SINGAPORE (Reuters) – Plastic use in G20 countries is on course to nearly double by the middle of the century unless a comprehensive and legally binding global treaty to curb consumption is drawn up, according to research published on Monday.

Existing programs to boost recycling or cut single-use plastic consumption only “scratched the surface” and a more comprehensive global plan is required, according to Back to Blue, a research group run by the Economist Impact think-tank and the Nippon Foundation, a private philanthropic organization.

The United Nations kicked off negotiations on an agreement to tackle plastic pollution in Uruguay in November, with the aim of drawing up a legally binding treaty by the end of next year. As many as 175 countries have signed up to the talks.

However, if negotiations fail, annual plastic production in G20 countries could rise to 451 million tonnes by 2050 according to current rates of growth, Back to Blue said—up nearly three-quarters from 2019.

“There should be no illusions that the treaty negotiations will be anything but difficult and treacherous,” the research group said. “The chances of failure—not just that no treaty emerges but one that is too weak to reverse the plastic tide—are considerable.”

It called for a more aggressive ban on single-use plastic together with higher production taxes and mandatory schemes to make firms responsible for the entire lifespan of their products, including recycling and disposal.

The combined measures could limit annual consumption to 325 million tonnes by 2050, Back to Blue said, but that would still be up by a quarter compared to 2019, and the equivalent of 238 million filled rubbish trucks.

Among the G20 countries that have yet to introduce national bans on single-use plastic products are Brazil, the United States, Indonesia and Turkey, the report said.