OCEAN Rebellion activists writhed all over the floor pretending to be dying mermaids, while bemused delegates clutched glasses of lukewarm white wine and chatted politely as they pretended to ignore them.

The scenes at the International Maritime Organization just two months ago were a study in mutual incomprehension.

Attendees at the Marine Environment Protection Committee session in the first week of July surely felt entitled to the free booze as a small reward for a hard day’s work hacking out a deal on greenhouse gas emissions. The protestors felt equally entitled to righteous indignation at its lack of scope.

Subsequent weeks have afforded an opportunity for reflection on the gelatinous achievements of MEPC80, which broadly commits the industry to getting somewhere around net zero sometime around 2050, providing it doesn’t inconvenience anybody too drastically.

Many were looking for a strong signal on what they should do next. What they got was better than most expected, but that has not stopped some from interpreting the agreements as an excuse to kick the can down the road.

Meanwhile, this summer has brought home the relentless and unforgiving impact of climate change, sometimes literally right to the doorstep of industry leaders.

A heatwave taking in the more salubrious suburbs of Athens — dwelling place of a fair number of shipping’s glitterati — saw the mercury top 40°C for several days in succession.

A sustained drought meant that water levels in the Panama Canal fall to a level necessitating capacity reductions and deadweight restrictions, which could drag on for ten more months.

Meeting the IMO’s targets is imperative. If there is to be any chance of success, the need for action is immediate, and as doctors habitually put it, this is going to hurt just a little bit.

Carbon-neutral fuels such as ammonia and hydrogen are touted in some quarters as the closest thing on offer to a Get Out of Jail Free card. Sadly, they fall a long way short.

There was good news of sorts this week, in the shape of a study from the Global Maritime Forum. On that body’s calculations, the cost gap between zero emission ammonia and conventional fuel oil could close significantly within just three years and reach price parity by 2030.

The snag is that if shipping were to rely on carbon neutral fuels as the sole means of securing the desired reductions seven years hence, it would eat up an estimated 40% of total world production.

Other industries also have emissions reductions goals and will be competing for the same finite supply. Higher margin sectors will have the financial firepower to outbid low margin shipping.

In the immediate future, methanol is likely to be the next big thing. It is far easier to live with than ammonia, but still emits carbon that will need capturing and storing.

The steady patter of studies and investments in carbon capture continues but the technology is still in its infancy. Many think it will never happen, let alone happen at the prodigious scale the world needs.

Even if the technology works, businesses will have no incentive to hoover up all that CO2 unless a use can be found for it, and a viable business created.

There will doubtless be much hoo-ha and hullabaloo surrounding the imminent naming ceremony of Maersk’s flagship dual-fuel CH₃OH vessel in Copenhagen later this month.

But in case you’ve forgotten your high-school science lessons, the C in that chemical formula stands for carbon.

That doesn’t mean Maersk’s efforts are not laudable. The mass-balanced methanol its ship will use on its maiden voyage will make possible a 65% reduction in greenhouse gas output.

That is a big and responsible step, as one would expect from an obvious industry leader. But it is not enough on its own.

Even though dual-fuelled methanol vessels now make up 8% of the overall orderbook, not every company will be as diligent as the Danes in their choice of what to burn.

Many planned ships will be powered by a grade known as grey methanol, which is somewhat dirtier than the mass-balanced kind.

That said, there is a case for using grey methanol in the early days of transition while people get used to it, as it is far less polluting and safer for marine life if spilled.

In sum, shipping needs to make faster progress on phasing out bunkers, but in the real world, none of the available choices are unproblematic.

We suspect that hippies dressed as mermaids will have pretexts to disrupt Albert Embankment wine receptions for some time yet.