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Suppose all areas of the Earth is suddenly covered in indestructible mirrors (assume they reflect 70% of solar energy that would hit the land/ocean), how quickly will the increase in albedo cause the temperatures to drop? What temperature would it stabilize at?

I'm mostly looking for rough estimates, like, would the temperature be cold enough solidify gases? Would the cooling take years or centuries to approach equilibrium etc.

If more information/complicating factors can greatly alter the answer, please let me know.

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Ignoring the greenhouse gas effects of the atmosphere and the earth's internal heat, and taking an albedo of 70%, Stephen Boltzman's law gives us a temperature of 206K (not showing the working here). That's -66 deg C, warmer than the lowest ever recorded temperature in Antarctica. Certainly not cold enough to freeze most gases (even CO2 freezes at -78). The actual heat conserving effect from the atmosphere keeps our (normal) earth warmer by 33 deg C than it otherwise would (actual avg temp of 15 deg C vs prediction of -18 deg C at an albedo of 30). Therefore, adding this to the -66 deg C gives us -33 deg C. That's warmer than a cold January night in Tomsk.

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  • $\begingroup$ That's just an average, though. The coldest places will also get colder, which could easily result in CO2 freezing out. $\endgroup$ Nov 30 '21 at 2:56
  • $\begingroup$ Yes, of course....CO2 could freeze at the more extreme latitudes in winter. And water vapour everywhere. But argon, oxygen, nitrogen....unlikely to get to the -180 deg C range for those to freeze $\endgroup$ Nov 30 '21 at 3:42

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