What is this meeting and why is it important?

This week is the 74th meeting of the marine environmental protection committee of the International Maritime Organization (IMO), and it represents one of the best hopes of reducing greenhouse gas emissions from a large and growing sector.

Based in London, the IMO is the UN agency with responsibility for the safety and security of shipping and the environmental impact of ships, and the only organisation bringing all the world’s nations together to regulate marine transport.

Shipping accounts for at least 3% of global greenhouse gas emissions, which may not sound a lot but is greater than the UK’s total: if shipping were a country, it would be the sixth biggest in terms of emissions share. And it is growing fast – shipping could produce 17% of global emissions by 2050, if left unchecked. About 90% of the world’s trade is carried by sea.

Even more significantly, those emissions are particularly harmful because they are mostly the result of burning heavy, pollutant-ridden fuels that are usually banned or subject to regulation onshore because of their toxic effects. Ship fuel produces sulphur, which contributes to acid rain; ships burn more than 3m barrels a day of residual fuel oil, with a sulphur content more than 1,000 times that of petrol for road vehicles. The dirty fuel also releases large quantities of black carbon – soot, made up of unburned particles – that is borne on the winds to the Arctic, where it stains the snow and increases the greenhouse effect, because dark snow absorbs more heat.

What will be discussed at the meeting?

Climate change and shipping’s contribution to it will be high on the agenda, the secretary-general, Kitack Lim, confirmed in his opening speech on Monday. There will be a discussion of the IMO’s target of halving emissions by 2050, compared with 2008 levels, and of a new review – its fourth – of shipping’s greenhouse gas emissions.

Also on the table will be IMO 2020, a plan to reduce the environmental harm from sulphur by stipulating that ships can only use fuel with a sulphur content of less than 0.5%. Marine plastic pollution will be discussed, with recent developments such as the UN’s agreement, excluding the US, to take steps to reduce the flow of plastic waste to the developing world.

What is the likely outcome?

There is expected to be progress on all of the above, probably in the form of resolutions to reaffirm existing commitments and the frames of reference for a new greenhouse gas study. The IMO on Monday evening also produced a blueprint for one of its main outcomes from the talks: GreenVoyage-2050, co-funded by the government of Norway, a plan to expand port management capacities in the developing world and set up demonstration projects that will help poor countries meet the goal of halving emissions by 2050.

Is that good enough?

Far from it, according to civil society groups and protesters. Extinction Rebellion activists are protesting outside the meeting in London, offering delegates deckchairs which they can rearrange as if on the Titanic – a reference to the futility of the efforts to regulate shipping so far, which have shown little progress over more than a decade.

Campaigning groups have differing demands from the talks. The Clean Arctic Alliance wants a ban on heavy fuel oil in the Arctic and moves towards a wider ban. A group of ten NGOs led by Stand.Earth is calling for a moratorium on the use of “scrubbers” to remove sulphur from ship exhausts, in favour of a straightforward switch to lower sulphur fuel. The Environmental Defense Fund wants to see zero-emissions ships on the water as soon as possible. Extinction Rebellion has a very specific demand: to reduce the speed of ships by 10%, which would result in a carbon saving of 30% on current levels.

Liam Geary Baulch, a spokesman for Extinction Rebellion, said: “It’s only our future at stake, so either the shipping industry can just keep rearranging the deckchairs … or they can tell the truth today and declare a climate and ecological emergency. They should act now by reducing emissions immediately. This can effectively be achieved through an immediate reduction in speeds.”

We have known about emissions from shipping for years. What progress has been made up to now?

Very little. The IMO first announced plans to move ships to fuels with a lower sulphur content in 2008. These plans will not come into force until next year. On greenhouse gases, the long-term target is a halving by 2050, compared with 2008 levels, but the industry is still stuck on carrying out yet another review. Shipping has largely escaped public scrutiny, as its emissions take place far out to sea, invisible to the consumers of the goods the ships carry.

Part of the problem is that shipping, along with aviation, has been excluded from international talks on climate change almost from the start. The initial reason was pragmatic – in the run-up to the Kyoto protocol of 1997, countries could not agree how international transport should be accounted for, and whether the ships’ home countries or the countries where the cargo was landed should be deemed responsible for the emissions. In order to get the agreement through, shipping and aviation were left out altogether.

This is effectively still the case, even though in the intervening two decades emissions from these sectors have risen sharply. The industries have largely been left to regulate themselves on a voluntary basis, and their plans to do so have been slow in coming, low on ambition, weak on enforcement and, so far, inadequate to the scale of the problem.

For the IMO to turn that situation around this week is as unlikely as a supertanker sailing up the Thames to its headquarters, but protesters are hoping that their activities will at least draw public attention to what has so far been largely a hidden scourge of the seas.