Geoengineering — An unavoidable gamble?

Michael Van Den Reym
4 min readOct 30, 2021


The politicians who met at COP21 Paris agreed for a 1.5°C ambition but they still haven’t come up with any concrete plans on how to achieve it yet. If the COP in Glasgow will be succesfull in making the plans more concrete, it still can just be too hard and too late to land within the safe 1.5°C or 2°C warning. Meanwhile, extreme weather events are rising and the IPCC reports get more alarming.

There’s still so much work left in fighting global warming and we may need to consider adding another weapon: solar geoengineering.

Currently, geoengineering is still neglected in the climate change discussion but this could change soon. Gernot Wagner, climate economist and founding executive direct of Harvard’s Solar Geoengineering Research program argues that geoengineering is not a question of “if we are going to use it”, but “when we are going to use it”.

What is geoengineering?

The idea of geoengineering is not new. In 1965, President Johnson’s scientific advisor proposed geoengineering by brightening the oceans and reflecting sunlight. They assumed that fossil fuels would continue to be used.

In the book of Gernot Wagner, “Geoengineering: The Gamble”, the author argues for further research on solar geoengineer by adding aerosols in the stratosphere to cool the planet.

A natural experiment was the explosion of the Pinatubo vulcano in 1991, causing additional SO2 emissions in the atmosphere. During the 3 years following the explosion, the earth temperature decreased with 0.4°C.

Mount Pinatubo (wikipedia)

Benefits and risk

Solar geoengineering can be a fast and easy way of cooling our planet. With mitigation and carbon removal costs of trillions dollars each year, as well as the land use needed for carbon removal— it’s certainly will be discussed at some point in time.

Wagner explains geoengineering would be a dominant strategy using his game theory knowledge. Once one country would start with geoengineering, others could follow fast.

Geoengineering is not a magical cure-all, despite what some people may think. Geoengineers are aware that there’s no way to stop the increase in acidity of the oceans due to CO2 emissions and they also know how difficult it would be for these techniques alone to offset the CO2 emissions being pumped into Earths atmosphere each year by humans.

Geoengineering does indeed have its limitations — as Alan Robock’s points out in his article 20 reasons against geoengineering. Some of the reasons he mentions can be discussed though, while other reasons against are just minimal effects or things that still needs to be researched.

The most scary thing to consider is that once you start geoengineering, there will be consequences for stopping. A temperature increase shock will happen when stopping geoengineering.

A balanced approach of migitation, adaptation, carbon removal and solar geoengineering would anyway be a far better option than only relying on the risky and imperfect technique of solar geoengineering.

Future scenarios

With the future being so uncertain, Wagner created in a next chapter 3 different future scenarios in which countries would have to make decisions about what actions they could take on climate change. One option was having them agree upon certain limits for how much emission and there would be international cooperation for migitation. But the migitation actions would prove to be very hard and come too slow. Therefore the international community could come together to make agreements about geoengineering and govern it rationally, starting with limited aerosol injections.

In another scenario: we would not act a lot on climate change, leading to extreme weather events and many climate deaths in the future. There would be no worldwide agreement on solar geoengineering either. A humanitarian coalition of countries could then decide to use solar geoengineering, but may have to take risks and go too fast.

In a third scenario geoengineering would become really cheap, making it possible for individual countries and even rich people to start geoengineering. There would be no international governance. Some countries, e.g. Saudi Arabia with high temperature and an economy based on fossil fuels may have the incentive to take many risks with solar geoengineering.

In all of the scenarios, geoengineering plays a role, but the first scenario is preferred. In all of the scenarios, early research on solar geoengineering would be helpful though.

No technological taboos

A case against researching or even discussing Solar Geoengineering would be the “moral hazard” problem. If we would know that there’s a simple technofix for climate change, we would stop migitating. But one study of Christiane Merk did found out that participants were even more likely to donate for a climate charity if the possibility of solar geoengineering was discussed with them in the experiment.

20 years ago, climate adaptation was a taboo. But in the world we currently live in, the research done on climate adaptation proofs to be useful. Carbon removal also is not a taboo anymore for IPCC as the IPCC scenario’s assume carbon removal in the 1.5–2°C scenarios.

Solar geoengineering is one next option to fight climate change in a porftofolio along with migitation, adaptation and carbon removal. It’s not a magical technofix, it won’t solve the root cause. But it’s one technology that could help us in solving the biggest problem of the 21st century and it would be pitiful to not research geoengineering.