Crutzen +10: Reflecting upon 10 years of geoengineering research

Special Issues
16 May 2016
18 March 2018
undefined cover image

The year 2016 marked the 10 year anniversary of Nobel laureate Paul Crutzen's seminal 2006 contribution on geoengineering, “Albedo enhancement by stratospheric sulfur injection: A contribution to solve a policy dilemma?” Crutzen’s paper in climatic change sparked an unprecedented surge of academic, public, and political interest in geoengineering. This collection comprises research and commentaries from leading experts in the field of geoengineering on the development of the discussion over the past decade and to consider where it may be going in the next 10 years.


Export Citation(s)

Table of Contents

Open Access

Reflecting upon 10 years of geoengineering research: Introduction to the Crutzen + 10 special issue

Miranda Boettcher, Stefan Schäfer,
Key Points

  • In the decade since Crutzen's seminal essay, the field has developed and diversified
  • This 10th anniversary special issue takes stock and reflects on possible future developments in geoengineering research
  • Contributions from a wide range of authors reflect the future-orientation and socio-political dimensions of geoengineering discussions

Open Access

Was breaking the taboo on research on climate engineering via albedo modification a moral hazard, or a moral imperative?

Mark G. Lawrence, Paul J. Crutzen,
Key Points

  • The 2006 Climatic Change special section facilitated opening up scientific research on climate engineering via albedo modification.
  • The “policy dilemma” between air pollution and climate change posed by Crutzen [2006] was eventually resolved by a shift in politics.
  • Attention is needed to limit the ethical risks like the moral hazard, for example, by embedding scientific research in broader societal dialogue.

Open Access

Geoengineering with stratospheric aerosols: What do we not know after a decade of research?

Douglas G. MacMartin, Ben Kravitz, Jane C. S. Long, Philip J. Rasch,
Key Points

  • Research should be strategic to inform possible future decisions about deployment of an intervention
  • Uncertainties include both “scientific” and “design” (or engineering) questions
  • Geoengineering research should aim both to reduce and manage uncertainties

Open Access

Solar geoengineering could substantially reduce climate risks—A research hypothesis for the next decade

David W. Keith, Peter J. Irvine,
Key Points

  • Solar geoengineering (SG) research needs policy-relevant hypotheses about performance of specific deployment scenarios and technologies
  • Research needs to move beyond tests of SG as a substitute for mitigation to tests of the efficacy and risks of SG as a supplement
  • As a testable claim, we suggest that if used to halve the temperature rise SG would reduce aggregate climate risks for all countries

Open Access

The futures of climate engineering

Sean Low,
Key Points

  • Appeals to the future drive the discourse, science, and policy of climate engineering in the present.
  • Future claims are implicit in framings and models; a prominent example is the inclusion of negative emissions in IPCC scenarios.
  • Foresight methods can provide a platform for structured communication on future claims under conditions of deep uncertainty.

Open Access

What do people think when they think about solar geoengineering? A review of empirical social science literature, and prospects for future research

Elizabeth T. Burns, Jane A. Flegal, David W. Keith, Aseem Mahajan, Dustin Tingley, Gernot Wagner,
Key Points

  • Empirical social science research on public views of solar geoengineering is methodologically diverse, focused mostly on the Global North
  • Framing solar geoengineering poses a particular challenge, as the mere introduction of the topic can bias views
  • Studies find some conditional—perhaps reluctant—openness to certain kinds of solar geoengineering research

Open Access

Mitigation deterrence and the “moral hazard” of solar radiation management

Duncan McLaren,
Key Points

  • The relevance of mitigation deterrence depends critically on the assumed goals of climate policy
  • The greater the divergence between perceived and actual substitutability of SRM for mitigation the more significant the hazard
  • More effective responses are needed in SRM research governance as well as in deployment governance

Open Access

Indicators and metrics for the assessment of climate engineering

A. Oschlies, H. Held, D. Keller, K. Keller, N. Mengis, M. Quaas, W. Rickels, H. Schmidt,
Key Points

  • Traditional climate change indicators and metrics may lose their relevance under climate engineering (CE)
  • A comprehensive assessment of CE and mitigation would benefit from common indicators and metrics
  • We propose an iterative process between scientists and stakeholders to define indicators and metrics for assessing CE

Open Access

Five solar geoengineering tropes that have outstayed their welcome

Jesse L. Reynolds, Andy Parker, Peter Irvine,
Key Points

  • Some claims about SRM persist in academic and popular literature despite evidence and strong arguments to the contrary
  • This paper describes and refutes five common claims regarding costs, risks, and politics of SRM that are unsupported by the evidence
  • Repeating unsupported claims do a disservice to the debate when there is a need for evidence-based, even-handed scrutiny of SRM

Open Access

Will China be the first to initiate climate engineering?

