[pmayrgundter]

Based on the discussion in the descendent thread with morsch, it seems like the runways are the real story, at 1000x the mass of the airport roof.

But concrete is not so CO2 intensive. Lumber has a +1.6 sequestration factor of CO2 emitted vs built mass, compared with concrete at -0.8.

So we'd need runways made mostly of wood, or combined with a Woodcrete that was net sequestering, and then maybe there's a way to make even our most CO2 intensive industries net neutral so long as we rebuild continuously.

Also, since construction is about 40% of global CO2 emissions, if it could become a net sequestration as a whole, maybe it could flip the sign to -40% and offset most of the rest of our industrial emissions.

This also got me interested in what's a good number for rebuild rate.

Found a study that concludes the "Apparent ecosystem carbon turnover time [T]" is 43±7 years.

So maybe we should be rebuilding our built environment at 2.3%, or probably higher since species have evolved to be more energy intensive, humans especially.

[T] https://essd.copernicus.org/articles/12/2517/2020/essd-12-25...