Stratospheric Sulfate Aerosols (geoengineering) - Possible Side Effects

Possible Side Effects

Geoengineering in general is a controversial technique, and carries problems and risks, such as weaponisation. However, certain problems are specific to, or more pronounced with this particular technique.

• 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.
• 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, and litter in the case of untethered balloons.