Based on computer models estimating population, plastic waste and production in 173 countries, a recent study in the journal Science found reducing plastic emissions by 2030 will take a massive global effort.

Co-author Erin Murphy of Arizona State University says, even under optimistic projections, it would take one-seventh of the world's population spending a day cleaning up plastic waste, and Americans reducing their plastics use by half.

That's significant given projections that everyday plastic use will continue to increase.

Yet Murphy stressed the task is not hopeless.

"But we need to understand the problem and make sure that the solutions we're implementing address the root of that problem," Murphy said. 

The research was spurred in part by a 2015 study by University of Georgia's Jenna Jambeck and her colleagues in the National Center for Ecological Analysis and Synthesis.

Their work estimated 8 million metric tons of plastics entered the ocean in 2010. Jambeck equated that to lining every foot of coastline in the 192 countries in her study with five plastic-filled grocery bags.

Jambeck's paper helped spark a global response among governments, nongovernmental organizations and environmentalists.

"However, we don't have a good idea of how effective that international action would really be at reducing the amount of plastics entering the ocean and other aquatic environments like major lakes and rivers," said Murphy.

So Murphy's group simulated three futures: a business-as-usual scenario, an ambitious scenario that assumed counties would honor existing global commitments and a target scenario that would reduce annual plastic emissions below Jambeck's 2010 level.

The group found that by 2030 plastic pollution could reach almost five times the levels estimated for 2016 (19-23 million metric tons) if business-as-usual condition continue.

They also found that, despite motivated mitigation attempts, the ambitious plan could produce plastics equaling or doubling 2016 levels.

To reduce plastic emissions below the 2010 number of 8 million metric tons annually would require much more, according to the paper. Depending on income level, countries would need to reduce plastic waste 25-40%, boost managed waste levels to 60-99% and recover 40% of annual global emissions by 2030.

Those figures could underestimate the problem's full scope.

Researchers struggle to estimate plastic emissions from lower-income countries, some of which receive plastic in trade from higher-income countries but may lack infrastructure needed to deal with it. Reporting standards vary from country to country. Moreover, the study did not include fishing gear or certain microplastics.

Meanwhile, the current boom in shale gas gives petrochemical companies ample reason to push plastics harder than ever.

"This is a really important revenue source for oil and gas companies. And there hasn't been a lot of focus on reduction of that production," said Murphy.