First, Space Mirrors. Apparently pushed as a means to ridicule the entire field of geoengineering, perhaps the author can identify even one serious scientific research establishment that is working on them . . . . The idea isnt even logical- if mirrors were used every one would need an energy source and a propulsion system to keep it properly aligned, otherwise it may drift to a point of reflecting extra sunlight onto the Earth. Simple opaque spheres would not have this problem, but would still be totally impractical in terms of delivery and of recovery once our atmosphere had been cleansed of fossil carbon,

Second, Stratospheric Aerosold Injection [SAI]. This technique was proposed by the infamous Dr Edward Teller in 1995 as an exit strategy for Cheney and the Global Climate Coalition plan for longterm obstruction of mitigation efforts, preferring to profit while letting AGW rip to the point of destabilizing Chinas regime. (Hasnt happened yet, but looks increasingly feasible). SAI has remained by far the most researched PAR option in the USA, not least because of the funding for it that has flowed to US universities.

Third, Termination Shock. This posits an unexplained global societal collapse to the point where neither aircraft nor ballons can be used to deliver sufficient aerosols to maintain a cooling stratospheric veil, and, in addition, where there has been no reduction in anthro-CO2 emissions so the atmospheric consentration has risen greatly. These wild speculations then proceed to ignore all of the immensely dangerous non-fail-safe systems we already have – such as nuclear fuels cooling ponds, germ warfare laboratories, etc, that are just as dependent on regular maintenance.

Fourth, the complacency of the anti-Geo-E lobby over the 8 “Major Interactive Feedbacks” [MIFs] needs to be challenged. These are reported to be accelerating, and their self-reinforcing advance is mostly driven by excessive ocean, air and land temperatures, which means that halting net global GHG emissions will not halt their acceleration. Only global cooling can do that. Since some MIFs generate potentially massive GHG emissions, causing further warming, and some such as the Albedo Loss MIF generate warming directly, their effect would be to advance to the point of fully offsetting the mitigation achieved by Emissions Control Strategies.

Fifth, what is needed is not an anti-science moratorium but an evaluation of the technology options to identify which offers the best prospect of proving both effective and reliably benign. The criteria for that evaluation will have to include issues such as options being testable without global deployment, being capable of termination swiftly if necessary rather than after a year or two, and at best being effective at slowing and then halting the destabilization of the global climate while operating only in Polar regions. Since only one means of cooling the planet can be trialled at a time, and very eminemt scientists such as Dr Peirs Forster have proposed the need of a decade of trials, the present urgent imperative is deciding the criteria by which the technology to be trialled will be selected.

Finally, does it really need saying that there should not be – and predictably wont be – any deployment of a benign PAR technology without all major nations having signed up to a binding phase-out of fossil fuels.

Regards,
Lewis