If the situation escalates, the car companies or their direct suppliers may have to support smaller companies in the supply chain to protect their production plans.
Rival retailers such as Zara, Boohoo, Uniqlo and Next already charge for online returns. Analysts said other retailers were likely to follow H&M in charging for returns.
The daily limits have contributed to a backlog of 116 vessels waiting to cross, well above normal, but below the more than 200 ships that were stuck last month.
Profitability is taking a back seat to technology transformation, supply chain and operational challenges, according to a survey released September 18 by Jefferson Wells.
It could take a while to really cut emissions, because it would still be cheaper to pay for the emissions rather than use more expensive marine biofuels.