[cheese_goddess]

> I'm very confused by why you think this is sustainable - this type of life uses FAR FAR FAR more resources than modern living.

Living in a society without heavy industry, without, electronics and without internal combusion engines uses up "FAR FAR FAR" more resources than living in a society with them? How so?

[ars]

Because the internal combustion engine is surprisingly efficient.

Did you know you release more CO2 walking a mile than driving a mile? It's surprising, but it takes a lot of energy to grow food, and then a lot of energy is lost by the time that food powers you.

Yes the CO2 from food is from the air, so not the same, but it's just an example of efficiency. Ignoring the source of CO2, a tractor emits less CO2 than a horse, for the same farm work.

You still need to heat your home, you still need to find fertilizer somewhere, you need fuel for cooking. You need to make clothing.

All those things take energy, and modern living uses less energy. The main difference from the past is there are more people now. And in the past a lot of that energy came from the sun, rather than being mined.

But back to resources (rather than just CO2): To live like a farmer you need wood, and you need more wood than can re-grow in the area available to you. Look at peat moss mines in Ireland - they mined so much, just for basic living, there's not much left.

[cheese_goddess]

No, the main difference from the past is that we have been taking fossil fuels out of the earth and burning it for the last 200 years, and releasing in that very short time the CO₂ that has been stored in them for many millions of years. This is much more than the amount of CO₂ that the environment's carbon sinks can bind and so we are warming the environment, and at a very fast pace.

Like you say, the CO₂ we breathe "comes from the air". Specifically, that CO₂, like the carbon gasses released by farming and agriculture, is part of the atmospheric carbon cycle that circulates carbon gasses between the biosphere and the atmosphere. This cycle is stable, it has been stable for millions of years and it has never caused a greenhouse effect, neither is there any risk that it will cause a greenhouse effect, now or in the future. There is certainly no chance that the CO₂ we exhale will cause the amount of CO₂ in the atmosphere to shift, because that's where we get our carbon in the first place.

The internal combustion engine on the other hand, efficient or not, is burning fossil fuels and is a primary driver of release of the CO₂ bound in fossil fuels, to the environment. This is a major mechanism of climate change.

That having been cleared up, you're making a weird argument that is very difficult to support. If I understand correctly your earlier comment that I quoted, you're saying that living, in summary, without burning fossil fuels, is not less sustainable than living while burning fossil fuels. You 're saying that this is because the internal combustion engine is efficient. You mean that it makes good use of the fuel it burns, but its fuel cannot be easily replaced (because it takes billions of years for it to be created by natural processes that we can't replicate at scale) and burning it is causing a greenhouse effect and climate change.

So, no, it doesn't make any sense that living without burning fossil fuels, without combustion engines, without all the trappings of modern life, is not more sustainable than living with them. We can discuss the benefits and risks of either way of life (I'm not keen to return at a pre-industrial time myself) but it is abundantly clear which way of life is sustainable, and which isn't. And that's not "more sustainable". Burning fossil fuels is just not sustainable anyway you cut it.