How Cities Might Reduce Greenhouse Gases, & Address Climate Change (Solutions & Strategies)

How Cities Can Reduce Greenhouse Gas Emissions, & Address Climate Change (Solutions, & Examples Of Cities Who Have Already Done It)

We’ve previously written about whether we should focus on addressing climate change at the city level, or the country level.

This is a guide about how cities might address climate change at the city level.

 

Summary – Reducing Emissions & Addressing Climate Change In Cities 

  • CBD and heavily urbanized areas tend to have a different carbon footprint to suburban and rural areas 
  • Every city also has it’s own unique carbon footprint – in terms of quantity of emissions, and where emissions come from (the activity that produces the emissions, the sector, whether they come from inside or outside the city via direct emissions or imported emissions from goods made elsewhere, and so on)
  • Roughly 70% of global greenhouse gas emissions come from cities (some sources say it’s higher when accounting for all production and consumption emissions)
  • The most developed cities in the world tend to have the highest total carbon footprints (read a list of the largest emitting cities in the world here)
  • Per capita footprint tends to be lower in denser cities that are built up instead of out, and that are more compact and efficient in their design
  • Developed cities tend have more emissions come from building energy, and developing cities tend to have more emissions come from industrial activity
  • The emissions from a city tend to be directly related to how clean the energy mix in the city
  • Reducing total consumption and rate of consumption (such as overconsumption) may be the best way to reduce emissions, along with being more efficient with emissions, rather than focussing on technology like renewable energy, electric cars and other similar solutions
  • Some estimates indicate that 90% of future city emissions will come from developing cities

 

But, other ways to reduce emissions in cities might be …

  • Having a cleaner energy mix (including a bigger contribution from renewables and low carbon energy sources, rather than fossil fuel energy sources)
  • More of a focus on mass transit, and walking, biking and public transport, as opposed to single person vehicles
  • Efficient building energy systems and designs (especially with the consumption of electricity for heating, cooling, refrigeration and lighting)
  • Focus on reducing emissions in other sectors as well, like food consumption, food waste and loss, waste management, government, road, pathways and infrastructure, health and education, and so on
  • [Energy generation and buildings, and transportation may be some of the biggest areas to focus on in developed cities. Food, waste, and water might be others]
  • Consider the lifecycle of products and materials for a full carbon footprint – production, consumption, exported, imported, inside the city boundaries, and outside the city boundaries [some cities may import a huge amount of emissions from goods and services made or produced elsewhere]
  • Population growth can be one multiplier factor in a city that increases emissions (both direct and indirect)

In the guide below, we’ve outlined that some of the biggest cities in the world have already put in place measures to decrease and peak their emissions. We’ve also listed some of the ways they’ve done this.

Ultimately, every city is different, and every city will need it’s own custom approach not only to address climate change (mitigation, adaptation, sequestration, etc), but also in becoming more sustainable overall to address broad sustainability issues like water supply, air pollution, land degradation, overpopulation, and so on.

 

The Different Types Of Cities & Their Carbon Footprints

Rural, urban and CBD/built up city areas all tend to have different emission rates.

Different types of cities tend to have different carbon footprint profiles in their own right as well.

Emissions can be measured by total emissions, or emissions per capita. There’s also another measurement not used as often – the carbon intensity of an activity.

The cities that emit the most total greenhouse gas emissions in total tend to be some of the biggest, most economically developed, urbanized and affluent/richest (in terms of lifestyle) cities.

There’s about 100 of these types of cities that make up around 20% of total global greenhouse gas emissions. 

These cities tend to be consumer cities (outsourcing production elsewhere but consuming inside the city boundaries), whilst developing cities tend to tilt towards being production cities.

The more developed a city becomes, the more their industrial sector emissions might reduce, and the more their emissions from building energy might increase (heating, cooling, refrigeration, lighting etc.).

Developing cities tend to have lower overall emissions, but more of their emissions tend to come from the industrial sector (which makes sense as they are building and developing their city). 

Having said that, in the future, around 90% of the emissions from energy use are forecasted to come from developing cities.

There’s also other factors and variables that contribute to the unique carbon footprint and emissions profile of different cities

Ideally, solutions and strategies to reduce emissions or address climate change would be suited to the profile of the city – developed vs developing, consumer city vs producer city, and identifying the sectors and activities in the city that emit the most GHGs, and where there is most potential for positive results.

