You have to be a bit careful here, though. If you think that "policy and regulatory reform" means international agreements limiting greenhouse gases are the way to go, unfortunately I am afraid you are in for a really long wait. On the other hand, policies that push for new technologies, then kind of yes, but then it is more difficult to distinguish which one, the policies or technologies are the more important source of leverage (personally I do no think that it is even a feasible comparison).

For example, "everyone" is laughing at Germany's super Energiewende that it is a expensive failure that has not managed to reduce Germany's dependence for coal at all. But then, if you have a look when Germany has built solar, it's share of the global new capacity at that time and compare that tho the learning curve and price development of solar, it is a bit difficult to conclude anything but Germany's policies have pretty much singlehandedly brought solar from laughably expensive novelty to something that actually can be competitive in certain markets. Then China continued from there, and now we are extremely close (if not already over) a tipping point where solar just keeps getting cheaper subsidized or not.