John C. Moore, Ying Chen, Xuefeng Cui, Wenping Yuan, Wenjie Dong, Yun Gao, Peijun Shi,
Key Points

  • China has been suggested as likely to initiate the climate engineering despite strong philosophical and cultural bias against this
  • China's history of “gardening” the natural environment means that it sees climate engineering in a different way than that in the West
  • Chinese attitudes and experience with engineered environments should be considered, and may provide useful guidance for global governance

Open Access

Reflecting on 50 years of geoengineering research

Ken Caldeira, Govindasamy Bala,
Key Points

  • Solar geoengineering has been a focus of inquiry for over 50 years
  • Sustained progress in “geoengineering” research will depend on sustained social and material support for experimental work
  • Future trajectories for carbon dioxide removal technologies may differ dramatically from those for solar geoengineering technologies

Open Access

The rationale for accelerating regionally focused climate intervention research

Michael C. MacCracken,
Key Points

  • Foreseeable cuts in CO2 and greenhouse gas emissions will not quickly and sufficiently forestall climate disruption and associated suffering
  • Negative emissions and climate intervention, although difficult and even problematic, may well be necessary policy steps, as Crutzen foresaw
  • Investigation and deployment of regional interventions may moderate severe impacts and provide insights about potential global intervention

Open Access

Development of geopolitically relevant ranking criteria for geoengineering methods

Philip W. Boyd,
Key Points

  • Events such as the Pinatubo eruption provide richly textured data sets that reveal multifaceted Earth System responses to perturbation
  • Despite governance impasses to advancing geoengineering research, natural events such as Pinatubo help to broaden ranking criteria
  • Development of geopolitical ranking criteria reveals a diverse range of diagnostics to intercompare geoengineering approaches

Open Access

Albedo enhancement by stratospheric sulfur injections: More research needed

Alan Robock,
Key Points

  • Paul Crutzen warned the world about dangerous global warming and inspired important geoengineering research in 2006
  • Stratospheric geoengineering could present a number of risks and concerns as well as benefits, but there are still many issues to address
  • More research on geoengineering is needed so that if society is tempted to implement geoengineering, it will be an informed decision

Open Access

Solar geoengineering economics: From incredible to inevitable and half-way back

Anthony Harding, Juan B. Moreno-Cruz,
Key Points

  • Economists were initially attracted to solar geoengineering because of the inexpensive implementation costs
  • After concurring engineering costs analyses estimating low deployment costs, economists began to see solar geoengineering as an inevitable response to the climate change
  • As economists have taken a closer look at the uncertainties, risks, and international politics of solar geoengineering, the feeling of inevitability of solar geoengineering has waned, but warrants more research
  • The work done by economists in solar geoengineering is built on work by researchers in other fields, and moving forward there is going to be an even greater need for interdisciplinary research

Open Access

Towards a comprehensive climate impacts assessment of solar geoengineering

Peter J. Irvine, Ben Kravitz, Mark G. Lawrence, Dieter Gerten, Cyril Caminade, Simon N. Gosling, Erica J. Hendy, Belay T. Kassie, W. Daniel Kissling, Helene Muri, Andreas Oschlies, Steven J. Smith,
Key Points

  • The paucity of climate impacts studies on solar geoengineering is a key missing link in the interdisciplinary research on this topic
  • The climate impacts community can use existing tools and datasets to assess many solar geoengineering effects on natural and human systems
  • Solar geoengineering could be tailored to produce different climate outcomes demanding innovative approaches to impacts assessment

Open Access

Regional climate engineering by radiation management: Prerequisites and prospects

Johannes Quaas, Martin F. Quaas, Olivier Boucher, Wilfried Rickels,
Key Points

  • The article introduces the concept of regional radiation management and its prospects
  • Regional-scale economic incentives are demonstrated on the basis of published data
  • Feasibility and traceability of regional climate modification need to be investigated and new governance options have to be conceived

Open Access

Geoengineering: A humanitarian concern

Pablo Suarez, Maarten K. van Aalst,
Key Points

  • Geoengineering decisions are a humanitarian concern: the deliberate manipulation of the global climate can impact vulnerable people not included in decisions
  • The Paris Agreement aspiration to keep global warming below 2°C did not aim to endorse SRM, but rather ambitious mitigation pathways
  • If resources must be directed towards exploring geoengineering options, the needs and role of the most vulnerable should be given full consideration
  • In the past 10 years, humanitarian players have been largely absent from discussions on geoengineering research and governance; a more proactive and anticipatory engagement is warranted

Open Access

Research for assessment, not deployment, of Climate Engineering: The German Research Foundation's Priority Program SPP 1689

Andreas Oschlies, Gernot Klepper,
Key Points

  • The bottom–up approach of concerned scientists has developed into an interdisciplinary research program to assess climate engineering
  • Research aims at critical assessment of climate engineering, not its deployment
  • A general trend of results so far indicates that the potential of climate engineering becomes smaller the closer we look

Open Access

Relevant climate response tests for stratospheric aerosol injection: A combined ethical and scientific analysis

Georges Alexandre Lenferna, Rick D. Russotto, Amanda Tan, Stephen M. Gardiner, Thomas P. Ackerman,
Key Points

  • Climate response tests aimed at detecting changes in regional climate impacts may not be achievable in time scales relevant for deployment
  • Other possible climate response tests face difficult ethical questions around uncertainty, justice, compensation, consent, intent, and hubris
  • Further research may help to narrow the scientific uncertainties related to climate response tests, and help inform future ethical debate