Sunday, October 18, 2009

Ditching the Fix - The Case Against Geo-Engineering Our Way Out of Global Warming

Sensing (quite correctly) that we really don't want to abandon our carbon addiction, the "fixers", those who want technological solutions to the plight our technology has created, are gaining momentum. These are people who claim the best solution is to geo-engineer our way out of global warming. Even though mankind has plainly shown that we weren't able to control the side-effects of the technology that got us in this mess, the fixers argue that doesn't matter, we can still control the technology to realign the climate of our planet.

The fixers are hatching all sorts of nutty schemes - from seeding the oceans with iron filings to placing enormous mirrors in earth orbit. One by one these cheap and dirty fixes have been debunked, usually because their advocates overlook the inevitable or at least likely side-effects.

One persistent proposal is to spread sulphur dioxide through the upper atmosphere where the particles will oxidize into aerosols that will block some of the sunlight reaching earth. The good folks at have posted a response to the lunacy of geo-engineering that argues our best hope is to change our behaviour.

Is geo-engineering a fix?

In a word, no. To be fair, if the planet was a single column with completely homogeneous properties from the surface to the top of the atmosphere and the only free variable was the surface temperature, it would be fine. Unfortunately, the real world (still) has an ozone layer, winds that depend on temperature gradients that cause European winters to warm after volcanic eruptions, rainfall that depends on the solar heating at the surface of the ocean and decreases dramatically after eruptions, clouds that depend on the presence of condensation nuclei, plants that have specific preferences for direct or diffuse light, and marine life that relies on the fact that the ocean doesn’t dissolve calcium carbonate near the surface.

The point is that a planet with increased CO2 and ever-increasing levels of sulphates in the stratosphere is not going to be the same as one without either. The problem is that we don’t know more than roughly what such a planet would be like. The issues I listed above are the ‘known unknowns’ – things we know that we don’t know (to quote a recent US defense secretary). These are issues that have been raised in existing (very preliminary) simulations. There would almost certainly be ‘unknown unknowns’ – things we don’t yet know that we don’t know. A great example of that was the creation of the Antarctic polar ozone hole as a function of the increased amount of CFCs which was not predicted by any model beforehand because the chemistry involved (heterogeneous reactions on the surface of polar stratospheric cloud particles) hadn’t been thought about. There will very likely be ‘unknown unknowns’ to come under a standard business as usual scenario as well – another reason to avoid that too.

There is one further contradiction in the idea that geo-engineering is a fix. In order to proceed with such an intervention one would clearly need to rely absolutely on climate model simulations and have enormous confidence that they were correct (otherwise the danger of over-compensation is very real even if you decided to start off small). As with
early attempts to steer hurricanes, the moment the planet did something unexpected, it is very likely the whole thing would be called off. It is precisely because climate modellers understand that climate models do not provide precise predictions that they have argued for a reduction in the forces driving climate change. The existence of a near-perfect climate model is therefore a sine qua non for responsible geo-engineering, but should such a model exist, it would likely alleviate the need for geo-engineering in the first place since we would know exactly what to prepare for and how to prevent it.

Those who advocate geo-engineering, and we can expect to see that spreading at the political level before long, are trying to tackle global warming on the cheap. Make that the "cheap and dirty." By leaving climate change unresolved until it's too late, by refusing to decarbonize our economies, there's every reason to expect our "leaders" will come to us at the 11th hour when solutions other than geo-engineering have been foreclosed by their inaction. In other words, they're going to put us in a climate change trap.

As I've written many times before, there are many solutions to the global warming problem. The best of these passed back as far as the 60's when we really didn't know better. At some point we are going to reach out to grasp a solution, some answer, but it won't be the best answer. That's the answer we have today - decarbonize the global economy right now. That's the best solution if only our leaders were altruistic enough to act on it.

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