Bridging the gaps – Summer Schools on Climate Engineering

Bridging the gaps – Summer Schools on Climate Engineering

As the study of climate engineering (CE) is an emerging field involving a wide range of disciplines, the summer schools described here aimed to bring young researchers together and help constitute a scientific community. Since Nobel Prize laureate Paul Crutzen published his controversially discussed article in 2006 calling for research into CE methods, technologies involving the “deliberate large-scale manipulation of the planetary environment to counteract anthropogenic climate change" 1 are being discussed seriously and the number of CE-studies is steadily increasing. While the first studies were carried out by atmospheric physicists, oceanographers, engineers, etc., social scientists, philosophers and ethicists have more recently begun to enter the field.

The growing number of disciplines involved in researching issues related to CE resulted in the call for increased interdisciplinary cooperation. The series of three interdisciplinary summer schools on CE aimed to encourage such interdisciplinary work, as well as facilitating communication and cooperation between universities from both sides of the Atlantic: University of Heidelberg (Germany), Oxford University (England), University of Calgary (Canada), Carnegie Mellon University (USA). Early researchers and experienced scientists from around the world attended the three schools and were able to exchange ideas and learn from each other. This multiple diversity proved to be very fruitful, although challenging.
The following report describes the three summer schools on CE, details the development of the academic discourse, outlines the scientific debate about if and shows, how CE could be translated into policy.

Organisation: Communicating and collaborating

The first summer school was held in 2010 at the University of Heidelberg, Germany where the interdisciplinary  research group “The Global Governance of Climate Engineering“ was initiated in 2009 (it ended in 2012).  More than forty international students and twenty professors from a wide range of disciplines including Human Geography, Philosophy, Political Economy, Political Science, Psychology, Law, Environmental  and Climate  Physics, as well as Economics met in Heidelberg at a week long summer school to discuss the wide range of issues related to CE. Although the focus of the summer school was on the natural science of climate engineering, several sessions discussed issues related to the technologies’ regulation and governance.  Speakers included pundits from a wide range of fields, including  international governance expert Catherine Redgwell, environmental physicist David Keith, atmospheric chemist Thomas Peter, environmental economist Timo Goeschl, and meteorologists Philip Rasch and Alan Robock, as well as the man credited with enlivening the CE debate with his seminal essay on the topic; Paul Crutzen.  

In his talk Paul Crutzen stressed his preliminary idea of developing CE 2 technologies only as a ‘Plan B’ in case of mitigation failure, and indicated that the wider discourse often referred to CE as ‘mad scientists’ ideas. Other speakers also emphasized the environmental and geopolitical risks involved in the deployment of CE technologies, especially of solar radiation management (SRM) 3 measures. Alan Robock (Rutgers University) discussed "20 reasons why geoengineering may be a bad idea" 4 (a frequently cited paper) and also added some comments on possible positive effects, for example the positive effect increased CO2 concentration could have on agriculture.

The various workshops supported interdisciplinary as well as disciplinary work to pool current knowledge and define research deficits. Using creative methods such as role playing and group brainstorming sessions, the school tried to generate ideas, which could answer hard natural and social science questions related to the development of CE technologies. For example, the participants in Catherine Redgewell’s (University College London) workshop were asked to put themselves into the role of a small island state, scientist, company, etc, and attempt to define principles for the regulation of research and development of CE measures. The results were then compared with the so-called Oxford Principles 5, and although many similarities emerged, it became clear that actors with varying interests also had differing opinions on levels and types of regulation and governance needed. The CE field experiments of the year 2012 demonstrated the strong need for regulation of private interests and patent concerns.

The University of Calgary housed the second summer school in 2011 in Banff, Canada. The more than 48 participants included young researchers from Europe, North America, China, and Russia. To facilitate the event major scientists like Edward Parsons (UCLA Michigan), Jason Blackstock (Oxford Geoengineering Programme), Jane Long (Lawrence Livermore National Laboratory in California), many professors from Heidelberg University, and other guests came in addition to the attendees of the 2010 summer school.

After several participants at the Heidelberg summer school had voiced their interest in more social science discussions, the Banff summer school reduced the number of natural science lectures in favor of sessions on the legal, ethical and philosophical aspects of CE research and deployment. In addition, the organisers attempted to actively facilitate the initiation of interdisciplinary research projects which could be developed over the course of the summer school. To assist in the creation of such interdisciplinary collaborations, several ‘speed dating’ sessions were organised, after which groups incorporating at least three varying disciplines were formed. These groups were expected to develop and present a project proposal to a panel of experts by the end of the summer school and, ideally, continue working together on the project after its conclusion. This practical approach led not only to many productive discussions, and the creation of several lasting collaborations, but also to the initiation of an online network of young CE researchers.

