I've never been much of a fan of geoengineering schemes. Most of the time I can dismiss geoengineering for a variety of technical reasons. For example, most schemes for sequestering carbon once it's been dispersed from the atmosphere are, I think, dead on arrival, because they are far too expensive to implement due to the mixing energy barrier (in the case of atmospheric scrubbers - it's "simply another chemical engineering process" but the economics will never work out compared to CCS at the source) or due to natural homeostatic mechanisms (for those who think fertilization and bio-sequestration in plants is the answer). They also suck up carbon dioxide or other greenhouse gases independently of the source, which requires an external entity - probably the government - to pay them for their services out of a carbon tax, all of which opens up problems of regulatory capture and government inefficiency. These reasons provide a pretty good blanket justification against all geoengineering ideas of this type.
However, for those schemes that directly mitigate AGW effects, e.g. sulfur aerosols dumped into the air as popularized by Steven Levitt, no matter how many technical justifications you offer it can't change the fact that there are possible technical solutions out there that might offer us a way out through active intervention in the climate. Unfortunately, there are good reasons to go against that approach as well.
That brings me to my title, and a little history. After some pretty horrific floods in 1916, the Dutch decided that the vast shallow saltwater inlet that separates Holland from Friesland called the Zuiderzee had to be tamed. They undertook a massive construction project to dam the Zuiderzee off from the rest of the North Sea, to shelter the inland areas from storm surges and high tides, completing it in 1932. Then, to capitalize on their success, they created polders, sheltered areas made of reclaimed land protected by high dikes, with land lying below water level and pumping stations to keep artesian groundwater seepage at bay. Today this reclaimed land is the Dutch province of Flevoland, population 400,000, and the Zuiderzee is now the IJsselmeer, a tamed freshwater lake. Since then there have been no major floods in North Holland and Friesland, not even in the devastating storm tide of 1953. This has long been held up as a major success in human intervention to tame nature.
|The former Zuiderzee, with the Afsluitdijk dam separating it from the sea in the center. The spur of land with straight coastlines and the island below are the polders that make up Flevoland. Source: NASA|
One can easily see the parallels with geoengineering. Damage from extreme events caused by unsustainable infrastructure practices is corrected with a marvel of human intervention. Nature is tamed, daily life is protected, and for only a few billion dollars (in today's money).
The problem with this story is that the people who live in Flevoland, the former Zuiderzee areas, and in all low-lying areas in the Netherlands in general are living in an unstable equilibrium that can quickly and catastrophically change. A breach in the Zuiderzee Works would plunge nearly half a million people into the sea nearly instantly, their livelihoods and posessions destroyed. I don't want to live there, nor do I want to live anywhere that depends on dikes or levees to protect my life.
Sooner or later every human-made solution fails. We as engineers can maximize the mean time before failure, design with a conservative risk assessment approach, perform regular maintenance and rigorous testing, but sooner or later nature has a way of throwing curve balls at us - witness recent failures of the safety mechanisms at Fukushima, in New Orleans, on the Mississippi and Sacramento rivers, and yes, in New York. And moreover, this still assumes that people are completely competent and prescient; experience should tell us that incompetence is not the exception but the rule. The Netherlands has been subject to catastrophic flooding for thousands of years so their civil engineers do better than most, but no system is completely robust to human stupidity.
So let's return to geoengineering. Suppose that all of these solutions actually do work and that we do have enough understanding of the climate to proactively intervene so that we can continue our current lifestyles. We have balloons in the air dispersing sulfur aerosols, we have autonomous ships in the pacific spraying seawater into the air to create water vapor, heck, let's say we even have reflector mirrors at the Earth-Sun L1 Lagrange Point to cut solar input and stop AGW in its tracks.
I think living in that kind of world would be as bad as living in a polder that still remembers the ghost of the Zuiderzee.
Geoengineering will undoubtedly require constant adjustment and constant maintenance. Stop for even a year and the results may be catastrophic, not only because change in the climate might permanently alter the world's landscape but also because the longer a geoengineering project commits to maintaining the status quo, the more the natural system's equilibrium will deviate. As the difference grows larger, the magnitude of the catastrophe that occurs when the system crashes to its natural, stable equilibrium is correspondingly larger.
Though we constantly live in a world of change and shifting equilibria, shifting equilibria are not insurmountable per se. The Sahara has been spreading slowly southward for millenia, and people have adapted. Rivers shift course and cities rise or fall. Coastlines give way to the sea. The difference between the unstable equilibrium that we daily experience and living under the protection of geoengineering or flood protection is that our current unstable equilibrium gives us decades to prepare and adapt; flood protection failures give mere minutes and geoengineering failures might give anywhere from a few minutes (a solar reflector failure) to a year at the outside (e.g. sulfur aerosols). Shifts cost money. At least in a slow shift we have time to save what we can. In a fast one we often do not.
What makes a geoengineering mitigation solution to AGW bad is that it commits the whole world to living in a polder. At least today's Netherlanders have a choice to not live behind a dike, today's Americans can choose to take the risks associated with living on the coastline. And moreover all of these people can flee to the high ground in a disaster. Committing to geoengineering takes both options away. As Carl Sagan aptly put it, we live on "spaceship Earth." There is nowhere else to go when the planet's metaphorical levees break. To me a slow but expensive shift to adapt to a new equilibrium is easily preferable to trying to maintain the status quo.
Interesting side note: While doing research for this entry on the history of the Zuiderzee I found this website, which among other things proposes that the IJsselmeer be connected to the sea by means of an Osmotic Power Plant. This would harvest power from the potential energy difference caused by the energy of mixing salt water and freshwater, in effect a concentration cell. Very cool. Unfortunately, osmotic power plants have a very high cost for the capacity, so it's probably nothing more than a showpiece until people start getting very desperate. But hey, shiny!