Chemotherapy for the climate: The need for risk-risk balancing in assessing Solar Geoengineering

Opinion by Claudia Wieners

Solar Geoengineering is a collection of (still theoretical) methods to cool the earth by reflecting a small fraction of the incoming sunlight. Recently, our colleagues from UU’s Copernicus Institute campaigned for a de facto ban on research into this topic, on the grounds that Solar Geoengineering causes environmental risks, cannot be governed inclusively and would distract from emission reduction.

These concerns are valid. But in my view, suggesting to ban Solar Geoengineering research is almost as one-sided as banning chemotherapy on the grounds that one mustn’t poison a patient. Chemotherapy is risky but can save lives if the patient’s condition demands it and the doctors know what they are doing. The risk of the therapy must be balanced against the risk of the illness.

Can decarbonisation alone save us?

Only decarbonisation can address the root cause of climate change, but even stringent mitigation can no longer guarantee to prevent disaster:

  • The latest IPCC Working Group I report shows that scenarios compliant with 1.5 or 2 degrees warming assume massive “negative emissions”, but it is currently uncertain whether these technologies will work in time and at the required intensity.
  • Even under the most ambitious scenario, 1.5 degrees will be exceeded if climate sensitivity is on the higher end of current estimates.
  • Even if warming can be kept below 1.5 degrees, impacts might already be disastrous, especially if tipping points are passed.

If we cannot rule out all three of these conditions, we should not reject Solar Geoengineering prematurely. If working well, it may help to avert catastrophes. But we need more research to know whether it works.

Governance challenges

Because of its low cost, Solar Geoengineering might be deployed unilaterally by (rich) countries, and governing Solar Geoengineering justly and inclusively is a huge challenge. However, governing a warming world without these techniques would also be an unprecedented challenge. Neither can we be sure that nations would adhere to a “Non-use agreement” if the pressure from climate change becomes unbearable. Timely research can reduce the chance of desperate last-minute actions, not least by exposing which strategies don’t work. Finally, I do not believe that a ban at the current stage, where many nations in the Global South lack the expertise to assess Solar Geoengineering, would be just and inclusive.

The way forward

Solar Geoengineering is an uncertain prospect and at best a plan C - decarbonization and negative emissions must get priority. But we must prepare for the possibility that they do not suffice. In my view, we should:

  • Timely and critically research Solar Geoengineering, from climate response to fair governance.
  • Stimulate public discourse.
  • Engage in capacity building in the Global South.
  • Impose regulations on outdoor experiments, ideally a procedure allowing researchers to apply for permits from an internationally legitimized body.
  • Be realistic about Solar Geoengineering’s limitations and stress its auxiliary role.

Our climate is ill. We cannot afford ignorance on therapies, even imperfect ones.

Claudia Wieners

Introduction IMAU newsletter April 2022