What is Climate Engineering?


Climate engineering, also known as geoengineering, describes a diverse and largely hypothetical array of technologies and techniques for intentionally manipulating the global climate, in order to moderate or forestall the (most severe) effects of climate change. In recent years discussions of climate engineering have grown considerably amongst scientists, policy-makers, and civic environmental groups engaged in addressing climate change. A frequent concern is how the development of climate engineering options might complement or weaken efforts at mitigation (reducing GHG emissions through changes in energy source or usage) and adaptation (buttressing societal capacities to endure climatic changes).
These technologies may target different areas of the climate system; possess varying mechanics, costs, and feasibilities; have diverse environmental and societal impacts on varying scales; and create their own sets of risks, challenges, and unknowns. They are commonly divided into two non-exhaustive suites:

  • Carbon Dioxide Removal (CDR) methods attempt to absorb and store carbon from the atmosphere; either by technological means, or by enhancing the ability of natural systems (e.g. oceans) to do so.
  • Solar Radiation Management or Sunlight Reflection Methods (SRM) aims to reduce the amount of heat trapped by greenhouse gases by reflecting sunlight back into space, either by increasing the reflectivity of the earth’s surfaces, or by deploying a layer of reflective particles in the atmosphere.

How did CLimate Engineering Emerge?

Propositions for climate engineering have existed quietly on the fringes of academic debate for decades. In assessing the debate’s recent growth, a number of commentators have linked climate engineering to previous initiatives to control regional weather and various other natural systems during the Cold War era. Others see climate engineering as akin to human attempts to modify their physical surroundings that have existed throughout time.
As a direct response to the issue of climate change, climate engineering research has until recently been absent from serious discussion, due to fears among scientists involved that the introduction of an “alternative” would reduce incentives and momentum to endure the transition to a low-carbon economy, or that the climate system is too complex to alter in a predictable way. However, the slow progress of recent UNFCCC negotiations and emissions reductions worldwide has led to increasing concerns that an exclusive focus on mitigation will not generate efforts timely enough to prevent a damaging degree of climate change from occurring within the next few decades. Indeed, some scientists believe that a certain amount of warming (in excess of 2 degrees Celsius) is already locked into the climatic system. This has prompted much greater attention to the possibilities of adapting societies and ecosystems to changing climatic conditions around the world. There has also been increasing interest in the capacity of CDR technologies to accelerate the removal of GHGs from the atmosphere or, more controversially, to cool the planet through SRM methods.
Two overlapping streams of activity have also contributed to the current wave of interest. A series of scientific ocean iron fertilization experiments from 1990 to 2009 have helped generate interest in (and criticism of) CDR techniques. SRM methods remained largely unexplored until 2006, when Nobel laureate Paul Crutzen penned an influential editorial arguing that using sulphate aerosols to reduce incoming sunlight might serve as an imperfect and temporary measure against climate change, should significant mitigation efforts continue to stall.
The last half-decade has seen a proliferation of scientific study and creation of dedicated research programs to gauge the physical and social effects for both suites of climate engineering technologies. Scientific work has been accompanied by increased attention from the media, public intellectuals, and environmental and technology watchdog groups. Government-commissioned assessment reports have been released by the UK, the US, and Germany, and scientific researchers have begun to increase literacy on the issue amongst policy-makers in both the global North and South. International governance frameworks for field research are being created at the Convention on Biological Diversity and the London Convention and Protocol. The Intergovernmental Panel on Climate Change has substantially expanded its discussion of climate engineering in its fifth assessment report compared to earlier reports.

Risks, Unknowns and Challenges

For now, the field of climate engineering consists of desk and laboratory studies and small-scale field research on some CDR and SRM methods. No technologies have been deployed at a scale that impacts the global climate. Yet, the intent behind climate engineering, its geographically large or even global impact, and the complexity and uncertainty of its potential effects upon climate governance – and human society – raise profound questions.

