David Keith and Solar Geoengineering

I have been thinking about geoengineering since 1989 when I started work that became one of the first assessments of the technology and its policy implications (1992, #9). My work includes:


Collaborative interdisciplinary assessment process are necessary for a topic with deep uncertainty that spans the science-policy interface. I was a member of the working group for UK Royal Society's 2009 report (#118), the first by a national science academy devoted to geoengineering as well as the more recent Bipartisan Policy Center Report. In 2010 I testified before committees of the US Congress and the UK Parliament. I presented to US National Academy meetings in 2000, 2009 and 2013 and was coauthor of the geoengineering sub-chapter (WG 2, 4.7) of the Third IPCC Report and served AR5.

Public engagement

Public engagement is vital given the (potentially) profound social consequences of geoengineering. Public engagement must be bi-directional because, while experts know their specialties, the questions at issue involve values in an essential way and expert's values should have no special standing. I work on two tracks. First, I have worked on structured process to elicit public and expert judgments about geoengineering (e.g., #150); and second, I work to communicate my with diverse audiences. I wrote a book that aims to introduce the topic to a non-specialist audience. My 2007TED talk has been widely viewed, see also a 2009 debate at the Royal Geographical Society an op-ed in the New York Times, and interview in November 2011 on BBC’s HARDtalk. For a more whimsical take see our 2013 Scientific American article (#116).


The technological challenges of solar geoengineering look simple in comparison to the challenge of building legitimate governance mechanisms for a high-leverage technology with global reach. I have been an early leader in organizing meetings on public policy and governance of geoengineering including meetings at Harvard in 2007, in Lisbon in 2009 (see IRGC), and helped launch the Solar Radiation Management Governance Initiative (SRMGI).


Since my 1992 paper which introduced a structured comparison of cost and risk (#9) and later review paper (#26) that first described the moral hazard and set geoengineering in the post-war history of weather control, I have attempted pragmatic answers to some of the big questions:

  • How unequal? – First quantitative analysis of regional inequality of solar geoengineering (#131).
  • How to reduce risks? – New method to reduce the amount of sulfur needed for a given radiative forcing (#127); and, a novel class of self-levitated particles that might limit ozone loss (#96).
  • What does the public think? – First large-scale survey of public perception (#150)
  • How to regulate? – Proposed two-threshold system that combines a deployment moratoria with a pathway for regulating small-scale research (#163).
  • How to evaluate trade-offs? – Early economic analysis of optimal decisions under uncertainty and a value-of-information analysis while supervising the first economics PhD to focus on geoengineering (#117).
  • Finally, with Jim Anderson I have started a Harvard based project to develop in situ experiments to test the risk and efficacy of aerosols in the stratosphere.

Research Funding

My work has been funded by the US NSF and Canada’s NSERC as well as by a grant from Bill Gates managed as FICER.