M. Granger Morgan (Carnegie Mellon University), professor for engineering and public policy, elaborated on some interesting problems regarding international CE policy. In his lecture he outlined that not all risk analysis and risk management techniques can be applied to every single CE technology, because there is “no utility for the world.“ Furthermore, if a single nation declares itself a victim of a climate emergency, urgent deployment would be possible. Therefore, we need research now, Morgan claimed. David Keith added that it is important to “squeeze the interest out of SRM”, because of its riskiness. For Edward Parsons, the inclusion of bad decision-making in policy models could be a way to think outside the box.

The third summer school took place in Oxford, England in 2012 with 54 participants and many facilitators as in 2011. While many of them did come back, some new researchers from different fields enriched the discussion. Its central aim was to help young CE researchers to learn more about the science-policy-interaction, as well as communication with the media and the general public. To promote more successful science-policy-interaction, experienced policy advisor Jason Blackstock organised a session focussing on identifying the type of information political representatives needed to enable informed decisions on CE. A skilled BBC journalist organised a workshop to coach young researchers on giving informative and succinct interviews to the media, and an open question-and-answer session involving academics, policy makers and the media facilitated an open exchange of knowledge and opinions.

In addition to the focus on communication with those outside the academic community, the Oxford summer school included several workshops to encourage and improve interdisciplinary communication. This included several very successful peer-to-peer-teaching sessions, during which natural scientists explained their work to social scientists and vice versa before the groups then presented to the plenum what they had learned. Social scientists got a basic understanding of climate modelling with the opportunity to ask elementary questions while the ethic course for natural scientists provided exercises in philosophical thinking. Both groups learned a lot.

With his inspiring talk, Andy Stirling (University of Sussex) brought insights from Science and Technology Studies into the discussion. He wanted to widen the perspective of knowledge creation. His talk explained knowledge creation and the problem of knowing knowledge and identifying not-knowing. But simple know-how is less important than know-why. Why should we do research on CE when we see that it is wrong? Stirling compared CE research with research on torture. No one wants torture (no one should want that), however, under this condition research doesn’t make any sense. Research could also be advocated by the public. The report from Ashley Mercer’s interaction with the public made clear that the public perception of CE is diverse. After publishing the results of their survey 6 – that suggest a broad support for CE research (but not deployment) – Mercer had 15 press interviews. The media interest in CE seems to rise constantly, notably with a unexpected and relatively high trust in science concerning a high risk project.
Similarly to at the Banff summer school participants were encouraged to start new projects or continue work on various collaborations at Oxford. A group led by Andy Parker (Senior Policy Adviser of The Royal Society) worked on the idea of a memorandum. Also existing online platforms – the new Oxford Reference Library (, provided by Oxford) and the Climate Engineering News Site (, provided by Kiel/Heidelberg) were able to coordinate the internet news distribution.

Evolution of the Scientific Discourse

Over the course of these three summer schools, the group of researchers involved became larger and more diverse, and the way CE was discussed, also changed: Rather than mirroring the development of the group by becoming broader and more heterogeneous, the scientific discourse on CE became more concrete, as notions were defined and a pattern of concepts and arguments became well established among the CE research community. While at the first summer school the participants were unable to decide on what to call the field they were researching (suggestions ranged from climate remediation and climate management to climate manipulation and climate geoengineering), and the debate as to whether it even made sense to study such measures was still going strong, at the last school several concepts had become well established among the attendees.

The first and foremost point made by the majority of CE researchers attending the summer schools (and almost all in the field) is that mitigation of CO2 emissions must remain the top priority of the global community. However, the notion, originally emphasized by Paul Crutzen, about the need for CE as a ‘Plan B’ in case of mitigation failure in the future has also become well established. It is argued that, as mitigation is likely to fail in order to prevent dangerous climate change, research into the risks and benefits of CE technologies is needed now to allow informed decisions about deployment can be made in a future emergency situation. The second point made by many members of the CE research community is that deployment of CE would be extremely risky and entail environmental and geopolitical side-effects. Therefore, research is needed. If enough research is done, knowledge can be improved, uncertainties can be reduced, risks can be quantified and thus informed decisions can be made for or against future CE deployment.

