Given the extreme unlikelihood that anything we could do to reduce emissions or suck carbon out of the atmosphere will prevent worsening global warming, we'll need to consider geoengineering, even though this is in itself a scary prospect. It will be a matter of the risks of letting greenhouse gases mount outweighing those of tinkering with the planet's thermostat.
Solar geoengineering might be the technique with the most practical promise. It's cheap and supposedly works well on paper. The idea mimics the well-known cooling effect that major volcanic eruptions produce, as aerosols get spewed into the the atmosphere. It doesn't take all that much aerosol to begin to moderate the heat of the sun.
If the scientific challenges seem pretty mild, the political ones are where the real problems begin. Even non-wealthy countries could use this technology, creating the probability of conflicts with neighbors, since you can't precisely limit the over-land effects of squirting aerosols into the atmosphere. Maybe adjoining nations don't want to be cooled, or maybe there will be side-effects for them that we can't yet anticipate, such as drought. Preventing conflicts by getting the world to agree on the best temperature profile for the planet, through the UN or any other means, has a fantasy flavor to it.
Even contemplating doing such a thing is a good prompt for us to reflect on our dominance over other life on earth. We take it into our own hands to change the environment because of what will benefit our own species. That is the moralistic angle.
The article I read asked whether the first nuclear war could erupt over nations having different agendas for geoengineering.http://hamptonroads.com/2015/01/parker- ... ture-earth