Short term, put curfews in place for increasing periods of time in town centres where there is a significant drinking problem. That means say, all pubs, clubs and restaurants shut at 9:30pm, no-one allowed on the streets after 10pm.
Do you ever go out?
What about the likes of myself who enjoys going out pretty much every friday, saturday and sunday night and who never actually leaves the house until after 10pm, having a few drinks in the house beforehand.
If you actually went out you'd realise how silly your idea would be.
That's like somebody with a 1.2 clio campaigning to ban all 3+ litre engined cars from the roads because big cars pollute the environment more.
Just for the record I drink in two towns/cities that have highly publicised drink-related problems occurring at weekends. That maybe affects 0.005% of people but the rest of us still go out to have a good time.
Sorry, not having a go at you.
Banning under 21's - no. The notion of getting to legal drinking age just gets hyped more and more.
Making drink more expensive - probably not a bad idea, because it's too cheap & accessible at the minute.
Enforcing the under-18 regulations - won't be done because it's still too easy for them to get a hold of, one way or another.
I think the only effective way is through education and your general upbringing but that's never going to change the world either. For whatever reason I have been drinking in my mum & dad's company since the age of 14 or 15 and have never thought of drink as a big taboo/mystery or a real big achievement to get a hold of. Nowadays I drink more, and more frequently than, any of my friends at present; but at university and the likes, unlike the same bunch of people I didn't really see the enjoyment in "getting a 10-glass and getting ****ed" approach, it's always been a social thing for me instead. But you can't just plant that idea in people overnight.
In summary - the world's probably going to end.