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Principles for Thinking about Carbon Dioxide Removal in Just Climate Policy



Carbon dioxide removal (CDR) is rising up the climate-policy agenda. Four principles for thinking about its role in climate policy can help ensure that CDR supports the kind of robust, abatement-focused long-term climate strategy that is essential to fair and effective implementation.
Forthcoming in One Earth August 2020. DOI 10.1016/j.oneear.2020.07.015
Principles for Thinking about Carbon
Dioxide Removal in Just Climate Policy
David R. Morrow1, Michael S. Thompson2, Angela Anderson3, Maya Batres4, Holly J
Buck5, Kate Dooley6, Oliver Geden7,8, Arunabha Ghosh9, Sean Low10, Augustine
Njamnshi11, John Noël4, Olúfẹ́mi O. Táíwò12, Shuchi Talati3, Jennifer Wilcox13
1 Institute for Carbon Removal Law and Policy, American University, Washington, DC, USA
2 Carnegie Climate Governance Initiative, New York, NY, USA
3 Union of Concerned Scientists, Washington, DC, USA
4 Independent scholar, USA
5 UCLA School of Law, Los Angeles, CA, USA
6 Australian-German Climate and Energy College, University of Melbourne, Melbourne, Australia
7 German Institute for International and Security Affairs, Berlin, Germany
8 International Institute for Applied Systems Analysis, Laxenburg, Austria
9 Council on Energy, Environment and Water, New Delhi, India
10 Institute for Advanced Sustainability Studies, Potsdam, Germany
11 Pan-African Climate Justice Alliance, Nairobi, Kenya
12 Department of Philosophy, Georgetown University, Washington, DC, USA
13 Chemical Engineering Department, Worcester Polytechnic Institute, Worcester, MA, USA
Carbon dioxide removal (CDR) is rising up the climate policy agenda. Four principles for
thinking about its role in climate policy can help ensure that CDR supports the kind of robust,
abatement-focused long-term climate strategy that is essential to fair and effective
Main Text
Carbon dioxide removal (CDR), sometimes called carbon removal or negative emissions, is the
practice of capturing carbon dioxide from the atmosphere and storing it for long periods of time.
There are many approaches to CDR, including nature-based solutions, like ecosystem
restoration, and more engineered approaches, like direct air capture with carbon storage.1
These encompass a variety of options for storing carbon, ranging from biomass and soils to
oceans and geological reservoirs to long-lived products like timber buildings or cement (Figure
1). CDR does not include fossil carbon capture and storage (CCS), such as CCS on a gas-fired
power plant, or carbon capture and use that embeds carbon in short-lived products, such as
synthetic fuels; they might reduce emissions, but neither of these technologies removes carbon
dioxide from the atmosphere.
CDR is rising rapidly up climate policy agendas because it could provide a useful—
perhaps essential—supplement to emissions abatement as the world works toward meeting the
Forthcoming in One Earth August 2020. DOI 10.1016/j.oneear.2020.07.015
Paris Agreement goals for limiting global warming.2 As a result, civil society organizations,
philanthropic funders, and government agencies are wrestling with the challenge of forming
positions on CDR, including whether to support it at all and, if so, what mix of approaches to
support, what kind of policies should govern it, and how to connect it to other elements of
climate policy. The following four principles crystallize some of the key ideas that shape our own
thinking about CDR. We present them here in the hope that others will find them useful as they
deliberate about their own positions.
Figure 1. Some Proposed Methods of Carbon Dioxide Removal. Some of the many
approaches that people have proposed for removing carbon dioxide from the atmosphere and
storing it, presented here without assessment of their respective potential for removing or
storing carbon or their social, environmental, or economic sustainability, which vary between
methods and depend on the details and context of implementation. These methods are often
divided into “natural climate solutions” and “engineered” approaches, with the precise boundary
between those categories contested and somewhat vague. Illustration by Matt Twombly.
Don’t forget the long game
First, CDR is only one part of a long-term climate strategy. Cutting greenhouse gas emissions
must remain at the center of that strategy: CDR would be too slow, expensive and technically
uncertain to replace the need for rapid emissions reductions.3 Furthermore, attempting to do so
would mean missing out on the social and environmental benefits of transitioning to clean
energy. Adaptation, both incremental and transformative, also plays an essential role, as do
measures to address loss and damage. The world needs to do all of these things to fight climate
change—a “both-and” approach, not “either-or.”
Different people and institutions will have different expectations about long-term climate
strategies. These include differences over the kinds of social, economic and technological
Forthcoming in One Earth August 2020. DOI 10.1016/j.oneear.2020.07.015
transformations that societies should or will use to decarbonize, the kinds of policies societies
should adopt to spur those transformations, and the urgency and speed with which the world
can completely decarbonize. These differences imply slightly different roles for CDR as part of
the long-term strategy or different roles for different approaches to CDR at different times. In
particular, some might see a role for CDR to mop up residual emissions while we figure out how
to decarbonize harder-to-abate sectors like construction, heavy industry, and heavy transport.
