GHG Emissions in Cities

Municipal climate action

Three wooden blocks have the letters G H G painted on them. A fourth block is being tipped by a finger from a red arrow pointing up to a green arrow pointing down.
Municipalities are on the front lines of climatic events.

Municipalities often are where big ideas translate into practical action—the city street is where the rubber hits the road. As such, municipalities are at the forefront of having to convert the economy to carbon neutrality. Of course, they must do this with limited budgets and limited time.

All regions have a vested social and economic interest in reducing greenhouse gases. Municipalities manage the day-to-day experience of citizens and are feeling the first effects of climate change. Cities are therefore often innovators in adopting serious climate action plans.

What is a climate action plan?

Climate action plans offer detailed steps to reduce greenhouse gas emissions—and to cope with climactic impacts. Measuring current emissions and bringing them to net zero is the goal. The plans must detail actions that can be implemented on current budgets, and so cost-effectiveness is usually important. Inventorying current emissions and finding energy efficiencies is one major strategy which is both cost effective and GHG reducing. Savings can be used for other, more expensive projects.

A man on a bike looks up at a skyscraper that has greenery on its cladding
Municipalities can make a difference with zoning, bylaws, and infrastructure.

Cities manage major GHG emissions sources

Although different countries, states, and provinces apportion governmental responsibilities differently, certain responsibilities typically fall to municipalities.

Land development

Municipalities generally have responsibility for zoning. They also provide most street level infrastructure. This power gives cities tools to encourage citizens to change their transportation and movement habits.  Transit that is affordable, accessible, and timely draws commuters away from their cars. Safe, attractive, and accessible pedestrian and bike paths bring people to the street where they create an attractive community (and shop!) It’s not just about transportation, either. Zoning neighborhoods for units of errands can transform a city into a quilt made of vibrant villages. Compare this to cities which are a series of freeways connecting residential areas to commercial ones.

When urban villages are enhanced with trees, parks, seating, art, and other amenities, the areas have walk appeal and therefore are more inviting. They are less likely to breed car dependance. Such community villages are an incentive to encourage lower-carbon transport choices in citizens. (They also enhance the health and quality of life of people in the area.)

Ways to disincentivize driving exist, like limiting parking and creating drive-free zones—but walkable community spaces need to come first, or cities risk creating economic hardship and political pushback from car-dependent citizens.

A woman sits on a bus: we see the back of her head as she looks out the window. People stand near the front of the bus.
Affordable, reliable transit helps encourage people to spend less time in their cars.

Urban transit

Creating workable, sustainable transit is an ongoing concern for city planners. There are myriad benefits to well-conceived transit plans—although there can be challenges in the transition from car-first to transit-first commuting systems.  Transit systems greatly reduce the GHG of a city. Transportation accounts for 25% of all GHG emissions, with road vehicles contributing 3/4 of that total.

Waste management

Waste is a contributor of greenhouse gases, both carbon and methane. Municipalities often have responsibility over waste management.

Methane created during composting and landfilling creates 3.2% of the world’s GHG emissions. To combat the methane produced in landfill, municipalities are now using a combination of composting, recycling, and waste incineration. Using gas capture in landfill and composting facilities also lowers the volume of released methane.

Carbon dioxide, however, is the major greenhouse gas. The energy sector, including electricity, heat, and transport, accounts for 73% of emissions. Municipal fleet vehicles are a tricky problem for cities to manage. Most municipal fleets run on diesel. Even if a municipality has moved to electric vehicles, electricity generation is often still fossil fuel dependent. 

One way that cities can lower their GHG emissions is to optimize the movement of fleet vehicles. Every gallon of fuel saved is less greenhouse gases released.

A man in a suit stands behind floating icons representing urban management concerns. An icon of water from a tap is highlighted green.
Wastewater processing produces carbon dioxide, methane, and nitrous oxide.

