We are going to develop geoengineering/anti-deterraforming techniques, I'm sure. Yes, there are numerous risks--carbon dioxide leakage from sealed storage areas come quickly to mind, many others exist--but these aren't relevant. Why? Jamais Cascio makes the case that only geoengineering is capable of saving human civilization from catastrophe.
Cascio starts by noting a US government report on future energy use , one which predicts that in a "little over 10 years from now -- coal will provide 10,200 terawatt-hours (TWh) out of a total of 28,700 TWh produced around the world, annually. By 2035, it's up to 12,900 TWh out of 35,200 TWh." He then links to a study on carbon dioxide emissions and climate, tracking the volume and speed of reductions in carbon dioxide emissions needed to avoid the 2 degree Celsius global temperature rise synonymous with existential catastrophe. "[I]if we have peak emissions of around 65 gigatons of CO2 equivalent in 2025, we have to be down to under 20 GtCO2e by roughly 2035, and to zero GtCO2 shortly thereafter."
In order to achieve this switch by shifting to new methods of energy generation--wind and solar and hydroelectric and quantum vacuum effect and stellar core tap and everything you can imagine--well over half of the world's energy-generating facilities will have to be switched over in a decade. Not only electricity-generating plants, mind, but vehicles, too.
Basically, we have to replace over 21,000 TWh of electricity generation from coal and natural gas (yes, natural gas is less-harmful than coal, but still has a greenhouse impact) with an equivalent amount from some mix of renewable, hydro, and nuclear. And do it in 10 years.
Except it will have to be more than that, at least another 15,000 TWh more, because we'll have to replace all of the gasoline and diesel-powered vehicles on the roads around the world with alternative forms of transportation, all of which has to be electric (or human/animal-powered). And also add however much new power is required to run the various production lines day and night to make all of the needed photovoltaics, wind turbines, electric buses, and such.
For comparison, the world added... 15 TWh in solar in 2010.
Cascio's analysis of the consequences of the impossibility of a shift?
1) We manage to get a real global agreement in place within the next five-eight years, and spend the subsequent 25 or so years undertaking the largest industrial transformation imaginable. Politically implausible.
2) We don't get a real global agreement in place before 2025, and have to cut emissions by 10% per year (as Roberts notes, the biggest drop we've seen is 5% after the USSR's economy collapsed). Physically implausible.
3) Neither of those happen, and we start to see truly awful impacts, mostly in the developing world at first, all of which make the world politically more hostile and economically more fragile -- and make it more difficult to cut carbon emissions effectively.
This is why I think geoengineering is going to happen. Desperate people do desperate things, and when you hear sober scientists say things like population "carrying capacity estimates [are] below 1 billion people" in a world of 4 degree warming, it's hard to argue convincingly that the uncertainty and risks around geoengineering are worse.
The bolding and italicization is Cascio's, incidentally.
Cascio's analysis--and my agreement with said analysis--assumes that the survival of human civilization is an inevitability. I don't think that it is, as such, but I would like to think that human civilization is adaptive enough to realize the potential for catastrophe and act accordingly. I certainly don't see any other options to geoengineering at present if global energy consumption is as predicted.
What say you?