IASS fact sheet 1/2017 Institute for Advanced Sustainability Studies (IASS) Potsdam, October 2017 Carbon Dioxide Removal

Miranda Boettcher, Stefan Schäfer, Matthias Honegger, Sean Low, Mark G. Lawrence

Despite extensive efforts, greenhouse gases continue to be emitted in vast amounts, with potentially devastating consequences around the world. This is why targeted interventions in the climate system, known collectively as ‘climate engineering’, are receiving increased attention. Proposed approaches are often divided into two groups: those intended to remove carbon dioxide from the atmosphere and those intended to reduce the amount of solar energy that reaches the Earth’s surface or is trapped in the atmosphere. There are some similarities between the two classes of activities, but they often raise different physical, political, and governance concerns. This series provides an introduction to each set of approaches.

220 200

180

160

140 © IASS Carbon Dioxide Removal

What is carbon dioxide removal? achieve the goals. Yet it is still unclear whether any of the proposed technologies, or a combination thereof, Carbon dioxide removal (CDR) refers to a set of pro- could be deployed on the scale and within the time- posals for actively removing carbon dioxide from the frame required to make a meaningful contribution to atmosphere to limit global warming and its effects. achieving the Paris Agreement targets. Also known as negative emissions technologies, these proposals would, if implemented on a global scale, What is the state of research? reduce the rate at which the climate is warming, as well as limiting ocean acidification. The main pro- Natural sciences and engineering posed technologies include afforestation, bio-energy All of the proposed carbon dioxide removal tech- with carbon capture and storage, biochar, direct air nologies are still in early stages of development. capture, enhanced weathering, and ocean fertilisation. Some exist as prototypes; others have been the subject of small-scale field-experimentation. Yet Why is carbon dioxide removal carbon dioxide removal in quantities that would being discussed? contribute significantly to the Paris Agreement goals would require infrastructures comparable in To limit the threat of global warming, at the 2015 scale to the major global carbon dioxide-emitting United Nations Climate Change Conference in Paris, sectors, i.e. energy, agriculture, mining, and mass world leaders agreed to limit temperature rise to well manufacturing. below 2 ° C above pre-industrial levels. This goal pre- supposes a peak in global greenhouse gas emissions In many cases the individual components of this by around 2020, followed by rapid decarbonisation to system – for example, mineral extraction facilities, net zero emissions and the stabilisation of greenhouse pipelines, shipping, forestry, crop harvesting and gas levels by the second half of the century. Yet none processing – are already in place. However, the of the major emitter countries has stringent mitiga- establishment of integrated systems, e.g. for direct tion incentives or regulations in place that would put air capture, followed by the instalment of mass it on track to achieving such a drastic transformation production facilities to enable large-scale deploy- of its economy within this timeframe. Given this dis- ment is likely to take several decades. Existing parity between the Paris Agreement goals and the research in the natural sciences also points to societal difficulties anticipated with rapid emissions other uncertainties, including potential changes to reductions, it is often assumed in socio-economic marine and terrestrial ecosystems due to the scenarios consistent with the 2 ° C limit that some energy, land, and water requirements of the vari- forms of carbon dioxide removal will be needed to ous proposals.

Table 1: Summary of Technology Brief description technologies for remov- ing atmospheric carbon Afforestation Large-scale planting or replanting of forests dioxide (CO2) Source: IASS Bioenergy with carbon capture Burning biomass for energy generation and capturing and

and storage (BECCS) geologically storing the resulting CO2 Biochar Biomass burning under low-oxygen conditions (pyrolysis) to produce charcoal, which is then mixed in with soils to increase the soil carbon content

Direct air capture (DAC) Capturing CO2 directly from the ambient air using chemical processes, followed by long-term storage, for example in underground reservoirs Enhanced weathering Enhancing natural weathering processes by extracting, grinding, and dispersing reactive minerals on land or the ocean Ocean fertilisation Fertilising parts of the ocean with nutrients to increase algal

growth and CO2 uptake in an attempt to increase the rate at which carbon sinks to the seabed in dead algae and is thus removed from the climate system

