The views expressed in this report are those of the authors. Their statements are not necessarily endorsed by the affiliated organisations or the Global Challenges Foundation.

What is at stake?

Two sets of new technologies known together as geo-engineering now make it possible to manipulate the atmosphere in order to reduce climate risk. The first set directly removes carbon dioxide from the atmosphere, and if emissions are eventually reduced to zero, may provide a lasting solution to climate change. The second, known as Solar Radiation Management, reflect the light and heat from the sun back into space, particularly through the injection of sulphates or other particles into the stratosphere. Solar radiation management is now ready for testing, but along with hope, it brings cause for concern that its deployment could have dramatic impacts on climate stability.

How much do we know?

Solar radiation management is the only known technique for quickly stopping or even reversing the rise in global temperatures. Although it does not solve the root cause of climate change, it could be used to manage temperatures during a period of transition, or provide insurance against a ‘climate emergency’. However, we know very little about the precise effects of the technology, and geo-engineering carries potentially considerable risks – in particular, it may destabilize local and global precipitation patterns, or have other unexpected effects on the climate and various elements of the global ecosystem. In addition, we know that sudden termination of solar radiation management would lead to rapid and severe global warming, with no time for natural and social systems to adapt. 

A complete geoengineering intervention would require considerable investment and involve drastic reduction of greenhouse gas emissions, but according to some estimates, solar radiation management intended as an interim solution could be deployed on its own for the relatively low sum of $10 billion per year. The cost is low enough that nation states, or even wealthy individuals or companies, could feasibly deploy this technology unilaterally without properly taking into account the interests of others. This not only could lead to serious geopolitical tensions, but if side effects prove to be negative, it also opens the relatively close prospect of climatic chaos triggered by reckless human intervention. 

Solar radiation management is the only known technique for quickly stopping or even reversing the rise in global temperatures.

What are key factors driving impact and probability?

  • Unless strong efforts on greenhouse gas reduction are made, the chances that geoengineering technology will be deployed increase. Conversely, geoengineering could present a serious moral hazard, and may lead countries to avoid emission abatement.
  • Better understanding of the climate system will improve our understanding of risks associated to geoengineering, and may lead to considerably safer interventions. 
  • One important risk factor is the potential for unilateral deployment, which better frameworks for global coordination could reduce. 

Janos Pasztor

Senior Fellow and Executive Director, C2G2 Initiative on Geoengineering, Carnegie Council