What is the relationship between decarbonisation and sustainability?

Question

What are the sound reasons (let's put aside the unsound reasons) why decarbonisation takes us further down the road to sustainability; and what real-world circumstances might mean that some specific decarbonisation measures make sustainability harder to achieve?

I'm using decarbonisation as shorthand for reducing the greenhouse gas emissions from electricity, heating, transport, industry, land use, land use changes and forestry. Where greenhouse gas emissions are taken to be those anthropogenic emissions that increase the net forcing effect - so not water vapour emissions, and not emissions of CO₂ where the carbon was already part of the carbon cycle.

Answer 1

Products and processes that provide a benefit while consuming resource(s) at a rate less than those resources are produced are sustainable. Those that consume any resources at a rate that higher than that resources rate of production, but lesser than in common practice are "more sustainable". Those resources that are non-renewable, or renew at very low rates relative to consumption and are definitative to our civilization are the most limiting. Hence why petrol is of such concern.

Reducing greenhouse gas emission does almost nothing to "take us further down the road to sustainability". Reduction of greenhouse gas comes as a consequence. Seeking such reductions as an objective is how all the psycho-greenies ruin good and productive environmental work.

Answer 2

I don't know how sound it is, but I have heard the argument that carbonisation takes us further from sustainability, because a high percentage of CO2 means that some of that CO2 gets absorbed into bodies of water (e.g. lakes), whereby the acidity of the water increases and microorganisms die, leaving the lake lifeless. A lifeless lake is quick to "erode" or dry up, resulting in unfertile land and less flora and fauna. And moving towards a nutrient-depleted earth is in the long run unsustainable.

Apparently, there are already lakes, which have "died", supposedly from the high CO2 content of the air. In that sense, decarbonisation should be part of a movement towards sustainability, at least for the moment.

Of course, more CO2 in the air could also mean more trees, more oxygen and more green, but I guess at the moment the amount of trees is not enough to absorb the effect of the carbonisation.