It is pointless to speculate on whether there are risks to geoengineering just as it would be pointless to speculate on whether there are risks to atomic energy. Geoengineering does not offer the level of risk of atomic energy (at least I hope not) but it has shown us enough that we need to exercise a great deal of caution. Instead of investigating methods of restructuring our planet, we should be putting full effort into efficiently using the resources that our planet so freely offers all around us.
No, there are not risks and unintended consequences with geoengineering, because it is largely a safe procedure. Engineers have gone to great lengths to make sure that geoengineering is done as efficiently as possible. Although there is always some risk in this type of activity, on the whole, it is safe, and the benefits outweigh the risks.