Richard Courtney is a AGW denier and PR guy for British Coal. Here is his excerpts from his take on Geo-Engineering:
I am firmly convinced that dangerous AGW is not a problem and cannot become one. However, I do think the possibility of the geo-engineering should be supported. My reason for this is a political ploy and I explain it as follows.
At present there is no empirical evidence of any kind that the AGW hypothesis is correct. But supporters of the AGW-scare assert that action must be taken now to avoid the possibility of dangerous AGW in the future.
Politicians are responding to the AGW-scare by trying to constrain anthropogenic emissions of greenhouse gases (GHGs), notably carbon dioxide (CO2). Such constraints would do much harm and, therefore, I think they should not be accepted. But politicians of several countries are committed to their having accepted the AGW-scare as being a potential threat which warrants the constraints.
The politicians need a viable reason if they are to back-off from this commitment to the constraints without losing face.
The geo-engineering option provides the needed viable reason to do nothing about AGW now.
The AGW-scare is founded on an unproven assumption that global temperature is determined by net radiative forcing, and increase to GHGs in the air provides additional positive radiative forcing.
Increase to aerosols in the air increases cloud cover to provide additional negative radiative forcing. So, increasing atmospheric aerosols would drop global temperature. And this could be done at relatively little cost, for example, by emitting sulphates from commercial aircraft.
Hence, if AGW does prove to be a problem then the geo-engineering is a method to immediately stop its effects when it is detected. Actions to constrain the GHG emissions could then be implemented. The cost of the geo-engineering would be much less than the costs of the constraints to GHG emissions in the period until effects of AGW are detected. Indeed, the costs of the geo-engineering would be trivial compared to the costs of 20% reduction to world-wide GHG emissions for a single year.
And if AGW does not prove to be a problem then no constraints to GHG emissions and no geo-engineering would be needed.
In either case, the geo-engineering option is preferable to adopting constraints on GHG emissions in the near future.
This suggested political ploy is not fanciful and it has precedent. Opponents of the nuclear industry have objected that there is no “safe” method to dispose of nuclear waste. The nuclear industry has responded by asserting that the waste could be vitrified. A practical method for the vitrification still remains to be developed, but assertion of the possibility of the vitrification has been sufficient to overcome objections to nuclear power in several countries for nearly 40 years. (incidentally, I am in favour of nuclear power).
In the past, Mr. Courtney has made similar remarks re carbon sequestration--ie it won't work but will provide political cover (allow politicians to say they're DOING something).