Injecting fine particles of sulphur into the stratosphere via aircraft has been proposed as a seemingly “cheap and fast” method to cool the planet. Known as stratospheric aerosol injection (SAI), this form of geoengineering could potentially slow the rise of global temperatures. However, recent research warns that such interventions may carry serious unintended consequences, including disruptions to crucial weather patterns like the monsoon and shifts in rainfall, which could also impact tropospheric ozone levels.
A study published in Scientific Reports on October 21 by researchers at Columbia University used advanced computer models to assess the potential effects of SAI. The concept is inspired by natural events, such as the 1991 eruption of Mount Pinatubo in the Philippines, which released roughly 20 million tons of sulfur dioxide into the stratosphere. This eruption temporarily cooled the planet by about 0.5°C for two years, but also triggered a drought in South Asia and caused strong winter stratospheric warming, highlighting the complex and unpredictable impacts of altering the atmosphere.
Atmospheric chemist Faye McNeill emphasizes that real-world outcomes could differ significantly from model predictions. Uneven particle distribution in the atmosphere could disrupt global air circulation and create heat imbalances, producing cascading effects on climate systems around the world. These uncertainties underscore that SAI is not a straightforward solution and could inadvertently harm regions dependent on stable seasonal rainfall.
The study suggests that while solar geoengineering might help mitigate global warming temporarily, it cannot replace efforts to reduce greenhouse gas emissions. Policymakers and scientists alike are urged to carefully consider the risks and ethical implications of such interventions, as attempts to artificially cool the planet could trigger droughts, acid rain, and widespread climate disruptions, ultimately complicating rather than solving the climate crisis.