How to Offset Flight Emissions Responsibly

Most of the reefs I love most are hard to reach by anything other than a plane. Moʻorea, Coron, the islands near Gili: you fly to get close to them, often more than once, and there is no honest way around that. So can you offset a flight responsibly? Partly. An offset funds a separate project, it does not undo the flight, and it only means something if you can verify it. This piece is narrower than a general “how to be a greener traveller” list. It is just about the flight itself: its real climate cost, what offsetting does and does not do, and what else is happening in aviation right now.

What does a flight actually cost the climate?

Aviation is often described as a small slice of global emissions, and by one measure that is true. Flying accounts for roughly 2.4 to 2.5% of global CO2 emissions, according to a 2021 study in Environmental Research Letters and a 2025 report from the U.S. National Academies. But CO2 is not the whole story at altitude. Jet engines also create contrails, and the cirrus clouds that can form from them, along with nitrogen oxides that change the chemistry of the air. The same 2021 study estimated that, once these effects are counted, aviation has caused about 4% of observed human-induced warming to date. Some later summaries give a figure closer to 3.5%, and estimate that the non-CO2 effects make up around two thirds of aviation’s total warming. The exact numbers are still debated, but the direction is clear. A flight’s climate cost is bigger than its CO2 alone, and that is worth knowing before you decide how to offset it.

What “offsetting a flight” actually means

Offsetting does not undo a flight’s emissions. It funds a separate project, usually verified against a named standard, sized to roughly match the flight’s estimated carbon. Two things decide whether that means anything: how the flight’s footprint was estimated, and how carefully the project behind the credit was checked.

On the aviation side there is also an industry-wide system worth knowing: CORSIA, the Carbon Offsetting and Reduction Scheme for International Aviation, run by the International Civil Aviation Organization. It requires airlines on certain international routes to offset emissions above a set baseline using approved credits. There was a voluntary pilot phase from 2021 to 2023, there is a voluntary first phase from 2024 to 2026, and a mandatory second phase starts in 2027, with exemptions for groups such as Least Developed Countries and Small Island Developing States. An IATA paper to ICAO in 2026 said 130 states were taking part, covering about 60% of international aviation emissions. Domestic flights sit outside it completely. And it works quietly in the background of airline operations, not as something a passenger buys. It is a different thing from the checkout offset you might see when booking a ticket.

The credits behind either system are only as good as their verification. Well-known independent standards include Verra’s Verified Carbon Standard and Gold Standard, which publish their credits in public registries. A standard’s name on a website is not proof on its own, but it gives you something to check. If you buy an offset for a flight yourself, through an airline add-on or a separate provider, look for those things: a named standard, a searchable registry entry, a plain description of the actual project. If none of that is visible, treat the claim with some doubt instead of assuming it checks out. We wrote more on how that verification works, and where the idea holds up better or worse, in our broader piece on carbon offsetting for travellers.

Where sustainable aviation fuel really stands

Sustainable aviation fuel, or SAF, is often called aviation’s long-term answer. It is a drop-in fuel that works in existing aircraft, and depending on how it is made, it can cut lifecycle emissions a lot compared with fossil jet fuel. The exact saving depends on the feedstock and the method, and published figures vary, so I prefer not to quote one number. What is clear is how small it still is. In December 2025, IATA estimated that SAF output would reach 1.9 million tonnes that year, double 2024, but still only 0.6% of all jet fuel used, and it expected about 0.8% in 2026. IATA also says SAF costs at least twice as much as fossil jet fuel. It is a real and promising piece of the puzzle. It just is not doing much of the work yet.

The choices around the flight itself

Some things are in a traveller’s hands without buying any offset. Direct routes often burn less fuel in total than routes with a connection, because every extra stop adds another takeoff and climb, the hungriest part of a flight. Staying longer in one place, instead of stitching several short trips together, works the same way by simple arithmetic: fewer flights for the same time somewhere. Neither is a dramatic fix, but both are free, and they shrink the number that needs offsetting in the first place. Small things add up on the ground too. A refillable water bottle and packing cubes cut single-use plastic on a long trip, a rash guard means less sunscreen in the water, and a mineral sunscreen from our picks is a reasonable choice when you do need it.

Holding both things honestly

I do not think the answer is to stop flying to see the ocean. Some of the most biodiverse water on earth can only be reached this way, and I would rather people go, learn something and come back caring more. But I also do not think a checkout offset should make it feel as if the flight never happened. The honest version is smaller than that: fly with intent, choose direct routes and longer stays where you reasonably can, and if you offset, choose something you can actually verify. If you are weighing which trip makes sense for you, ask us about the simplest way in and out of each destination, and read who our local partners are.

Questions people ask

If this made you curious about one longer, slower trip instead of several short ones, you can explore our upcoming retreats.

Wildlife encounters are never guaranteed and never forced. Ocean Calling works only with vetted, ethical local operators, and every animal is free to approach, or not, entirely on its own terms.