[MperorM]

no, it is absolutely the marginal numbers that matter. All else equal, starting anywhere but the place with the most pollution per $ produced is a sub-optimal place to start.

In a world that has climate change under control, there's for sure going to be a reduction in pollution produced by global shipping, but in the world we live in there's much better places to start than by limiting global shipping.

[adrianN]

The proposal in this thread is also taking into account the carbon cost of shipping when doing border adjustments. That's different than limiting shipping. It's internalizing an externalized cost. Exactly want you want to do if you want the market to find the most cost effective spots where carbon emissions can be reduced.

[MperorM]

I completely agree, I merely meant to point out that making decisions based on the absolute pollution of something will lead you horribly astray.

That said a carbon tax certainly does limit shipping, as some of it will no longer be profitable. Fortunately when doing it with a carbon tax, it just so happens to be the shipping that we shouldn't have been doing in the first place!