Cities looking to reduce their impact on the environment often overlook the main source of their carbon emissions. Here a Leeds research group argue that we are targeting climate change in the wrong way
We tend to think about our contribution to climate emissions in relation to our direct consumption of fossil fuels. The petrol we pump into our cars, the gas feeding our boilers, the electricity keeping our lights on. The hum of a million energy demanding activities pervade every aspect of urban life, and the vast majority of that energy — 80% — comes from burning fossil fuels.
However this only tells part of the story. We should also consider the energy and emissions needed to produce the goods, services and infrastructure in the places we live — even if these emissions are released halfway around the world.
Vegetables in the grocery store don’t release carbon emissions, but they likely travelled in the back of a van for hundreds of miles, and were grown with fossil fuel based fertilizers and pesticides. The steel, glass, concrete and asphalt in roads and buildings that make up urban environments were usually scraped, pulverised, melted and moulded far from where they sit today — processes that generate large amounts of emissions.
Although many cities have adopted targets to reduce their carbon emissions, most of these only take the emissions that are released within their city limits into account — the city’s direct consumption emissions. But it doesn’t matter to the planet whether our emissions are released where we live or from carbon ‘embedded’ in the products we buy.
In 2017 global production — and global consumption — produced 41 gigatonnes of CO2. However, at the city level production emissions and consumption emissions can be dramatically different. In London total emissions from consumption are more than double the production emissions — the amount of emissions actually released within the city.
New research by our team at Leeds suggests that thinking about urban carbon emissions in terms of consumption, rather than production, substantially reorients our thinking about the how city policymakers, and urban dwellers, can address climate change.
Industrial cities produce less CO2
Industry uses vast amounts of energy, and as a result emits substantial amounts of greenhouse gas emissions. By contrast, the service sector produces less emissions. Cities with large industrial sectors therefore typically emit high amounts of emissions, while cities dependent on the service sector have lower emissions.
But when looking at consumption emissions this relationship is reversed. While large industrial sectors emit a lot of emissions, they are typically found in cities that are at a lower level of economic development. Lower development means lower wages, and lower wages mean less consumption of goods and services that emit carbon emissions when they were being produced.
In cities where the service sector is large production emissions are usually lower, but income levels are generally high. Higher incomes lead to higher consumption of goods and services that emitted carbon when being produced. In other words, cities with little industry can be more dependent on industrial activities than the cities that actually house those factories.
This shift in our perspective of which are high carbon cities also shifts where the responsibility for climate action lies. In wealthy cities like New York and London, direct emissions may be low, but the goods we buy mean that these cities may have a much larger responsibility to act on climate change than we previously thought.
Beijing is no longer Chinese
And neither is New York American, or London English — at least in climate terms. Each is a wealthy global consumer city whose emissions profile is more similar to other wealthy consumer cities than other cities in their respective countries.
Similarly, cities at lower levels of income are often more similar — in terms of their level of emissions and the source of emissions — than other cities in the same country.
This suggests that when cities consider the best approaches to fighting climate change, looking to their national capital or a global megacity that speaks the same language may be a poor approach. Rather, fundamental urban characteristics like population size, income level and economic structure may be better indicators of a similar urban climate context.
The food you eat may be more important than your car for reducing emissions
Cars are major sources of emissions. Indeed, in the US transport recently overtook electricity as the largest source of emissions. But for an individual city dweller, especially one who lives in a wealthy, dense, urban area, what you eat, how much you waste, and how you dispose of waste, may be of greater importance.
In Bristol in the West of England reducing food waste by half could reduce emissions by the same amount as more than £3 billion worth of investment in hi-tech buildings and roads.
In other words, addressing the most obvious and immediate ways we emit carbon may not be the best way to have an impact. Almost everything around us, our clothes, the materials in buildings, even the WiFi signal connecting our phone to the internet, required carbon emissions to exist. And by examining these processes we can get a better idea of how we can address our greenhouse gas footprint in the most effective way.
These findings are not to diminish important, and necessary, actions to reduce our use of fossil fuels in urban areas across the globe. And it is important to recognise that reducing production emissions is often complementary with reducing consumption emissions.
However, these findings suggest that consumption emissions have been overlooked as a target of low carbon action in global cities — should we really be investing in expensive technologies to reduce our emissions before we’ve learned how to waste less food?