You're focusing on "today" when this is a twenty or thirty year machine. Twenty or thirty years from now a gas furnace will still be a 100% emitter. A heat pump

You're focusing on "today" when this is a twenty or thirty year machine. Twenty or thirty years from now a gas furnace will still be a 100% emitter. A heat pump has the ability (without upgrades) to move an increasing quantity of the energy to renewables.