The Eiffel Tower is illuminated by green lights in order to celebrate the ratification of the Paris Agreement. Geoffroy Van Der Hasselt/Anadolu Agency/Getty Images

After plenty of of delayed meetings and cloak-and-dagger mystery, President Trump is apparently poised to take the US out of the Paris agreement.

An official decision is expected any day now, but it appears his advisors that severely dislike the pact – including Breitbart alum Steve Bannon and Environmental Protection Agency (EPA) chief Scott Pruitt – are winning the argument.

Although plenty of people have heard of the Paris agreement, few know exactly what it does, and why it would be, in the view of IFLScience, a terrible mistake for the US to withdraw from it. Here is your primer, dear readers.

What The Paris Agreement Does

The Paris agreement was signed by almost every single country in the world back in December 2015, with China and the US – the world’s first and second-most prolific greenhouse gas (GHG) emitters by far, respectively – being the key brokers of the deal.

It was rightly seen at the time as a groundbreaking call to arms: a legitimate, workable attempt to stop the world warming any more than 2°C (3.6°F), and preferably no more than 1.5°C (2.7°F), by the end of the century, as requested by a swath of developing and vulnerable nations.

Each of the nations that have signed the Paris Agreement has had to submit their plans to draw down their GHGs over the next few decades. Importantly, as noted in the pact, each nation’s framework for cutting GHGs has to get stronger and more ambitious over time. They are legally mandated to keep informing the UN as to how they are progressing in this manner, but there isn’t a punitive measure in place for those that fall behind.

Wind power is rising fast. Mimadeo/Shutterstock

Poorer nations already plagued by climate nightmares will have a harder time cutting their GHG levels, which is why wealthier nations have agreed to contribute billions in aid payments to ease their transition from fossil fuels to renewables.

For its part, the Obama administration pledged $3 billion in such aid. It donated $1 billion before Obama left office, and the $2 billion is not expected to be handed over by his successor.

That, in a nutshell, is what Paris is about – so what would or could happen if America withdrew from it, and the agreement ultimately fails?