Launched in 2011 as the Earth Hour City Challenge (EHCC), OPCC is a biennial, global challenge for cities to present ambitious, holistic, inspiring, and credible plans for low-carbon development, including a dramatic increase in the use of sustainable and efficient renewable energy solutions, as well as sustainable urban transport systems today and beyond. Including the Philippines, OPCC runs in 20 countries, covering 320 cities. 

Since its inception, WWF has partnered with ICLEI-Local Governments for Sustainability, mainly through the carbon Climate Registry (cCR). The cCR is a global reporting platform for local and subnational climate action where participating cities can report relevant data, plans, and actions.