Late last month, Long Beach, California, signed onto a historic effort to clean up the shipping industry when city council members unanimously passed a resolution to reach 100 percent zero-emissions shipping by 2030.

The move comes just months after a similar declaration from Los Angeles, whose port abuts Long Beach’s to make up the San Pedro Bay Port Complex — the U.S.’s largest port, handling more than 275 million metric tons of furniture, car parts, clothes, food and other cargo every year. Together, the two cities’ resolutions represent one of the world’s most aggressive shipping decarbonization targets and reflect a growing desire among policymakers and environmental advocates to drive down the industry’s emissions…

But getting to net-zero shipping is a monumental task that will require significant technological advancement and investments in alternative fuels — in addition to ambitious pronouncements from policymakers. Although some zero-emissions solutions already exist, experts say they need to be refined, scaled up and supported by government policies to facilitate industry-wide decarbonization.