Book a flight, and you will often be offered the chance to "offset" it for a few pounds. Companies advertise themselves as "carbon neutral" through offsets. The idea sounds almost too convenient - pay a small sum and cancel out your emissions. Carbon offsetting is a real and sometimes useful tool, but it is also one of the most contested in climate policy, because its quality varies wildly. Here is how it works, where it goes wrong, and how to think about it sensibly.
What carbon offsetting is
A carbon offset is a tradable credit representing one tonne of carbon dioxide equivalent that has been reduced, avoided or removed from the atmosphere somewhere else. Buy one tonne of credits, and the claim is that you have balanced one tonne of your own emissions.
The appeal is straightforward. A tonne of carbon dioxide warms the planet the same amount wherever it is emitted, so - in theory - a tonne cut anywhere can compensate for a tonne released anywhere else. Offsets let money flow from those who want to balance their emissions to projects that reduce or remove them, often in places where cuts are cheaper. This connects directly to measuring a carbon footprint, since you cannot meaningfully offset what you have not first measured.
The two broad types
Offset projects fall into two families, and the difference matters.
| Type | What it does | Examples |
|---|---|---|
| Avoidance / reduction | Prevents emissions that would otherwise happen | Protecting threatened forests, replacing fossil power with renewables, capturing landfill methane |
| Removal | Takes carbon out of the atmosphere | Planting trees, restoring peatland and soils, direct air capture and storage |
Both can be valuable, but they answer different questions. Avoidance keeps carbon out of the air; removal takes it back out. As the world moves toward net zero, attention is shifting toward genuine removals for the residual emissions that cannot be eliminated, because avoidance alone does not draw down what is already up there.
How a credit is created
A typical project follows a recognisable path:
- A project is designed - say, protecting a forest that would otherwise be cleared, or building a wind farm.
- A baseline is set - an estimate of the emissions that would have occurred without the project.
- The benefit is measured against that baseline and verified, ideally by an independent body to a recognised standard.
- Credits are issued, each representing one tonne of CO2e, and entered on a registry.
- Buyers purchase and "retire" credits, marking them as used so they cannot be sold again.
Every step in that chain is a place where integrity can hold - or break.
Why quality varies so much
This is the heart of the debate. A credit is only as good as the real-world benefit behind it, and several tests decide whether it is genuine.
- Additionality. Would the emissions cut have happened anyway? If a wind farm was going to be built regardless, paying for its "offset" changes nothing. Only additional reductions should count.
- Permanence. Is the benefit lasting? Carbon stored in a forest can be released if the trees burn, are felled or die from disease. Removals need to stay removed.
- Accurate measurement. Baselines can be set too generously, overstating the reduction and producing more credits than the real benefit justifies.
- No double counting. The same tonne must not be claimed by two parties - for instance by both the project's host country and the buyer.
- No leakage. Protecting one forest must not simply push the logging next door.
A bad offset is worse than no offset: it lets the buyer believe a problem is solved while emitting as before. Quality is not a detail here - it is the whole point.
Independent investigations have repeatedly found that some projects fail these tests, which is why scrutiny and better standards matter. The market is steadily tightening rules to weed out weak credits, but buyers still need to look carefully.
Offset versus reduce: the order matters
Even a perfect offset does not change the fundamental point: offsetting should come after cutting your own emissions, not instead of it. The widely accepted sequence is:
- Measure your emissions honestly.
- Reduce them as far as is technically and economically feasible.
- Offset only the residual emissions that genuinely cannot yet be eliminated.
- Choose quality - verified, additional, durable credits.
- Be transparent about what you have reduced versus offset.
The danger is the "licence to pollute" effect, where cheap offsets become an excuse to avoid harder changes. This is the same reason terms like "carbon neutral" attract scepticism: a claim built mostly on offsets, with little real reduction, is weak. Real progress comes from levers like renewable energy and electric cars, with offsets mopping up what is left.
The role offsets can legitimately play
None of this means offsetting is worthless. Used well, it has real value:
- Funding climate action that might not otherwise be financed, especially in lower-income countries.
- Channelling money into nature - forests, peatlands and soils - that delivers benefits beyond carbon, alongside wider habitat restoration.
- Addressing genuinely hard-to-cut emissions while cleaner technology catches up.
The test is always the same: is this balancing emissions I truly cannot yet avoid, with credits I can trust?
How to use offsets sensibly
If you or your organisation choose to offset:
- Reduce first; offset only the remainder.
- Favour credits verified by reputable, independent standards.
- Prefer projects with strong evidence of additionality and permanence.
- Be wary of suspiciously cheap credits - genuine removals are not free.
- Keep your reduction and offsetting claims separate and honest.
The bottom line
Carbon offsetting lets you pay for emissions cuts or removals elsewhere to balance your own, with each credit standing for a tonne of CO2 equivalent. It comes in two flavours - avoiding emissions and removing carbon - and its value depends entirely on quality: additionality, permanence, accurate measurement and no double counting. Offsets are a legitimate tool for the emissions you genuinely cannot yet cut, but a poor substitute for cutting them. Measure, reduce, then offset only the residual with credits you can trust.