Hey A. Robichaud - great question that I think many people are thinking about.  Although I don't really think that the ultimate answers will come from geo-engineering 'solutions', they are discussed much and have become popular as society's "quick-fix" answer to what is rapidly becoming more clear as one of our greatest problems, climate change.  I say all this in the context that simple solutions are not going to solve our problems and we cannot just come up with an engineering solution for magically getting rid of all the CO2 or changing the laws of biochemistry or physics.  The largest set of themes in the drawbacks for coming up with these geo-engineering solutions is that we do not understand the systems-level properties enough to make drastic changes.  There are simply too many unknown variables, feedbacks, and buffering mechanisms.  In short, we are ignorant of the egregious consequences that could happen.  As en example of one of these situations, I can relate a question I asked a visiting engineer that gave a presentation about fixing tonnes of CO2 under the ocean in large 'condoms at high pressure and low temperature.  His solution was to pump all the CO2 into the ocean condom that would lie at the bottom of the ocean.  I asked the speaker to go through a scenario about what would happen if the CO2 condom broke.  He could not answer the question, but dodged it with excuses about how unlikely that event would be.  The drawbacks are that the nature of natural systems prevent an engineering solution to be viable at the scale it would have to be in oder to be considered as a global solution to climate change.

I don't think these Geo engineering project have some drawbacks unless we just enhance their potential, I mean effeciencies.

Well Tirthankar, in any technology project there very often if not almost all the time drawbacks, some might be hard to foretell and surprises might come. The discovery of  CFC's is a good example. Invented in 1928, CFC's was the miracle solution at the time.

CFCs were then developed as ideal gases in refregiration because of their special characteristics, inflammability and non-toxicity to human beings,  For the rest, we now know the damage it has made to ozone layer.

We do not want a Frankenstein planet if geo-engineering present a hidden threat.

Hello Everyone,

It is my understanding that scientists pushing Geo-engineering, especially of the stratospheric aerosol/solar radiation management type (SAG-SRM), led by Dr. David Keith of Harvard University, have no clue as to the potential problems that may arise from actively Geo-engineering the planet, especially under conditions of mounting uncertainty.

These seem to be military-backed operations with no real regard for the planet or the climate, but masquerading as globally beneficial science. Climate change has different manifestations in different parts of the World, and there should be no 'one-quick-fix', without first of all studying local / regional conditions prior to determining the best course for action.

Similar Question:

https://www.researchgate.net/post/Is_the_Havard_Geo-engineering_experiment_a_practical_example_of_science_gone_rogue

https://www.academia.edu/22032445/Engineering_Options_for_Climate_Protection_Solution_or_Armageddon_A_Critical_Review_of_Global_Warming_Mitigation_Strategies_through_Geo-engineering

Reducing the incoming solar flux through geoengineering will seriously affect the solar resource, hence will decrease the output of solar power plants that are precisely being built in an a attempt to curb CO2 emissions, per the IPCC's own recommendations. So what is the global gain?

Reducing CO2 emissions drastically would be a more long-term solution, in my view.