@halfbyte ... which would have been a much better statistic to highlight in terms of impact
@whitequark that said, one last tidbit from the article that mentioned the counter weights (a refitting of a Swiss A330 btw.), they ended up with an emission factor of ~5 due to the 1,5t counter weight. Guess which seats actually got lighter in the refitting. Also the counter weight obviously means higher overall emissions for the flight.
That's just completely bananas.