According to their data here (which is, for various reasons, wildly overstating the case) buying 3 paper books per month for four years yields roughly a metric ton of CO2. That's the equivalent of 110 gallons of gasoline. Less then 3,000 miles for a decent car!
If *publishing companies* want to take steps to reduce their footprint, that's great -- they have the scale to do real good. But to pretend that changing your individual purchasing habits for books is going to achieve anything is nonsensical.
I was in a proper academic research discussion about the power consumption (~10kW) of their quantum computer, and I had to stop it by reminding them that if they really run out of power, I can skip going to sauna one evening. The ratio of quantum computers to saunas in Finland is about 1:2.000.000.
Did they consider that the act of reading 3 books a month itself reduces carbon emissions because it's an activity that doesn't require driving, electricity etc?
For a sense of the scale of comparison, simply look at the sheer volume of books in a house and compare them to the house itself. I have a fair libary, but it's still negligible compared to the materials & processes that have gone into the kitchen or bathroom, the walls, floors, roof, windows.
Also a minuscule fraction of the amount of paper that gets churned just printing things out for immediate consumption and destruction in corporate America every single day