IPCC: City Planners Face “Make-or-Break” Moment for Climate Action

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City populations are projected to increase from 55 to 68 percent of the world’s population, while greenhouse gas emissions in cities are already substantial and continue to rise. Despite cities’ significant contribution to climate change, the IPCC finds that they also represent a huge opportunity for ambitious climate action — if swift and aggressive measures are taken.

The good news is cities are starting to mobilize. Since 2015, over 10,000 cities have joined the Global Covenant of Mayors for Climate & Energy, together representing a mitigation potential equivalent to more than half of all greenhouse gas (GHG) emissions in the United States in 2019. Over 800 cities have also gone as far as to pledge to reach net-zero emissions by 2050. While this positive momentum to address climate change at the city level is growing, the IPCC report makes it clear that more needs to be done. To support this effort, the report gives cities a roadmap for action to lead the world in large-scale climate action. We read the IPCC’s Chapter 8: Urban Systems and Other Settlements and pulled out the top four key takeaways for cities.

1: What cities do in the next decade will make-or-break global climate action

Cities are responsible for the majority of CO2 and methane emissions, producing between 67 and 72 percent of emissions in 2020 from the production and consumption of goods and services. The science is clear: by taking aggressive and immediate action for electrification, energy and material efficiency, renewable energy, and socio-behavioral changes, cities could approach net-zero emissions by 2050. But without immediate and significant action, the urban emissions could double by mid-century as urban populations, land areas, and economic impact continue to grow. The actions cities do or do not take in the next decade matter. The good news is, the latest IPCC report lays out three strategies for cities to dramatically reduce their emissions:

  1. Reduce urban energy consumption across all sectors, including through land use and transportation planning and infrastructure;
  2. Electrify and switch to net-zero emissions resources; and
  3. Enhance carbon stocks and uptake through urban green and blue infrastructure, which can also offer multiple co-benefits.

To pursue aggressive climate action, cities must first know where they stand in terms of GHG emissions. But many cities face challenges related to GHG emissions monitoring. Currently, most cities use old greenhouse gas inventories that don’t allow practitioners to model the impacts of various policies and programs in real-time. Other cities struggle to create basic inventories as sustainable development and other challenges compete for city staff’s attention and limited government capacity. To help cities around the world overcome this barrier, RMI is working with multiple partners on the City Climate Intelligence Initiative (CCI). CCI is working to unleash the transformative capacity of high-resolution, near real-time CO2 monitoring and GHG emissions reduction scenario simulations to increase citizen buy-in, support decision-making, and drive CO2 emissions reduction investments within cities.

2: Better urban planning can lead to significant long-term emissions reductions

Better planning can support the behavior change needed to reduce vehicle miles traveled (VMT) and the associated emissions. According to the report, “Integrated spatial planning to achieve compact and resource-efficient urban growth through co-location of residences and jobs, mixed land use, and transit-oriented development could reduce GHG emissions between 23-26% by 2050 compared to the business-as-usual scenario.”

Many residents have little choice but to drive to reach everyday destinations such as offices, grocery stores, retail centers, and schools on account of sprawling land use patterns. But this inefficient city layout is not the inevitable result of market forces. Especially in North America, a century of exclusionary planning rules have led to both residential segregation and car dependence. RMI’s Climate Aligned Urbanism initiative is working to support cities with land use planning, housing reform, and mobility solutions to reduce emissions and improve quality of life for urbanites.

Reforming housing rules is an opportunity to reduce emissions while enhancing equity, yet it is often missed by local climate action plans. One of the key ways housing reform reduces emissions is by reducing VMT. RMI’s analysis shows that the United States needs to reduce VMT by 20 percent to limit warming to 1.5°C. This can be done through smart growth strategies such as infill development and transit-oriented development that promote more compact, walkable cities. Additionally, stopping inner city highway expansion can curb an increase in VMT. Our SHIFT calculator enables users to estimate long-run (i.e., after 5 to 10 years) induced VMT and emissions impacts from capacity expansions of large roadways in US metropolitan areas and urbanized counties.

Photo by Cynthia Shahan, CleanTechnica
3: Cities are leading on renewables and electrification, but they can and need to do more

Electrifying mobility, heating, and cooling systems; decarbonizing the electric grid; and switching to net-zero materials and supply chains are critical strategies for urban mitigation. Electrification and energy efficiency can help cities globally reduce emissions by 6.9 gigatons of CO2e by 2030 and 15.3 GtCO2e by 2050. Integrating solar PV and all electric vehicles alone could supply affordable clean energy to cities and reduce CO2 emissions by 54-95 percent. The latest IPCC report shows that this can be done with existing technologies.

Cities are already taking action for renewable energy and electrification. Between 2015 and 2021, US cities completed deals amounting to over 16,000 MW of new renewable energy capacity. Additionally, cities are engaging with their utilities, electricity operators, and legislators to implement more renewable energy and stop new fossil fuel infrastructure. But cities need to do more. That’s why RMI has been working with over 200 US cities to advance their transition to renewable energy, scale up their electrification of heating and cooling systems, and more.

4: The dual challenge of rising GHG emissions in cities and increased projections of extreme climate events require solutions that integrate mitigation with adaptation, including urban green and blue infrastructure

Cities will need to pursue solutions that integrate mitigation with adaptation to protect urban dwellers from current and future impacts of climate change. One solution highlighted in the latest IPCC report is urban green and blue infrastructure, such as street trees, green roofs, urban parks, and blue spaces. In addition to helping store and sequester carbon, urban green and blue infrastructure can help cities reduce their energy use, offset the impacts of the urban heat island, and withstand flooding and other extreme weather events.

Cities are increasingly experiencing the impacts of climate change, including extreme summertime heat and worsening winter storms. RMI is supporting cities at the intersection of mitigation and adaptation through projects such as helping cities pursue passive urban cooling strategies to decrease the need for mechanical cooling. We are also working with cities in Texas to enhance resilience to extreme weather events while enhancing local mitigation efforts through residential weatherization, community resilience hubs, and municipal fleet electrification.


The latest IPCC report paints a clear picture that climate action must accelerate and reach net-zero emissions by 2050 to limit global temperature rise to 1.5°C (2.7°F). The chapter on “Urban Systems and Other Settlements” gives cities a roadmap to achieve net-zero emissions by mid-century while supporting multiple co-benefits and Sustainable Development Goals. Additionally, the report highlights the potential for cascading effects when implementing systems thinking for multiple urban and city scale interventions. When integrating land use planning, electrification, and urban green and blue infrastructure, the mitigation potential is more than the sum of its parts.

As we work to recover from COVID, there is an opportunity for city planners to integrate climate change action and come back stronger by pursuing an infrastructure agenda that is cleaner, more resilient, and more equitable for all.

By Mia Reback

© 2022 Rocky Mountain Institute. Published with permission. Originally posted on RMI Outlet.

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Since 1982, RMI (previously Rocky Mountain Institute) has advanced market-based solutions that transform global energy use to create a clean, prosperous and secure future. An independent, nonprofit think-and-do tank, RMI engages with businesses, communities and institutions to accelerate and scale replicable solutions that drive the cost-effective shift from fossil fuels to efficiency and renewables. Please visit http://www.rmi.org for more information.

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