Managing sunlight

[mindstalk]

Questions for pompe and anyone else who can answer:
if we used space mirrors so that the nightside of the Earth got the same sunlight as the dayside, would we totally roast? How quickly/badly?

What if we get the same total sunlight as now, but split and redirect it, so that the tropics at noon get less than half what they do now, but the entire planet gets that same level, 24/7? I imagine net thermodynamics wouldn't change much, weather would be massively changed, but I'm most interested in plant productivity -- is it more productive to have a constant moderate level of light everywhere, rather than some times and places with intense light and others with none, or vice versa?

Comments

[mindstalk.livejournal.com]

Thanks.
Quick reply: tropics are larger than the poles? The poles themselves aren't much, but I thought the tundra/taiga area of Canada and Russia was pretty extensive. Top-heavy planet and all.

Yeah, ineffective photosynthesis is what I was thinking of -- that plus one ecologist saying that plants were actually 20% or more efficient at low light levels. Which is why I often think of CO2 extraction as the limiting factor... and thought that evening out the light supply would be a net productivity boon, after adjustment. Hadn't thought of dew though, never mind what rainfall would be like in this system.

[tempter.livejournal.com]

I remember learning long ago that plants effectively undergo a kind of rest cycle based on when it's dark out. I don't remember the term for the cycle or process, but I remember the experiment to test it: if you take two identical plants (control and test) and interrupt the test subject's dark time with bursts of light every hour or two throughout the night, the plant ends up dying off. I'm pretty sure the result extends to having no dark time at all.

So, my answer's a cop-out -- I don't know how quickly we'd fry, but I don't think we'd last too long without plant life recycling CO2 for us.

[pompe.livejournal.com]

It differs between plants. Some plants are shade species as an example.

About fifty percent of Earth's surface lies between 30 degrees north and south.