Overall, it would make sense to not only implement policies, strategies and solutions that bring about mitigation, adaptation, and sequestration for climate change, but are also sustainable in general so they can address other issues like air pollution, over population, waste management, and so on.

Cities are well placed in this regard as solutions and strategies may be able to be implemented more quickly and effectively than at the national or even State/province wide level (or even global level).

 

Solutions & Strategies For Reducing Emissions & Addressing Climate Change In Cities

We’ve paraphrased and listed ideas and solutions from various sources below (and expanded them, or connected them to other ideas ourselves) about how some cities might decrease emissions and address climate change.

Check out the resources list for the full resource if you’re interested:

 

  • The real key to reducing emissions from cities in the future might not be renewable/green energy or electric vehicles – but, a reduction in [total] consumption [and rate of consumption]
  • Decreasing consumption of goods and services, improving electricity efficiency, and decreasing the use of single person cars and transport and encouraging ride sharing, mass transport and clean transport, are just some ways to reduce consumption
  • Increasing urban density can lower emissions per capita
  • Improving urban design to avoid sprawl can lower emissions per capita
  • Improving city public transit and mass transit can reduce overall emissions
  • Changing building practices and increasing building efficiency can reduce emissions overall
  • Changing sources of energy to more efficient, greener, renewable and cleaner energy sources can reduce overall emissions
  • Compact cities tend to be the most efficient in terms of emissions per capita, compared to sprawling urban areas
  • Be aware that population increase within a city not only increases emissions directly (for example through electricity usage), but increases demand on resources like freshwater which may in turn increase energy required to deliver more water, and even energy to run desalination plants (both of which can result in greenhouse gas emissions)
  • Place a focus on cities that are highly developed, urbanized, and rich/affluent for addressing high greenhouse gas emissions right now
  • Developing cities might be where we place most focus in the future for mitigating greenhouse gas emissions from energy and the industrial sector
  • For developed cities, there might be more focus on emissions coming from buildings, their energy use, and heating, cooling, refrigeration and lighting 
  • Higher city densities (more people using less land surface area) tends to result in less emissions per capita
  • Building up (tall buildings) instead of out (urban sprawl) is one way to increase per capita carbon emission efficiency
  • Social norms and culture within cities can impact emissions – if more people buy into the concept of sustainable cities, emissions might be lower based on behavior and other factors
  • The energy mix within a city is usually directly proportionate to the greenhouse gas emissions produced – so, focus on cleaner energy mixes. Coal tends to be the dirtiest fuel, followed by oil, and then natural gas behind that. Renewables, hydroelectricity and nuclear are some of the cleanest
  • Understand that more electric vehicles and desalination plants in the future will only means more energy consumption and higher potential for an increase in GHG emissions
  • Spatial organization of cities and urban areas matter – single family homes, further away from services and with private cars, tend to have higher emissions than multi unit buildings that are built up, close to public transport and services
  • Shorter electricity transmissions lines might mean less loss of power in delivering energy, which might be a save on emissions
  • Limiting the number of trucks, automobiles, and aircrafts coming in and out of the city limits the need for more concentrated energy within city limits (after looking at electricity generation, this is probably the second biggest way a city can ensure they are monitoring where their emissions come from)
  • Look at every aspect of the city for an idea of where emissions are coming from i.e. all sectors – Resource use, water consumption, wastewater production, toxic releases, and solid waste generation, and so on.
  • Food waste and loss, waste generation and disposal and other areas are important
  • Get an accurate picture of the geographic boundaries of a city for an idea of where emissions are happening
  • Understand how far up the production and supply chain you are counting emissions – indirect supply, transport, delivery and manufacturing chain can all be included or excluded
  • Variables like deforestation and mining can be difficult to factor into carbon footprints for cities because of how disconnected they can be from final consumption
  • Per capita emissions can be influenced by factors like a cold climate
  • Per capita emissions can be influenced by a variety of physical, economic, and social factors specific to the unique urban life of each city
  • Infrastructure investments quickly become long-term sunk costs. The transportation system that a city develops largely defines the final shape of the city, as influenced by local geography. Roads and public transit lines are the bones of a city, with water, wastewater and power services fleshing out the city. Once buildings grow around transportation and service nodes, they are all but locked-in. Understand these factors as factors that might be hard to change and may limit a city’s final emission footprint.
  • The variation in per capita emissions in cities results from differences in wealth, sectoral specialization, energy sources, the general climate, and the structural efficiency of the urban form, which includes buildings and transport infrastructure

