• Commonly: Geoengineering, but confusion on terms
  • = Deliberate and large scale intervention on climate
  • Most agree that it is not a solution, but can be part of a array of solutions
  • Risks must be evaluated vs. risks of dangerous climate change

Solar geoengineering / Albedo altering

  • Do not reduce CO2 concentration = not a substitute to change mitigation, ex. no impact on climate accidification
  • Cheap: tens of billions of USD
  • Seems reversible
  • Could be used to avoid tipping points for example
  • Different types
    • Stratospheric aerosol injection
    • Marine cloud brightening
    • cirrus cloud thinning
  • Some are based on natural phenomena
  • Key governance issue:
    • Who decides? How?
    • How much?
    • What type?
Main issue is risk and unknowns

Carbon dioxide removal

  • Carbon removal / sequestration
    • Sucking it out of the athmosphere
      • Direct air capture
      • Carbon Capture and Storage with Bioenergy
        • Leakage?
    • promoting natural processes that do so
      • Reforestation / Afforestation
  • Slow, expensive
    • Their impact is proportional to their scale
    • Can they be scaled?
  • Some don't see it as cliamteengineering because it's small scale
  • Key governance issue
    • Like reductions: making sure everyone caries their load
What touches the causes? what touches the symptomes? Main issue is scale and speed


  • Because it is intentional: different morally than unintentional climate change: do we have the right to do so?
  • Religion play a role in the debate
    • Some say we cannot play the role of god
    • others that we are stewards of his creation
  • How do we choose the target temperature? target climate?
    • Different regions, different expectations
    • Politically: how do we get to an agreement when we can't even decide on reductions? Currrent negotiation frameworks do not work.
What if a region wants to IMPROVE their climate? (less cold)
  • Climate justice issue
    • Who will suffer? most likely not the ones that are benefiting from the emissions (north / top100 companies)
    • On the other side: the rich will pay for climate engineering, it helps mitigate inequalities
  • Positions
    • Some do not know where they position themeselves
    • Some are opposed
    • Some are ok with nature-based CO2 removal: afforestation...
    • Think tanks opposing emission reductions are generally supportive
  • Risk compensation: risk that emissions will not lower because we think there is a solution = reluctance to even discuss it
    • Other research shows that the threat of geoengineering might actually increase emission reduction
Why are we not even discussing it? Need to explain this point


  • There is no global governance
  • Part of the Convention on Biological Diversity
    • 2010 - "climate-related geo-engineering activities that may affect biodiversity" until these are governed, they are scientifically justified, and associated risks have been considered.
  • Oxford Principles used by the UK / created by Oxford U
    • Principle 1: Geoengineering to be regulated as a public good.
    • Principle 2: Public participation in geoengineering decision-making
    • Principle 3: Disclosure of geoengineering research and open publication of results
    • Principle 4: Independent assessment of impacts
    • Principle 5: Governance before deployment

Public perception

  • Low! <20% reported prior knowledge
  • Seen as risky. Removal preferred over solar engineering
  • Seen as last resort
  • Unorthodox claims: secret government actions are already creating winter / fires etc.


  • What we know today is mostly based on:
    • Lab experiments
    • Observations of natural phenomena
    • Models
  • Some technics are based on natural phenomena (ex. Pinatubo)
  • It's very early stage ... we don't know much.
  • The Royal society concludes that the focus should be on reductions + investigate in case it becomes necessary (tipping point)