TOKYO (BLOOMBERG) - As Japanese Prime Minister Shinzo Abe highlights the global scourge of seaborne plastic waste during the Group of 20 summit in Osaka this week, evidence of his own country's reluctance to address the problem will be sitting just outside the window.
Osaka Bay contains as many as three million plastic shopping bags, according to a study released earlier this month by a local university researcher.
The carpet of mud-covered plastic lining the seafloor illustrates the ecological cost of Japan's obsession with packaging, helping to make the country the world's second-largest per capita consumer of disposable plastics after the United States, according to the United Nations.
While Mr Abe has vowed to advance efforts to tackle ocean-plastics pollution at the G-20, the country has fallen behind other developed nations on reducing usage of the material.
Some of that stems from Japan's own reliance on plastic to satisfy cultural expectations of cleanliness and attention to detail.
A dredging study of Osaka Bay led by Associate Professor of Public Economics Sadao Harada of Osaka University of Commerce concluded that the 1,450 sq km water body contained an estimated three million plastic shopping bags - along with six million other pieces of plastic. Associate Prof Harada said most of the bags probably weren't deliberately discarded.
Osaka Bay, which provides several southern Japanese ports access to the Western Pacific, sits just outside the Osaka International Convention Centre, where the principal G-20 events will be held.
Mr Abe told a Cabinet meeting last month that he would ensure the problem of ocean plastics was a key part of the summit agenda.
"Global efforts are essential for a solution," Mr Abe said in Tokyo. "A shared global vision requires that each country implement concrete measures to tackle the problem."
Japanese consumers are believed to use about 30 billion plastic shopping bags a year, Associate Prof Harada said.
Japan is planning to introduce compulsory charges for plastic bags next year, although the details have yet to be decided.
By contrast, the European Parliament voted in March to ban single-use plastics, Canada plans to do likewise, and less wealthy nations like Rwanda have prohibited plastic shopping bags.
A poll conducted by the Mainichi newspaper on June 15-16 found 70 per cent of respondents were in favour of charging for plastic shopping bags, and 73 per cent said they wouldn't use plastic bags if they had to pay for them.
The UN has warned that plastic pollution causes at least US$13 billion (S$17.6 billion) of damage to the marine ecosystem annually.
Plastics can block waterways and exacerbate natural disasters, as well as damage natural habitats and make their way into the food chain.
The problem in Osaka Bay comes despite the fact that Japan is not thought to be among the worst offenders in terms of ocean plastic pollution.
Some governments and companies are highlighting moves toward more sustainable practices ahead of the G-20, with Seven & i Holdings Co saying that the more than two billion rice balls sold each year at its 7-Eleven convenience stores will now have plant-based packaging.
One town in nearby Tokushima prefecture has initiated a trial project to demonstrate that a Japanese community can reduce its waste to zero by next year.
"As consumers, we need to stick to the producers to change and also to pressure the government to support the producers to change," Ms Akira Sakano, chairwoman of Zero Waste Academy Japan's board of directors, said, adding that plastic bags weren't necessary.
"You can replace them with your own bags. If we are only discussing plastic bags, then there are so many other easy alternatives. And there is no reason not to ban them."