Well, my favourite policy would be a large government (federal in the US, concerted at EU level here) program in sustainable development.

And long term. If the State committed to buying this kind of equipment on a grand scale for a couple of decades, then small companies would get created to provide the supply (especially if we guarantee them a large share of the orders). Which would then make it possible for individuals to join in the purchase, help technology get better...

We have, regrettably, let complacency build up huge State debts which do limit what can be done. But I'm very happy to help finance that through a carbon tax.

Think. Whatever capital would join in that program would be truly productive. It would make economies more competitive than those not doing it in a world where primary resources are going to be increasingly expensive. It would reduce healthcare costs. It would provide jobs unlikely to disappear with a bubble bursting...

Earth provides enough to satisfy every man's need, but not every man's greed. Gandhi