Excellent post as always @mountainwashere with cool figures.

I always like how we end up using a solution to a problem by changing a system that we do not always completely understand prior to changing it. e.g. geoengineering. Change one variable, what are the outcomes? I agree with you that it is dangerous...

Too many of one thing, bring in something else that kills something else that becomes a larger problem than the initial problem.

Getting back to your topic, this (geoengineering) for climate change was addressed as the key plot point of an roaring fun film, snowpiercer:

This scene, the start of the film, humans decide to geoengineer to save the planet, doing so they (we) send the planet into a new ice age (i.e. taking things a bit too far by not truly understanding the problem or the solution). There are some chemtrail stuff that I am not promoting by this was the only video link to cover the starting scene of this cool flim.

Now as a scientist I like seeing how the system reacts on the fringes. Warm something too much and things start to change. With climate change, the climate is changing, more warming, places like Greenland and Antarctica start to melt more, putting more cold fresh water into the Ocean system. With cold water pulsing south from Greenland, this hits the warm Gulf Stream, weakening it and reducing the warming effect it has on Europe and global climate, further changing the climate. See figure below from the journal Nature. Really interesting food for thought.

Figure 1: From Thornalley et al., 2018 - 11 - April - Nature.

I personally do not think we should geoengineer until we understand everything. Who knows, there may be a big natural eruption that does the same thing for us and if we geoengineer at the same time, suddenly we cool things down too much. Cue the Snowpircer train. Who knows, wait and see (well we could model it, but garbage in, garbage out). Cheers!