>From current issue of 'NewScientist' << Astronomers have begun to sniff out the chemical make-up of a few exoplanet atmospheres, finding spectral lines of CO2, CH4, H2O and Na. These substances have been found around giant planets that orbit very close to their starts, making them relatively easy to detect. In principle it should also be possible to see the much fainter spectral signature of synthetic gases such as the CFCs in the atmosphere of an Earth-like planet. Unintentional pollution would probably be at too low a level for us to detect, and if it lasts only decades or centuries we'd have to be very lucky to spot it anyway. But such gases might be used to warm planets to make them suitable for habitation. "I think the only way we would see something like this over interstellar distances would be as a signatures of artificial global warming", says Mark Claire at the UEA, UK. "If we were to colonise Mars, we might consider engineering the climate with CFCs or NaF6 to make it warmer." >>
This raises two interesting (albeit far-fetched) possibilies: 1) We could potentially scan the cosmos for active geoengineering schemes on other planets. Likely, what we'd be able to detect most easily is more akin to terraforming - using greenhouse gases to raise temperature, as described above. However, it is also perhaps possible that we might look for effects of manufactured aerosol haze, etc. I can't think of a way to do this, but a successful detection would have two effects. Firstly, letting us detect an alien civilisation (pretty cool). Secondly, being able to spot which geoengineering technologies are most popular among alien civilisations - potentially giving us a heads up on which techniques work well. If we find for example that plenty of planets have sulphur haze schemes, it suggests that they can be safely used (although not necessarily with our own technology). This would potentially be the first possible interplanetary technology transfer. (Trust me, I'm an alien) 2) We should give consideration to the interplanetary risks of geoengineering schemes. While it's likely that any long-lived alien civilisation would be able to find humans by looking for albedo changes resulting from land use change, or spectral lines in our atmosphere from pollution, it's nevertheless a non-zero possibility that geoengineering would be the first detectable 'tell tale' of an industrial civilisation. As such, we should at least consider the possibility that geoengineering would directly betray our existence to aliens. Bearing in mind the history of contact between technological and primitive societies on Earth, breaking cover might not be a very smart thing to do. I accept that this is all very speculative, but it's nevertheless interesting. Furthermore, most big steps forward start with seemingly ludicrous ideas : TV, manned flight, moon landings, etc. A -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/geoengineering?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
