Tackling urban heat by building greener cities

The number of cities exposed to extreme temperatures will nearly triple over the next decades. By 2050, more than 970 cities will experience average summertime temperature highs of 35˚C (95°F). Cities are specifically vulnerable to rising temperatures due to the Urban Heat Island (UHI) effect, which shows that urban areas are 3 to 8 degrees Celsius warmer than rural areas. Urban surfaces absorb more sunlight and heat than natural landscapes, and urban areas lack vegetation to cool through evaporation. Extreme temperatures compounded by the UHI effect trigger an increase in building energy use due to increased cooling needs, which in turn increases air pollution causing significant health impacts for urban residents, and reduces quality of life. Cities can reduce urban temperatures by using cooling surfaces, alternative materials and design, and green infrastructure. 

Many cities are taking several measures to address the urban heat island effect in their local jurisdictions. These early successes represent a significant opportunity for knowledge sharing and collaboration among C40 cities. Cities participating in the Cool Cities Network, led by the City of Athens, have prioritised focus areas around which they are actively sharing policies and strategies with one another.

Focus areas:
  • Heat & vulnerability mapping
    Measuring urban heat & assessing vulnerabilities to target future action
  • Heat wave emergency management
    Developing heat wave emergency response systems (cooling centres, heatwave public communication)
  • Integrating heat into long-term planning
    Developing urban heat strategies and integrating heat action into long-term planning (setting heat reduction targets & measuring progress)
  • Making the case for heat action
    Highlighting co-benefits of heat action to gain political support
  • Heat mitigation solutions
    Evaluating green and cool solutions and methods for implementation, such as cool roofs & pavements, green building envelopes, street trees, urban forests and alternative cooling techniques

Partners: Global Cool Cities Alliance

Cities participating in the network: Accra, Athens, Austin, Barcelona, Berlin, Boston, Buenos Aires, Cape Town, Dar es Salaam, Durban, Freetown, Guadalajara, Lisbon, London, Los Angeles, Madrid, Medellin, Melbourne, Mexico City, Miami, Milan, Montréal, New York, Paris, Philadelphia, Phoenix, Quito, Rio de Janeiro, Rome, Rotterdam, Salvador, Sao Paulo, Sydney, Tel Aviv – Yafo, Tokyo, Toronto, Tshwane, and Washington DC.