I'm all for Geo-engineering if it is done in the right way to further benefit all of society and the planet. Sadly as humans we have never all come together for the benefit of the planet yet, and I am doubtful we will in the near future.
My fear is that once people figure out how to Geo-engineer things with fine tuned results that it will eventually be used as a weapon.
Imagine if you could turn up the temperature of an area to create a drought?
Or flood/freeze out an area?
This could be done covertly as it would be hard to identify the exact cause if done under the 'radar'.
No bomb shells or traces left behind to place blame.
I'll pass on homo-sapiens ego presuming they are smarter than the planet and can fix any problem using technology and our brains.
Maybe for the first time in History we may be smart enough to mitigate the potential ill effects of the climate cycle, however this planet was here long before humans and will probably be here long after.
There was a joke once, about human's being the planets Herpes, which seems to be a good metaphor for our existence on this rock.