I'm always suspicious about carbon offsets. From what I've seen buying flights for example, the price seems surprisingly low. Either being carbon neutral is not as economy-killing as some say, or the true price is much higher. Does anyone have more expertise on this?
The flight in question was a roughly 1500 km + 1500 km = 3000 km roundtrip. I remember the airline offered to make my flight CO₂-neutral for about €20 or so. ICAO's emissions calculator [1] put my total contributed CO₂ emissions at about 280 kg. An economically very very inefficient baseline for counteracting CO₂ emissions is just extracting it from the air and storing it [2]. This is hard and expensive because the concentrations are so low in the atmosphere in general (away from emissions sources), but even in that case, numbers from pilot projects come out at $94-$232/ton [3]. Taking the optimistic estimate, that would mean my emissions could be undone for as little as roughly $26. Things seem to work out in roughly the right ballpark.
Of course the airline doesn't use direct air capture for this offsetting, but I looked into it and seem to recall the money going to sane projects. Another comment points out some of the much lower-hanging targets for emissions reductions out there, and they are of course much more effective per buck spent than direct air capture: https://news.ycombinator.com/item?id=24469438
[1] https://www.icao.int/environmental-protection/Carbonoffset/P...
[2] https://en.wikipedia.org/wiki/Direct_air_capture
[3] https://www.cell.com/joule/fulltext/S2542-4351(18)30225-3