In the New UN Climate Report, a Better Understanding of Solar Geoengineering


The latest report from the UN Intergovernmental Panel on Climate Change offers not only a clearer view of the causes and consequences of global warming, but also a better understanding of some extreme and untested solutions to the climate crisis, including solar geoengineering — the process of modifying clouds or spraying tiny reflective particles into the upper atmosphere to block a portion of the sun’s light, thereby cooling the planet, Reuters reported.

While previous climate models showed only how much solar geoengineering, also called solar radiation modification, would lower the average temperature of the planet, new models run on supercomputers indicate how temperatures would vary at different latitudes and also how geoengineering would affect rainfall and snowfall.

Releasing sulfate aerosols into the upper atmosphere to block sunlight would lower average precipitation, the report found. Thinning high-altitude cirrus clouds, by contrast, would increase average precipitation.

“The side effects of any of the known geoengineering techniques can be very significant,” Paulo Artaxo, an environmental physicist at the University of Sao Paulo and a lead author of the report, told Reuters. “Society has to consider if these side effects are too big to try any strategy.”

Overall, a drop in temperature would allow plants, soils, and the oceans to take up more atmospheric carbon dioxide, helping to curb the rise in C02 levels, according to the report. However, as long as humans continue to pollute, carbon dioxide will continue to accumulate in the atmosphere and will continue to make the oceans more acidic. And while it would take one or two decades of consistently injecting aerosols into the stratosphere to see a discernible effect on the climate, if humans were to suddenly stop releasing aerosols, it would lead to rapid warming.

“The science is there,” Govindasamy Bala, a climate scientist at the Indian Institute of Science and a lead author of the report, told Reuters. “I think the next big question is, do you want to do it? … That involves uncertainty, moral issues, ethical issues and governance.”