2024-12-19
How could we actively cool the earth? These thoughts were with me this morning on waking up, and I suspect partly inspired by part of a Veritasium video about entropy. There, Derek points out that the earth's energy balance is roughly equal, in terms of energy coming from the sun and energy radiated away. So, I was thinking, how could people either change this balance so that more heat was radiated than was received; or, how could some of this energy be captured and not lead to warming the earth? Here are a few ideas some of which are obviously bad. But I wonder if any of them could actually contribute a little to mitigating our climate crisis?
As in the ice ages, when a lot of the Earth's surface is covered in white, it reflects much more of the incoming sunlight without absorbing it. So how about we cover as much as we can with whitewash of some kind?
Actually not such a great idea. This might work in deserts. And definitely an idea for urban areas… make roofs and road surfaces white? Why not? But I don't think the impact would be huge.
Cover as much surface as you can … more efficiently reflective than whitewash, but even more difficult to arrange, along with the fact that to radiate heat at night one would need to remove the aluminium to stop it actually insulating the ground and preventing infra-red radiation escaping. Bad idea!
My idea here is inspired both by biochar in general and by the geological deposition of fossil “fuels” in the earth over millions of years.
If we could recreate the conditions in which the deposits were laid down e.g. in the Carboniferous geological period, then we could start doing that — which would mean that the sun's energy absorbed by vegetation would be captured and stored, rather than used up through decay and other biological and chemical processes, releasing the energy, and recreating the carbon dioxide that was absorbed. That may be possible, but here's what I see as a more hopeful option.
I'm glad to see that the Wikipedia article on Biochar points to a further, more detailed page on Biochar carbon removal. I came across the biochar concept only last year, in the Ecovillage Design Education course, where its benefits were explained in detail.
To fill this out, I imagine forests being selectively cropped and the wood turned into biochar, to be used to enhance the soil on farmland. Selective felling, leaving many or most of the trees standing, could also be a good way to promote biodiversity in woodland. But then I have no special knowledge of these things. I'm just glad someone has thought about it — though disappointed that it doesn't seem to be a big thing yet.