Rather than trying to save the oceans with such bans in rich countries, we need to focus on tackling the inferior waste management and poor environmental policies in developing regions.

Research from 2015 shows that less than 5 per cent of land-based plastic waste going into the ocean comes from OECD countries, with half coming from just four countries: China, Indonesia, Philippines and Vietnam. While China already in 2008 banned thin plastic bags and put a tax on thicker ones, it is estimated to contribute more than 27 per cent of all marine plastic pollution originating from land.

Moreover, banning plastic bags can have unexpected, inconvenient results. A new study shows California’s ban eliminates 40 million pounds of plastic annually. However, many banned bags would have been reused for trash, so consumption of trash bags went up by 12 million pounds, reducing the benefit. It also increased consumption of paper bags by twice the saved amount of plastic – 83 million pounds. This will lead to much larger emissions of CO₂.

When Kenya banned plastic bags, people predictably shifted to thicker bags made of synthetic fabric – which now may be banned. But Kenya had to relent and exempt plastics used to wrap fresh foods such as meat and other products.