“Geoengineering will not solve the problem of climate change”

Mr Vattioni, what is the subject of your study?
We looked at a method called solar geoengineering. This is a technology that involves releasing aerosols into the upper atmosphere, where they would reflect some of the solar radiation back into space. In our study, we investigated which aerosols would be best for this purpose, and what processes affect the efficiency of the reflection.

What are aerosols?
Aerosols are tiny particles suspended in the atmosphere. They have a cooling effect on the climate as they reflect solar radiation. A natural example of this effect are volcanic eruptions that emit sulphur dioxide. In the atmosphere sulphur dioxide forms sulphuric acid aerosols, which have a cooling effect on the climate. Consequently, most research in this area has focused on sulphur dioxide emissions.

What did you find out?
Using computer simulations, we were able to show that diamond dust – tiny particles of pure carbon – would be particularly suitable for solar geoengineering. It reflects sunlight the most and mitigates some of the negative environmental impacts that would result from injecting sulphur dioxide, for example.

Can you explain that?
Sulphuric acid aerosols warm the upper atmosphere locally, which could change global atmospheric circulation and global precipitation patterns. Diamond dust, on the other hand, has virtually no warming effect on the upper atmosphere. Sulphuric acid aerosols also cause acid rain, which diamond dust does not.

It sounds almost too good to be true. Are diamonds in the atmosphere really a solution to climate change?
No, absolutely not. Solar geoengineering will not solve the problem of climate change. However, it has the potential to temporarily mitigate some of the negative effects of climate change. The only sustainable solution to climate change remains the rapid reduction of global greenhouse gas emissions to net zero and the implementation of greenhouse gas removal technologies.

How well are these efforts progressing?
Unfortunately, it does not appear that global greenhouse gas emissions will fall dramatically in the next few years. This carries the risk that we could pass irreversible environmental and climatological tipping points. To reduce this risk, solar geoengineering could temporarily reduce further warming of the atmosphere until we reach the net-zero target and implement greenhouse gas removal techniques.

Isn’t this far too risky for our ecosystem? Many experts warn of the collateral damage of geoengineering.
We need to take these concerns seriously. While there is evidence that diamond dust and other aerosols are less harmful to the environment than sulphur dioxide, there is still significant uncertainty. More research is therefore needed before we can even consider a possible application. There are also moral concerns about the use of solar geoengineering: for example, who should decide whether and to what extent such technologies should be used? Nevertheless, it is always important to weigh up these concerns against the risks that we are likely to face in the future if climate change continues unabated.

The media coverage of your study quotes a figure of around USD 175 billion to reduce the average global temperature by 1.6 degrees Celsius. How did you arrive at this figure?
We did not look at the cost of potential deployment. However, other studies show that the production of synthetic diamond dust is very expensive and energy-intensive. In our study, however, we were able to show that calcite particles perform similarly almost as well as diamond dust. Limestone is made up of calcite and is found in large quantities in all parts of the world. The cost of production would probably be similarly inexpensive compared to that of sulphur dioxide.

Why is this research necessary?
Given the dismal outlook for climate change, I believe that we need research to explore the benefits and, more importantly, the potential risks of this technology. Not researching or even banning this technology would also be a risk, as it would mean shunning a technology that could help mitigate some climate risks.