Cities have emerged as pioneers in climate action, with mayors working to improve public transit, reduce traffic congestion, promote walking and biking, create more green space, and also often to promote renewables, energy efficiency, and measures to boost climate resilience.

Through high-profile alliances such as C40 and the Compact of Mayors, urban leaders have also become prominent advocates for global climate action, urging their peers to tackle greenhouse gas emissions in their communities, sharing knowledge, and promoting best practices.

Yet as important a role as cities play, a new SEI analysis funded by Bloomberg Philanthropies shows that on their own, they can only achieve a fraction of their mitigation potential. To achieve the rest, support from national and state/provincial governments will be crucial: from new laws, regulations and standards, to funding, to reforms that give cities the powers they need to take action.

“Many cities today are leaders and pioneers, pushing policy forward in a bottom-up fashion, and the work they’re doing is essential, but it’s not enough,” says Derik Broekhoff, a Seattle-based researcher at SEI-US and lead author of the study. “What is really needed is for all levels of government to work together to address emissions in the fastest, most effective, and most efficient way possible.”

The study, What Cities Do Best: Piecing Together an Efficient Global Climate Governance , builds on prior work by SEI that showed that urban mitigation actions could reduce greenhouse gas emissions by up to 3.7 Gt CO2e in 2030 relative to current trends, and up to 8 Gt CO2e in 2050; that is up to 15% of the global GHG reductions required to stay on a 2°C pathway, the authors estimated.

The new analysis identifies three potential roles that cities can play in achieving those reductions:

  • They can be the primary policy architects and leaders. Spatial planning, transit systems, and waste management are prime candidates for this, as city governments are likely to have the technical capacity, and knowledge of local circumstances and stakeholders is paramount.
  • They can be critical implementers of policies developed and enacted at higher levels of government. Energy efficiency standards for buildings, appliances and vehicles, for example, have the greatest impact when they are widely applied, and the greatest potential to transform markets.
  • They can be strategic partners, by pursuing locally targeted actions to maximize the impact of policies orchestrated at higher levels of government. In this case, cities would not implement the national policies, but undertake separate, complementary actions.

Broekhoff and his colleagues set out to identify the ideal role for city governments in each area where there is high potential for urban GHG mitigation, assigning roles and responsibilities to cities or higher levels of government depending on each level’s relative strengths. They found that actions for which cities are best positioned to lead account for about 20% of the potential; actions where cities’ ideal role would be as critical implementers or strategic partners each accounted for about 40%.

“Cities are really good at certain forms of governance and tackling certain kinds of problems,” says Broekhoff. “They should be leaders in designing compact communities and sustainable transportation systems, for example. But some actions needed to address urban emissions, such as improving building energy codes, would be better undertaken at higher levels of government.”

The study shows that national engagement is critical, because even where cities have political will and resources, they may face realistic limits to their ambitions, especially if a majority of other cities are not similarly engaged and coordinated in pursuing GHG reductions. The key roles identified for national governments are:

  • Establishing national policy frameworks and incentive structures: National political and policy direction is often a strong enabler of urban GHG mitigation, especially when accompanied by efforts to coordinate policy formulation at multiple levels of government. Fiscal and political incentive mechanisms can also be effective for enabling city-level action.
  • Providing, or improving access to, financial resources: Often city governments are best positioned to undertake mitigation measures, but they are budget-constrained. National governments can address this shortcoming by providing direct support and by enacting reforms to improve cities’ access to private capital.
  • Strengthening capacity and improving governance structures: Through training and outreach programs, national governments can assist local governments in obtaining the technical capacity they need to effectively undertake specific kinds of mitigation actions. National governments can also promote better sharing of information and expertise among different levels of government to enable smarter policy design and implementation.
  • Aligning policies and eliminating conflicts: In some cases, national or state policies may actively conflict with city government priorities, or otherwise inhibit city-level actions. Aligning policies and properly delegating authority can enable cities to pursue urban mitigation more effectively.

To provide more concrete examples, Broekhoff and colleagues also explored case studies on vertical integration in the U.S., China and Brazil, providing a survey of priorities across those three countries. They found all three could benefit significantly from greater integration.

The new Paris Agreement recognizes the contributions being made by cities and other sub-national entities, and invites them to continue to scale up their efforts and share them through the NAZCA (Non-State Actor Zone for Climate Action) platform. Some “intended nationally determined contributions” (INDCs) submitted for the Paris conference also aimed to advance urban action.

“A number of INDCs showed movement towards vertical integration, which is a promising sign,” says Broekhoff. “Progressive cities should continue pressuring national governments for more action, including actions that enable all cities to fully engage in reducing emissions and adapting to climate change.”

Read the SEI working paper »

Read a policy brief summarizing the analysis »

See more stories and opinion from SEI at COP21 »