Others might prefer to limit CDR to compensating only for agriculture and land-use emissions or
to use it after complete decarbonization to draw down “legacy carbon” remaining in the
atmosphere from past emissions.
It turns out that these disagreements have relatively little impact on the question of
whether to devote time and resources to CDR research, development, and deployment now.
Even if the world can completely decarbonize quickly without CDR, almost any path to
decarbonization still leaves the world facing dangerous climate impacts.2 By cleaning up legacy
carbon, CDR could lower carbon dioxide concentrations and reduce climate risk, though
lowering concentrations significantly would require removing hundreds of billions of tonnes of
carbon dioxide.4
To reach that scale, societies can begin rolling out some approaches now, such as
ecosystem restoration, informed by decades of experience at the intersection of land
management and climate policy. Other approaches, such as enhanced mineralization, require
further research, development, demonstration, and deployment. Whatever mix of approaches
societies adopt, scaling up CDR capacity to the multi-gigaton scale, if feasible, would take
several decades.5 Therefore, if we want to remove hundreds of billions of tonnes by the end of
this century, whether as part of a net-zero strategy or to clean up legacy carbon,6 now is the
time to begin developing and adopting appropriate policies for CDR research, development, and
At the same time, thinking only about the long game isn’t enough. Reducing emissions
and adapting to climate change must remain top priorities in the near term.
It’s not all about the carbon
Second, social, economic, and environmental impacts matter. Different approaches to CDR
have different resource requirements and different social and environmental impacts.1,7 Whether
it is an individual farmer adopting cover crop rotations or a large corporation building a direct air
capture facility, the value of any CDR project depends not just on whether and how much
carbon it can sequester at what financial cost, but also on the project’s environmental, social,
and political impacts. In some cases, especially with natural climate solutions, positive impacts
could justify adoption independently of the climate benefits. In others, negative impacts could
outweigh any climate benefits. In all cases, those impacts depend on the context and details of
the project, not just on the particular technology or practice in question. For example, compare a
small bioenergy with carbon capture and storage (BECCS) facility fueled by local municipal
waste with a BECCS system in which huge swathes of commercially farmed land provide
switchgrass to fuel large power plants that pipe carbon dioxide long distances for sequestration.
These two approaches would have very different impacts, which could include impacts on land
use, water use, infrastructure needs, food prices, and biodiversity. Evaluating CDR at the level
Forthcoming in One Earth August 2020. DOI 10.1016/j.oneear.2020.07.015
of broad technologies or practices obscures these differences. As a result, technology-level
assessments tend to focus on things that can be calculated in the abstract, such as cost and
total carbon sequestered. Those aspects of CDR matter, but a complete assessment of CDR
requires assessing not only cost and sequestration potential, but also environmental and social
Three questions about social and political context deserve special attention. The first is
whether a particular project, program, or policy comports with equity and the principle of
common but differentiated responsibility and respective capabilities. CDR is fundamentally
about cleaning up pollution. It makes sense for the polluters to pay for it, with excess costs
falling on those who are best able to bear them. It would be patently unfair for the Global North
to pass the responsibility for cleaning up carbon pollution to the Global South, which contributed
much less to the problem. Some observers worry the very corporations that contributed so
much to carbon pollution could use CDR to evade accountability, but it could be that assigning
these corporations responsibility to undertake or finance CDR offers a way to hold them
accountable. Thus, a key social and political question about any CDR undertaking is the extent
to which the costs and the social and environmental burdens associated with it fall on those who
bear the greatest responsibility for the problem.
The second question is about the overall political and economic context in which CDR would
be deployed in the future. Many civil society organizations argue that nothing short of radical
social transformation will enable us to stop climate change, with some fearing that CDR would
be used to delay that transformation. But a vast, decades-long carbon clean-up operation would
look very different after a radical social transformation than it would in the current political and
economic climate. Moreover, because CDR at the multi-gigaton-scale would require vast
infrastructure, and because some options, like direct air capture, assume widespread cheap
renewables, large-scale CDR implies widespread voter willingness to fund carbon clean-up and
deep decarbonization, making CDR a consequence of social transformation, changed values,
and renewables deployment, rather than an obstacle to them.8 We may need to stretch our
imaginations to envision economic and political futures in which CDR fits into the world we want,
rather than delaying or undermining it.
The third question is about the level of transparency included or required for any given
CDR undertaking. It is difficult to assess an undertaking’s social, economic, and environmental
impacts without adequate transparency, making transparency essential for effective and
legitimate decision-making.
