It is just curiosity that forced me to ask this question. At some point in time, if we can't control global $\sf{CO_2}$ emissions, temperature will increase until a tipping point and it will be a complete catastrophe. However, if we could prepare ourselves through geo-engineering (e.g. carbon removal, blocking solar radiation), then we may return the temperature back to normal. I am not saying that we have to experiment with mother Earth, but if we may do weather-engineering experiments in controlled labs just like the Large Hadron Collider(LHC), we may some day be able to save the planet from catastrophe.

So, my question is, how bad does geo-engineering go as far as controlled experiments done in totally isolated labs?

In NWP models, it is mostly possible to control the evolution of $\sf{CO_2}$, solar radiation, moisture, temperature etc. Given the current computation power is better than in the past and will most likely be better in the future, once we have calibrated and validated those climate/weather models, can we use them to fight extremes of weather like floods, drought, hurricanes and all other wind storms?

The accuracy of current weather predictions is better for forecasts 5-10 days ahead. So, this may give enough time to do controlled simulations before and after our intervention. Based on that we may act on to, for example, increase precipitation (e.g. through controlled spraying of condensation nuclei) where there is drought, hit and disperse hurricanes or change their directions before they hit and damage cities etc. How wrong can one be to think like that?

• Why do you say that geoengineering is 'bad'? In point of fact, what's happening now WRT CO2 is (unintended) geoengineering. Most of the proposed geoengineerings (at least the technically feasible ones) I've seen are 'bad' only in the sense that they are at best band-aid fixes, which attempt to treat the symptoms instead of addressing the root cause. – jamesqf Feb 26 '16 at 6:26
• @jamesqf: that sounds like a bad idea to me. It's like taking pain killers to make it easier to walk on a broken leg. Sure, you can't feel it as much, but you're letting yourself do more damage than you would if you just stopped walking for a while, and you will probably have to live with that damage for ever. – naught101 Mar 3 '16 at 2:24
• @naught101 Strange analogy, but if you get shot, the doctor often doesn't work to treat the root cause, but to stem the troubling symptoms. Bandaids and gauze pads and sutures aren't a bad thing then! Likewise during a heart attack, the most vital thing is the doctor gets your heart beating. Then (and prior) he tries to get fixed what's causing the troubles. Point is, while the fixes aren't usually the most positive option... geoengineering seems about like bandaids and heart paddles in terms of keeping things going when the problem cannot (or will not) be fixed. – JeopardyTempest May 28 '17 at 11:12
• weather is not climate, and its not a good idea to confuse the two. Accuracy of weather models has little to do with accuracy of climate models. – John May 28 '17 at 19:05
• @John. Climate is an average of weather. Weather models are an initial value problems but climate models are a boundary value problems. But the physics is the same. So, at the base they both are the same. There is no confusion here. Geo-engineering could be applied to solve both a weather and climate problems. – Gemechu Fanta Garuma May 28 '17 at 20:42

The bad part about geo-engineering are the unknown unknowns, to paraphrase a certain US politician.

Our climate models are wrong. All models are wrong, but some are useful.. Our models are useful, but not quite useful enough to trust them when they tell us massively spraying stuff into the stratosphere or the oceans is mostly harmless. Our models can't properly reproduce our current climate. They agree about some trends, but there's lots of stuff that they're missing.

We used to use lots of toxic chemicals in our fridges. That was a bad idea, so we found some stuff that wasn't toxic. Great, no? Decades later, scientists realised this was destroying ozone above Antarctica. At first the measurements were rejected because they didn't make sense. Contrasted with our understanding of the atmosphere, and why would ozone suddenly disappear anyway?

Our climate system is complex. Very complex. Mess with one of the symptoms, and who knows what side effects are going to be? It's a risk that we cannot quantify, and those are probably the scariest risks out there. If even with stuff that doesn't seem remotely connected to each other (fridge coolants and ozone) we almost messed up very seriously, who is to say actively messing with our atmosphere or ocean isn't going to have nasty unintended consequences?

Better than offsetting one set of geoengineering (deforestation, ocean acidification, enhanced GHG emissions) with another equally radical one, it might be safer — from a risk management point of view — to try to not do any geoengineering at all. Certainly as long as our understanding of climate is just starting.

Note that weather models are initial value problems and climate models solve boundary value problems, so mathematically speaking, the two are completely different.

Seconding eveything that @gerrit mentioned.

Additionally, another major problem with geo-engineering is that once we've started these processes and essentially borrowed time to offset mitigation measures, we'll have put ourselves in a situation where these measures will need to be continued almost indefinitely, regardless of the risks of negative side effects of geo-engineering to begin with (ie: chemical intrusions, biological system degradation, geopolitical concerns). Present climate models suggest that if we were to engage in climate engineering and then remove these after several years, warming rates will come back with force (http://iopscience.iop.org/article/10.1088/1748-9326/4/4/045103).

• This is particularly the case with artificial aerosol cooling, because you're masking warming, and as soon as the aerosols are removed from the atmosphere, the warming starts again (and with more CO2, so stronger). It's also a problem with Carbon Capture and Storage, which always has some minor leakage - you're effectively putting off the warming from now, and saving it for later. It's still going to happen, either way. – naught101 Mar 3 '16 at 2:23