Inspired by this thread. If, as an Evil Overlord I concoct a fiendish plan whereby I use a orbiting mirror to block out the sun and freeze the Earth, thus making it possible for me to restock it with humans of my chosing (all selected beforehand, of course) after thawing the planet back out, how long would I have to wait once I’ve removed the mirror from between the Earth and the sun? Would Earth’s increased albedo effect delay this significantly? If I shifted the mirror so that it reflected sunlight on to the Earth, would this speed the process up?
Yes, the albedo of the ice caps will delay this- on the plus side, cloud cover will be less on a snowball earth, so the oceans will absorb heat more readily. Concentrate the heat on the Pacific side of the world.
Try covering the ice with a layer of soot; this should help absorbtion…
adding greenhouse gases to the atmosphere would help as well,
such as CO2 and Methane- you want to have worked out a way of getting rid of them later as well, when you reach your desired temperature.
If you can find some Methane Hydrate deposits under the sea try liberating them- you will find your world is melted in no time.
As a worldbuilder I am often faced with frozen waterworlds - if a mirror isn’t powerful enough to melt the ice, beam some extra power in via laser from near solar orbit.
There are designs available for converting parts of the solar atmosphere into magnetically controlled lasers-
er how evil an evil overlord are you?
We wouldn’t want these plans to fall nto the wrong hands…
SF worldbuilding at
http://www.orionsarm.com/main.html
While you’re building your mirror, make a million-mile-wide convex lens as well. Then you can park the lens between Earth and the Sun.
Be careful with the focus! You want a million-mile cylinder of sunlight coned in on the Earth, but you don’t want a sharp focus on the Earth’s surface. Otherwise you’ll melt through the ice, the crust and the mantle, and eventually release the liquid-NiFe outer core. That’s harder to recover from than a major Ice Age, let me tell you!
Best wishes,
Malacandra
PS - Don’t even think about using Mars for a dry run. I would have to take a very dim view of that.
I find that the defrost setting on a honkin’ big microwave oven works best.
I think there have been some articles published on the use of 1920s-style Death Rays in similar situations.
In The Merchant’s War (the sequel to the classic The Space Merchants) Frederck Pohl has the temperature of Venus altered by using Ranque-Hilsch tubes. These things really exist, and are the closest thing to a Maxwell’s Demon achieved in real life (see the description and references in Jearl Walker’s The Flying Circus of Physics) That’s a different way of heating or cooling a planet without using mirrors or lenses.