Split, don’t lump
Third, assessing CDR requires going beyond technology-level analyses. This follows from the
second principle. Not all carbon removal is created equal in terms of social, economic, and
environmental impacts, and nuanced positions are needed to distinguish better technologies,
practices, projects, and policies from worse ones.
Broad categories, such as the ones in Figure 1, usefully convey the breadth of options
for CDR, but they also conceal important differences between specific technologies and
practices. For instance, forest restoration and monoculture tree plantations might both fall under
the heading of reforestation, but only the former can promote adaptation, preserve biodiversity
Forthcoming in One Earth August 2020. DOI 10.1016/j.oneear.2020.07.015
and deliver long-term carbon storage.9 To take another example, spreading finely ground basalt
on cropland and scattering olivine pebbles on coastal seabeds both count as enhanced
weathering, but the former requires far more energy to grind the rocks, and the two approaches
involve very different social, economic, and environmental systems.
Furthermore, the social, economic, and political context in which people implement CDR
will affect its acceptance and impacts. For example, consider a direct air capture facility
financed by fossil fuel companies or a petrostate. Some would regard such a facility’s fossil fuel
financing as unforgivable. Distinguishing between different projects and different contexts,
however, allows those who oppose fossil fuel financing to take a nuanced position that opposes
that particular project while leaving open the possibility of direct air capture projects that operate
free from fossil fuel influence and in a context of transparency and good governance. That
makes it important to assess CDR on a case-specific basis, rather than just as abstract
technologies. It is only at this level that organizations can distinguish between bad technologies
or practices and bad projects, taking account of the environmental, social, political, and
governance contexts of specific projects.
In short, fine-grained analyses of carbon removal projects, programs or policies allow us
to avoid throwing the good out with the bad or allowing the bad in with the good. By analogy,
support for emissions reductions doesn’t automatically translate into support for every strategy
that would cut emissions.10 Some see some kinds of low-carbon energy as better than others,
and many outright oppose certain technologies or practices, such as nuclear power plants or
large hydroelectric dams, because of costs, risks, or impacts on vulnerable communities and
ecosystems. It is even possible to support a particular technology while opposing specific
projects. For example, an organization may support policies to incentivize development of solar
energy while opposing a specific project because it is sited on high value biodiversity land. CDR
deserves the same nuanced analysis.
Don’t bet it all on being right
Fourth, climate policy needs to be resilient against unexpected outcomes. The long-term
scenarios that the Intergovernmental Panel on Climate Change (IPCC) analyzed for their Fifth
Assessment Report in 2014 and their Special Report on Global warming of 1.5°C relied heavily
on vast plantations of bioenergy crops for BECCS to keep warming below 2°C or 1.5°C.2,11
Critics noted that counting on future CDR in this way puts future generations’ well-being at risk:
if large-scale CDR never emerges, for whatever reason, then future generations will find
themselves saddled with dangerous levels of atmospheric carbon dioxide.12 We agree that
precaution precludes us from betting it all on CDR panning out as the models project. We also
worry about making the opposite mistake by counting only on rapid emissions abatement: if the
world fails to decarbonize quickly, for whatever reason, or if we decarbonized quickly but the
climate did not respond as we expected, then future generations could find themselves saddled
with dangerous levels of carbon dioxide. Robust, flexible, precautionary climate policy requires
recognizing that, despite our best-laid plans, future generations might benefit from large-scale
CDR in the second half of this century. Ensuring that large-scale CDR is a possibility by mid-
century means beginning research and development now. Playingwait and see” with CDR
Forthcoming in One Earth August 2020. DOI 10.1016/j.oneear.2020.07.015
could leave us with several extra decades of global heating that could have been avoided and
increased risk of crossing climate tipping points.
Why It Matters
What’s at stake in making the right call on CDR? We worry about three things with respect to
CDR: societies could do too little, they could do too much, or they could do it wrong. On the one
hand, if the world does not devote enough time and resources to developing and deploying
CDR, we will face higher carbon dioxide concentrations--and therefore a more dangerous
climate--than necessary. On the other hand, societies that pursue CDR at too large a scale,
adopt the wrong mix of approaches for their circumstances, or govern CDR ineffectively could
face serious social and environmental downsides. By engaging thoughtfully with CDR based on
the principles we have outlined, civil society organizations, funders, and government agencies
can help ensure that CDR plays a positive role in the kind of robust, abatement-focused long-
term climate strategy that is essential to fair and effective climate policy.
