alt Hacker NewsI'm going to speculate that it won't "add" ships at all
As you say, ships are moving in and out of the EU each year - the question is, how many have "back loads" - if some percentage of the ships leave Europe empty to return to Asia for more manufactured goods, then it seems very likely that they can have the containers of unwanted clothes as part of the trip.
Oh cool, so I can fly commercial all I want at zero marginal CO2 emissions just because they don't have to build an extra plane just for me? I can burn that jet fuel and not feel bad because they were going to burn that gallon of fuel anyway?
Some of these arguments are so silly that I'm starting to understand why the EU thinks regulations are a free lunch to improve the environment with no costs whatsoever.