– siteresources.worldbank.org

 

  • It’s important to know where the boundaries are of a city when you are calculating emission footprints
  • Look at emissions both in the city boundary and outside (on site and off site emissions)
  • Look at emissions from both consumption and production – goods and services can be produced outside the city and consumed inside, they can be both produced and consumed inside the city, or they can be produced inside the city and consumer outside the city boundaries
  • To calculate consumption = production – export + import
  • Imported goods that were produced outside the city tend to have the biggest footprint, followed by within the city for both, and then produced inside and exported outside – so focus on imported goods and what can be done there
  • Consumer cities are responsible for about 80% of GHG emissions, while producer cities are for 20% – so focus on consumer type cities
  • Look at emissions from both imported and exported goods and services
  • Cities need to work with other cities that they trade with otherwise supply chain emissions will rarely be counted or addressed
  • Look at supply chains all the way through – deforestation and land clearing, mining, sourcing, manufacturing, processing, delivery and transport, waste and loss etc.
  • Look at emissions across all city sectors and activities
  • Capital and buildings, utilities and housing, food, beverage and tobacco, Public transport, private transport and government tend to have the biggest carbon footprints
  • This is followed by clothing, furnishing and household equipment, restaurants, hotels, recreation and culture, communications, education and health, miscellaneous goods and services, and other sources of emissions
  • Over 70% of consumption-based GHG emissions come from utilities and housing, capital, transportation, food supply and government services – so this may be where focus in placed
  • There are good reasons why most cities focus on sector-based GHG emissions. They occur from sources over which cities often have more direct influence; are easier and more reliable to estimate and monitor
  • Cities may not have much direct influence over the carbon intensity of power used in the manufacturing process of an imported product, or whether that product is transported by train or truck, as end users and centres of innovation and change
  • Different regions and countries in the world have different profiles for both consumption and production, and also the sectors of their city that make up their total footprint – so, understand what type of city you are looking at and what makes it unique from an emissions perspective
  • [The biggest or most developed] cities rely heavily on the supply of goods and services from outside their physical boundaries.
  • The results of this study show that the GHG emissions associated with these supply chains are significant, particularly for C40 cities in Europe, North America and Oceania.

– c40.org

 

  • … tourism to, and inside of some cities [can be made] more sustainable – more train travel and less plane and car travel for example
  • Understand that cities like London, Paris, New York, Toronto, or Sydney are consumer cities who no longer have large industrial sectors – their emissions come from consumption, but also from the production of products outside of the city boundaries [that are imported for use inside the city]
  • Understand that cities like India, Pakistan, or Bangladesh generate [significant] industrial pollution and carbon emissions in the manufacture of products that will be sold and consumed in Europe and North America
  • We can’t just outsource emissions to other cities and think we are making an impact by minimising emissions within our own city
  • We are going the wrong direction with climate change – the next step is to reduce consumption – not using more renewable energy and mass transit
  • Smarter purchasing, buying local, and reducing waste are part of what can be done to reduce consumption emissions
  • Service-based economies that consume the things that other cities make can rank better for emissions – so new carbon footprint calculations need to take into account inside and outside city emissions. We also need to take into account other factors like local production which is better than foreign production
  • We can change our diets to reduce emissions at the agricultural, forestry and land use level [reducing food waste and loss is also another opportunity to do this]
  • Retrofit buildings and ensure new buildings are efficient – another way to reduce emissions in developed cities

– nationalgeographic.com

 

  • … a very small number of cities, about 100, emit about 20% of the world’s total greenhouse gas emissions. So, we might focus on these cities as a priority
  • … within countries, The bulk of a country’s consumption-related carbon emissions can be concentrated in just a few cities … For example, residents of South Korea’s capital, Seoul, account for about 45 percent of that nation’s overall carbon emissions; in the U.K., London, Manchester and Birmingham combined contribute more than 20 percent of national output; whereas in the U.S. people living in Chicago, New York and Los Angeles combine to account for nearly 10 percent of the country’s overall footprint.
  • … roughly one third of an urban resident’s footprint is determined by that city’s public transportation options and building infrastructure … If cities would switch to a more efficient energy source or make their public buses electric … they could slash their emissions by at least 25 percent …There is a lot of power in cities … and … at the more local level of government you can take faster action than at the national level

