A carbon emission reduction toolkit for global cities

By 2080, summer in Charlotte, North Carolina may be almost 4 degrees warmer and 73 percent wetter. Winter in Vancouver may be more than 4 degrees warmer and almost 25 percent drier.

These are the trends in just two of the 540 cities that researchers from the University of Maryland plotted on an interactive map to predict the effects of climate change in major American metropolitan areas over the next 60 years.

“The idea is to translate global forecasts into something that's less remote, less abstract, that's more psychologically local and relevant,” Matt Fitzpatrick, the lead researcher on the project, told WIRED Magazine in February. Translating global data patterns into local and tangible insights is especially important for getting widespread climate change buy-in—cities will account for two-thirds of the world’s population by 2050.

Cities aren’t just where the effects of climate change may be felt, but also the where we can find solutions. As engines of today’s global economic growth, cities are responsible for more than 80 percent of the world’s GDP. But cities are also the primary drivers of pollution, consuming more than two-thirds of global energy and emitting more than 70 percent of global greenhouse gases. Many municipal leaders are already experimenting with initiatives to reduce emissions, but the challenge is understanding where to focus.

Our analysis, conducted in partnership with C40 Cities, reveals the benefit of placing maximum effort and resources in a handful of solutions, or ‘focused acceleration,’ rather than skimming the surface of many smaller initiatives. Below are twelve opportunities across four action areas that will affirm cities’ roles as climate change leaders and help stall the rise of global temperatures within the ‘safe’ limits of below 1.5 degrees Celsius.

12 ways cities can achieve net-zero carbon emissions by 2050

Grid decarbonization through greater renewable power generation could achieve up to 45 percent of emissions reductions.

1. Cities, utilities, and regulators can take advantage of declining costs and improved availability of renewables to build out centralized renewables over the next decade. The most straightforward way to do this is to facilitate direct investment in, or purchase of, renewable energy. Copenhagen, for example, launched a cooperative through its own utility to invest in a 40-megawatt wind farm not far off its coast, attracting more than 8,000 investors in the local community.

2. The cost of distributed renewables, such as rooftop and community-scale solar PV, continues to decrease, which makes them one of the more cost-effective ways to reduce city emissions. By investing in a $200 million distributed renewables and demand reduction technologies program, for example, New York City’s utility Con Edison has been able to postpone construction of a new $1.2 billion substation.

Shifting to cleaner technologies in building appliances and in buildings themselves, reduces energy use and can cut carbon emissions between 20 and 55 percent.

3. Tightening new building efficiency standards is one of the biggest emissions reduction opportunities across all cities. One of the simplest ways to achieve this is to ensure new buildings adhere to certifications systems such as Leadership in Energy and Environmental Design (LEED), Building Research Establishment Environmental Assessment Method (BREEAM), and Passive House. In 2011, Brussels passed a requirement binding all new buildings to Passive House standards. Since then the cost per square meter of a Passive House residential building there is the same as traditional construction.

4. For existing buildings, envelope retrofits to upgrade walls, roofs, windows, and doors can reduce building heating and cooling demand by about 40 percent. Usually, major building renovations only occur every 30 to 50 years. Cities have taken steps to bypass these natural renovation cycles by tying upgrade requirements to more frequent triggers, such as changes in ownership. New York, for example, requires owners of large buildings to complete periodic energy audits and retro-commissioning of equipment.

5. Upgrade HVAC and water-heating systems to low-carbon technologies such as electric heat pumps, high-efficiency air-conditioning systems, and electric- or solar-based water heating systems. In Scandinavian cities, electric heat pumps account for 55 percent of building heating systems sales.

6. Shifting to LEDs can reduce electricity demand for lighting by 30 percent compared with fluorescent lights, and by 80 percent compared with incandescent light bulbs. Los Angeles has put 114,000 LED streetlights in place to date and reduced its annual costs for electricity and maintenance by $7.5 million and $2.5 million, respectively.

7. Expand use of building automation and control systems such as adaptive thermostats, and lighting sensors to optimize energy efficiency. In our analysis, automation and controls can achieve 2 to 5 percent reduction in building energy use and cities can achieve installation in 15 to 40 percent of buildings by 2030.

Next-generation mobility, including the modes of transport, as well as the design and development of urban centers, can lead to 20 to 45 percent emissions reductions.

8. Densification through smart planning is one of the biggest opportunities to reduce transportation emissions. Denser development in city centers and near employment nodes can reduce average travel time and encourage more buildings, transport systems, and other infrastructure to be constructed for greater efficiency, such as in Johannesburg’s Corridors of Freedom development, which links mixed-use development nodes along transport arteries.

9. Support alternatives to private vehicles, such as protected cycling lanes, bus rapid transit, and renovated metro stations. Boston’s four new stations running between the central business district and the southern outskirts of the city boosted mass transit and spurred the revitalization of areas along the route. Enhancing walking and cycling infrastructure also has benefits including better health and reduced car mileage.

10. Enabling four interrelated trends in next-generation vehicles could help usher in an era of seamless low-carbon mobility: vehicle electrification; shared mobility, as in car-share fleets and e-hailing services; autonomous (self-driving) vehicles (AVs); and wireless connectivity, enabling communication between vehicles.

11. Reduce emissions from last-mile urban transport and delivery through solutions such as night deliveries, parcel lockers, and electric delivery vehicles. In Hamburg, for example, UPS worked with city officials to support the goal of no motorized vehicles in the city core, which has, according to UPS, reduced carbon-dioxide equivalent emissions by more than 70 metric tons.

Improved waste management can achieve up to 10 percent of emissions reductions while bringing myriad resource and health benefits to local communities.

12. Cities can tackle waste emissions in a resource-effective way by adopting a “highest and best use” approach which has four broad levels:

  • First, reduce initial waste levels by, for example, reducing food spoilage and construction waste sent to landfills.
  • Second, repurpose as much product as possible before it becomes waste. Excess food can be channeled to food assistance services or processed for animal feed.
  • Third, segregate waste and divert it to recycling, composting, anaerobic digestion, mechanical biological treatment, or similar treatments.
  • Finally, manage disposal with technology such as landfill gas capture systems to minimize emissions of any remaining organic matter. Ninety-seven percent of global direct emissions from waste is methane, a greenhouse gas with 86 times the global warming potential of carbon dioxide.

Multiple returns on investment

Over these 12 areas, cities have the potential to achieve 90 to 100 percent of emissions reductions needed by 2030, and to put in place much of the infrastructure needed to reach zero-carbon emissions by 2050. Cities will need a clear vision, sustained commitment, and significant investment. Yet with a strategy of focused acceleration, this goal is clearly in reach.

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