2_IASS Fact Sheet 1/2017 Carbon Dioxide Removal Carbon Dioxide Removal

Social sciences and governance nical feasibility. An exception is ocean iron fertilisa- Socio-economic research has largely focused on two tion, which has received attention due to 13 scientific approaches: bioenergy with carbon capture and stor- field experiments conducted in the 1990s and 2000s, age and, to a more limited extent, afforestation and as well as high-profile campaigning and attempted reforestation. This has been supplemented by solicita- demonstrations in ocean waters by private companies tion of views from public and expert groups. hoping to use ocean iron fertilisation towards earning carbon credits. Besides this, most other social science Researchers highlight the need for further investiga- research has been conducted in the form of case stud- tions into land-use constraints and other repercus- ies that explore more general issues in relation to the sions for crop production, food pricing, and land man- development of controversial technologies rather agement and ownership. Other open questions than contemplating the concrete application of car- concern the possibility that the promise of carbon bon dioxide removal technologies. dioxide removal could delay or impede immediate and comprehensive mitigation efforts by reducing incen- Future research fields tives to switch to renewable energy sources. Further exploration of the environmental and eco- nomic implications of deployment is likely to draw on Research in the social sciences on direct air capture or earth systems models, impacts and integrated assess- marine-based approaches like enhanced weathering is ment models, and calculations of investment and almost non-existent, with assessments generally lim- infrastructural needs. This will need to be comple- ited to calculations of costs, energy demand, and tech- mented by critical assessments of the assumptions

Figure 1: Climate engin- eering measures can be divided into two CLIMATE ENGINEERING MEASURES UNDER DISCUSSION groups: those intended to remove atmospheric carbon dioxide and those intended to alter 3 the Earth’s solar radia- tion balance. © IASS 5

4 2

6

7 8 1

9

1 2 3 4 5 Marine cloud Cirrus cloud thinning Reflective aerosol Ocean fertilisation Enhanced weathering brightening particles

6 7 8 9 Large-scale Biochar Bioenergy with carbon capture Direct chemical capture

production and storage and storage of CO2

Altering the Earth's radiation balance Removing carbon dioxide (CO2) from the atmosphere

3_ IASS Fact Sheet 1/2017 Carbon Dioxide Removal

underlying model calculations of large-scale deploy- There are already growing calls for coordinated ment from the perspectives of the different stakehold- national and international governance frameworks ers that would be affected by each approach. Com- for research into the associated risks and benefits of paratively more advanced debates on carbon capture the suite of carbon dioxide removal technologies. and storage, biofuels, and forest carbon projects can Such governance could not only ensure that research also be examined as analogies for many carbon diox- is conducted safely and transparently, but also help to ide removal technologies, especially in light of over- mobilise the necessary funding for applied research laps in technological approaches, risk profiles, and and testing and point science towards policy-relevant relevant stakeholders. research.

Are the proposals technically and Ocean fertilisation has served as an entry point for politically feasible? analyses of international governance. The London Convention and Protocol on Marine Pollution pro- While numerous technologies for removing carbon hibits ocean fertilisation for reasons other than “legit- dioxide have been proposed, it is at present unclear imate” scientific research and provides assessment whether any individual technology or set of technolo- frameworks for such activities. Although these devel- gies could be deployed on the scale and within the opments are currently relevant only to marine envi- timeframe that is implicitly assumed in scenarios ronment-based approaches, the possibility of them consistent with the 2 ° C limit. Even if this were pos- serving as templates for the international governance sible in principle, the costs – both operational and of a wider raft of technologies has been raised. societal – and the possible risks and benefits beyond climate stabilisation are uncertain. There is, however, Several initiatives are currently examining governance a broad scientific consensus that while carbon diox- options for research into, and the potential deployment ide removal may complement mitigation efforts, none of, a variety of climate engineering approaches. These of the technologies can substitute for them or obviate range from the development of broad guiding princi- the need for some adaptation to climate change. ples and more specific codes of conduct to assessments of how existing international and national regulatory How could carbon dioxide removal mechanisms could apply to research and deployment. be governed? However, most efforts in this area have been focussed on solar radiation management, and very little analysis The large-scale deployment of measures that alter of governance for individual carbon dioxide removal biological processes to remove additional atmos- technologies has been carried out to date. pheric carbon dioxide, such as afforestation, ocean fertilisation, or growing biomass for bioenergy with What role could carbon dioxide carbon capture and storage is likely to alter local and removal play in achieving the regional ecosystems. This may have complex effects goals of the Paris Agreement? on human and state security, water availability, food production, biodiversity, and energy. Approaches that Recent assessments conclude that a combination of the are not based on biological processes, such as direct different carbon dioxide removal technologies could air capture and storage, are expected to have their make it possible to stay within the 2 ° C limit, assuming own governance challenges related in particular to that large emissions cuts are made at the same time. their expected high energy requirements and ele- However, this is at the upper end of what most esti- vated cost. Although in many cases the governance of mates consider feasible and depends on overcoming carbon dioxide removal activities is likely to fall numerous challenges, including: technology develop- under national regulatory frameworks, some large- ment, upscaling, infrastructure construction, resource scale approaches may have transboundary effects and extraction and availability, carbon or carbon dioxide could therefore require forms of internationally coor- storage site identification and total capacity, earth sys- dinated governance. In addition, incentivising the tem and environmental side effects, economic costs, effective large-scale deployment of all carbon dioxide competition for resources such as biomass for fuel and removal technologies would probably require the food production, public acceptance, and international establishment of an international price on carbon. cooperation on implementation and governance.