1. Royal Society and Royal Academy of Engineering. (2018) Greenhouse Gas Removal.
(Royal Society)
2. IPCC. (2018) Global Warming of 1.5°C. An IPCC Special Report on the impacts of
global warming of 1.5°C above pre-industrial levels and related global greenhouse gas
emission pathways, in the context of strengthening the global response to the threat of
climate change, sustainable development, and efforts to eradicate poverty. Masson-
Delmotte, V., Zhai, P., Pörtner, H.-O., Roberts, D., Skea, J., Shukla, P.R., Pirani, A.,
Moufouma-Okia, W., Péan, C., Pidcock, R., et al., eds. (in press)
3. Smith, P., Davis, S.J., Creutzig, F., Fuss, S., Minx, J., Gabrielle, B., Kato, E., Jackson,
R.B., Cowie, A., Kriegler, E., et al. (2016) Biophysical and Economic Limits to Negative
CO2 Emissions. Nat Clim Change 6, 42–50.
4. National Research Council (U.S.). (2015) Climate Intervention: Carbon Dioxide Removal
and Reliable Sequestration. (National Academies Press)
5. Nemet, G.F, Callaghan, M.W., Creutzig, F., Fuss, S., Hartmann, J., Hilaire, J., Lamb,
W.F., Minx, J.C., Rogers, S. and Smith., P. 2018. Negative Emissions—Part 3:
Innovation and Upscaling. Environ Res Lett 13, 063003.
6. Meadowcroft, J. (2013) Exploring Negative Territory Carbon Dioxide Removal and
Climate Policy Initiatives. Clim Change 118, 137–149.
7. Fuss, S., Lamb, W.F., Callaghan, M.W., Hilaire, J., Creutzig, F., Amann, T., Beringer, T.,
de Oliveira Garcia, W., Hartmann, J., Khanna, T., et al. 2018. Negative Emissions—Part
2: Costs, Potentials and Side Effects. Environ Res Lett 13, 063002.
8. Buck, H.J. (2019) After Geoengineering: Climate Tragedy, Repair, and Restoration
9. Seddon, N., Turner, B., Berry, P., Chausson, A., and Girardin, C.A.J. (2019) Grounding
nature-based climate solutions in sound biodiversity science. Nat Clim Change 9, 84–87.
10. Bellamy, R., and Geden, O. (2019) Govern CO2 Removal from the Ground Up. Nat
Geosci 12, 874–76.
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11. Fuss, S., Canadell, J.G., Peters, G.P., Tavoni, M., Andrew, R.M., Ciais, P., Jackson,
R.B., Jones, C.D., Kraxner, F., Nakicenovic, N., et al. (2014) Betting on Negative
Emissions. Nat Clim Change 4, 850–853.
12. Dooley, K., and Kartha, S. (2018) Land-Based Negative Emissions: Risks for Climate
Mitigation and Impacts on Sustainable Development. Int Environ Agreem-P 18, 79–98.
The authors gratefully acknowledge helpful comments from the editor at One Earth. Note that
the views expressed in this Commentary are those of the authors and do not necessarily reflect
the views of their respective organizations.
... As the call for this special forum has noted, the implications of climate change for rural places and peoples are profound, from the expansion of techno-fixes and extension of neoliberal capital to the need to understand increasingly reactionary agrarian politics . Notably, without addressing the preexisting power structures that have created climate vulnerabilities in the first place, many potential 'solutions' like NETs run the risk of deepening these problems (Morrow et al. 2020;Newell 2022). ...
... Such approaches are bolstered by use of modeling that often fails to include social factors in analysis of the feasibility of NETs (Schweizer et al. 2020). In contrast, agrarian studies scholarship that foregrounds the experiences and expectations of rural peoples can help identify potential risks and roadblocks before NETs are deployed, as well as designing strategies and investments that are more beneficial to rural peoples, including through attention to multiple forms of justice (Morrow et al. 2020;Batres et al. 2021;Healey et al. 2021). ...
... As noted, most of the considerations of feasibility of NETs have focused on technical rather than social or justice elements (Morrow et al. 2020). Agrarian studies scholars can highlight problematic assumptions used in these approaches, such as unclear marginal lands definitions that have influenced the deployment of biofuels (German, Schoneveld, and Pacheco 2011). ...
Negative emissions technologies (NETs) for carbon dioxide removal (CDR) are increasingly important responses to achieve global climate change targets, but to date, there has been insufficient attention to land-based NETs (including afforestation, biochar, and other measures) as an agrarian challenge for the global South. This paper explores the implications of different NETs for land, labor, capital, and politics in rural spaces and contributes to articulating agrarian climate justice by demonstrating the potentially unjust implications of many NETs. The paper concludes with how these measures might be designed to be less negative for rural peoples in future implementation.
... Next, we categorized the activities as 1) nature-based (actions that protect, manage, or restore ecosystems (Cohen-Shacham et al., 2016;Griscom et al., 2017); 2) engineering-based (actions that would not occur without technology); or 3) a hybrid of the two (actions that enhance natural processes through engineering). We note that activities fall in a spectrum between fully nature-based and fully engineering-based (Morrow et al., 2020), and this categorization is based on a value judgment of what constitutes as "natural" (Bellamy and Osaka, 2019;Osaka, 2021). Following CarbonPlan's classification (Rinberg et al., 2020), we use a fourth category for activities that avoid emissions by storing it in a permanent form (called "avoided emissions" on the map). ...
