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.

Before signing the order, Trump declared his reasons to an arena of cheering supporters, describing the global agreement as an 'unfair, one-sided Paris climate accord rip-off'

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.