A country could just offer to buy a increasing amount of zero emission electricity and sell it on the free market until electricity was no longer generated from sources that yielded carbon.
The same approach could work for battery cells that could be used in cars until non-electric vehicles were no longer competitive.
This could be funded by that country's current (probably) progressive tax system.
This doesn't cover air, sea, heating and agriculture emissions. But a carbon tax may not be an adequate incentive to develop electric aircraft or cargo vessels in any case.
The parent is arguing for extreme subsidization to alter the market for electricity and vehicles (etc).
They effectively want the government to spend a lot of money to bankrupt the fossil fuels industry and fossil fuel vehicles, with subsidies toward the generation of renewables and producing electric vehicles.
They're wrong that spending is easier however. Republicans control Congress and the US made a massive mistake in taking on ~$15 trillion in new public debt between 2000 and 2015. Simply put, the US doesn't have vast excess spending room (which means it would require tax increases or new taxes). It would cost trillions over a few decades to pull off the parent's plan.
I agree that a subsidy is infeasible policy. But it wouldn't be effective even if it were feasible to pull off.
Suppose the government gives out free Priuses. Well, then people are going to drive more. Even though some people may be driving more fuel efficient cars, it's not clear that total carbon emissions decrease.
Suppose the government provides free solar cells for everyone. Then people will use a lot more electricity. But solar cells require some carbon emissions to produce, and since people use so much more electricity overall, it's not clear whether carbon emissions decrease or increase.
Either way it's just a totally goofy thought experiment, since a carbon tax is exactly the right answer, and this subsidy idea is so misguided that it could possibly even increase carbon emissions
A country could just offer to buy a increasing amount of zero emission electricity and sell it on the free market until electricity was no longer generated from sources that yielded carbon.
The same approach could work for battery cells that could be used in cars until non-electric vehicles were no longer competitive.
This could be funded by that country's current (probably) progressive tax system.
This doesn't cover air, sea, heating and agriculture emissions. But a carbon tax may not be an adequate incentive to develop electric aircraft or cargo vessels in any case.