The oceans are inundated with plastics. Ideas about how to address the problem abound, but we have no time to waste.

The final session of the International Symposium on Plastics in the Arctic and Sub-Arctic Region ended on Tuesday with a call from Iceland’s environment minister for the countries of the United Nations to adopt a global treaty to prevent plastic pollution.

“There is only so much that Iceland or Arctic states or the Arctic Council can do. Marine plastic pollution is a truly global challenge, we need a global instrument to tackle it,” Guðmundur Ingi Guðbrandsson, the environment minister, said in an address during the symposium’s closing session.

At the most recent United Nations Environmental Assembly last month, many countries called for a new global agreement to address plastic pollution. Guðbrandsson hopes they will take decisive steps toward such an agreement during the assembly’s next session, in February 2022.

Much about plastic in the oceans, and especially plastic in the Arctic Ocean, remains unknown, and more research is needed. But scientists have learned more than enough to know that immediate action is required.

What they have discovered is in many ways appalling, including how microplastics make their way up the food chain to species humans consume, how discarded fishing nets slowly strangle seals and other animals, and how some birds now lay eggs that contain traces of chemicals found in plastics. The worst, though, may be yet to come: If no serious action is taken to change course, by 2040 the amount of plastic that enters the oceans could nearly triple, to 29 million metric tons a year, or the equivalent of dumping 50 kilograms of plastic on every meter of coastline in the world.

Acknowledging the contributions of the nearly 100 scientists, diplomats, and NGO leaders who spoke or made presentations during the five-day online symposium, Guðbrandsson urged decision makers to heed their message that plastics are choking the ocean.

“We need to act now, or otherwise face a future of plastics entering the marine ecosystem in a way that is difficult or even impossible to reverse,” Guðbrandsson said. “We have designed many of the tools we need. Let us act on the science. Let us act on a global treaty on plastic pollution.”

Earlier in the day on Tuesday, and throughout much of the symposium, experts expressed support for a global agreement or treaty to address growing amounts of plastic in the oceans. But some, including David Balton, a senior fellow with the Polar Institute at the Wilson Center, cautioned against letting progress on a treaty distract from other efforts to prevent plastic pollution.

A treaty, he believes, would have its benefits, but it would take many years to come into force. “We can’t assume that everything else stops while we are waiting for this as the panacea,” he said. “We need to take other actions now.”

Balton suggested moving forward to develop plastics made from organic material, such as fungi. He also called for holding an annual coastal clean-up day in all eight Arctic countries, an idea he had argued for while serving as chair of the Arctic Council’s Senior Arctic Officials. An Arctic clean-up, he said, would have the immediate effect of removing pollution, while at the same time drawing local and international attention to the scope of the problem.

Critics of such clean-up events often describe them as futile. Even proponents admit they are small-scale, short-term solutions. However, Julia Hager, a marine biologist, has found that they do have a long-term impact on those who take part in them.

As a guide on an expedition cruise ship that sails the waters near Svalbard, Hager organizes beach clean-ups that passengers can take part in. The activities are combined with educational sessions to inform people about where litter comes from and its impacts.

“Most travellers are shocked by the amount of plastic waste and want to know what they can do,” Hager said. “Many of them show their willingness to change their lifestyle and reduce plastic consumption.”

Activities aimed at cleaning up what is already in the ocean have their merits in other respects, too. Removing lost fishing gear is particularly important. Discarded nets make up 70 per cent of the plastics in the ocean by weight, according the Global Ghost Gear Initiative (GGGI). These nets continue to do what they were designed to do – trap fish – while also entangling birds and marine mammals. The GGGI has found that lost nets may reduce fish stocks by as much as 30 per cent. Getting old gear out of the water will also prevent it from washing up on beaches or breaking down into small pieces that are consumed by marine life.

But, with plastic production expected to almost quadruple by 2050, the solutions are more likely to be found on land, reckons Eva Bildberg of the Keep Sweden Tidy Foundation.

“We need to have commitments, and regional conventions are really important, but we have to start working with them and do what we said we would do,” she said. “I think we actually have many solutions for stopping the litter at the source, we just need to work with them.”