On a basic level, there are technical questions about the costs and feasibility of development and deployment of various technologies, as well as the geophysical processes that they aim to manipulate. Given our imperfect knowledge of both the technologies and the climatic system, there are worries about unintended environmental and ecosystem side effects. Even if the technologies function as intended, they will not “turn back the clock” from a climate influenced by rising GHG emissions to a previous climate – an engineered climate will be a new and different one.
Climate engineering arises in an equally complex social and political context. Its physical impacts – both intended and unintentional – may alter natural surroundings and weather patterns as well as the lives and livelihoods dependent upon them, with unknown effects upon a slew of existing governance issues: from human and state security, to water availability and food production, biodiversity, and energy. Potential for unilateral deployment of swift-acting methods, such as the injection of reflective particles in the atmosphere to screen the sun, exacerbates these concerns. One of the strongest fears is that developing climate engineering technologies may siphon resources and momentum away from already flagging efforts to reduce carbon emissions, and that this would further disrupt tenuous negotiations at the UNFCCC. Others criticize what they see as the postponing of transitioning off fossil fuels to later generations, the unequal capacity between states to research and deploy the technologies, or shifting the effects of what would have been GHG-driven climate change to countries and demographics that will suffer from the changed environmental conditions that result from engineering the climate. At an overarching level, others question how climate engineering alters (or confirms) humanity’s relationship to the environment in the Anthropocene, as well as the hubris (or ingenuity) of applying technological solutions to complex issues. The wisdom of climate engineering at a moral and ethical level is likely to be highly contentious as discussions of the topic increasingly reach beyond the scientific realm.
It is still an open question as to whether the risks of climate engineering outweigh the risks of climate change, or how climate engineering might be integrated with existing climate policies. Much discussion dwells on how to frame, explore, research, and perhaps even deploy these technologies under conditions of uncertainty- in essence, that decisions on climate engineering have to be made despite the fact that we cannot know the exact unfolding of an engineered climate beforehand, and that it may or may not be more disruptive than the effects of a warming world with rising emissions. Indeed, it is likely that we will never retrospectively know which climate version is preferable, given the uncertainty in climate models, the difficulties in detecting and attributing climatic changes, and the resulting difficulty of constructing a convincing counterfactual.

Critical GLobal Discussions

The complexity of the issues associated with engineering the climate presents a challenge for shaping even the most basic research and engagements with the public and policy-makers today. It is difficult to predict how the debate on climate engineering will influence – or be influenced by – future developments in technology, the climate system, or the international order.

Hence, efforts to probe the boundaries of the discourse- and their effects upon the public imagination- are still evolving. Although research, engagement efforts, and media coverage are growing, they are still largely limited to a handful of countries and actors in the global North. Visions and risks of a climate-engineered future are imagined scenarios extrapolated from early developments or from previous, analogous debates on novel technologies (e.g. nanotechnology or genetic recombination) by small networks of academics, practitioners, and journalists. Early governance frameworks that are being generated in international negotiations and by the academic community remain untested. Even the terms of reference of the debate undergo periodic questioning, with researchers proposing alternative labels and categories for the solar and carbon-targeting suites of climate engineering technologies.
How can we explore a social and technological imaginary, whose discussion might be deemed necessary by some, but will have far-reaching impacts across the global community? We must acknowledge climate engineering as an issue that intersects with other fields and larger trends; in all geographic regions and at all levels of governance. The global community must develop an understanding of the social, environmental, cultural, political and ethical issues involved in a wide and heterogeneous array of climate engineering technologies, in order to efficiently determine whether any of them are appropriate and available in our efforts to address climate change. If we are ever to intervene in the climate in a manner that is broadly equitable across societies, we must first enter into critical global discussions.

Key Resources on Climate Engineering

The Royal Society (UK)

Geoengineering the Climate: Science, Governance and Uncertainty (2009)



Solar Radiation Management Governance Initiative

Solar Radiation Management: the Governance of Research (2011)



The Bipartisan Policy Center’s Task Force on Climate Remediation Research (US)

Geoengineering: A National Strategic Plan for Research on the Potential Effectiveness, Feasibility, and Consequences of Climate Remediation Technologies (2011)



House of Commons Science and Technology Committee (UK)

The Regulation of Geoengineering (2010)



Congressional Research Service (US)

Geoengineering: Governance and Technology Policy (2010)



United States Government Accountability Office (US)

A Coordinated Strategy Could Focus Federal Geoengineering Research and Inform Governance Efforts (2010)



United States Government Accountability Office: Center for Science, Technology, and Engineering (US)

Climate Engineering: Technical Status, Future Directions, and Potential Responses (2011)



The Federal Ministry of Education and Research (Germany)

Large Scale Intentional Interventions into the Climate System? Assessing the Climate Engineering Debate (2011)



IPCC Expert Meeting on Geoengineering (Lima, Peru, 20-22 June 2011)

Meeting Report (2012)



European Transdisciplinary Assessment of Climate Engineering (EuTRACE)

Collaborative project of 14 partner organizations from Germany, UK, France, Austria and Norway, to explore a European perspective toward climate engineering



Climate Geoengineering Governance (CGG)

Collaborative project between Universities of Oxford and Sussex, and University College London to provide a basis for the governance of geoengineering methods



Deutsche Forschungsgemeinschaft / German Research Foundation (DFG)

DFG Priority Program for projects exploring ‘Climate Engineering: Risks, Challenges, Opportunities?’




News-aggregator website for all publications and projects on climate engineering



Geoengineering Google Group

Forum for the discussion of all climate engineering topics, and for updates on projects and publications