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Potential risks of Stratospheric Aerosol Injection (SAI): biodiversity and ecosystem disruption

Summary​

Stratospheric Aerosol Injection (SAI) could disrupt biodiversity and ecosystems through three main pathways: climate system alterations, acid rain formation, and ozone layer damage. Climate modeling suggests temperature reductions might decrease global precipitation while creating regional imbalances, affecting monsoon-dependent ecosystems. Sulfate aerosols could induce acid rain in pristine environments, altering water chemistry. Ozone layer depletion might increase UV radiation exposure, damaging DNA and photosynthesis processes. These potential impacts remain uncertain but require comparison against ongoing climate change damage.

SAI has the potential to impact biodiversity and ecosystems through changes to the Earth's climate and precipitation patterns, damage to the ozone layer, and through acid rain. Damage to the Earth's ecosystem is a large uncertainty related to SAI as the delicate nature of ecosystems and their subsystems makes them highly vulnerable to perturbation.

Effects on existing climate systems​

The Earth's climate system is a complex interconnection of interactions between subsystems. The controlled release of aerosols into the atmosphere could disrupt these systems and cause unexpected and potentially harmful effects such as disruptions to precipitation patterns and natural disasters. Much of the Earth's biodiversity relies on regular and predictable precipitation patterns such as the monsoon seasons in Africa and Asia, and the wet season in South America. It has been shown through climate modeling of SAI that there will be a general reduction of global average precipitation as reduction in global temperatures will reduce the amount of ground-based water evaporation, which could lead to droughts in some regions and floods in others 1. If research and experimentation revealed that major climate systems would be affected by SAI, the risks would need to be compared to the current destruction of ecosystems by climate and the potential for further destruction if tipping points are reached.

Effects of acid rain​

The deployment of SAI can lead to acid rain which can impact ecosystems by reducing the pH of waterways, lowering the overall quality of the water, and damaging the health of the animals that rely on it 1. Locally, these changes to the water chemistry can lead to a cascade of negative effects. A key concern with SAI is the introduction of acid rain into pristine environments that are normally not affected due to their distance from the combustion of fossil fuels which locally contribute to acid rain 2.

Effects of ozone depletion​

SAI can damage the Earth's ozone layer through a number of pathways. Ozone is vital for protecting the Earth's surface and life from harmful ultraviolet (UV) radiation. High quantities of UV radiation can lead to increased rates of skin cancer, cataracts, and other health problems in humans and animals. Plant life which relies on sunlight for photosynthesis is even more vulnerable to UV damage, as it does not have the ability to avoid sunlight like animals do. UV radiation directly damages the DNA of living organisms which can lead to damage and growth defects 3. UV radiation also damages other important functions such as growth regulators, pigmentation, and photosynthesis 4.

The fragility of the Earth's ecosystem means that any significant and rapid changes can have wide-reaching effects. A global geoengineering project like SAI is bound to result in large impacts on the ecosystem. However, these impacts may outweigh the damage being caused by anthropogenic climate change, which is why more research and experimentation is immediately required to explore the effects of SAI on biodiversity and ecosystems.

Sources​

Footnotes​

  1. Tracy, S. M., Moch, J. M., Eastham, S. D., & Buonocore, J. J. (2022). Stratospheric aerosol injection may impact global systems and human health outcomes. Elementa: Science of the Anthropocene, 10(1), 00047. https://doi.org/10.1525/elementa.2022.00047 ↩ ↩2

  2. Visioni, D., Slessarev, E., MacMartin, D. G., Mahowald, N. M., Goodale, C. L., & Xia, L. (2020). What goes up must come down: Impacts of deposition in a sulfate geoengineering scenario. Environmental Research Letters, 15(9), 094063. https://doi.org/10.1088/1748-9326/ab94eb ↩

  3. Solomon, K. R. (2008). Effects of ozone depletion and UV-B radiation on humans and the environment. Atmosphere-Ocean, 46(1), 185-202. https://doi.org/10.3137/ao.460109 ↩

  4. Hollósy, F. (2002). Effects of ultraviolet radiation on plant cells. Micron, 33(2), 179-197. https://doi.org/10.1016/S0968-4328(01)00011-7 ↩