– scientificamerican.com

 

  • Place a focus on the top 100 to 500 cities for addressing total emissions
  • Place a focus on the top 100 to 500 cities for addressing per capita emissions
  • Radical decarbonization measures (limiting non-electric vehicles; requiring 100% renewable electricity) can induce substantial emissions reductions beyond city boundaries. In wealthy, high-consumption, high-footprint localities such measures may require only a small investment relative to median income, yet accomplish large reductions in total footprint emissions
  • Local action at the city and state level can meaningfully affect national and global emissions
  • You have to know the scope included in the final footprint – what emissions are being counted, what source are they coming from, are they counted inside or outside the city, and how far back in the manufacture or supply process is being counted (just as examples)

– citycarbonfootprints.info

 

When addressing climate change involves mitigation, adaptation and sustainability strategies … areas to focus on for solutions might be:

  • Adaptation and implementation – connecting cities, cool cities, urban flooding
  • Improving Air Quality – minimising air pollution and emissions
  • Energy and buildings – Clean Energy, Municipal Building Efficiency, New Building Efficiency, Private Building Efficiency
  • Transport – Land Use Planning, Mass Transit, Mobility Management, Walking & Cycling, Zero Emission Vehicles
  • Food, waste and water – Food Systems, Sustainable Waste Systems, Waste to Resources

– c40.org/networks

 

  • It’s also worth noting that sequestration of GHGs in the air might be achieved through sequestration technology, or simply greening up cities with more plant and vegetation matter
  • Some cities do this on building rooftops, on building facades or even have sequestration towers built
  • Some cities are also starting to have a much heavier emphasis on walking, biking and non vehicular movement and transport

 

Examples Of Cities That Have Already Reduced Greenhouse Gas Emissions

You can find examples of cities that have already got results or done something to reduce greenhouse gas emissions at c40.org

Something they mention about cities currently attempting to reduce emissions:

  • 27 of the world’s greatest cities, representing 54 million urban citizens and $6 trillion in GDP have peaked their greenhouse gas emissions.
  • New analysis reveals that the cities have seen emissions fall over a 5 year period, and are now at least 10% lower than their peak.
  • The cities are: Barcelona, Basel, Berlin, Boston, Chicago, Copenhagen, Heidelberg, London, Los Angeles, Madrid, Melbourne, Milan, Montréal, New Orleans, New York City, Oslo, Paris, Philadelphia, Portland, Rome, San Francisco, Stockholm, Sydney, Toronto, Vancouver, Warsaw, Washington D.C.

 

Some of the ways they achieved this were:

  • Decarbonisation of the electricity grid
  • Optimizing energy use in buildings
  • Providing cleaner, affordable alternatives to private cars
  • Reducing waste and increasing recycling rates
  • Investment in sustainable infrastructure and policies
  • Collaborating with national and regional governments and businesses operating within cities, as well as citizens, to deliver the collective action needed to cut emissions

 

Tracking How Cities Are Addressing Climate Change & Sustainability

One place you can go to see how some cities are tracking in terms of how they are addressing greenhouse gas emissions & sustainability is c40.org

 

Sources

1. http://siteresources.worldbank.org/INTUWM/Resources/340232-1205330656272/4768406-1291309208465/PartIII.pdf

2. https://news.nationalgeographic.com/2018/03/city-consumption-greenhouse-gases-carbon-c40-spd/

3. https://www.c40.org/researches/consumption-based-emissions

4. https://www.c40.org/press_releases/27-cities-have-reached-peak-greenhouse-gas-emissions-whilst-populations-increase-and-economies-grow

5. Moran, D., Kanemoto K; Jiborn, M., Wood, R., Többen, J., and Seto, K.C. (2018) Carbon footprints of 13,000 cities. Environmental Research Letters DOI: 10.1088/1748-9326/aac72a

6. http://citycarbonfootprints.info/

7. https://www.scientificamerican.com/article/heres-how-much-cities-contribute-to-the-worlds-carbon-footprint/?redirect=1

8. https://www.c40.org/cities

9. https://www.c40.org/networks

10. https://www.bettermeetsreality.com/addressing-climate-change-should-we-focus-on-the-country-level-or-the-city-level/

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