Liners, already feeling the heat from their major clients to slash their carbon footprint, will likely get more urgent calls following the release today of a report highlighting which retail chains are polluting the most in America thanks to their shipping choices.

A study released from NGOs Pacific Environment and Stand.earth is the first report to quantify the environmental and public health impacts from some of the biggest American retailers’ reliance on overseas manufacturing and fossil-fuelled, transoceanic shipping.

By cross referencing a comprehensive set of cargo manifests with a dataset on individual ship emissions, researchers were able to estimate the pollution associated with each unit of cargo on shipping routes heading to the US and, for the first time, assign those emissions to retail companies. Walmart topped the list, responsible for 3.7m tons of climate pollution from its shipping practices in 2019, more than an entire coal-fired power plant emits in a year. Target, IKEA, Amazon, and eleven other companies were also investigated.

“Major retail companies are directly responsible for the dirty air that sickens our youth with asthma, leads to thousands of premature deaths a year in US port communities, and adds to the climate emergency,” said Madeline Rose, climate campaign director for Pacific Environment.

A poll conducted last October for Pacific Environment by Yale University, George Mason University and Climate Nexus found that 74% of American voters would be more likely to shop at companies that use cleaner ways to ship their goods. The poll also found that 70% of American voters would continue to shop at these brands even if using clean ships raised the price of their goods.

Maersk, the world’s largest containerline, revealed in February that around half of its largest customers have set – or are in the process of setting – ambitious science-based or zero carbon targets for their supply chains, and the figure is on the rise.