For fun I ran some ballpark figures, a 30 gram manual, 1 billion smartphones, primary shipping by sea, and it's on the order of 5000-10000 metric tons of CO2 to ship the manuals.

Sure, the "CO2 budget" is measured in gigatons so not a huge dent. But add up a lot of these rounding errors and it might actually make a slight difference. And since the climate interactions are non-linear, slight differences can have a large effect over time.

And from the figures I'm seeing, it'd be about 15,000,000 metric tons of CO2 for the manufacture of the phones to go with those manuals.

At first I was impressed by 30 billion grams (with little finger to mouth)

But that's only 30,000 tonnes.

10,000 tonnes of co2 for 30,000 tonnes of cargo seems... Wrong.

This seems to back me up https://timeforchange.org/co2-emissions-shipping-goods

10 - 40g co2 per tonne. So about an order of magnitude less.

Edit: Doh see below. This is per km

I used the same page :)

The key is it's per ton per km transported.

For reference, Shanghai to Rotterdam route (a bit of a worst case I guess) is just shy of 20000 km[1].

[1]: https://sea-distances.org/

You're right (sorry) wow so worst case 800kg of co2 / tonne. And that's excluding the return journey which is typically empty. So could well be 1:1!

Airfreight is 500g /tonne/km so 10 tonnes of co2 / tonne of freight.

Guess that's why co2 calculators always ask about flying.

I missed the per km at first as well.

Air freight is not clean indeed. Which leads to a kind of ironic situation here in Norway. Salmon export is hailed as one of the primary income sources once the oil is gone, yet significant portion of the salmon is exported via air to Asian markets. Not exactly a very green change...

Coudn't that be mitigated with factory ships that produce the product en route and drop off at the end location? Ship to ship transfer is easily possible. I'm honestly asking as I don't know the true logistics behind this, but I thought factory ships already existed and did this.

I should note that the 1 billion phone figure was the 2017 figures, 1.5 billion, minus half a billion I estimated for sales in China. Then again, inland transport in China may not very green so... anyway back of the envelope, order of magnitude stuff.