How many cars and trucks versus the number of ships move each day in Souther CA? In terms of fuel consumed or energy used, I suspect ships isn't even in the margin of error in comparison to land vehicles.
Perhaps another FReeper can find the stats on this.
Some huge percentage of So. Cal air pollution is due to Long Beach alone. 20%-30% maybe?
Cars in CA are now very clean, while shipping has never changed.
In terms of marginal costs, which Enviros never consider, this should have been addressed long ago.