For many of our environmental challenges these days, the only way that they can be tackled is by changing people's behaviour en masse. But how can we achieve this across multiple sectors of society and how do we know whether the change is going to happen fast enough before it is too late?
Schools are the obvious place to start. There is no better way to get an idea into the entire population than to include effective tools in the national curriculum. Over time, the educated masses become a generation that has the essential knowledge that will cause them to change the way they treat the environment.
But if you need to make it happen faster than that, a diverse quiver of interventions is required.
Positivity is crucial to get people on board of course (if you make people think the challenges are too great to overcome, then you will breed cynicism and inaction), but there is inevitably some who - no matter how much you explain to them the pitfalls of environmentally damaging practices - are stuck in their habits. To change this demographic, they need to be hit in the pocket with a fine and coerced into change.
This is what has happened for the last 50 years in Singapore - a traditionally authoritarian state that is the cleanest big city I have been.