There are over 600 US cities that are members of ICLEI, the International Council for Local Environmental Initiatives, now known as Local Governments for Sustainability. ICLEI institutes the UN Convention on Biological Diversity treaty that was withdrawn from a vote on the Senate floor in 1994, so the treaty, designed for UN control, is being implemented in cities.
Here's the description of the program from ICLEI's own website:
Our programs, and projects promote participatory, long-term, strategic planning process that address local sustainability while protecting global common goods. This approach links local action to internationally agreed-upon goals and targets such as:
the Rio Conventions:
The UN Framework Convention on Climate Change,