During the recently concluded climate change talks, Conference of the Parties (COP) 21, there were few surprises, more than a few disappointments on the lack of resolve to do more, and several actual, realistic advances. One of the highlights was the growing commitment of cities to take concrete climate change actions above and beyond what their national governments were willing or able to do. A lot of the work is happening through collective action under the auspices of groups such as C40 and Local Governments for Sustainability (ICLEI).

C40 has recently published a report on its work called Climate Action in Megacities 3.0. C40 is a network of more than 80 of the world’s megacities, representing over 550 million people and one quarter of the global economy. Through C40, cities commit to addressing climate change by sharing knowledge and collaborative programs through direct technical assistance; facilitation of peer-to-peer exchange; and research, knowledge management and communications. The report was based on data provided by 66 of the member cities.

In 2005, then Mayor of London, Ken Livingstone, brought together leaders of 18 cities to develop cooperative ways to reduce greenhouse gases (GHGs). In 2006 the group, then numbering 40 participants, created a formal structure, C40, to carry out its work and since then it has formed cooperative arrangements with Local Governments for Sustainability (ICLEI), with the Clinton Initiative, and with the World Bank to advance its programs.

Why Cities?

The world’s cities occupy only 3 per cent of the Earth’s land, but currently about 50% of the world’s population live in urban areas/cities and that number is expected to grow to over 70% by 2050. Cities also account for about 60-80 per cent of energy consumption, and 75 per cent of carbon emissions. Cities are a major player on the global stage and a potential powerful force for change.

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Cities are also on the front line of climate change impacts as many of the largest cities were founded and have grown along coasts, rivers and lakes. With climate warming and sea level rise, and more extreme weather events, cities are already experiencing direct hits from climate change and have a vested interest in developing viable mitigation and adaptation infrastructures.

The urban density also allows for more productive and cost effective means of reducing greenhouse gases (GHGs), including use of mass transportation and energy efficiencies in building practices. Cities are also more manageable, politically, than nations. Leaders of cities are closer to the people they govern and usually more accessible than national figures.

Cities can serve as laboratories for experimenting with new ideas and new technology for climate action, with results shared through C40 and other organizations. If climate change actions can be implemented in cities they will have the potential to reach almost 70% of all peoples.

To avoid myopia, we need to point out that cities also become dense through building of slums, and the infrastructure of cities, especially in developing economies, can be challenging and even dangerously inadequate.

The C40 Report

The areas of focus for C40 include 16 thematic networks and six overarching initiatives. The six initiatives cover Adaptation & Water; Energy; Finance & Economic Development; Solid Waste Management; Sustainable Communities; and, Transportation. About 30% of all initiatives are the result of city-to-city collaboration, and since few countries have more than one C40 city, the collaborations tend to be international in scope. Implementing climate change actions through collaboration between cities is a hallmark of C40.

The report shows that the cities’ capital costs for climate actions range from less than $100,000 (36%), to those costing less than $1,000,000 to those costing over $10 million (26%). Most cost under $500,000 and of these projects 70% are funded through the city’s own budget. The more expensive actions are often started with pilot schemes funded by grants, subsidies, and contributions from private parties. Once the pilot scheme is proven, the cities are then more able to commit their own funds. Funding for longer-term projects is often through bonds, tolls, and developer contributions. Working on collaborative projects with other cities was also found to have opened up broader funding sources.

While many cities are able to find the funds to develop climate actions, the report acknowledges that cities in developing countries are more reliant on national and international institutions to develop low carbon initiatives.

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Since the last climate talks in Copenhagen, in 2009, C40 cities have taken 10,000 climate actions and committed to reducing their CO2 emissions by 3 GT CO2 by 2030, a savings equivalent to India’s annual carbon output. These actions are generating jobs in green industries. In 2015, ten cities alone employed more than 485,000 people in these green jobs. And cities are increasingly assigning staff to the specific task of working on adaptation strategies and initiatives, with about 43 of the over 80 members having done so.

The most often cited risks are: hotter summers; increased frequency of large storms; more frequent droughts; more frequent heat waves; more hot days; more intense rainfall; and, sea level rise. Of these, extreme temperature and flooding are reported as the most common.

Adaptation actions in general are an area of increasing significance for C40 cities over the past 4 years as 98% of the cites reporting stated that climate change presents a significant risk to their city. Given the location of many of the megacities along water bodies, it is not surprising to see that the most popular adaptation action was in flood mapping, including identifying status of flood-prone areas, detailed mapping of high-risk neighborhoods, and broader GIS modeling for the entire city. Besides flood mapping, other adaptation actions of note are storm water capture systems, green roof and walls, and tree planting and creating green spaces.

While the average term of office for mayors is four years, the report found that the average span of time for their strategic climate plans is fifteen years, and that over 80% of C40 cities have adopted such plans.

The C40 report also looks at the different governing structures, or typologies, that characterise how cities operate and it assesses how those structures might affect how the cities collaborate on climate action. Not surprising, cites with a collaborating governance typology engage in more collaboration with other cities on climate change. This aspect of the report seems somewhat artificial or forced, and is less helpful than others.

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In addition to the generalised findings applicable to mega-cities, as well as to other cities, the report provides case studies of various actions undertaken by cities across the globe. For instance, Paris is retrofitting its 600 primary schools to reduce energy consumption by 30%, with support from EU funding, at a cost in excess of $10 million. Ho Chi Minh City has developed flood control measures with assistance in funding and technical support from the Dutch government. Washington, D.C. requires large development projects to install green infrastructure practices (e.g., rain gardens, green roofs, permeable pavements), and part of that obligation can be met by buying credits from other property owners who voluntarily install green practices.


Several key findings emerge from the C40 report. There is a shift by the cities toward more focus on adaptation than mitigation and that makes sense. Cities are on the frontline of the growing impacts from climate change, as with sea level rise and extreme weather events, and more and more people are moving to cities. The priority is to protect people from current and growing impacts while regional, national, and international organizations address mitigation, as in the UN climate talks and in regional and national cap and trade programs.

In addition, the report demonstrates how effectively cities are becoming the laboratories for climate action, especially for adaptation. The cities increasingly are networking and collaborating on best practices and possibilities for climate action, and they do so with an ease that does not seem as available to regional and national and international entities. Finally, since much of the collaboration cuts across several countries, and C40 represents cities across the globe, the practices and projects that are developed originate in and are disseminated to cities across the globe.


C40, Climate Action in Megacities 3.0 (December 2015).

Rockefeller Foundation, 100 Resilient Cities

United Nations, 2015: Time for taking Global action – Goal 11: Make cities inclusive, safe, resilient and sustainable

John Vidal, “Feted by Hollywood, city mayors take starring role in Paris climate talks,” The Guardian (7 Dec 2015).






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