World Agrees to Cut Shipping Emissions 50 Percent by 2050

The new International Maritime Organization agreement to shrink shipping’s climate impact is a first. Island states facing sea level rise say it's still too weak.

Shipping emits about as much greenhouse gases as Germany. Its emissions are projected to rise 250 percent by 2050 unless controls are imposed. Credit: Daniel Bockwoldt/AFP/Getty Images
Shipping emits about as much greenhouse gases as Germany, and its emissions are projected to rise 250 percent by 2050 unless controls are imposed. Credit: Daniel Bockwoldt/AFP/Getty Images

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The UN’s International Maritime Organization has approved the world’s first broad agreement to cut greenhouse gas emissions from worldwide ocean shipping and said it hopes to phase them out entirely “as soon as possible in this century.”

The agency called the agreement, reached by countries on Friday, a first step and promised further action in the future. Some negotiators and observers said it was not yet strong enough to guarantee that shipping, a rapidly growing contributor to global warming, will come into line with the Paris climate agreement. The IMO called it a “pathway” in that direction.

The IMO called on shipping companies to reduce emissions by the year 2050 to 50 percent of their 2008 level, with emissions growth peaking as soon as possible. The organization is a specialized United Nations agency with 173 member states who cooperate on regulations governing the international industry, including setting pollution standards.

Even relatively modest first steps would require considerable changes in how cargo ships are built, fueled and operated. At present, ships run almost entirely on fossil fuels, generally the dirtiest grades of oil, and burn them inefficiently to boot.


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Meeting the new goals would require shippers to significantly increase fuel efficiency and to shift to low- and zero-carbon fuels such as biofuels or perhaps hydrogen, while adopting new propulsion technologies, some of them still unproven.

The next step is for the IMO to decide whether to make some of these short-term measures mandatory and determine how to enforce the rules. The deal is to be reviewed and perhaps tightened in five years.

Cutting Shipping Emissions Takes a Global Deal

Until now, little has been done to address the industry’s carbon pollution. Shipping is not directly controlled by the Paris agreement, and it is widely neglected in the Paris pledges made by individual nations.

About 90 percent of global trade in goods travels by ship, and the vessels together emit about as much greenhouse gases as Germany, the nation with the sixth-highest emissions in the world. Emissions from shipping have been projected to rise 250 percent by 2050 unless controls are imposed. For competitive reasons, and because ships are registered in various countries without regard to where their owners are based or what ports they visit, this can only be done by a global agreement.

Delegates from many countries, meeting in London this week, spoke of the need to do more.

The Marshall Islands made clear from the outset that it would not endorse any agreement that fell short of the Paris targets. The low-lying Pacific Ocean archipelago is probably doomed unless carbon dioxide emissions are reined in sharply and rapidly, but it is also home to one of the world’s biggest shipping registries. The vessels registered there fly a flag of convenience as the islands’ people face an inconvenient truth.

“I will not go home to my children, and my country’s children, endorsing an outcome from the IMO that fails to face up to the greatest threat of the century,” Environment Minister David Paul said.

After the decision, President Hilda Heine of the Marshall Islands said the outcome “made history.”

“While it may not be enough to give my country the certainty it wanted, it makes clear that international shipping will now urgently reduce emissions and play its part in giving my country a pathway to survival,” she said.

Kitack Lim, the IMO secretary-general, told delegates, “I am confident in relying on your ability to relentlessly continue your efforts and develop further actions that will soon contribute to reducing GHG [greenemissions from ships.”

Island States Wanted a Zero-Emissions Target

Climate advocacy groups welcomed the move as a long overdue step but called it insufficient.

“Without concrete, urgent measures to cut emissions from shipping now, the Paris ambition to limit warming to 1.5 degrees will become swiftly out of reach,” said Veronica Frank of Greenpeace International. “Although the deal lists possible mitigation measures, the lack of an action plan for their development and the tone of discussions at the IMO does not give much confidence that measures will be adopted soon.”

A more suitable target, some say, would be to aim for zero emissions from shipping as early as 2035, as was demanded by the Marshall Islands and several other small island states. European Union countries were willing to cut more deeply than the IMO decided; Japan wanted to move more slowly than the IMO target. In the end, they compromised.

For the world’s nations to achieve the Paris targets of keeping warming well below 2 degrees Celsius, scientists say net emissions of carbon dioxide from all energy systems need to be reduced rapidly, reaching zero some time in the second half of this century.

Here’s How Shipping Can Cut Its Emissions

While it may sound Pollyannaish to talk of rapidly bringing emissions from shipping down to anything close to zero, the Organization for Economic Cooperation and Development (OECD) published a report as the negotiations began describing possible pathways to get there.

Technology: “Maximum deployment of currently known technologies could make it possible to reach almost complete decarbonization of maritime shipping by 2035,” it said. “This reduction equals the annual emissions of approximately 185 coal-fired power plants.”

Less Fossil Fuel Use Globally: Some progress might come simply from a worldwide reduction in the use of fossil fuels, especially coal and crude oil. Much of these commodities move by sea. Declining exports from producing countries would reduce the amount of shipping, and that alone would make a dent in smokestack emissions at sea.

Electrified Ports: In addition, lots of the pollution from ships is given off while they are in port, their engines idling to produce on-board power. Plugging them in to clean electricity supplies would prevent that—and would considerably reduce the local smog and soot that choke some port cities.

Slowing Down: The next obvious way to cut emissions is by simply slowing ships down. Just as Americans used to save gasoline by driving at 55 miles per hour on highways, ships can cruise more efficiently if they go slower. Of course, that means more ships are needed to carry the same amount of fuel. New shipbuilding would be an opportunity to build modern, efficient ships or new varieties that incorporate novel technologies, such as fuel cells or other electric propulsion.

Alternative Fuels: Then there’s the possibility of substituting alternative fuels. One approach would use synthetic biofuels. This would require careful attention to life-cycle emissions, since biofuels don’t always have a lower carbon footprint, especially in the short run. Another approach would substitute fuels like hydrogen for the heavy, dirty fuel oil that is commonly used.

A Price on Carbon: The most effective way to spur this kind of change, the report said, would be to impose a price on greenhouse gas emissions, such as a carbon tax. Then the marketplace could decide what methods to use to hold down emissions and avoid the tax.

“An effective carbon price coupled with technology and operational improvements will be key to unlocking the huge potential for pollution-free shipping,” said Kelsey Perlman, international transport policy officer for Carbon Market Watch.