When it comes to confronting climate change, the world’s cities are proving that there’s strength in unity. The historic climate agreement reached in Paris in December, which was approved by nearly all of the world’s nations, was made possible in part by the progress that cities have made by working together.

Today, the two biggest coalitions of cities in the world – the EU-based Covenant of Mayors and the UN-backed Compact of Mayors – are forming an alliance to link more than 600 million city dwellers in the fight against climate change.

Cities are key to solving the climate change challenge. They account for most of the world’s carbon emissions, and mayors often have control over the largest sources. Just as importantly, mayors have strong incentives to attack those sources because steps that reduce carbon also improve public health and strengthen local economies.

Clean air is increasingly a factor business leaders weigh when deciding where to invest. Cities can also act quickly to confront climate change, without the political and bureaucratic hurdles that often hold back national governments.

By sharing smart strategies, cities of all sizes have led the way in addressing climate change, and as a result, the UN has given cities an official role in international climate diplomacy for the first time. In the European Union as well, cities are increasingly seen as crucial allies in the transition to a low-carbon economy.

Our new alliance, now called the Global Covenant of Mayors for Climate & Energy, will provide unprecedented support for city efforts and accelerate progress against climate change in a number of ways, including:

Coordinating city efforts

The Global Covenant will link more than 7,100 cities, representing more than 600 million people, in one unified effort to address the causes and impacts of climate change. Cities will speak with one clear, coordinated voice, sending a strong signal to national governments that they are committed to this fight and to assisting one another. It will also help us expand and recruit new members, with a focus on parts of the world where cities are growing most rapidly, including Africa, Latin America and south-east Asia.

Improving measurement

The Global Covenant will enable cities to collect and report climate data in a standardised, comparable way, allowing them to track their progress and hold one another accountable. It will also allow the UN to identify the contributions that cities are making toward the goals set in Paris, which will underscore how important cities are to meeting them.

Helping cities invest

Modernising infrastructure networks can be costly, and city governments are increasingly turning to private investors to help finance such projects. But, especially in developing nations, many cities lack credit ratings and cannot access international capital markets. To help remedy this, the Global Covenant will feature an advisory group of financial institutions that will offer guidance to cities. The goal is to direct more capital to low-carbon urban infrastructure that will generate economic returns.

Advocating for greater responsibility

One of the best steps national governments can take to fight climate change is to empower their cities with the tools and autonomy they need to act. Some cities aren’t able to borrow money on their own. Others don’t have the authority to write their own building codes or energy efficiency regulations. Others lack control over mass transit. The more cities are given control over their own operations, the more progress nations will be able to make reducing emissions – which will incentivise more national governments to empower their cities.

In the fight against climate change, cities are where the action is. The new Global Covenant of Mayors is a historic milestone for the global community of cities, and it will go a long way toward ensuring that the nations of the world are able to meet – and exceed – the goals they set in Paris.

Michael Bloomberg andMaroš Šefčovič

This article first appeared on the Guardian

edie is part of the Guardian Environment Network

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