I can't understand why the writer used -ing form of verb in my example after conjunctive adverb "therefore".
However, I know that 'therefore', 'however', 'hence', 'nevertheless', .. are conjunctive adverbs. They have to connect two independent clauses.
I am still confused why we use 'ing' form after adverbs, because we often use 'ing' form after prepositions not adverbs.
"They could also impose ‘green taxes’ on drivers and airline companies. In this way, people would be encouraged to use public transport and (they would be encouraged) to take fewer flights abroad, therefore reducing emissions."