Another report on another geoengineering method that is likely too risky to try and utterly not cost-effective: Injecting aerosols into the atmosphere to slow warming (which would do absolutely nothing about ocean acidification, by the way).
Aerosol geoengineering hinges on counterbalancing the forcing effects of greenhouse gas emissions (which decay over centuries) with the forcing effects of aerosol emissions (which decay within years). Aerosol geoengineering can hence lead to abrupt climate change if the aerosol forcing is not sustained. The possibility of an intermittent aerosol geoengineering forcing as well as negative impacts of the aerosol forcing itself may cause economic damages that far exceed the benefits. Aerosol geoengineering may hence pose more than just "minimal climate risks," contrary to the claim of Wigley (2006). Second, substituting aerosol geoengineering for CO2 abatement fails an economic cost-benefit test in our model for arguably reasonable assumptions. In contrast, (and as shown in numerous previous studies) fast and sizeable cuts in CO2 emissions (far in excess of the currently implemented measures) pass a costbenefit test. Third, aerosol geoengineering constitutes a conscious temporal risk transfer that arguably violates the ethical objectives of intergenerational justice.
More on Geoengineering
Geoengineering Unable to Fully Stop 21st Century Sea Level Rise: Report
Iron Fertilization Experiment Proves Goe-engineering Unpredictable