Thanks for this article Geoff, it gives people like us a new image. Having a "terra-forming green roof" on our house sounds so much better than living in an underground bunker, as our friends are apt to call our endeavours to live in harmony with the environment. 20 years ago we built an earth-covered house. We collect rainwater, have solar panels for all our electricity and cook on a combustion stoveand and have lived with the social odd-ball image of having to live below ground ever since.
With this new image we might even get over the condescending smiles of understanding, with which our friends and visitors accept our social excentricity.
Keep it up, Geoff!
alfred.

Curious. Under the climate modelling assumptions the addition of vegetation to rooftops would actually contribute to global warming because the albedo of the rooftops would be reduced from increased heat absorption by the vegetation.

The rooftop vegetation may reduce daytime temperatures but nightime temperatures will be higher, producing a net warming effect.

The greatest contribution to reducing global warming by rooftops would be to maximise their reflective capacity and put them on houseboats in those parts of the tropical oceans that have minimal cloud cover.

Oceans absorb 96.5% of insolation and reflect only 3.5% (albedo). Vegetation ranges from 75% absorption, 25% albedo (in deserts), up to 90% absorption by dense forest. But the world's clouds take the planetary mean absorption to 70% with 30% reflected.

The most reflective surfaces are snow and some newly developed paints etc that can achieve 90% reflection.

So the placement of highly reflective roofing material on houses floating on water (preferably in the tropical high pressure zones adjacent to desert landscapes) will maximise the amount of reflected solar radiation and do most to cool down the planet.

But the climate muddlers have yet to incorporate the cooling effect of increased albedo from land clearing that has already taken place and also refuse to measure the warming effect from increased heat absorption by widespread regrowth and woodland thickenning.

All they, and the green spiverati, have bothered to do is measure the carbon in cleared regrowth (while pretending it is high volume old growth) and speculate on the warming caused by the released carbon. And this inconvenient half truth is why the models predict a global warming. They left out the equal and opposite cooling.