Earlier quoted context omitted.
The nice thing about space mirrors is that of all the climate mitigation methods I've heard, they are by far the most controllable. Solutions like "let's stuff the oceans full of iron to grow plankton to absorb CO2", even assuming they work as intended, have the problem that they are irreversible. Space mirrors can put heat where we want it, and remove it from where we want it, and can do so on hours of notice. It's…
What makes it simplistic for me is really the idea that we can make the climate better by tinkering with a single variable (temperature in this case) - I'm not convinced we even know what 'better' is, let alone have enough understanding to predict what the side effects would be. What if we cause some imbalance that doesn't immediately manifest any problems but has a detrimental longer term effect? I do take your poin…
"but there is conservation of energy" - true, but the earth has more than enough energy stored up to heat up the surface to 6300 degrees celcius (at least). The fact that these stores exist means that they got their energy from somewhere. If said energy intake were to increase temperature would obviously drop, potentially by a lot (well, not by that much, it can only drop another 300 degrees after all, but if it were to drop 30 degrees we're all dead anyway, so small changes suck as well). We don't know what affects heat transfer from athmosphere/oceans mantle and reverse, we just know big transfers exist. Suppose, one of the variables had something to do with co2 ... "whoops"
So you want to change earth's climate in a controlled manner ? Too bad. It's the same kind of problem as walking on water. It's perfectly possible to walk on water, you just have to generate the correct amount of force in the correct direction by pushing water down with your feet. You might actually succeed in doing this for the first step, but then you get waves. There is no law of physics that states this directed splashing can't work, but I'm sure you can see what is going wrong in practice.
If we modify earth's climate, we'll be creating all sorts of different waves, which will affect our future modifications to the climate, and since we won't be able to correctly predict those waves, we can't know beforehand how things will interact.
Unless there are major errors in the theory, changing the climate in predictable ways is impossible.