While I was in the shower, I thought of a brilliant idea! Let’s trigger several smaller volcanic eruptions that release a semi-controlled amount of volcanic ash into other atmosphere. That will cool down the atmosphere, which should buy us some time to fix our carbon emissions.
Then I realized, that doing so would block visible light. Plants need the light to grow, and we need the plants to breathe and eat. Obviously, this is not going to be a long term solution. Oh, and how do you even make sure the volcanic eruption doesn’t spiral out of control and suddenly spew out 50 times the ash we were aiming for. Oh, and volcanoes also spew CO2 and even nastier gases, so… It sounded so good while I was still in the shower. The more I think about it, the worse it gets.
This is called Geoengineering, and we don’t need volcanoes for that. Current approaches mostly consider injecting sulfates or other reflective aerosols directly into the atmosphere to influence how much solar radiation reaches the Earth. The principle is the same as behind volcanoes. This method is in fact already being employed and has been used in the past, albeit only for regional climate engineering.
Why don’t we do this to stop climate change? As you yourself kinda noticed, the consequences could be very unpredictable and dangerous because the effects are difficult to model. However, maybe after everything else has failed Geoengineering could be a viable option.
But the aerosols would also amplify the green house effect right?
There are actually anti-greenhouse gasses like SO₂ (of acid rain fame(!))
https://en.m.wikipedia.org/wiki/Stratospheric_aerosol_injection
This brings up an important point. Greenhouse effect is not the only factor in global temperature changes. There’s also solar input rate which varies enormously with cloud cover.
If we could selectively reflect only IR, but not visible light, then I might be more convinced.