I just saw this article about how Copenhagen’s tourism office is launching a pilot program that rewards visitors for going green. "Starting July 15, participants who engage in a sustainable activity will earn a gift of appreciation, such as a free kayak rental or coffee and Danish pastry."
It's a really nice idea. Obviously Copenhagen does not have the problems that Barcelona does, and this is a small program, but I do think that in many cases, proactive solutions work better than reactive measures.
https://wapo.st/3zsicN5 (unlocked)