Handwavy? Nuclear is real, EV automobiles are real, heat pumps for heating and AC are real, insulation for buildings, planting more trees in urban areas helps with the heat island, and creating more green is trivial and helps with storm water management.

Electrified rail.

Low CO2 concrete. Real, already used.

The list is almost literally endless.

But anyway, all of these are simply cost based choices. A carbon tax would literally overnight shift the consumer choices. And the cost effectiveness depends on the market, and that is usually the best we can get.