Easy as pie. Easy, peasy. All we have to do is tweak a few laws.
New law. Matters relating to climate change and including claims for consequential human suffering and loss shall no longer be protected by the laws of limited liability but shall extend to investors personally, either as lenders, shareholders or as corporate directors, jointly and severally.
Don't just pierce the corporate veil, shred it into tatters. For this one, civilization-threatening crisis, you're on the hook, personally, for every last cent you have. The corporate fiction was intended to facilitate commerce, not to destroy mankind. What was meant to serve us now exists to ruin us. We made it, we can remake it.
Relax, they'll never do it. The sort of reform I'm suggesting would probably shut down the fossil fuel industry quite abruptly when we're far from prepared to rely on alternative energy sources. The important point is that Big Fossil is only able to inflict this potentially catastrophic damage because the individuals pulling the strings are personally immune from the consequences.
There are probably many coal and oil executives who go to work in the morning fully aware of the need to throttle back on fossil fuel consumption. Yet, once they get to the office they're duty bound to do everything possible to make their companies profitable, to maximize shareholder return. If they don't, then they can be sued, held personally liable to the company and its shareholders.
The irony is that the same body of laws that renders these corporate controlling minds personally immune from liability for making decisions that contribute to undermining the viability of our environment, attach personal liability to those same individuals for failing to make those same decisions. That is why we vest government with the authority to regulate these situations, an essential power that government too often these days refuses to exercise.