I remember when my local grocery store started charging five cents per plastic bag. Within weeks, I saw people walking in with their own totes. Nobody needed a lecture or a new law telling them bags were bad—the price just nudged everyone in the right direction. That's the core insight behind a global carbon tax. It doesn't dictate which technologies to use or which industries to punish. It simply makes emitting carbon cost what it actually costs, and then lets millions of individuals and companies figure out the most efficient way to reduce those emissions. That's why it's the best tool we have. Other approaches—subsidies, regulations, bans—are piecemeal and easy to game. A uniform price on carbon covers every sector, every country, every source at once. It's transparent, hard to evade, and it rewards innovation naturally. If we're serious about coordinating a global response, a carbon tax is the closest thing we have to a single, fair, effective lever.

You're treating enforcement as a fatal flaw, but that's true of any global climate agreement—including the R&D fund you're proposing. At least a carbon tax creates a self-reinforcing incentive: once industries in honest countries pay a price, they'll push their own governments to level the playing field. The free-rider problem gets smaller, not bigger, as more nations join. And the "no alternatives yet" argument actually cuts the other way. A carbon tax is precisely what makes those alternatives viable. The reason green steel or sustainable aviation fuel isn't scaled up is that fossil fuels are artificially cheap. Tax them, and the investment case for alternatives becomes obvious. You don't need regulators to pick winners—the market does. On regressivity, that's a design issue, not a fatal one. You can rebate the revenue to households, which is what British Columbia does. The yellow vests protest wasn't about carbon pricing, it was about a government adding a tax without returning the money. The question is whether we want a single coordinated lever or a patchwork of subsidies. I'll take the lever.

Take the steel industry. If I'm a steelmaker in a country with a carbon tax, and my competitor next door isn't paying one, you're right, I'm at a disadvantage. But that's precisely why a global carbon tax would include border adjustments. Countries that tax carbon can apply a fee on imports from nations that don't. That doesn't make leakage disappear overnight, but it makes the tax itself a diplomatic lever, not just a price signal. It gives honest countries a concrete reason to push laggards into line. On substitutes, your cement example assumes we just accept the current tech and pass the bill. But the tax is the thing that funds the pivot. The revenue it generates can finance exactly the R&D you say is missing. British Columbia shows it can be done fairly. The tax isn't the only tool, but it's the one that makes every other tool work harder.