The linked article implies that governments (USA, EU, China, Russia, etc.) are actively evaluating how to weaponized geoengineering:
Extract: "Using the weather as a weapon to subjugate the globe sounds like the modus operandi of a James Bond villain, but a senior climate scientist has expressed concern over the US intelligence services’ apparent interest in geoengineering."
See also the "CIA-Funded Geoengineering Study" thread here:
Just to play the Devil's advocate. Shell estimates that in the real world at best it will take until about 2100 to reach a Net Zero Emissions condition where anthropogenic emissions match that absorbed by the natural environment. Furthermore, several researchers believe that sometime after 2050 Negative Emission Technology, NET, will be economic to suck C02 from the sky (beyond what nature does).
Therefore, it almost seems inevitable that between 2050 and 2100 several countries will band together to implement, solar radiation management (SRM), most probably using stratospheric aerosols, even though Pierrehumbert (& sidd) call this possibility "barking mad". Nevertheless, Lockley says that Pandora's Box is already open so we should thoroughly investigate and evaluate this SRM, together with NET, option starting immediately.
Thus, I provide some links (& selected extracts) to(from) two Wikipedia articles, with the first on general SRM and the second on Stratospheric Sulfate Aerosols geoengineering, including a partial list of risks associated with this approach.
Raymond T. Pierrehumbert http://www.slate.com/articles/health_and_science/science/2015/02/nrc_geoengineering_report_climate_hacking_is_dangerous_and_barking_mad.html
Extract: "So yes, albedo hacking is still barking mad, but people are often driven to do barking mad things out of desperation, and we are heading to the breaking point now with our continued fossil fuel binge."
Extract: "However knowledge of the necessary methods cannot be erased, so Pandora's box is already open. Tough choices have to be made about what will be permitted - from basic scientific research to full deployment.
Studying this new-found power is now an important academic endeavour, and both public and academic interest is growing rapidly."http://en.wikipedia.org/wiki/Solar_radiation_management#Stratospheric_aerosols
Extract: "Sulfate aerosols have been shown to enhance ozone depletion. However, other aerosol types may be more efficient at cooling the climate or less damaging to the ozone layer. Such aerosols include the highly reflective titanium dioxide.
United States Patent 5003186 suggested that tiny metal flakes could be "added to the fuel of jet airliners, so that the particles would be emitted from the jet engine exhaust while the airliner was at its cruising altitude." Alternative proposals, not known to have been published in peer-reviewed journals, include the addition of silicon compounds to jet fuel to make silicon dioxide particles in the exhaust."http://en.wikipedia.org/wiki/Stratospheric_sulfate_aerosols_(geoengineering)
Extract: "According to Paul Crutzen annual cost of enough stratospheric sulfur injections to counteract effects of doubling CO2 concentrations would be $25–50 billion a year. This is over 100 times cheaper than producing the same temperature change by reducing CO2 emissions."Partial List of Risks Associated with Stratospheric Sulfate Aerosols geoengineering
"• Drought, particularly monsoon failure in Asia and Africa is a major risk.
• Ozone depletion is a potential side effect of sulfur aerosols; and these concerns have been supported by modelling.
• Tarnishing of the sky: Aerosols will noticeably affect the appearance of the sky, resulting in a potential "whitening" effect, and altered sunsets.
• Tropopause warming and the humidification of the stratosphere.
• Effect on clouds: Cloud formation may be affected, notably cirrus clouds and polar stratospheric clouds.
• Effect on ecosystems: The diffusion of sunlight may affect plant growth. but more importantly increase the rate of ocean acidification by the deposition of hydrogen ions from the acidic rain
• Effect on solar energy: Incident sunlight will be lower, which may affect solar power systems both directly and disproportionately, especially in the case that such systems rely on direct radiation.
• Deposition effects: Although predicted to be insignificant, there is nevertheless a risk of direct environmental damage from falling particles.
• Uneven effects: Aerosols are reflective, making them more effective during the day. Greenhouse gases block outbound radiation at all times of day. Further the effects will not give a homogeneous effect across the regions of the world.
• Stratospheric temperature change: Aerosols can also absorb some radiation from the Sun, the Earth and the surrounding atmosphere. This changes the surrounding air temperature and could potentially impact on the stratospheric circulation, which in turn may impact the surface circulation.
Further, the delivery methods may cause significant problems, notably climate change and possible ozone depletion in the case of aircraft, ...
Use of gaseous sulfuric acid appears to reduce the problem of aerosol growth."