C40 Partners with Global Cool Cities Alliance to Tackle ‘Heat Island Effect’ in Cities

The urban ‘heat island effect’ is a term perhaps little known outside policy circles, but the phenomenon will be familiar to city dwellers the world over. Cities are up to eight degrees Celsius warmer than rural areas; this is because built environments absorb more of the sun’s heat, while also emitting heat from air conditioning and other building energy use. Warmer temperatures brought by climate change exacerbate the issue – and its knock-on effects on local air quality – posing a serious threat to the health and well-being of urban populations.

To tackle this issue, C40 has partnered with the Global Cool Cities Alliance to advance policies and actions in cities that increase the solar reflectance of building roofs and pavements. These measures tend to be low-cost, for example coating a roof surface white, but are highly effective, making them a viable solution for emerging cities in developing regions. By cooling cities, we not only reduce climate risks, but also cut greenhouse gas emissions through lower energy demand.

Photo Credits: Global Cool Cities Alliance.

“C40 is excited about collaborating with the Global Cool Cities Alliance, a leader in its field, which brings a wealth of knowledge and experience, as well as a comprehensive tool-kit for tackling the heat island effect in global cities. Through our partnership, we will go far in helping C40 cities develop solution-oriented approaches to lowering urban temperatures”, said C40’s JT McLain who is leading the creation of a global network of C40 cities focused on this issue.

There is a great opportunity for knowledge sharing and collaboration among C40 cities – learning from the experiences of early-adopting cities and accelerating the worldwide dissemination of successful strategies to mitigate urban heat islands.

New York City has taken a comprehensive approach that includes volunteer efforts, a law requiring that new roofs be cool, and a program to monitor progress and results. To date, the city has coated more than 3.2M square feet of rooftops across 388 buildings and engaged nearly 4,000 volunteers. It estimates that every 1,000 square feet of coated rooftop reduces CO2 emissions by 1 ton; and these efforts could save residents $100 million per year in energy costs alone by reducing urban temperatures by as much as 1 degree. New Delhi recently announced that most new flat roofs would have to be reflective in order to qualify for a building permit. Other cities such as Houston, London, and Tokyo have also undertaken measures to reduce the impact of urban heat islands.

“These local efforts have a global impact,” said Kurt Shickman, Executive Director of the Global Cool Cities Alliance. The warming effect of 500 coal power plants-worth of carbon dioxide emissions can be cancelled by transitioning to white roofs where it makes economic sense to do so. Reducing urban heat with cool surfaces helps mitigate the effects of climate change while making our cities more resilient, enjoyable, and healthy. We are very excited to support C40 cities’ efforts to deploy this strategy.”

The two organizations have already begun to work together. This week, they are co-presenting at a the Cool Buildings and Community Conference in New Delhi, India, hosted by the US Department of Energy and the Indian Bureau of Energy Efficiency, and drawing cities from the region to share best practices and experience. Going forward, C40 and the Global Cool Cities Alliance will provide interested C40 cities the tools and resources to assess the issue at the local level and design successful policies and programs.

Changing Planet


Meet the Author
The C40 Cities Climate Leadership Group (C40) is a network of large and engaged cities from around the world committed to implementing meaningful and sustainable climate-related actions locally that will help address climate change globally. Recognizing that cities consume over two-thirds of the world’s energy and account for more than 70% of global CO2 emissions, our organization’s global field staff works with city governments, supported by our technical experts across a range of program areas to reduce carbon emissions and increase energy efficiency in large cities across the world. The current chair of the C40 is Rio de Janeiro Mayor Eduardo Paes, and 108th Mayor of New York City Michael R. Bloomberg is President of the Board. The Steering Committee includes: Berlin, Buenos Aires, Copenhagen, Hong Kong, Houston, Jakarta, Johannesburg, London, Los Angeles, Rio de Janeiro, Seoul and Tokyo.