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wouldn't large scale usage of a device like this essentially increase the planetary albedo and help fight climate change? especially if you just skip the "envir

wouldn't large scale usage of a device like this essentially increase the planetary albedo and help fight climate change? especially if you just skip the "environmental heat transfer" part

coolradmab 5y ago
Short answer not really https://what-if.xkcd.com/84/ https://what-if.xkcd.com/84/
- wolfram74 5y ago
  That's more a "we haven't made enough paint to cover a large fraction of the planet" argument than a "what would the thermal ramifications of such an act be" argument. Which I was excited to read about, but alas.
  - jschwartzi 5y ago
    You would need a really big roller with a lot of knap too. Although I suppose you could paint most of the midwest and avoid the mountains with a flatter roller.
  - samatman 5y ago
    For an interesting toy model related to this, check out Lovelock's Daisyworld simulation: https://en.wikipedia.org/wiki/Daisyworld https://en.wikipedia.org/wiki/Daisyworld The argument (and the related Gaia hypothesis) has some important and subtle connections to the facts of climate change. Though even if it's correct, and the biosphere will tend to naturally reassert homeostasis, there's no guarantee we'll enjoy living through it.
- Tade0 5y ago
  This makes me think: Earth's energy imbalance is around 0.5W/m2, while such a paint sends how much, 40W/m2 through the transparency window? So we'd only have to paint 1/80 of the Earth. That's ~6.4mln km2, or 2/3 the area of the USA. Still a lot, but not impossible. I'm sure paint manufacturing scales better than li-ion batteries, and those more than doubled in production volume over the last decade.
  - david-gpu 5y ago
    Interesting, but even if we solved the temperature problem, we would still have the issue of the acidification of the oceans due to excess CO2. In the end we must remove CO2 from the atmosphere one way or another.
  - IgorPartola 5y ago
    All that would do is offset things so that we can pollute more. Not to mention the CO2 and other emissions from such a project. And it would ruin a huge amount of space because of course this would run into “not in my neighborhood”. It’s far better to fix the problem than to paint over it.
alex_h 5y ago
There's some numbers here for what it would take. https://www.cell.com/joule/pdf/S2542-4351(19)30354-X.pdf https://www.cell.com/joule/pdf/S2542-4351(19)30354-X.pdf Basically we need 1W/m^2 of cooling for the earth, so if you could get a radiative cooling device with 100W/m^2 you'd need to cover about 1% of Earth's area
- hatsunearu 5y ago
  I assume the actual radiative power is greater than the cooling capability, since cooling power = radiative power - heat intake from atmosphere - heat intake from sun so the math works out even better than it seems...?
- davidjytang 5y ago
  Let's say human inhabit roughly 10% of Earth surface. If we cover all rooftops in the world, that ought to make some effect yeah?

wouldn't large scale usage of a device like this essentially increase the planetary albedo and help fight climate change? especially if you just skip the "environmental heat transfer" part

coolradmab 5y ago

Short answer not really https://what-if.xkcd.com/84/ https://what-if.xkcd.com/84/

wolfram74 5y ago
That's more a "we haven't made enough paint to cover a large fraction of the planet" argument than a "what would the thermal ramifications of such an act be" argument. Which I was excited to read about, but alas.
- jschwartzi 5y ago
  You would need a really big roller with a lot of knap too. Although I suppose you could paint most of the midwest and avoid the mountains with a flatter roller.
- samatman 5y ago
  For an interesting toy model related to this, check out Lovelock's Daisyworld simulation: https://en.wikipedia.org/wiki/Daisyworld https://en.wikipedia.org/wiki/Daisyworld The argument (and the related Gaia hypothesis) has some important and subtle connections to the facts of climate change. Though even if it's correct, and the biosphere will tend to naturally reassert homeostasis, there's no guarantee we'll enjoy living through it.
Tade0 5y ago
This makes me think: Earth's energy imbalance is around 0.5W/m2, while such a paint sends how much, 40W/m2 through the transparency window? So we'd only have to paint 1/80 of the Earth. That's ~6.4mln km2, or 2/3 the area of the USA. Still a lot, but not impossible. I'm sure paint manufacturing scales better than li-ion batteries, and those more than doubled in production volume over the last decade.
- david-gpu 5y ago
  Interesting, but even if we solved the temperature problem, we would still have the issue of the acidification of the oceans due to excess CO2. In the end we must remove CO2 from the atmosphere one way or another.
- IgorPartola 5y ago
  All that would do is offset things so that we can pollute more. Not to mention the CO2 and other emissions from such a project. And it would ruin a huge amount of space because of course this would run into “not in my neighborhood”. It’s far better to fix the problem than to paint over it.

alex_h 5y ago

There's some numbers here for what it would take. https://www.cell.com/joule/pdf/S2542-4351(19)30354-X.pdf https://www.cell.com/joule/pdf/S2542-4351(19)30354-X.pdf Basically we need 1W/m^2 of cooling for the earth, so if you could get a radiative cooling device with 100W/m^2 you'd need to cover about 1% of Earth's area

hatsunearu 5y ago
I assume the actual radiative power is greater than the cooling capability, since cooling power = radiative power - heat intake from atmosphere - heat intake from sun so the math works out even better than it seems...?
davidjytang 5y ago
Let's say human inhabit roughly 10% of Earth surface. If we cover all rooftops in the world, that ought to make some effect yeah?