... Although their omittance could be the product of the database being incomplete, it may also reflect the relative infancy in their research and development . Their omittance may also reflect the notion that not all suggested CDR activities are necessarily good ideas, as some have unknown or high risks, sideeffects, or have implementation barriers Minx et al., 2018;Morrow et al., 2020;Williamson, 2016). A process to evaluate which CDR activity is not only promising but also fit-for-purpose, and where targeted research efforts would speed up the development of standards would support a more diverse representation of CDR activities. ...
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Carbon Dioxide Removal (CDR) will be necessary to fulfil the hundreds of pledges to reach net-zero by 2050. As with any industry, standard methodologies and certification are crucial to guarantee successful and reliable activities. However, buyers and policymakers currently face challenges in evaluating the ecosystem of CDR certification. The issue is not with CDR, nor with individual certifications – some of which may be very robust – but with the lack of transparency in the overall ecosystem. To bring some clarity, we present a snapshot of the CDR certification and standards ecosystem for the year 2021–2022. We find a complex ecosystem with at least 30 standard developing organizations proposing at least 125 standard methodologies for carbon removal from 23 different CDR activities and selling 27 different versions of certification instruments in voluntary and compliance markets. This exercise reveals many more existing standards for nature-based than for engineering-based activities and more diversity from standards serving the voluntary rather than the compliance market. It also highlights a proliferation of standards for the same activity, and a plethora of activities without standards. The process revealed ambiguity on what constitutes carbon removal, with many standards certifying activities that remove CO2 already in the environment as well as activities that avoid or reduce new emissions by sequestering the carbon into reservoirs. This mapping highlights key gaps and potential starting points for reforms to strengthen the CDR certification industry; it also underscores the need for independent oversight. Key policy insights • The CDR certification ecosystem is complex and evolving rapidly, raising questions about oversight and quality. • Targeted support would be necessary for the timely development of standards for nascent but promising CDR activities, and oversight would be required to ensure the quality of certification. • Ensuring a minimum quality would require clarifying the treatment of emission reduction, removal, and avoidance, amongst other concerns.
... Many fear a false sense of certainty regarding the feasibility and desirability of CDR (Low and Honegger, 2020). Avoidance of delaying, displacing or otherwise undermining decarbonization efforts is thus a prominent demand (also referred to as "mitigation deterrence, " or "moral hazard" (McLaren, 2016;McLaren and Markusson, 2020;Morrow et al., 2020). Scaling CDR to levels anticipated in IAM scenarios will take decades and is highly uncertain in light of limited technological maturity. ...
... Calls for "separate" or specific targets for CDR and for emissions reductions are common in the CDR-policy literature (McLaren and Markusson, 2020;Morrow et al., 2020). A widely shared justification for focusing on CDR separately from emissions reductions is the need to incentivize action on both, without one (usually CDR) undermining the other. ...
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Climate change mitigation actions, including those aimed at developing and scaling carbon dioxide removal (CDR) activities spanning the industrial, energy, and agroforestry sector, emerge in a context of internationally shared norms that include governance objectives, legal provisions and informal expectations, and societal expectations. Established governance principles provide normative orientation for policy including when targeting the development and scaling of CDR. Knowledge of these principles can guide effective discussion and evaluation of policy options. To facilitate discussion of mitigation options among experts and CDR practitioners, this study excerpts governance principles from legislative texts, the climate governance literature, and the CDR literature with relevance to CDR policy considerations. To illustrate the relevance of the governance principles found for evaluating policy options, we apply them to three technology groups of CDR: Bioenergy with Carbon Capture and Storage (BECCS), Direct Air Carbon Capture and Storage (DACCS), and forestry. This exercise indicates the importance of more intensive attention to the normative dimension of mitigation policies in ongoing deliberative and planning processes. Such efforts can help disentangle normative and factual dimensions and sources of (dis)agreement on the role of CDR in specific climate policy contexts.
... In other words, the focus on quantitative information about the different CDR options is a delimitation of scope rather than a normative statement about what parameters are most important. Clearly, socio-political parameters matter for the deployment of CDR options (see e.g., Buck, 2016;Honegger et al., 2020;Morrow et al., 2020;Waller et al., 2020). ...
