The impact of the decision by 175 countries at UNEA's formal session in Kenya may take a few years to be felt. Governments now start the hard work of writing the treaty, a process they say will be open to input from all stakeholders. They hope to finish in two years.
In the broad framework they adopted, the countries at UNEA said they want the treaty to take a life cycle look at plastics, including production, design and disposal.
Over the long term, it's going to have a major impact on how plastics are used and regulated.
For starters, the treaty will add momentum to the rethink going on around single-use packaging, giving another boost to different business models.
Packaging is a complex question. It has vital functions, keeping food from spoiling and making sure what we buy gets to us without breaking.
But the treaty's going to increase pressure to have packaging that's reusable, compostable, designed with better recycling in mind or that has recycled content. Seems like that's something our technology and science ought to be able to figure out.
Plastics are valuable, but the low recycling rates and low recycled content use compared to other common materials is a problem that needs to be fixed.
Over the last two decades, we've seen very little improvement in plastics recycling in the United States. That's depressing. It's a failure of both government and industry.
Beyond the packaging rethink, it's clear from watching the UNEA proceedings online and talking to those attending, that the treaty's going to lead to other things.
Maybe the biggest will be to elevate conversations around fossil fuel-based virgin resin production.
Some environmental groups want the treaty to cap virgin resin production, a point that plastics industry groups sending their own delegates to UNEA pushed back on strongly.
A cap would be a major step, and not something the treaty would likely do directly.
Like with the 2015 Paris Climate Agreement, any deal very much depends on how nations choose to implement it. National governments retain their powers under any treaty, and it's hard to see the U.S. putting a hard cap on virgin production.
But the idea of some sort of limits on resin manufacturing were on the table at UNEA. Senior UNEA leaders at the closing press conference mentioned it, along with resin taxes and extended producer responsibility systems.
The idea of got a boost from businesses too.
A Unilever plc executive, speaking on a panel at UNEA, blamed the "artificially low price" of virgin resin for hurting its plans for using more recycled plastic in its packaging.
The Unilever rep told UNEA that "unchecked" growth of virgin plastic production will make it difficult for his company to deliver on the treaty's goals. Unilever is part of a coalition of global companies that want to see the see treaty reduce virgin plastic production and use.
Whatever emerges in the final treaty, it seems likely it will cover a lot of ground. Nations will be debating recycling standards, product design and financing of better waste management, all of which are crucial to getting more circular use of plastics.
I think UNEA is also going to elevate the debate about a newer topic: plastic additives and building blocks, the degree (or not) of their toxicity, and the impact that will have if we're going to be using a lot more recycled materials in our products.