What is GE? Why is it bad? What do we suggest? 

GE has a variation of definitions but they all say roughly this:
"It's the deliberate large scale modification of planet Earth and its systems."
There are different types of GE, and below we give a short introduction to the two main types 
that usually are suggested as solutions: CDR & SRM. 
CDR (Carbon Dioxide Removal)
CDR technologies use biological, chemical, or physical processes to cause the ocean or terrestrial biosphere to absorb atmospheric CO2 or directly store it geologically. Ocean fertilization, BECCS and Biochar are some examples.
SRM (Solar Radiation Management), also RM or "Albedo modification"
SRM technologies aims to “dim” or reflect the sun. One concept is to mimic the dimming and cooling effects of a volcanic eruption (and existing particulate pollution made by human activity). Another concept is 'whitening' clouds to reflect the sun’s rays. Both concepts means spraying aerosols into the sky, using compounds like Aluminum, Sulphur and Barium. More.
Why is it bad?
Climate engineering/geoengineering can radically disrupt weather patterns and the hydrological cycle (causing drought in some areas, flooding others), deplete the ozone layer, and contaminate the entire planet with toxic fallout from  atmospheric spraying. As if this was not enough, dimming of the sun also results in degradation of many biological processes (including in humans).
In short: GE (especially large scale SRM) will attack our wellbeing and even the foundation for all life as we know it. More.
What do we suggest?
This issue is not only related to other issues like Climate or Pollution, it's also just as big and serious as these issues. We recommend not to use GE in general, but if someone still considers it we recommend the following compromise:
1) Biochar (CDR) in organic versions
2) All other CDR technologies
(3) SRM (never use these technologies)

Will we change the destructive ways of mankind, or will we force planet Earth to adapt to mankind?

Some additional info
Science articles: GE is not a solution + Scientist terrified of GE + Scientists warn against GE + GE is barking mad + Less rain from GE? + GE ineffective + Fixing the sky (book) + Unintended hazards of GE .
Research: GE in general. Biochar. BECCS. Ocean fertilization. Ozone depletion. Sun as the engine of life 1 , 2 , 3. Health effects of Nano particles , Barium and Aluminum (+ environment)
More sources here
News: Climate engineering + A review of the new global climate agreement.
+ COP 13 (the Biodiversity summit) keeps restrictions on GE.

Below: GE according to IPCC.