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In its latest assessment report the IPCC stresses the need for carbon dioxide removal (CDR) to counterbalance residual emissions to achieve net zero carbon dioxide or greenhouse gas emissions. There are currently a wide variety of CDR measures available. Their potential and feasibility, however, depends on context specific conditions, as among others biophysical site characteristics, or availability of infrastructure and resources. In our study, we selected 13 CDR concepts which we present in the form of exemplary CDR units described in dedicated fact sheets. They cover technical CO2 removal (two concepts of direct air carbon capture), hybrid solutions (six bioenergy with carbon capture technologies) and five options for natural sink enhancement. Our estimates for their CO2 removal potentials in 2050 range from 0.06 to 30 million tons of CO2, depending on the option. Ten of the 13 CDR concepts provide technical removal potentials higher than 1 million tons of CO2 per year. To better understand the potential contribution of analyzed CDR options to reaching net-zero CO2 emissions, we compare our results with the current CO2 emissions and potential residual CO2 emissions in 2050 in Germany. To complement the necessary information on technology-based and hybrid options, we also provide an overview on possible solutions for CO2 storage for Germany. Taking biophysical conditions and infrastructure into account, northern Germany seems a preferable area for deployment of many concepts. However, for their successful implementation further socio-economic analysis, clear regulations, and policy incentives are necessary.
... With the principle of ''common but differentiated responsibilities and respective capabilities'' lying at the heart of the Paris Agreement, there has been recently an increasing reflection on the role and value of CDR at the national scale and the need for equity in sharing its global burden. 51,52 Different burdensharing principles, 53 based on equity, climate change responsibility, or financial capacity for instance, have been investigated in the context of CDR. 51,54 Importantly, the amounts of CDR deployed in global and cost-optimal IAMs scenarios fail to reflect the responsibility of each nation for climate change, or any other socio-economically fair establishment of its share of the global CDR burden. ...
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The international community aims to limit global warming to 1.5°C, but little progress has been made towards a global, cost-efficient, and fair climate mitigation plan to deploy carbon dioxide removal...
... With the principle of "common but differentiated responsibilities and respective capabilities" lying at the heart of the Paris Agreement, there has been recently an increasing reflection on the role and value of CDR at the national scale and the need for equity in sharing its global burden 51,52 . Different burden-sharing principles 53 , based on equity, climate change responsibility, or financial capacity for instance, have been investigated in the context of CDR 51,54 . ...
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The international community aims to limit global warming to 1.5°C, but little progress has been made towards a global, cost-efficient, and fair climate mitigation plan to deploy carbon dioxide removal (CDR) at the Paris Agreement's scale. Here, we investigate how different CDR options - AR, BECCS, and DACCS - might be deployed to meet the Paris Agreement's CDR objectives. We find that international cooperation in climate mitigation policy is key for deploying the most cost-efficient CDR pathway - comprised of BECCS, mainly (74%), and AR (26%) -, allowing to take the most advantage of regional bio-geophysical resources and socio-economic factors, and time variations, and therefore minimising costs. Importantly, with international cooperation, the spatio-temporal evolution of the CDR pathway differs greatly from the socio-economically fair regional allocation of the Paris Agreement's CDR objectives. With limited, or no international cooperation, we find that the likelihood of delivering these CDR objectives decreases, as deploying CDR pathways becomes significantly more challenging and costly - particularly when leading to the deployment of DACCS. Moreover, we show that developing international cooperation policy instruments - such as an international market for negative emissions trading - can deliver, simultaneously, cost-efficient and equitable CDR at the Paris Agreement's scale, by incentivising participating nations to meet their share of the Paris Agreement's CDR objectives, whilst making up for the uneven distribution of CDR potentials across the world. Crucially, we conclude that international cooperation is imperative, as soon as possible, to preserve the feasibility and sustainability of future CDR pathways, and ensure that future generations do not bear the burden, increasingly costlier, of climate mitigation inaction.
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Negative emission technologies (NETs) or the drawdown of atmospheric carbon is increasingly essential to meeting climate targets. Many options (e.g., afforestation) may not however meet the scale of removal and permanence of storage needed. Scientists and engineers are thus turning to new alternatives involving technology bundles using direct air capture of C0 2 and storage. However, the social acceptability of these is presumed unlikely given the sheer complexity of their components, governance arrangements, perceived advantages and disadvantages, and the different moral and value positions at play. This paper explores public perceptions of a proposed system including above sea and potentially more positively viewed components (wind energy to power direct air capture of carbon) alongside deep-ocean and potentially more negatively perceived components (injection and storage as carbonate rock). Using a representative survey of n = 2120 US and Canadian residents nearest a proposed system pilot, analysis reveals two very different profiles of perceivers, pro and con. Rejection of the system as a whole is driven by concern for storage or below sea components, physical risks (e.g., leakage), and belief that such a system constitutes a moral hazard, enabling continued fossil fuel dependence. Conversely, those who support such a system perceive it as economically, climatically, and ethically beneficial now and for future generations, express a strong sense of climate severity and urgency, and see themselves as responsible for natural systems. We close with cautions as to the social licence for negative emission technologies, and the fragility of hope as these possibilities unfold.
