Can geoengineering save the world from man-made global warming? A 2020 NOVA documentary, with the somewhat uncertain title "Can Geoengineering `Undo´ Climate Change?" (note the scare quotes around "undo") at least tries to sound optimistic about it. I recently saw it on Swedish TV, thankfully with a Swedish narrator replacing the American one (at least on NOVA´s site, the narration sounds terrible).
The documentary cockily claims that we can stop carbon emissions entirely within a couple of decades by a mix of wind, solar, whatever-whatever, yada yada and (a bit of a surprise) nuclear power. Which, of course, we can´t. There is just one catch even if we learn Harry Potter magic: the carbon dioxide already in the air. NOVA (or the Swedish editors?) clearly have the figures wrong, since at one point they claim that 1000 gigatons of CO2 have been emitted since the beginning of the industrial revolution, while later its "only" 660 gigatons. Either way, *a lot* of CO2 have to be literally removed from the atmosphere even if we stop all new carbon emissions, otherwise Earth climate is seriously screwed anyway. "Can Geoengineering `Undo´ Climate Change?" then discusses various more or less fanciful technologies that supposedly can make this happen, none of them really operational at the moment.
There is the Swiss company Climeworks, with its "carbon dioxide air capture technology". Then there is CarbFix, which stores captured CO2 in the Icelandic basalt deep underground (it takes a lot of water to accomplish this). Even NOVA admits that this technology can´t be scaled up, and that it probably needs too much energy to begin with. But perhaps the evil molecules can be recycled instead?
An enormous solar panel can turn CO2 into "solar methanol" by heating up a solar reactor. The solar methanol can be used as fuel to power airplanes! The catch: it´s six times more expensive than fossil fuels. Another team of mad engineers have developed a technology that can turn CO2 into essentially any product: cutlery, cement, wrist watches, what have you (the cements being the most important). Once again I wonder about the energy needs of this industrial neo-revolution? Don´t get me wrong, I unironically *like* technology like this, and used to believe in its possibilities myself, but then somebody pointed out to me that there are such things as economy and energy (not to mention politics...) which put definite limits on what even ingenious humans can accomplish.
Slightly more sinister are the plans to literally geoengineer the Earth itself, or rather its weather systems. One method is to enhance the reflectivity of naturally occuring clouds by spraying them with aerosols to stop global warming. 15 to 20 years of research is said to be needed to do this properly. A more radical version would be to spread the aerosols directly in the stratosphere. This way less sunlight would reach the Earth, thereby stopping global warming...but perhaps also other things, screwing up our weather for good.
NOVA also mentions two more organic solutions to the crisis. One is to plant one trillion trees, something that is (perhaps) possible to do according to a controversial study. Trees are "carbon-capture machines". The problem is that the land used for tree-planting might be needed for other things, perhaps agriculture when the population continues to rise and more mouths need to be fed. I also wonder how safe these trees would be for forest fires? Aren´t they increasing already, due to climate change? Finally, there is composting, which binds CO2 in the land but also leads to less methane emissions - methane (which constantly "leaks" from our agriculture) is an even more potent greenhouse gas than carbon dioxide! Composting also makes plants (food plants?) grow better. Win - win? Yet, the scientist interviewed admits that more research is still needed before the results from local experiments can be extrapolated to "all of California" or the entire world.
Despite the modestly optimistic tone of this production, I have to admit that I became modestly more pessimistic after watching it. My trollish side even smiled, at the hubris of modern civilization, a civilization I nevertheles feel very comfortable with. Perhaps I´m laughing at myself, who knows...
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