You can of course buy carbon offsets for everything and then claim that it's carbon neutral, even the flight. It seems to me that the answer should be "yes" if all that saved them was the offsets.

@Avery - But that's not really an apples-to-apples comparison, is it? Shouldn't you either be comparing fly with offsets vs. boat with offsets, or fly without offsets vs. boat without offsets? If you compare "one means of transport with offsets" vs. "one means without offsets", then the one with offsets will win every time, even if it's "coal-powered steam engine with extra coal-burning stoves wherever there's room for them, with offsets" vs. "walking without offsets".

So the answer is technically yes, but its not the gotcha the masses with an irrational hatred of Greta think it is

-1 The answer is yes. There is an agenda being saying no. Moreover, offset does not mean one completely compensates for the effects (you cannot re-imprison the carbon under the Earth).

-1. I smell a Red Herring.

@Zonata Carbon capture is absolutely a plausible technology. Whether the carbon offsets go towards actually achieving that is another question entirely, I suppose, but still.

@Zonata you can offset by planting trees. But i agree this comparison is not fair.

"Shouldn't you either be comparing fly with offsets vs. boat with offsets, or fly without offsets vs. boat without offsets?" Why, when that wasn't the purpose of the trip? If Greta taking a boat helps get a law passed that reduces CO2 by 20% in some country, wasn't it one of the biggest carbon savings of all time? There is a lot of pettiness involved in crying for an "apples-to-apples comparison" that includes only the apples YOU like and leaves out larger factors, including things like WHY carbon offsets were purchased. (BTW, pleased to have earned the "Cosmic Brain" hat for this answer...)

@LightnessRaceswithMonica Although, reading the quotes, both Nikki Henderson and Greta Thunberg are saying "yes, but..." - for example "To make the point that there isn’t a sustainable way to travel yet, and there needs to be.". Going by the comments, many of the downvotes are because Avery is misrepresenting the quotes by saying that the answer is "no". While the facts and quotes are reasonable and right, the conclusion drawn is wrong or biased.

@Chronocidal Only insomuch as it's premised on the idea that carbon offsets effectively result in not "producing more CO2". You can disagree with that notion if you like, but it's actually fundamentally what carbon offsetting means. Calling this answer "wrong" is unfair, and calling it "biased" is just vindictive.

@LightnessRaceswithMonica Yes, offsets were purchased to reduce CO2. Yes, this means that the net CO2 change is lower. No, this doesn't mean that the CO2 produced (i.e. the actual question) by the journey was lower - which is exactly what the quotes say. As an exaggeratedly-extreme example, it's like suggesting giving birth to twins and then killing someone isn't murder, because the net result is an increase in population... I agree that carbon emissions are bad, I agree that offsets effectively reduce your contributions, I disagree that this is the same as "producing less CO2".

@Chronocidal For what it's worth, I don't entirely disagree, and I think the answer would be better off being reworded to address that distinction. But accusing its author of bias is really a stretch.

@ Zonata That's not entirely accurate. Carbon capture and sequestration technology does exist, but it hasn't been scaled up to the point to remove atmospheric carbon dioxide yet. Best we can do at an industrial scale requires connection to a point source.

I don't understand the -1s. It's a lie by omission to claim just that the trip cost more carbon than flying did (as the article does). "Yes, but" is not the same as "yes," and because the article claimed that reduced emissions was the Thunberg's mission it's false.

I feel like the victim of a bait and switch. I came here to find out if traveling by boat can end up having a bigger carbon foot print then traveling by air. Nice simple question topic. After reading all of this carefully I still have no idea. I don't want he said, she said, they bought. I want to know if it's even close to true because I thought planes were orders of magnitude less efficient. It'd be nice to know how close they are.

@candied_orange - I think the issue is due to Nikki Henderson flying out from the UK to US to skipper the boat - not the carbon footprint of the two modes of transport. So maybe the question title should be edited to be less "bait and switch"

@candied_orange - I don't think such an answer is forthcoming as I do not think an exact CO2 footprint can be calculated for this specific voyage with its specific weather conditions.

@pipinstallMonica "Yes, but" is also not a "no."

So they gave money to some organization in hopes said organization will do something useful with the money to reduce carbon in the atmosphere in the future? That doesn't sound like they really made anything carbon neutral - it's just yet another "feel good, do nothing" token.

@MartinSmith Given what I've found here yes the topic could use editing. Sad that the promise of a simple useful fact has to die in favor of political fluff.

@candied_orange you are absolutely right. It depends on the nature of the ship, speed of travel, length of travel, etc. The bottom-line is: If we're talking about a cargo ship, the carbon emission tends to be lower... Especially over short distances. If we're talking about a passenger ship, the carbon emission tends to be higher. If we're talking about a monstrosity like a cruise ship, the carbon emission is tremendously higher compared to flight.