TEN years ago, the idea of the International Maritime Organization enacting a global emissions regulation was laughable.

Five years ago the word “levy” was akin to a swear word in the Albert Embankment.

Now a levy on shipping pollution looks like the frontrunner among the basket of measures the IMO is hashing out to bring shipping to net zero by or around 2050. Such a measure, if it happens, may well be a world-first.

It would also raise vast sums: up to $90bn a year for the most ambitious proposal on the table so far, a levy of $150 per tonne of CO2 equivalent.

Some shipping groups have no problem with a straightforward levy, and unlike the diplomats, they have no trouble picking big numbers. Commodity trader Trafigura wants $250-$300 per tonne; Maersk reckons $450 per tonne is more like it.

That money should be spent helping shipping go green. The need for new renewable power to make the fuels alone is titanic, and ships running on green fuel will guzzle twice the volume of it as the fuel oil they burn today. MR tankers may one day be needed to do the job of bunker barges.

We wish we could insist here that the IMO stick to greening shipping and put the bigger politics aside. But the regulator — a consensus-driven forum of 176 member states, does not work like that.

Poor countries will bemoan any extra tax burden on their economies, while small island states, that will soon be underwater barring a Disneyesque, last-minute twist of fate, rightly ask for a share to compensate them for what all those shipping emissions are doing to their homes and health.

Poor, import-dependent islands also worry what such a carbon tax will do to their food and fuel bills.

Why should customers in, say, New Caledonia have to fork out more for their basics to help European and American tech firms develop cleaner engines?

Then again, why should the shipping industry have to foot the bill for rescuing the planet when it is responsible for just 3% of global CO2 emissions?

It has always suited the shipping industry to hide from regulatory oversight, to stay at one remove from the economy it enables. The “we are just taxis” argument will be back on stage at Posidonia in a fortnight.

But shipping’s unique need — and the power of its regulator to enact global change at the stroke of a pen — make it a natural test case for the kinds of problems better dealt with at COP meetings.

That makes there is a chance something will get done. Moaning aside, once the IMO does get its act together, its unholy union with the industry it regulates means change can be swift.

But it is a naive waste of time to pretend that the IMO can dodge this question. It is written into the terms of reference for the legal tools in play that an emissions tax should help a just and equitable transition.

Shipping should use its powers to help the IMO make something everyone can live with. There is no time to lose.