Carbon Tariffs

From Matt Yglesias a few days ago:

The EU, Canada, and Japan are in the aggregate much more significant trade
partners than China/Mexico/Brazil. And the case for them charging us carbon
tariffs seems about as good as the case for us charging the Chinese.

I think we're missing the bigger issue: Why a carbon tariff? Why not just a tax on carbon content for domestically and foreign produced goods? Why give domestic producers a "carbon subsidy?"