We’ve been talking a lot recently about why a lower-carbon future will only be possible if we change the way we do things. This does not mean we have to break everything and start again. In many cases, practical changes are already within reach — and some of them could have a meaningful impact on the direction of travel.

We were reminded of this recently during a trip to London Heathrow while flying back to Hong Kong. The automated bag-drop system was struggling in the summer heat, which gave us unexpected time to observe what was happening around us — and to reflect on what it might mean.

Depending on your class of travel and your airline status, you can check multiple bags into the cargo hold. With the airline we were travelling on, an economy ticket with no membership status allowed one 23 kg bag per passenger. At the other end of the scale, a first-class ticket combined with top-tier status allowed up to seven bags of 32 kg each.

How much baggage an airline chooses to carry is ultimately a commercial decision, and airline membership programmes undoubtedly create brand loyalty. But given the sheer volume of flights and the environmental cost of air travel, reducing the weight carried — even marginally — could have a meaningful cumulative impact.

Reducing baggage allowances does not have to be the only option. Airlines could preserve the value of membership benefits while making the carbon cost more visible. For example, what if the airline absorbed the carbon cost of one checked bag, but passengers paid the carbon cost of any additional bags?

Watching the bag drop made the issue tangible. Some passengers travelled light; others checked in a significant amount of luggage. The difference was visible before anyone even boarded the aircraft.

Using the UK GHG Protocol framework as a reference point, a 23 kg bag on this flight would be associated with around 248 kg of carbon emissions, depending on the assumptions used for flight distance, aircraft type and allocation of weight.

Carbon credits remain a minefield of complexity, with low-value and uncertified products still plentiful. At the same time, higher-quality products with stronger verification are emerging, which should help build greater confidence in the system. High-integrity reforestation credits are currently priced at around USD 25 to USD 60 per tonne, depending on project quality, verification standard and permanence assumptions.

That brings the question back to us: would we pay between USD 6 and USD 15 to net out the carbon impact of our bag?

If we were presented with that choice without any further information, we would probably say no. Not because we object to the cause, but because we would want confidence that the money was going to the right place and creating the impact being promised. There has been too much negative press around carbon credits underachieving on their environmental commitments.

But if there were real assurance that the money would genuinely net out the carbon impact, we probably would pay it. Or perhaps the visible cost would make us pack less in the first place. Either way, the environment wins — and that is the point.

That is where the individual choice becomes a systems question. One bag may not feel material on its own, but when the same behaviour is repeated across millions of passengers, it starts to become a very different kind of problem. Based on industry estimates, airlines carry around 205,000 metric tonnes of checked passenger baggage per day, with an average flight distance of 1,500 km.

If we were to target just 10% of this baggage with a credible carbon programme, the potential impact could be material. Based on these assumptions, it could equate to more than 10 million tonnes of carbon addressed each year. That is a large number — and it shows why small changes in high-volume systems can matter.

If we took it one step further and removed this weight from aircraft altogether, estimates suggest airlines could burn up to 4 billion litres less aviation fuel per year. To put that into perspective, IATA estimated that airlines used 2.4 billion litres of sustainable aviation fuel in 2025.

We do not always need expensive consultants to work this stuff out. Sometimes we just need to take a step back, look critically at what we do and why, and ask whether the incentives we have created still make sense. This stuff is not always hard — but we often make it harder than it needs to be.