More people should upvote your post. If there is a rank of how easily humanity can destroy itself and make the earth uninhabitable for itself geoengineering is probably second only to thermonuclear war.

Also I object to the use of the term geo-engineering. Engineering supposes we know exactly what the outcomes will be following centuries/decades of experience with similar systems. Including many failed experiments. Thinking we can geo-engineer a predictable change when there is no way to experiment, fail and learn safely because we only have one shot at this is massively stupid. Anyone that claims "but we've been geoengineering for decades with our greenhouse gas emissions etc" is simply wrong. No, we haven't been "geoengineering". Engineering implies conscious intent. Humanity didn't start burning coal to increase co2 content in the atmosphere. Confusing these two things are akin to finding a victim of a vehicle accident and doing a roadside open heart surgery by a random bystander. "Hey, the guy is already sliced open, we've already started the surgery so we may as well continue right?" No, wrong. That is insane.

The biggest lie today is that we comprehensively know how climate works. We don't. We don't even measure the earth's temperature properly. We extrapolate huge amounts of data. If we _really_ wanted to learn how climate works it would require not just arrays of sensors covering the entire planet's surface, but also ocean depths and the the entire thickness of the atmosphere. No, satellites are not a replacement. Anyone that knows the limitations of satellite sensing knows we can measure a lot, but reliably measuring temperature, humidity, and wind direction across the entire thickness of the atmosphere is not something we can do. We can roughly approximate some measurements across the entire thickness, in theory in good conditions we can narrow it down to certain attitudes and on this basis we make conclusions on the entire state of the system pulling the missing data from our "models". If we discovere the models are wrong? We just tweak them to match the historic data. We might know the measures in this particular place and time, but we use our "models" to "approximate" everything we are unable to measure.

This is one of the major reasons why we cannot reliably predict weather for next 3 days, and why our attempts at making climate predictions are laughable. We know a certain number of principles so we can make some conclusions like more co2/h2o/ch4 = more temperature, but even in this we have to accept there are processes (positive and negative feedback) we have zero idea of.

Furthermore, our planet has shown us huge climatic variability in the geological record. Within that variability the most dangerous to human life are periods of excessive glaciation (ice ages). We're "just" in the warming period after the last one. Is humanity taking part in accelerating the warming? Yes, is it a licence for stupidity like attempting to "stabilise" something that is inherently unstable and periodic(climate) risking we overdo it and find ourselves in a "mini ice age"? No.

Has it ever stopped us before? No. Anyone interested in results of previous "geoengineering" efforts should read up on the soviet attempts at it and what catastrophe it wrought on the region including the Sea of Azov. People in the entire Black Sea region can consider themselves extremely lucky they haven't implemented more than few percent of their plans. It is generally accepted today had more of Soviet attempts at geoengineering been implemented it would've had same horrible consequences we see near the Sea of Azov far and wide.