President Donald Trump announced his decision to withdraw the United States the the Paris climate agreement. The deal, joined by all but two countries (Syrian and Nicaragua), is a broad framework designed to nudge nations to prevent catastrophic climate change.

The deal was the result of tense negotiations in December 2015 and what it does is pretty simple. Let's have a look:

The goal of the Paris agreement is the global target of keeping global average temperatures from rising by the end of the century. Beyond 2 degrees, we risk dramatically higher seas, changes in weather patterns, food and water crises, and an overall more hostile world.

But the agreement doesn’t detail exactly how these countries should do so. Instead it provides a framework for getting momentum going on greenhouse gas reduction, with some oversight and accountability. Under Trump’s current policies, that goal is impossible.

A lot of countries have agreed to it. But there’s also no defined punishment for breaking it.

So as part of the Paris agreement, richer countries, like the US, are supposed to send $100 billion a year in aid by 2020 to the poorer countries. And that amount is set to increase over time. Again, like the other provisions of the agreement, this isn’t an absolute mandate.

The Paris agreement is largely symbolic, and it will live on even if Trump withdraws the US. But it will for sure weaken the global coalition around climate change.