As the father of five-year-old twins, I'm an expert in leakage of all kinds. I'll talk about the carbon kind.
What you don't want is what my colleagues alluded to, which is that firms simply move across the border and continue to emit the same emissions they would have emitted in your country, and keep all the revenues and jobs there. That's the lose-lose option.
What you do want, though, is to keep your firms here and give them an incentive to be among the leaders in low-carbon production, because then they're going to get ready to compete where the world is going.
You want to have both, which is why you want to ease the economic transition. That would be the same as we did with an economic transition on the free trade agreement here for a few years, as you moved from a closed economy to an open one. There will be an economic transition here. Things like output-based pricing, things like accelerated capital cost allowance, and things like revenue recycling help firms as they make the transition to being low-carbon competitive without having to move elsewhere to do that.
It shouldn't be a long-term solution. In the long term, free markets are going to determine this, but this country has supported firms during economic transitions for a hundred years, and we should do the same here.