Written both for general readers and college students, Dialogues on Climate Justice provides an engaging philosophical introduction to climate justice, and should be of interest to anyone wanting to think seriously about the climate crisis. The story follows the life and conversations of Hope, a fictional protagonist whose life is shaped by the terrifyingly real problem of climate change. From the election of Donald Trump in 2016 until the 2060s, the book documents Hope’s discussions with a diverse cast of characters. As she ages, her conversations move from establishing the nature of the problem, to engaging with climate skepticism, to exploring her own climate responsibilities, through managing contentious international negotiations, to considering big technological fixes, and finally, as an older woman, to reflecting with her granddaughter on what one generation owes another. Following a philosophical tradition established by Plato more than two thousand years ago, these dialogues are not only philosophically substantive and carefully argued, but also distinctly human. The differing perspectives on display mirror those involved in real-world climate dialogues going on today. Key Features: - Written in an engaging dialogue form, which includes characterization, clear exchanges of ideas, and a compelling story arc - Clearly organized to allow readers both in-depth consideration and rapid overviews of various topics - Memorable examples that enable and encourage discussion inside and outside the classroom - An introduction to the book aimed at instructors, which includes helpful instructions for teaching the book and engaging student assignments
Geoengineering is sometimes touted as a partial solution to climate change but will only be successful in conjunction with other mitigation strategies. This creates a potential for a “moral hazard”: If people think geoengineering alone will mitigate climate change, they may become overly optimistic and reduce support for other necessary mitigation efforts. We test this in a series of economic games where players in groups must prevent a simulated climate disaster. One player, the “policymaker,” decides whether to implement geoengineering. The rest are “citizens” who decide how much to contribute to incremental mitigation efforts. We find that citizens contribute to mitigation even when the policymaker uses geoengineering. Despite this, policymakers expect that citizens will engage in moral hazard. As a consequence, policymakers do not use geoengineering even though everyone would be better off if they did so. Anticipating moral hazard undermines mitigation even though moral hazard itself does not.
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The current narrow focus on afforestation in climate policy runs the risk of compromising long-term carbon storage, human adaptation and efforts to preserve biodiversity. An emphasis on diverse, intact natural ecosystems — as opposed to fast-growing tree plantations — will help nations to deliver Paris Agreement goals and much more.
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The most recent IPCC assessment has shown an important role for negative emissions technologies (NETs) in limiting global warming to 2 °C cost-effectively. However, a bottom-up, systematic, reproducible, and transparent literature assessment of the different options to remove CO2 from the atmosphere is currently missing. In part 1 of this three-part review on NETs, we assemble a comprehensive set of the relevant literature so far published, focusing on seven technologies: bioenergy with carbon capture and storage (BECCS), afforestation and reforestation, direct air carbon capture and storage (DACCS), enhanced weathering, ocean fertilisation, biochar, and soil carbon sequestration. In this part, part 2 of the review, we present estimates of costs, potentials, and side-effects for these technologies, and qualify them with the authors' assessment. Part 3 reviews the innovation and scaling challenges that must be addressed to realise NETs deployment as a viable climate mitigation strategy. Based on a systematic review of the literature, our best estimates for sustainable global NET potentials in 2050 are 0.5–3.6 GtCO2 yr⁻¹ for afforestation and reforestation, 0.5–5 GtCO2 yr⁻¹ for BECCS, 0.5–2 GtCO2 yr⁻¹ for biochar, 2–4 GtCO2 yr⁻¹ for enhanced weathering, 0.5–5 GtCO2 yr⁻¹ for DACCS, and up to 5 GtCO2 yr⁻¹ for soil carbon sequestration. Costs vary widely across the technologies, as do their permanency and cumulative potentials beyond 2050. It is unlikely that a single NET will be able to sustainably meet the rates of carbon uptake described in integrated assessment pathways consistent with 1.5 °C of global warming.
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We assess the literature on innovation and upscaling for negative emissions technologies (NETs) using a systematic and reproducible literature coding procedure. To structure our review, we employ the framework of sequential stages in the innovation process, with which we code each NETs article in innovation space. We find that while there is a growing body of innovation literature on NETs, 59% of the articles are focused on the earliest stages of the innovation process, 'research and development' (R&D). The subsequent stages of innovation are also represented in the literature, but at much lower levels of activity than R&D. Distinguishing between innovation stages that are related to the supply of the technology (R&D, demonstrations, scale up) and demand for the technology (demand pull, niche markets, public acceptance), we find an overwhelming emphasis (83%) on the supply side. BECCS articles have an above average share of demand-side articles while direct air carbon capture and storage has a very low share. Innovation in NETs has much to learn from successfully diffused technologies; appealing to heterogeneous users, managing policy risk, as well as understanding and addressing public concerns are all crucial yet not well represented in the extant literature. Results from integrated assessment models show that while NETs play a key role in the second half of the 21st century for 1.5 °C and 2 °C scenarios, the major period of new NETs deployment is between 2030 and 2050. Given that the broader innovation literature consistently finds long time periods involved in scaling up and deploying novel technologies, there is an urgency to developing NETs that is largely unappreciated. This challenge is exacerbated by the thousands to millions of actors that potentially need to adopt these technologies for them to achieve planetary scale. This urgency is reflected neither in the Paris Agreement nor in most of the literature we review here. If NETs are to be deployed at the levels required to meet 1.5 °C and 2 °C targets, then important post-R&D issues will need to be addressed in the literature, including incentives for early deployment, niche markets, scale-up, demand, and—particularly if deployment is to be hastened—public acceptance.
