CO₂ emissions in international shipping 2022, by ship type

Container ships and bulk carriers are the leading contributors to international shipping carbon dioxide (CO₂) emissions. In 2022, container ships emitted an estimated 221.5 MtCO₂, while bulk carriers followed closely with 208.8 MtCO₂. Together, these vessels account for half of the international maritime industry’s carbon footprint.

Decarbonizing shipping

With international shipping emissions having doubled since 1990 to more than 700 MtCO₂ per year, the industry faces mounting pressure to reduce its carbon footprint. The International Maritime Organization has set the target of reaching net-zero GHG emissions for international shipping by or around 2050, hitting interim targets of at least 20 percent by 2030, relative to 2008 levels, and at least 70 percent by 2040. To achieve these goals, the industry will need to improve the energy efficiency of ships fueled by fossil fuels, as well as switch to low-emission fuels like hydrogen and ammonia.

Environmental concerns beyond CO₂

While CO₂ emissions remain a primary concern, the shipping industry also grapples with other environmental challenges. Several harmful air pollutants are emitted by ships, including sulfur dioxide, black carbon, and nitrogen dioxide. Although many ships are fitted with “scrubbers” to reduce air emissions, contaminants removed from the exhaust gas by these cleaning systems are dumped overboard in the form of washwater, which creates a different type of pollution that poses a significant threat to marine ecosystems.