Solar geoengineering, the concept of artificially cooling the planet, is beginning to look more like science than fiction. Solar geoengineering focuses on letting heat escape and reflecting the sun’s heat away to achieve cooler temperatures on Earth. These ideas can theoretically be achieved in three ways: spraying sea salt into marine clouds to increase their reflectivity, thinning cirrus clouds to allow more heat to escape, and the most researched method, injecting the atmosphere with sulfur dioxide to produce reflective sulfates. Past volcanic eruptions have cooled the Earth by releasing sulfur into the atmosphere, and scientists believe the same effect can be achieved by artificially adding sulfuric particles to the atmosphere.
In 2020, Congress ordered the U.S. National Oceanic and Atmospheric Administration (NOAA) to study solar geoengineering via observation and modeling. Now, NOAA is preparing to move into the next phase of that project. Beginning this week, NOAA will utilize NASA’s WB-57 high-altitude research aircraft to “study the transport, chemistry, microphysics and radiative properties of aerosols” in the atmosphere. Researchers hope the flights will help them better understand how sulfur interacts with heat-absorbing organic particles.
Computer modeling studies suggest that solar geoengineering has the potential to reduce the effects of greenhouse gases, including greatly lowering regional temperatures and reducing precipitation changes. Further, temperature inversion, a warm layer of atmospheric air that lies above cooler air, can cause sulfate particles to linger in the stratosphere for years – a finding that is encouraging for researchers. Overall, solar geoengineering techniques appear to be relatively low-cost, fast-acting, and simple to implement. The potential of solar geoengineering has attracted groups such as the National Academies of Sciences, Engineering, and Medicine, who recommended a U.S. research program with an initial investment of $100 million to $200 million over five years.
Though many scientists, academies, and the U.S. government support further research into solar geoengineering, the topic is fraught with controversy. Many scientists believe that developing this type of engineering would be a grave mistake. 400 scientists from around the world called for an international “non-use agreement” to keep solar geoengineering at bay before “it’s too late”. The nature of solar geoengineering would require it to be maintained regularly. If for some reason this maintenance were to stop, some scientists believe this could lead to “termination shock” – the idea that, like releasing flood gates, pent-up warming would swelter the Earth. Additional concerns from members of the scientific community include the possibility of altered rainfall patterns and damage to the ozone layer.
Some scientists worry that developing solar geoengineering would encourage polluters to continue polluting. Katharine Ricke, a climate scientist, states that a pursuit of cooling the Earth rather than mitigating emissions would neglect to address other concerns associated with pollution, namely ocean acidification. As carbon dioxide increases in the atmosphere, its levels increase in the ocean, as well. This causes a pH reduction in the ocean that jeopardizes marine life. She also worries that elite interests would control the use of solar geoengineering and neglect its effects on vulnerable communities.
There is currently little information on the effects that solar geoengineering would have on global and regional weather, agriculture, and health. However, this is the exact reason many scientists are urging for the research to continue. The potential of solar geoengineering warrants further research, and further research is needed to determine any negative effects of its use.