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This paper focuses on the risks associated with “negative emissions” technologies (NETs) for drawing carbon dioxide from the atmosphere through photosynthesis and storing it in land-based sinks or underground. Modelled mitigation pathways for 1.5 °C assume NETs that range as high as 1000 Gt CO2. We argue that this is two to three times greater than the amount of land-based NETs that can be realistically assumed, given critical social objectives and ecological constraints. Embarking on a pathway that assumes unrealistically large amounts of future NETs could lead society to set near-term targets that are too lenient and thus greatly overshoot the carbon budget, without a way to undo the damage. Pathways consistent with 1.5 °C that rely on smaller amounts of NETs, however, could prove viable. This paper presents a framework for assessing the risks associated with negative emissions in the context of equity and sustainable development. To do this, we identify three types of risks in counting on NETs: (1) that NETs will not ultimately prove feasible; (2) that their large-scale deployment involves unacceptable ecological and social impacts; and (3) that NETs prove less effective than hoped, due to irreversible climate impacts, or reversal of stored carbon. We highlight the technical issues that need to be resolved and—more importantly—the value judgements that need to be made, to identify the realistic potential for land-based NETs consistent with social and environmental goals. Given the critical normative issues at stake, these are decisions that should be made within an open, transparent, democratic process. As input, we offer here an indicative assessment of the realistic potential for land-based NETs, based on a precautionary assessment of the risks to their future effectiveness and a provisional assessment of the extent to which they are in conflict with sustainable development goals related to land, food and climate.
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To have a >50% chance of limiting warming below 2 °C, most recent scenarios from integrated assessment models (IAMs) require large-scale deployment of negative emissions technologies (NETs). These are technologies that result in the net removal of greenhouse gases from the atmosphere. We quantify potential global impacts of the different NETs on various factors (such as land, greenhouse gas emissions, water, albedo, nutrients and energy) to determine the biophysical limits to, and economic costs of, their widespread application. Resource implications vary between technologies and need to be satisfactorily addressed if NETs are to have a significant role in achieving climate goals.
Scientists and policymakers must acknowledge that carbon dioxide removal can be small in scale and still be relevant for climate policy, that it will primarily emerge ‘bottom up’, and that different methods have different governance needs.
The signals are everywhere that our planet is experiencing significant climate change. It is clear that we need to reduce the emissions of carbon dioxide and other greenhouse gases from our atmosphere if we want to avoid greatly increased risk of damage from climate change. Aggressively pursuing a program of emissions abatement or mitigation will show results over a timescale of many decades. How do we actively remove carbon dioxide from the atmosphere to make a bigger difference more quickly? As one of a two-book report, this volume of Climate Intervention discusses CDR, the carbon dioxide removal of greenhouse gas emissions from the atmosphere and sequestration of it in perpetuity. Climate Intervention: Carbon Dioxide Removal and Reliable Sequestration introduces possible CDR approaches and then discusses them in depth. Land management practices, such as low-till agriculture, reforestation and afforestation, ocean iron fertilization, and land-and-ocean-based accelerated weathering, could amplify the rates of processes that are already occurring as part of the natural carbon cycle. Other CDR approaches, such as bioenergy with carbon capture and sequestration, direct air capture and sequestration, and traditional carbon capture and sequestration, seek to capture CO2 from the atmosphere and dispose of it by pumping it underground at high pressure. This book looks at the pros and cons of these options and estimates possible rates of removal and total amounts that might be removed via these methods. With whatever portfolio of technologies the transition is achieved, eliminating the carbon dioxide emissions from the global energy and transportation systems will pose an enormous technical, economic, and social challenge that will likely take decades of concerted effort to achieve. Climate Intervention: Carbon Dioxide Removal and Reliable Sequestration will help to better understand the potential cost and performance of CDR strategies to inform debate and decision making as we work to stabilize and reduce atmospheric concentrations of carbon dioxide. © 2015 by the National Academy of Sciences. All rights reserved.
Greenhouse Gas Removal
Royal Society and Royal Academy of Engineering. (2018) Greenhouse Gas Removal. (Royal Society)