ABS chairman and chief executive Christopher Wiernicki has issued a direct call for the International Maritime Organization to pause and reassess its regulatory approach to maritime decarbonisation.

Speaking at the ABS Sustainability Summit at London International Shipping Week,  the class society chief urged the global UN regulatory body to take a “timeout” and rebuild its Net-Zero Framework, which will come to vote at the extraordinary meeting of its Marine Environment Protection Committee next month.

“The IMO needs to approach this as if it were building a ship — systematic, explicit, specific and achievable,” said Wiernicki.

“The stakes are high, timelines are short, and the current gaps between fuel options are significant.”

His remarks come amid growing industry concern that the IMO’s current trajectory risks misalignment with commercial realities, technological readiness and infrastructure development.

Last week, DNV Maritime chief executive Knut Orbeck-Nilssen also stated he had “major concerns” over the current form of the IMO’s decarbonisation blueprint.

One of the most vocal in opposition has been US President Donald Trump, who last month made the position of his administration abundantly clear in rejecting the IMO’s draft agreement, labelling it a “global carbon tax on Americans”.

Wiernicki, who is retiring at the end of the year, stressed the need for a more balanced, transparent and implementable regulatory framework — one that reflects the physics of propulsion, the economics of fuel, and the realities of global trade.

“We still have time,” he said. “Let’s not waste it.

“What we do now impacts many generations. The question is whether we have the right game plan — and whether it’s supported by the right regulatory and commercial balance.”

Wiernicki called for a phased strategy for decarbonisation, advocating for the protection of transitional fuels such as liquefied natural gas and biofuels, which he described as “mission critical”.

He cautioned against prematurely sidelining these options in favour of emerging fuels such as ammonia, methanol, hydrogen and nuclear, which face significant scalability and affordability barriers.

“There is no clear pathway for green fuel availability and infrastructure support,” he said.

“We are overlooking viable transitional fuels while placing significant reliance on technologies that are still maturing.”

In this context, Wiernicki laid out a three-phase road map to decarbonisation.

First, he said, the industry must “protect the bridge” by controlling methane slip and optimising LNG use; second, “extend the runway” through energy efficiency and onboard carbon capture; and third, “prepare for the endgame” with nuclear and zero-carbon fuels beyond 2035.

He was also clear on how safety must remain a “non-negotiable” principle throughout the transition.