Last week, cities around the world made bold commitments to confront climate change. The Compact of Mayors, announced at the UN Climate Summit in New York City, convenes cities to set ambitious targets and report their performance transparently. It builds on commitments to reduce their contributions to global climate change. Analysis shows that 228 cities, home to 436 million people, have voluntarily committed to saving 13 gigatons of greenhouse gas emissions by 2050.

Through the Compact, some of the world’s leading city networks – C40 Cities Climate Leadership Group, ICLEI – Local Governments for Sustainability, and United Cities and Local Governments (UCLG) – in partnership with 25 organizations including the World Resources Institute (WRI), will mobilize their cities to amplify and expand commitments to address climate change.

Specifically, cities will:

• Set ambitious targets to reduce greenhouse gas emissions
• Develop strategies to mitigate and adapt to climate change
• Track, report, and publicly disclose data about their emissions

Considering the sheer scale, these commitments are significant. But what makes the Compact even more notable is its link to tangible action. The Compact is linked to measurement, built around the transformational power of mayors and city leaders, and supported by parallel initiatives to unlock finance and spread knowledge.

Here is how the Compact of Mayors and its parallel initiatives will lead to tangible action.

1.  Mayors take action, get results

The Compact taps into city leaders to lead the fight against climate change. Cities, historically engines for innovation, account for roughly 70% of global carbon emissions. Mayors possess executive power to directly influence much of the infrastructure and behavior that contribute to climate change. As accountable, local leaders, mayors are central figures in negotiating how cities will absorb 1.4 billion new urban residents by 2030, while providing for human needs and addressing climate change. Plus cities stand to gain immense local economic benefits by pursuing a climate-smart path to growth. The Better Growth, Better Climate report finds that connected, compact cities could save $3 trillion in infrastructure investments over the next 15 years while curbing climate change and improving air quality and public health.

Already, the ambitious commitments made by cities are backed by real, tangible progress. For example:

• Qingdao and Chengdu, China, both adopted aggressive “low-carbon development blueprints” – with WRI’s support – that prioritize investments in public transit, building efficiency, low-carbon industries, and efficient water systems. China’s central government has formally designated both cities as pilots to receive investment, demonstrate low-carbon strategies, and share best practices.
• Rio de Janeiro, Brazil, where urban transport accounts for the majority of greenhouse gas emissions, is building Latin America’s largest bus rapid transit (BRT) system, 300 kilometers of bike lanes, and the continent’s largest bike-sharing system. Already, 133 kilometers of BRT are up and running, many with support form EMBARQ Brasil.
• Vancouver’s Greenest City 2020 Action Plan features 100% carbon-neutral buildings from 2020 onward; expanded waste-to-energy district heating; and investments to promote walking, biking, and public transport – together expected to reduce emissions by a third by 2020.
• Dhaka, Bangladesh’s integrated solid waste management plan will improve collection and recycling, reduce waste, clean existing landfills, and introduce composting – all powerful measures that will reduce methane leakage.

2.  Measuring and managing greenhouse gas emissions

The Compact commits cities to adopting a common accounting standard for measuring their emissions, the Global Protocol for Community-Scale Greenhouse Gas Emission Inventories (GPC). In addition to the GPC, the carbonn Climate Registry will compile data into a central repository for global transparency.

The GPC – developed by WRI in collaboration with C40 and ICLEI – will help cities comprehensively account for all greenhouse gas emissions, including those that cross city boundaries, such as electricity from power plants outside the urban area or car commuting from the suburbs. The GPC will enable city leaders to understand the main sources of their emissions, identify reduction opportunities, compare their successes and failures to other cities, and show that they are committed to transparent, accountable reporting.

In addition to the Compact itself, parallel movements to unlock finance and accelerate the flow of knowledge will help make these commitments achievable.

3.  Financing low-carbon, resilient cities

Alongside the Compact, this week’s Summit also saw the launch of a parallel effort to link city climate action to finance.

According to the World Economic Forum and World Bank, more than US$1 trillion is needed annually to finance low-carbon and resilient infrastructure in the Global South. To this end, the Cities Climate Finance Leadership Alliance aims to help 300 cities over five years to access the capital necessary to close this gap. The Alliance will provide training and technical support to improve financial management, enhance creditworthiness, and expand access to private capital. While not yet formally linked, the Compact opens the door to climate financing for low-carbon infrastructure by introducing a credible, reliable measure of emission reductions.

4.  Accelerating the global flow of ideas for innovative cities

Innovating and adapting the best ideas from other cities are two key parts of any city’s successful climate program. There is no better example than the 180 cities that have replicated BRT since it was invented in Curitiba, Brazil as an affordable, low-carbon mass transit option. To facilitate this type of knowledge exchange, city networks like C40 and “think and do tanks” like the WRI Ross Center for Sustainable Cities will link mayors to learning and technology transfer.

The time is now for city climate action

All of this comes at a pivotal time, when momentum for climate action is building. The Compact of Mayors was signed on the heels of the momentous People’s Climate March and the signing of a parallel Compact of States and Regions.

The road does not end here. A more explicit link to finance and knowledge sharing would make these commitments even more achievable. In addition, the GPC will be finalized this December at the UN’s COP 20 climate negotiations in Lima. National governments must empower cities with sufficient autonomy and finance and supportive regulations.  And most importantly, cities will need to measure, take action, and report for these commitments to be real.

The WRI Ross Center for Sustainable Cities will help make this progress happen – by finalizing the GPC; supporting the Finance Leadership Alliance; and continuing to help cities set targets, measure, and learn and adapt best practice.

Momentum is growing for climate action, and cities are at the center of that movement. So far, the future in city leaders’ hands is looking brighter.