As a frustrated environmentalist myself. I would just like to say, burning or not burning natural gas for heating is dependent on a lot of factors. But the GP is generally right in most of the US because the energy is already coming from coal or natural gas. Both of which are back of the envelope about 50% efficient at converting heat from the burnt coal/gas to electricity. Add in the transmission and distribution loss (aka step up/down transformers, increasing distances to the electric plant as they are moved farther outside of cities/etc) and its another ~5-10% loss, and then the final conversion assuming a heat pump has a 50% gain. So its roughly a wash, and the actual gain/loss is dependent on electric mix (nuke+hydro), how cold it is outside (heat pumps for heating get really inefficient as the temps drop until they are basically restive heating, which many switch to after a certain point to avoid just burning up the compressor).
There are similar problems around wind/solar, which tend to just be green washing natural gas peaker plants, many of which aren't even combined cycle. So the easy back of the envelope here is, that if your not getting ~50% of your power from a nuke its likely that burning the gas in your house is more CO2 friendly (the places with lots of hydro also have nukes, so 1rst order approximation).
And the plastic bag thing, is again feel good because those bags both have a very short time to degrade (despite all the environmentalist misleading people into thinking they last decades, which is true when they are buried in a landfill, but that isn't the case they then talk about which is finding them in the open environment where UV destroys them in a few months to a couple years).
The plastic drink bottles though? Those are much more robust, but just about no one banned them in favor of recreating the commercial bottle washing systems we had before and that exist in mexico/etc. But again, one had to be very careful about total system costs, which is how we get back to nukes. We have to shift the energy curve away from CO2 sources, and the only way to really do that is to find a significantly more energy dense mechanism. And we have one, which is somewhere in the ballpark of 7 million times as dense per Kg and instead of arguing about the CO2 being emitted to move or manufacture things, we could basically zero it out with 40 year old technology and likely gain another order of magnitude of efficiency if we built energy systems with modern technology that actually burnt the entire fuel load rather than calling it "waste".
Most environmentalist are just as uninformed as the climate deniers, which is why we are stuck.
PS: once you start to understand much of the above you can also see how premium electric cars can frequently be worse for the climate than econobox gas. The numerical systemwide advantage isn't so overwhelming to wipe out the disadvantages in places that get a lot of power from coal.
