To combat climate change, a global Compact of Mayors from cities across the world was launched today at the UN Secretary-General’s Climate Summit today at UN Headquarters.

Cities are currently responsible for about 70 percent of global greenhouse gas emissions and can play a critical role in reducing these emissions and strengthening resilience.

UN Secretary-General Ban Ki-moon and former New York Mayor Michael Bloomberg, now UN Special Envoy for Cities and Climate Change, announced that the Compact of Mayors’ key partners are the world’s three preeminent global city networks: C40 Cities Climate Leadership Group, ICLEI – Local Governments for Sustainability, and the United Cities and Local Governments, with support from the UN’s lead agency on urban issues, UN-Habitat.

The Compact will enable cities to publicly commit to deep greenhouse gas emissions reductions; make existing targets and plans public; and report on their progress annually, using a newly-standardized measurement system that is compatible with international practices.

ICLEI represents more than 1,000 metropolises, cities, urban regions and towns that are home to more than 660 million people in 88 countries.

Many cities are now setting bolder targets of slashing 40, 70, or even 100 percent of their greenhouse gas emissions by 2050 and improving climate change resilience.

Collectively, they will be crucial in delivering substantial cuts in global greenhouse gas emissions and ensuring the safety of their citizens, infrastructure and environment.

New research by the parties to the Compact shows that existing city commitments alone could reduce annual emissions by 454 megatons of CO2 equivalent in 2020 and a total of 13 gigatons CO2e by 2050.

The Compact will help regions, nations and financial institutions better understand the potential impact of local climate actions, and where they can offer support, such as funding much-needed mass transit systems or energy-efficiency measures.

Under the Compact, local emissions data will be collected through existing city platforms, and will be made publically available through ICLEI’s platform, the Carbon Climate Registry.

Together, city networks will engage thousands of cities to join the Compact of Mayors and to register their greenhouse gas inventories, climate adaptation and mitigation plans and targets.