Buildings are among a city’s worst contributors to emissions, accounting for 50 per cent of energy use in newer cities and more than 70 per cent in older urban areas. In New York, for example, electricity, natural gas, fuel oil and steam consumed by buildings make up 79 per cent of the city’s total count of heat-trapping gases, a recent study found.

Clinton announced the partnership on Wednesday, joined by mayors of several of the cities, as part of an international climate summit he is hosting this week in New York City with Mayor Michael Bloomberg. It was the second meeting of the C40 Large Cities Climate Summit, which was created so mayors and local governments could share strategies for reversing the trends of climate change.