The Marshall Islands’ foreign minister wasn’t holding back last year when he told global maritime regulators that “carbon emissions, including those from shipping, pose an existential threat” to the island’s and its 50,000 inhabitants.

Addressing the International Maritime Organization (IMO), a branch of the United Nations, nearly a year ago, Foreign Minister Tony de Brum used moral suasion in urging a commitment to cut shipping fleet carbon emissions.

Despite its tiny population, the Marshall Islands plays an outsized role in international shipping. It’s the flag state of more than 3,000 vessels carrying 40 percent of the tonnage of all goods shipped on the high seas, and earning the small country lucrative service fees.

An archipelago of hundreds of tiny coral outcroppings, with a combined surface area only about twice that of Manhattan, the Marshall Islands rises at most about 20 feet above the surface of the Pacific Ocean. It’s one of the countries most vulnerable to sea level rise, caused by warming ocean waters and melting glaciers.

Maritime emissions pre- and post-Paris Agreement?

Cargo ships on the high seas emit nearly a billion tons a year of carbon dioxide – about 2.4 percent of global greenhouse gasses – as much as large countries like Japan or Brazil. Under the Paris Agreement adopted in December, these and most other countries have pledged to cut fossil fuel use substantially in the coming several decades.

But international shippers anticipate burning ever more fuel, even as critics of maritime carriers say the industry must do its share in reducing its carbon footprint. They say that ships of the future could be powered at least in part by wind, using a combination of technologies already at hand and yet to be invented. Energized by the Paris Agreement, they say that if the IMO doesn’t make shipping cut it’s use of fossil fuel, some other agency should. The European Union has already instituted requirements that, starting in 2018, ships servicing their ports must measure and report fuel use. This could be the first step to regulating emissions of such vessels.

In the 1990s, during negotiations over the Kyoto climate agreement, diplomats handed to IMO the authority for regulating the carbon footprint of international maritime shipping. Negotiators realized that the treaty, intended to regulate the carbon dioxide output of countries, could not easily control sources of uncertain geographical jurisdiction such as international cargo ships. (They handed authority for regulating carbon dioxide from prop planes and jet engines, also a major source, to the International Civil Aviation Organization, ICAO.)

Think of it: If a Greek-owned freighter, flagged in Panama, on its way to New York fueled-up in Rotterdam, which country would take responsibility for the carbon dioxide rising up from its stacks?

”Shippers’ Click To Tweet

The IMO has only sparingly exercised its authority to regulate ship CO2 emissions, even as international freighter traffic has grown steeply. The agency has issued a requirement that ships built after 2025 must be nearly one-third more efficient than current models in production, a rule de Brum of the Marshall Islands considers overly modest.

Some powerful countries see things differently, and Russia, Brazil, and India have all opposed de Brum’s efforts. After a cursory debate at an annual meeting on environmental issues in May 2015, the IMO tabled the idea.

That left maritime shipping, along with air travel, about the only major industrial activity on Earth not either currently, or anticipated soon to be, controlled in some way to slow global warming. (The ICAO February 8 announced a proposal for improving the efficiency of airplanes. That too, however, would affect only aircraft marketed beginning in 2028 and it would not reduce the absolute carbon footprint of air travel given rapidly rising passenger air miles. Environmental groups, concerned about too little/too late, criticized the ICAO for letting airlines off easy.)

In the Paris talks in December, nations of the world agreed to cut the amount of CO2 they release into the air, compared to a baseline year or a “business as usual,” projection, in coming decades. That would leave maritime freight shippers with a growing share of emissions.

But the IMO, in a report last year, said emissions from the international freighter fleet will rise, not fall: It predicted that rapid growth in the volume of goods traded will far outweigh any gains expected in fuel efficiency. According to the report, by 2050 international marine cargo transport will consume 50 to 250 percent more fossil fuel than it does currently.

Things ‘on the verge of happening …’

That prospect doesn’t sit well with Michael Traut, an engineer at the Tyndall Center on Climate Change Research at the University of Manchester in the United Kingdom, who says that the shipping industry can and should do much better. The European Union Commission recently hired a team of researchers, including Traut, from four European universities to study the potential for wind to power cargo ships – in whole or part.

”With Click To Tweet

Steam had put an end to the “Age of Sail” in the mid-19th century. The diesel engine, reliable and efficient, now powers virtually all ships. But just as quaint Dutch windmills blossomed into today’s colossal off-shore turbines, schooners and sloops could foreshadow a new wind-driven cargo fleet. A diverse collection of engineers and visionaries (and a few cranks) tout wind’s potential. Traut is not convinced yet, though he says “things are on the verge of happening.”

Traut will be looking into a number of ideas for the EU Commission – some familiar and others seemingly whacky – about how to harness wind to drive cargo ships. In 2008, the German company SkySails introduced a wing-shaped kite the size of a tennis court able to tow an ocean-going container ship hauling a 10,000-ton cargo. The company says that under ideal conditions its kites can cut fuel use by 30 percent. But SkySails now has “down scaled,” Traut said in a recent Skype interview. “There was no economic case for the time being,” he said, because oil is “ridiculously cheap.”

Entrepreneurs need ‘a sense of eternal optimism’

Other ideas for wind-power have likewise been slow to get under way. Diane Gilpin, a British entrepreneur, says that with an investment of about $5 million, her firm Smart Green Shipping Alliance, could draw up blueprints for a modern sail-powered cargo ship 400 feet long. Huge venetian blinds appear to hang from four masts shown in promotional literature that boasts of the lack of rigging and “push-button operation.”

The design would be patterned after The Maltese Falcon, a 300-foot-long high tech yacht launched in 2006, with three carbon-fiber masts that rotate to orient its 15 sails. Wind could provide at least half of the power of her ships, Gilpin says.

But “there has been little appetite for renewables,” and she has been unable to market the ship. In January she was heartened to read a report by staff at International Monetary Fund recommending that marine fuel be taxed, a policy that would favor wind.

“As an entrepreneur, you have to have a sense of eternal optimism,” Gilpin says. Otherwise you’d never get out of bed.”

One promising technology for wind powered propulsion was invented in the early 20th century by a German engineer. Anton Flettner mounted two cylinder-like wide masts onto a ship’s deck. A motor turned them on their long axis. The Flettner Rotors, as they’ve become known, propelled the ship forward just as a wing lifts an airplane.

Now, decades after the Flettner Rotor was abandoned, ship builders are giving it a second look. In 2010 the German wind turbines builder Enercon unveiled the E-Ship 1, a freighter outfitted with four Flettner Rotors (and nine diesel engines), each 85 feet high and 13 feet wide. The company says wind supplies 30-40 percent of the ship’s power.

As for Traut, he says no one knows if these or other proposed wind technologies could reliably and substantially cut the amount of fuel used for shipping cargo.

“I’m confident we can answer that question in the next few years,” he said, but doing so will require a concerted research effort – most likely subsidized by governments – and rigorous testing of full-scale prototypes. He said that in the long run, wind will probably not provide the fuel savings the shipping industry needs, considering the growth of international cargo it forecasts.

To prevent shipping from becoming an increasingly large share of global carbon dioxide emissions, he said, some other as yet barely-imaginable technology will be required, perhaps hydrogen- powered engines fueled by a global network of hydrogen depots.

“We’re certainly not on track,” Trout acknowledges, “but you could argue that the world will take this problem more seriously.”