Canada has joined a global coalition of countries pushing for an international treaty to tackle the world's plastic pollution crisis. Led by Norway and Rwanda, the group of 20 countries will advocate for rules to reduce plastic production and eliminate plastic pollution by 2040.

The decision comes as the federal government faces two lawsuits from a group of major plastic manufacturers over domestic rules to reduce plastic pollution, including a recent ban on six single-use plastic items.

World leaders in February agreed to start working on a global treaty to reduce plastic pollution, with official negotiations starting this fall. They hope to reach an agreement in two years. Environmentalists warn any agreement must include strong measures — including limits on plastic manufacturing — to be effective.

The new "high-ambition" coalition has pledged to "restrain" plastic production, boost efforts to make reusable items more mainstream and improve recycling, and develop more sustainable methods to dispose of plastic waste. It has also said it will push to "eliminate problematic plastics" with bans and restrictions on some items.

The cost of a weak treaty is high. According to the Organization for Economic Co-operation and Development, the volume of plastic in the world's waterways will more than quadruple to reach 493 million tonnes by 2060 if nothing is done to deal with the problem. Plastic consumption is also expected to skyrocket during the same period, driving pollution and sustaining demand for harmful oil and gas extraction.

"Overall, it's really welcome as an initiative and it's great to see a group forming to build support around some of the critical elements of the treaty and setting sights on an ambitious goal," said Christina Dixon, ocean campaign leader for the Environmental Investigation Agency. The group is among dozens of environmental and civil society organizations and researchers who have urged countries to implement strong limits on production.

Environment and Climate Change Canada said in a statement that Canada is "committed" to dealing with plastic pollution. The country is pushing for the future agreement to be "ambitious, legally binding" and to apply to all plastics from the moment they are produced until their disposal. The U.S. — a major plastic producer and Canada's largest plastic trading partner — has not joined the coalition.

"It's really important for countries to, as we go into these negotiations, be upfront about the ambitions they have for the treaty," said Karen Wirsig, plastics program manager for Environmental Defence.

The world's $558-billion plastic industry is dominated by a handful of powerful petrochemical companies, whom Wirsig said will fight back against regulations on plastics with lawsuits, lobbying and PR campaigns. A Canada's National Observer series has followed the tactics — most recently, two lawsuits — used by Canada's plastic industry to push back against efforts to tackle the plastic pollution problem.

"(These) companies make their bread and butter polluting the world with plastic, and they will be pushing back hard against the treaty," Wirsig said. "We need a real united front against these industry bully tactics."