Water management

Municipalities are often responsible for wastewater treatment, which is a process that mimics and speeds up the natural processes that clean the water in the earth’s water cycle. As with waste management, water treatment produces carbon dioxide, often though use of energy. Methane and nitrous oxide are also produced through the natural decay of organic material. Wastewater processing is therefore a GHG emissions target area. Lowering carbon emissions by lowering energy use in the treatment plant is the biggest goal to overall impact. However, new treatment options and gas capture within the plants can also remediate the nitrogen and methane emissions.

Stormwater is another place where thoughtful management may lower GHG emissions. Low oxygen ponds, often smaller ponds that capture stormwater, may be a source of carbon dioxide and methane. These ponds may be vital to an ecosystem as habitat for indigenous plants and animals; however, in some jurisdictions they may be built simply as a way to manage flooding. In these instances, a conversion to a green-seam water recapture plan can lower GHG emissions. With a green seam approach, rain and run-off is encouraged to return to the water-table or ground water through the use of bioswales and rain gardens. Local ecosystems can make these bioswales more or less effective. Monitoring these swales for efficacy can help with the active management of groundwater return.

Smart management and the digital city

In the 21st century, we have become accustomed to being able to pull out our phones to quickly access a library’s worth of information. In a second, we can find a list of every movie an actor’s worked in, discover the name of a plant we’re seeing at the side of the road, or see a video showing how to change a tire. The internet has become an efficient network of general knowledge.

This same ease of informational access is available in smaller networks of specialized knowledge—businesses and organizations have their own data systems.

This is why sensors and smart information analysis are becoming increasingly important to businesses, so that the ease of access of information so available on the web become available in their specialized domains.  Known as “the internet of things,” or IoT, data is returned from objects that sense changes in the environment. This sort of information is becoming increasingly valuable to cities. With the right information, managers can make changes to make the city more energy efficient.

Heavy traffic in LA covers 8 lanes of highway in two directions
In order to plan and reduce GHG emissions cities must measure current levels.

Measuring GHG emissions

Greenhouse gas emissions are often measured by calculation. For example, the average GHG output per kwh for energy generation in a region is known. Therefore, adding the energy use of all buildings using that grid creates a good estimation of the total release of GHG through energy use. Municipalities lower their use within buildings—perhaps by optimizing temperature control, switching lightbulbs, or building more efficiently—and lower their overall carbon footprint. This slow optimization helps wean energy inefficiency out of the system, as much as is possible.

Waste emissions calculators are available that estimate total emissions based on recycling, compost, and landfill input.

Fleet vehicles are another substantial source of emissions. Again, total fuel consumption over the fleet offers a good estimation of greenhouse gas emissions. Fleet use can also be optimized. However, in many municipalities, crews moving through the city, inspecting and determining issues, are a way to forestall large problems.

In these cases, having a solution where the streets become self-monitoring, allows managers to optimize crew movements. Why burn the fuel to check many city waste bins if the waste bins are empty? Why not have smart sensors warn of sewer overflow events before they reach street level, reducing the need for emergency crews or route inspectors? If a city manager can pull out their phone and ask where there are problems with waste or water overflow in the city, they can have specialized information about their region at their fingertips. The knowledge allows the sort of optimization already happening within buildings. Greenhouse gas emissions are prevented. Additionally, fuel costs are saved, and teams can be dispatched to higher priority issues.

A picture from a drone of the city of Aspen in winter, rows of houses in front and the snow covered mountain rising behind
Some municipalities are already succeeding at innovative GHG reduction plans.

Why should municipalities take the lead?

With bread and butter issues being important to voters, and limited budgets available to municipalities, climate change can seem an overwhelming issue for municipalities to tackle. However, according to the Federation of Canadian Municipalities, municipal governments have influence over 50% of all GHG emissions. Boston is one large city leading the way with an ambitious plan that includes both “carrots” (better transit investment) and “sticks” (an increasing tax on carbon-based fuels.)

Successes have already been seen. Aspen, CO reached a 2015 target of having all electricity generated with renewable sources.  A grassroots group in San Luis Obispo, CA created a climate action plan, and with the municipal government is on target to reach net zero emissions by 2035.

Perhaps the next great municipal competition will be in GHG emission reductions. With innovative ideas in towns small and large, there is a lot of room for creative solutions.