C40 is a network of the world’s megacities committed to addressing climate change.

This is the Executive Summary of the report

Click here to download the full report

This report reveals the true scope and scale of urban impacts on the environment; the role of mayors and other urban stakeholders in addressing them; and how consumption-based emissions could be fairly and equitably addressed while many citizens in C40 cities still do not meet their basic needs. It attempts to answer whether it is possible to avert climate breakdown given that the current rules of the global economy encourage ever-increasing consumption.

Fig. 1: Emission reductions needed per consumption category to meet the desired target.

Cities are at the centre of the world economy and decisions made in them have a significant impact on emissions beyond their boundaries. New information shows that fast-growing urban consumption is a key driver of climate change. When a product or service is bought by an urban consumer in a C40 city, resource extraction, manufacturing and transportation have already generated emissions along every link of a global supply chain. Together, these consumption-based emissions add up to a total climate impact that is approximately 60% higher than production-based emissions.  It is crucial that emissions from consumption are measured when considering how to reduce a city’s full impact on climate change.

Consumption-based emissions account for the total climate impact accumulated around the world of a good or service, allocated to the place where an end-product is used or consumed. Take a pair of jeans, for example. Its climate impact includes the GHG emissions that resulted from growing and harvesting the cotton used for the fabric, the CO2e emitted by the factory where it was stitched together, and the emissions from ships, trucks or planes that transported it to the store. Its impact also includes the emissions from heating, cooling or lighting the store the jeans were bought in and the CO2 emitted by the end-consumer washing and drying it over its lifetime.  A consumption-based inventory gives a fuller picture of a city’s climate impact.

Fig. 2: Production-based and consumption-based emissions by category.

An assessment of cities’ consumption-based emissions takes into account the total emissions associated with goods and services produced and consumed within the city, plus emissions from goods and services imported from the rest of the nation or the world, minus emissions from goods and services produced within the city but exported elsewhere. This differs from a production-based approach – the standard methodology used by national governments – which accounts for emissions from activities within a geographic boundary, such as heating up a building or driving a vehicle. A production-based methodology is less suitable for cities than countries, because many cities consume a far greater quantity of CO2-emitting products than they produce.

By compiling consumption-based inventories for all C40 cities, C40 has been able to develop an understanding of what sustainable urban consumption looks like. In 2016, C40 launched Deadline 2020, the first route map which shows how cities could deliver on the Paris Agreement from the point of view of production-based emissions. Since then, Deadline 2020 has established the pace and scale of climate action in C40 cities. However, the scope of this work was defined by a production-based approach to emissions accounting.

In 2018, C40 published a consumption-based GHG emissions inventory for a cohort of cities, which highlighted the global climate impact that cities have as centres of consumption.

This report takes this analysis one step further by examining previously unconsidered urban opportunities for climate action and analysing how effective a number of interventions to stimulate more sustainable consumption can be, in terms of reducing emissions, alongside a continued delivery of Deadline 2020 commitments to reduce emissions from production.  This report shows that tackling urban consumption gives C40 cities a greater scope to influence global emissions. Consumption-based emissions in C40 cities have been estimated to account for 4,5 GtCO2e out of a global total of 45 GtCO2e in 2017.

Fig. 3: Breakdown of 2017 direct sources of C40 consumption-based emissions.

C40’s 94 member cities can therefore influence roughly 10% of global emissions. By contrast, the total production-based emissions of C40 cities in 2017 are estimated to be 2,9 GtCO2e. When considering C40 cities’ consumption-based emissions, mayors, businesses and urban residents can influence an approximately 60% larger share of global GHG emissions than previously thought. Cities and urban consumers have a huge impact on emissions beyond their own borders since 85% of the emissions associated with goods and services consumed in C40 cities are generated outside the city; 60% in their own country and 25% from abroad.

In order to stay within established GHG budgets and limit global warming to 1,5°C – the internationally agreed upper-limit for a climate-safe future – the average per capita impact of urban consumption in C40 cities must decrease by 50% by 2030 and 80% by 2050. Therefore, C40 cities’ consumption-based emissions need to peak by 2020, then decrease by half by 2030, before halving once again by 2036, and finally stabilising at 0,7 tCO2e per capita by 2050. This transition to a low-carbon economy will require a rapid alignment of climate policies on global, national and local levels in order to deliver this unprecedented level of climate action by individuals, business and government.

Without further climate action, C40 cities’ consumption-based emissions will nearly double (+87%) by 2050. Under such a scenario, C40 cities will use up their entire 1,5°C-compliant GHG budget in just 14 years.  High-income cities must immediately steeply reduce the climate impact of their consumption by two thirds within the next decade. Much of this reduction will take place in Europe, North America and East Asia, and climate action over the coming decade will decide whether C40 cities, and the world at large, can reduce consumption-based emissions in line with a 1,5°C trajectory.  At the same time, rapidly-developing economies need to adopt sustainable consumption patterns as they grow. For C40 cities in Latin America, South and West Asia, South-East Asia and Africa, the challenge is to prevent further increases in per capita consumption-based emissions after 2020, before steadily reducing emissions in line with a 1,5°C trajectory.

City governments and urban stakeholders can deliver 35% of the necessary emission reductions on their own, by committing to Deadline 2020 (an emissions trajectory consistent with a 1,5°C scenario for production-based emission) and by working with local and global partners to meet the consumption targets set out in this report. C40 cities that are already delivering on their Deadline 2020 commitments will simultaneously be addressing 25% of their consumption-based emissions, due to an overlap between production-based and consumption-based emissions. However, urban stakeholders can go a step further and address their full consumption-based emissions by taking additional climate actions on food; buildings and infrastructure; private transport; aviation; clothing and textiles; and electronics and household appliances.

