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Minneapolis, Minnesota, became the third U.S. city to endorse a carbon neutrality goal for shipping this month, joining the California cities of Los Angeles and Long Beach in unanimously passing a so-called “Ship It Zero” resolution.

Minneapolis’ resolution takes aim at corporate maritime importers like Walmart, Amazon, and Ikea. It asks them to “abandon fossil-fueled ships” — most of which are contracted out by separate shipping companies — and adopt emissions-saving practices like wind-assisted propulsion and lower-speed travel. It also asks the big brands to commit to docking only 100 percent zero-emissions ships by 2030 and to disclose all maritime greenhouse gas emissions in public, annual reports.

“I join the call to top maritime polluters, especially those with large footprints in Minneapolis, to commit to immediate and impactful decarbonizing efforts,” Minneapolis City Council Member Aisha Chughtai said in a statement. Although Minneapolis closed its cargo port on the Mississippi River in 2014, the city is notable for being home to the retail brand Target, a major contributor to shipping emissions.

The international shipping industry is one of the world’s biggest climate polluters, emitting roughly 1 billion metric tons of carbon dioxide into the atmosphere each year — about 3 percent of global emissions and more than all U.S. coal plants combined. This is partly because of the scale of international trade, 90 percent of which is facilitated by shipping, and partly because of the carbon-intensive fossil fuels that most ships still rely on.

Shipping also poses environmental justice problems. Besides greenhouse gases, fossil fuel-powered ships generate hazardous particulate matter and sulfur oxide pollution, contributing to elevated rates of childhood asthma and cancer, as well as some 250,000 premature deaths each year. Because port communities tend to be low-income communities of color, they are often most brutally affected by these hazards.

Ship It Zero resolutions are “shining a light on this issue that is affecting people’s lives, shortening lives,” says Dawny’all Heydari, Ship It Zero campaign lead for the nonprofit Pacific Environment, one of the environmental organizations that coordinates the Ship It Zero coalition. For port communities in Long Beach, California, where she lives, Heydari said that life expectancy is up to eight years lower than for communities living away from the ports.

Experts say that fully decarbonizing shipping will be difficult. Today’s solar panels take up too much space to be used on massive cargo ships, batteries are too heavy, and zero-emissions fuels like green hydrogen and ammonia are still too expensive to power a global shipping fleet. Hydrogen and ammonia are also less energy-dense than fossil fuels, potentially necessitating ship redesigns for optimal storage. Ammonia has also been known to release hazardous nitrogen oxide or unspent fuel when combusted, posing additional safety problems.

At present, there aren’t any zero-emissions shipping companies that could accommodate the needs of a major corporation like Target. But experts and environmental advocates say that resolutions like Minneapolis’ can help create the conditions necessary for decarbonization. By demanding fossil fuel-free shipping on an accelerated timeline, policymakers can spur research, generate demand, and increase pressure on major corporations — all of which can help make the Ship It Zero goals achievable.

“It’s becoming more of an imperative for these companies to take action because their consumers are demanding it,” Heydari says. “I think we’ll see a race toward the top, where it’ll increasingly become an economic business imperative to decarbonize to maintain a 21st-century reputation.