The Paris agreement is complex and works in a slow bureaucratic manner. It’s a mostly voluntary climate pact originally written in ways that would both try to reduce a worsening climate change problem and withstand the changing political winds in the United States.

Trump signed an executive order that begins the process of withdrawing from the Paris Climate Agreement, which he also did during his first term.

Trump's executive order called for an immediate withdrawal from the Paris Agreement. The Agreement requires one year notice, but there's room for interpretation.