numbers, not adjectives — D. J. C. MacKay

2  The 50x Climate Multiplier

Carl Edward Rasmussen, May 18, 2026

When a nation like the UK, with ~1% of the world population, invests in reducing greenhouse gas emissions, the climate benefits manifest ~1% nationally and ~99% in foreign nations, because we all share the same atmosphere. This poor national Return On Investment (ROI) is one of the main reasons national politicians are reluctant to act.

Exchanging unilateral action with conditional common commitments – “I will if you will” – changes everything. If nations responsible for just 50% of global emissions agreed on action conditional on others doing the same, the national pay-off becomes 50 times larger than with unilateral action. Your individual national cost remains the same, but because 49 other nations are matching your action, your national climate benefit is 50 times larger. At no extra national cost.

It is not that emission reductions don’t pay off, it’s just that under our current unilateral system, they pay off mostly elsewhere. But that doesn’t mean we shouldn’t act; it means we should act within a framework that guarantees that national investments pay off nationally. And that is what conditional common commitments do. The best possible common commitment will be to price greenhouse gas emissions, ensuring a level playing field across all participating economies.

But why would other nations join? Because we’re all trapped in precisely the same situation. Every other country looks at the global map and hesitates for the exact same reason we do. Joining a conditional common commitment is good for you and its good for everyone. This is not about going first at additional exposure, it’s about acting together.

This has nothing to do with altruism. It’s about aligning your selfish goals with the common good. It replaces the common narrative that “we all have a moral duty to reduce our individual carbon footprint”.

But what about possible free-riders, nations who refuse to join? The 50x argument doesn’t require global membership to work. Conditional common commitments are still much better than unilateral action even without unanimity. And the moral justification of sanctioning free-riders would be compelling.

This isn’t utopian fantasy. It is a structural design we could simply adopt. The Themis Mechanism is a concrete proposal for deploying conditional common commitments. Are you content to continue to embrace the tragedy of unilateral action, or are you ready for a 50x better framework?