4_IASS Fact Sheet 1/2017 Carbon Dioxide Removal

The value of critical global discussions technologies on large scales or on how – and even if – carbon dioxide removal could be incorporated We are at an early stage in our understanding of into strategies to achieve the ambitious targets of the potential role of carbon dioxide removal in cli- the Paris Agreement. Models and assessments can mate policy, and in this situation the value of open provide a basis for collective reflection and discus- and critical global discussions on the topic cannot sion, but decision-making on the potential future be underestimated. To date, the development of role of carbon dioxide removal in climate change climatic scenarios, technical assessments, and pro- policy will need to be informed by a variety of per- totypes has not been accompanied by correspond- spectives on the means, ends, and challenges of ing discussions among policymakers and publics each approach. on the societal implications of deploying such

Summary

Interest in carbon dioxide removal Key uncertainties revolve around has grown due to concerns that the capacity of sinks to safely emissions reductions strategies sequester carbon, the likelihood of might not be enough, or take place conflicts over land use for agricul- too slowly, to keep the climate with- ture or biodiversity preservation, in the level of warming agreed to in ecosystem impacts, and the ques- the Paris Agreement. tion as to whether the development of carbon dioxide removal tech- Nearly all socioeconomic scenarios nologies may reduce incentives to consistent with achieving the Paris switch to renewable energies. Agreement goals rely heavily on some kind of carbon dioxide remov- In addition to extensive further al deployment. research, broad societal engage- ment will be required to establish The state of research and poten- whether research on and the possi- tial readiness varies greatly from ble implementation of carbon one technology to the next. It is at dioxide removal technologies are present unclear whether any indi- consistent with broad societal vidual technology or set of tech- norms. nologies could be technically and politically feasible on large scales.

5_IASS Fact Sheet 1/2017 Carbon Dioxide Removal

Institute for Advanced Sustainability Studies Potsdam (IASS) e. V. The Institute for Advanced Sustainability Studies (IASS) conducts research with the goal of identifying, advancing, and guiding transformation processes towards sustainable societies in Germany and abroad. Its research practice is transdisciplinary, transformative, and co-creative. The institute cooperates with partners in academia, political institutions, administrations, civil society, and the business community to understand sustainability challenges and generate potential solutions. A strong network of national and international partners supports the work of the institute. Among its central research topics are the energy transition, emerging technologies, climate change, air quality, systemic risks, governance and participation, and cultures of transformation. The IASS is funded by the research ministries of the Federal Government of Germany and the State of Brandenburg.

IASS Fact Sheet October 2017

Institute for Advanced Sustainability Studies e. V. (IASS) Berliner Strasse 130 14467 Potsdam Tel: +49 (0) 331-28822-340 Fax: +49 (0) 331-28822-310 E-mail: [email protected] www.iass-potsdam.de

To contact the authors: [email protected] [email protected]

Editing: Alexander Grieß/Anne Boden

ViSdP: Prof. Dr Mark G. Lawrence, Managing Scientific Director

DOI: 10.2312/iass.2017.017