My thanks to Ben Wouters, who posts as Ben AW here at the talkshop. He has been patient and easygoing throughout the N&Z debate, injecting his own perspective in various comments, some of which I’ve pulled together here to form a loose narrative of his line of thought. To my own way of thinking, his ideas don’t actually conflict with N&Z’s theory. I’ll explain why in comments.
Lets call the earth + atmosphere ‘SYSTEM earth’.
Looking from space system earth is a sphere that receives ~1364 W/m^2 on a disk with the same radius as system earth and radiates away to space from all sides.
Just draw a sphere (circle in 2D) and show incoming from one side, and outgoing everywhere.
If anywhere in this system radiation is 100% reflected, it doesn’t influence the energy of system earth, and may as well not be there.
So in my opinion albedo is the same as throttling down the sun, or placing a partly reflecting mirror outside system earth.
Assuming 30% reflected radiation incoming solar is 955 W/m^2 on the mentioned disk, distributed over the whole sphere makes ~239 W/m^2. If the averaged outgoing is also ~239 W/m^2, sytem earth is radiatively in balance with incoming solar, and the total energy (and temperature) doesn’t change over time.
What happens inside system earth and what the temperature is at some places is what everybody is arguing about. I have a very simple model in mind, that explains to me all kinds of processes, without going into much details initially. Everything that happens INSIDE system earth is just redistribution of energy, having no influence on the total energy.
Incoming solar is either:
- absorbed somewhere and transported or re-emittted and thus part of the energy budget of system earth
- or it is reflected without doing anything and may as well not exist for system earth.
I’m not interested in black, gray or purple bodies in whatever flux field you can imagine. It’s not relevant for my system earth.
It seems 239 W/m^2 IS the average outgoing radiation, so incoming HAS to be reflected partly to match this number.
Can we continue and use 70% of incoming solar after albedo as realistic and have a balanced radiation budget?