Solar geoengineering for the climate?

Everyone is now aware of the consequences of climate change. But what if global warming could be prevented by dimming the sun? The USA has published a report on this. This would be possible with the help of solar geoengineering. But the topic is controversial. Find out more here.

The Intergovernmental Panel on Climate Change defines geoengineering as “a broad group of methods and technologies that aim to intentionally alter the climate system in order to mitigate the effects of climate change”. Solar radiation management (SRM) is a subtype of geoengineering. It aims to reduce the rise in temperature by influencing solar radiation.

SRM methods for reflecting sunlight:

• Brightening surfaces
• Brighten low-lying sea clouds with sea salt aerosols
• Introducing aerosol particles into the stratosphere
• Inoculate cirrus clouds with aerosols so that they absorb more infrared radiation than they would reflect sunlight
• Space-based methods, such as sunscreen from space and moon dust to reduce solar radiation

Solar geoengineering is arousing the interest of politicians in many countries. The EU is also currently examining measures to deflect solar radiation. The first draft stated: “These technologies pose new risks to people and ecosystems, but could also increase the power imbalance between nations, trigger conflicts and raise a variety of ethical, legal, political and governance issues”.

A few months ago, the USA published a report on the potential dimming of the sun. Here, 60 scientists, led by the renowned climate researcher James E. Hansen Alarm, asked for more detailed research into SRM. The researchers want to investigate the effects of geoengineering before it is put to practical use in the fight against climate change. Their position is as follows: “While we fully support exploration, this does not mean that we support the use of solar geoengineering.” The White House emphasized with regard to the report that there are no plans for a comprehensive research program focused on modifying solar radiation.

The letter shows that there are considerable knowledge gaps in the field of SRM. This can be attributed to the lack of uniformity in research to date. It also points to areas of research that could help to better understand the benefits and risks of SRM. This is because SRM has both climatic and social and environmental impacts. You have to understand: SRM doesn’t just have a local or regional impact, it can change the entire world.

So geoengineering sounds tempting, but its actual effectiveness remains uncertain. The methods would have to be tested in practical experiments. But that is risky. The global climate is a complex system of interactions and dependencies. And humans are not yet sufficiently familiar with these relationships. This means that when we set something in motion, we can only guess at the consequences to a limited extent. Temperature, precipitation and solar radiation, for example, are responsible for what kind of animal and plant species exist in a certain area. SRM could suddenly change precipitation patterns, such as monsoon rainfall. Imagine the impact on agriculture and the livelihoods of many.

Many critics point out the irony that the work of researching SRM should rather be devoted to climate change. Or is SRM a kind of science fiction diversion? Because the main cause of global warming remains CO₂ emissions. SRM advocates, on the other hand, see the need for an experiment at Earth system level. But that would be an experiment with eight billion people.