It could be years before the International Maritime Organization implements measures that would shrink the price between fuel oil and alternative fuels, and that could make it hard for shipping companies to make investment decisions.

That was the warning from Ocean Network Express chief executive Jeremy Nixon at the Global Maritime Forum’s annual summit in New York, where he said market-based measures like a carbon tax are needed to make conventional fuels more expensive relative to low-emission alternatives.

“As an industry, we can do a certain amount of pioneering there, but we cannot move to big scale unless there’s some levelling up,” said Nixon, who is also co-chairman of container shipping industry group World Shipping Council (WSC).