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.

President Donald Trump on his first day in office again withdrew the U.S. from a landmark global pact to fight climate change. So what is the Paris Agreement? And what happens to it now?

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

The 2015 Paris Agreement is a treaty signed by 196 countries that agrees to limit global warming to “well below 2 degrees Celsius” (3.6 degrees Fahrenheit), and, ideally, cap temperature increases at 1.

Billionaire Michael Bloomberg said his foundation will fund the UN climate change body after President Donald Trump withdrew the US from the Paris Agreement.