Wealth is an important factor. Greater levels of disposable income in wealthy cities allow consumers to buy more goods and services, which result in higher levels of consumption-based emissions.  Consumption patterns and consumption-based emissions are not uniform across all cities. Within the C40 network, consumption-based GHG emissions vary from 1,2 to 39,7 tCO2e per capita per year, a difference that is equivalent to 20 return flights between London and New York City.

This report outlines six consumption categories (food; buildings and infrastructure; private transport; aviation; clothing and textiles; and electronics and household appliances) that cities can focus on, as well as the emission-reduction impact of selected consumption interventions. Cutting consumption-based emissions will deliver wider benefits for a city and its residents. Individuals, businesses and city governments all stand to gain if the changes are delivered in the right way.

Some benefits include:

  • Using existing buildings more efficiently and avoiding new construction would save London, for example, more than $11-billion over the next five years.
  • Eating less red meat and more vegetables and fruits could prevent annually 160 000 deaths associated with diseases such as cancer, heart disease, diabetes and stroke in C40 cities.
  • By reducing vehicle ownership, 170-million m2 of on-street parking could be released back to the public realm in C40 cities, providing enough space for 2,5-million trees and 25 000 km of cycle lanes.
  • By buying fewer new clothes and textiles, residents in all C40 cities could collectively save $93-billion in one year.
  • Reducing flights and adopting sustainable aviation fuels could collectively avoid $70-million in damages from air pollution that would impact human health, buildings, infrastructure and agricultural production.

This study finds that leaders in the C40 cities network can exert influence over global emission reductions by promoting changes in the production and consumption of food, buildings and infrastructure, private transport, aviation, clothing and textiles, and electronics and household appliances. Individuals, businesses and governments in C40 cities can affect what and how goods and services are bought, sold, used, shared and re-used all over the world. The network of C40 cities can use their global spending power to speed up a transition to low-carbon production.

Immediate and ambitious action on consumption-based emissions is needed from everyone to achieve a swift transition to a low-carbon economy. Mayors, national governments, business and individual consumers have to work together to decarbonise global supply chains and shift to sustainable consumption practices. An accelerated transition to cleaner production will require much more ambitious national targets than the Nationally Determined Contributions (NDCs) nations have committed to under the Paris Agreement.

Reducing consumption-based emissions will require significant behavioural changes. Individual consumers cannot change the way the global economy operates on their own, but many of the interventions proposed in this report rely on individual action. It is ultimately up to individuals to decide what type of food to eat and how to manage their shopping to avoid household food waste. It is also largely up to individuals to decide how many new items of clothing to buy, whether they should own and drive a private car, and how many personal flights to take.

As this report shows, these are some of the most impactful consumption interventions that can be taken to reduce consumption-based emissions in C40 cities. Furthermore, businesses and elected leaders often respond to consumer demands and voter priorities. Signs of broad behavioural change will therefore support low-carbon corporate and political action. If C40 cities are to cut their consumption-based emissions in half by 2030 and reduce them by 80% by 2050, it is critical that large-scale behavioural changes occur as soon as possible, and that governments and businesses support a swift transition to more sustainable consumption through policy incentives and new business models. However, achieving the necessary emission reductions will also require greater international action than is currently planned.

Compared to a future scenario with no further climate action, this report demonstrates that a global transition to low-carbon production of goods and services, in line with current national government targets, could reduce emissions significantly. If, in addition, Deadline 2020 commitments are also met and a series of ambitious consumption interventions are carried out, C40 cities could reduce their consumptionbased emissions by 70% over the period up to 2050. This is a significant reduction, but it still leaves an emissions gap in C40 cities, compared to a 1,5°C scenario.  To fully reduce emissions in line with a 1,5°C trajectory, an accelerated global transition to cleaner production must take place, supported by national targets that go well beyond current nationally-determined commitments. These developments must initiate sweeping decreases in the carbon-intensity of industrial processes such as the making of steel, cement and petrochemicals.


If C40 cities can reduce their consumption, under a scenario with an accelerated transition to cleaner production, global, national and city action will close 95% of C40 cities’ consumption-based emissions gap by 2050. If cities then develop additional bespoke consumption interventions, for a wider set of diverse goods and service categories that have not been the focus of this report, C40 cities could close their full consumption-based emissions gap by 2050. While national action is necessary, C40 cities do not have to wait for it. The C40 network represents 25% of the global economy, and vast amounts of goods and services are produced around the world in order to meet consumer demands in C40 cities. Mayors and city governments are well-positioned to bring together urban residents, businesses, civil society groups and national governments to collaborate on the delivery of transformative climate solutions.

To achieve necessary emission reductions, we need deep shifts in the way that economies and societies operate. The wide range of action required to achieve a 1,5°C scenario leaves little room for delay or failure over the coming decade; other broad, supporting policies can provide a safety net by bringing about complimentary emission reductions. Examples of such policies are a wide deployment of carbon capture and storage (CCS), particularly in industries that emit direct emissions, and carbon pricing mechanisms that can underpin action across entire economies and markets. However, even deeper paradigmatic shifts may be relevant, such as adopting more useful measures of societal development than just economic growth. In practice, no one city or nation will follow the exact same emissions reduction pathway, but this report provides direction on the type, scale and timescale of policies that will need to be implemented.


This Executive Summary of the report is published here with permission.

Click here to download the full report

Contact C40,





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