1992 Groundbreaking Rio Earth Summit
The summit results in some of the first international agreements on climate change, which become the foundation for future accords. Among them is the UN Framework Convention on Climate Change (UNFCCC) [PDF], which aims to prevent “dangerous” human interference in the climate system, acknowledges that human activities contribute to climate change, and recognizes climate change as an issue of global concern.
The UNFCCC, which went into force in 1994, does not legally bind signatories to reduce greenhouse gas emissions and gives no targets or timetables for doing so. But it requires frequent meetings between the ratifying countries, known as the Conference of the Parties, or COP.
As of 2019, it has been ratified by 197 countries, including the United States.
Source: Timeline: UN Climate Talks