In contrast to these arguments in favour of CE research, several counterarguments have also become central to the scientific discourse, e.g., the concept that continued CE research could potentially constitute a ‘moral hazard’ by offering the public the idea of an alternative to mitigation and thereby weakening the incentive to reduce the CO2 emissions. A second key concern is the idea that research on CE will put us on a ‘slippery slope’, meaning that the development of deployable technologies will most likely lead to their deployment. Those social phenomena were introduced a few years ago and remain a constant factor in CE discussions concerning climate political options. ‘Moral hazard’ and ‘slippery slope’ arguments are still not solved and maybe unsolvable.

Thus, despite a general agreement within the scientific CE community that research should continue, concerns about the implications of research remain prominent. These concerns have led to repeated discussions about the need for regulation and governance of CE research. To date there is neither a research regulation nor a governance structure for possible deployment. Edward Parsons suggested taking a step back to first establish the ability for governance 7. Scientific research and regulation have to be built up slowly and will need to be adapted constantly.

How the research strategy should proceed is still far from clear. At the second summer school Ulrich Platt (Heidelberg University) presented new ideas for CE measures using some methods which are well known in the discussion, like stratospheric aerosol SRM (SSRM) and cloud brightening. The question here is: Should research be done with a broader scope or focused on the most feasible/most efficient/least risky technologies? SSRM technologies are being described as possibly highly effective as well as highly uncertain, despite the fact that atmospheric scientists, volcanologists and other scientists have been working on this idea for some years. Platt’s concept was to think outside the box and create new ideas. But still there is no agreement on research priorities.


The summer schools have helped to create a network of researchers who constitute an interdisciplinary CE research community. Various disciplines and the full range of academic ranks, from students to professors, came together to discuss a global, high-risk topic.

The ideas about altering the weather and atmosphere were born in military and grew in science 8, but even David Keith admits that the most difficult problems related to CE are social. The summer schools integrated social sciences and ethics from the start and strengthened their position in the discussion.

Over the course of the three summer schools, the academic CE discourse became increasingly homogenous, but a consensus on research strategies is far from being reached. While the notion of anthropogenic climate change is agreed upon inside of climate science 9 the ideas of CE will stay controversial for a while.


1 The Royal Society (2009): Geoengineering the climate: science, governance and uncertainty. London. Online:
2 There are two main categories of CE: Carbon Dioxide Removal (CDR) and Solar Radiation
Management (SRM). CDR methods reduce the levels of carbon dioxide (CO2) in the atmosphere, allowing outgoing long-wave (thermal infra-red) heat radiation to escape more easily. SRM methods reduce the net incoming short-wave (ultra-violet and visible) solar radiation received. See The Royal Society (2009).
3 SRM involves reducing the amount of solar radiation reaching the Earth by means of a) increasing the reflectivity of clouds, b) placing reflectors in space or c) injecting reflective particles (commonly discussed methods focus on the injection of sulphur particles) into the stratosphere. For a comprehensive overview see Royal Society (2009).
4 Robock, Alan (2008): 20 Reasons why geoengineering may be a bad idea, Bulletin of the Atomic Scientists, 64 (2), pp. 14-18/> Blog: <>.
5 The Oxford Principles of CE research were originally authored in 2009 by Steve Rayner, Tim Kruger and Julian Savulescu of the Oxford Geoengineering Programme, together with Catherine Redgwell (University College London) and Nick Pidgeon (University of Cardiff). In December 2009 these principles were submitted to UK House of Commons Science and Technology Select Committee on “The Regulation of Geoengineering”. The Committee endorsed the principles and recommended that they be developed further.
6Mercer, Ashley Megan; Keith, David W.; Sharp, J. D. (2011): Public understanding of solar radiation management. In: Environ. Res. Lett 6 (4), pp. 1–9.
7 Parson, Edward; Ernst, Lia N. (2012): International Governance of Climate Engineering. In: eScholarship – University of California. See:
8 Fleming, James Rodger (2010): Fixing the sky. The checkered history of weather and climate control. New York: Columbia University Press.
9 Anderegg, W. R. L.; Prall, J. W.; Harold, J.; Schneider, S. H. (2010): Expert credibility in climate change. In: Proceedings of the National Academy of Sciences 107 (27), pp. 12107–12109. See:, zuletzt geprüft am 15.01.2013.