The recent deliberation at the United Nations Environment Assembly centered on a resolution concerning solar radiation modification, a contentious technology designed to alleviate climate change impacts by redirecting sunlight away from Earth. Nevertheless, there are concerns that such geoengineering endeavors might exacerbate the instability of our already disrupted climate system, and the comprehensive ramifications remain uncertain until implementation occurs.
The draft resolution proposed an expert group to examine the benefits and risks of this technology, but it was withdrawn due to lack of consensus. Some Global South countries called for a “non-use” of solar radiation modification, a stance that is strongly supported as human-caused climate change is already one planetary-scale experiment too many.
Solar geoengineering is gaining prominence in some circles as a response to the climate crisis. However, research consistently identifies potential risks, including unpredictable effects on climate and weather patterns, biodiversity loss, undermining food security, and infringing human rights across generations.
Examples of solar radiation modification include an American startup releasing weather balloons from Mexico in 2022 to cool the atmosphere by deflecting sunlight. The reduction in warming would be sold as “cooling credits”. However, appreciably cooling the climate would require injecting millions of metric tons of aerosols into the stratosphere, altering global wind and rainfall patterns, leading to more drought and cyclones, exacerbating acid rainfall, and slowing ozone recovery.
Another technology, marine cloud brightening, aims to make low-lying clouds more reflective by spraying microscopic seawater droplets into the air. Trials have been underway on the Great Barrier Reef since 2017, but there’s no empirical evidence yet that cloud brightening could reduce sea surface temperatures or protect corals from bleaching. Scaling up attempts would require significant resources and could have unclear effects on marine life.
The potential consequences of these technologies are far-reaching. For instance, the stratospheric aerosol injection would need to be carried out continually for at least a century to achieve the desired cooling effect. If stopped prematurely, it would lead to an unprecedented rise in global temperatures, far outpacing extreme climate change scenarios.
Moreover, the marine cloud brightening technology, despite its ongoing trials, has not yet produced any empirical evidence that it could reduce sea surface temperatures or protect corals from bleaching. The Great Barrier Reef, which is the size of Italy, would require up to 1,000 machines on boats, all pumping and spraying vast amounts of seawater for months during summer. This operation is hardly “environmentally benign” as its proponents claim.
Furthermore, the effects of these technologies on marine life remain unclear. Less sunlight and lower temperatures could alter water movement and mixing, potentially harming marine life. The infringement of human rights across generations is another significant concern, as these technologies pass on huge risks to future generations.
