So, I'm creating a world in a dystopia format and I'm curious on other peoples opinion about how they would think a fully enveloping Dyson Swarm would affect the earth's temperature. I want the swarm to be close enough to the sun to block out a good percentage of the sun, too. It would definitely drop the temperature, but making it a permanent solution, are we looking at an increasing drop, constant winter, or a chance where it would all balance out.
Earth weather is highly dependent on how much solar energy reaches the lower atmosphere and the surface of the oceans.
If your swarm decreases the solar energy the Earth receives by let's say 25%, then that by itself would be enough to create a new "Iceball Earth" where most temps would be like Antartica levels or colder.
Supposedly, this may have happened once in the past. It took increased volcanic activity (with its release of gases into the atmosphere) to stabilize the situation.
Alternately, if people are still on the planet, they could increase their activities that generate greenhouse gases to warm up the planet. In that scenario, burning lots of coal would be considered eco-friendly.
A lot depends on what the swarm is for in the first place. If it is for converting solar energy to electricity that is beamed to the Earth, then the consumption of that electricity would generate some heat that would partially offset the decrease in temps.
The Earth is a delicate balance. If you dropped the sunlight, it would rebalance after awhile. But if you go too far and trees start dying and polar zones grow, then you will have a run away freeze and the Earth dies.
If this swarm is smart though, it could shift itself to allow sunlight to the Earth as the Earth orbits. Creating a gap in the swarm that moves as the Earth moves.