Part of the reason for the decrease is the increase in renewable energy. The vast majority of renewable energy technologies are or were supported by government subsidies to jump-start the industry. Most of those are tapering over the next decade or so, but the government (federal, state, and local) was instrumental in getting the renewable energy industry started in the USA.

Taking one example of a specific accord and saying, "because we didn't need this government [thing], we don't need any government [thing]," is a faulty generalization. Truth is, we need the government and the markets and several other things that work together in an extremely complex way (that no single human can understand fully) to solve global climate change.