Comments to USGCRP Strategic Plan Update

The U.S. Global Change Research Program (USGCRP) coordinates the climate change research efforts of 13 Federal agencies “to assist the Nation and the world to understand, predict, assess and respond to human-induced and natural causes of global change.” In 2012, the USGCRP published its strategic plan that outlined its priorities and goals for the following decade. This past November, the USGCRP released a draft of an update to this strategic plan for public comment, in which the USGCRP specifically asked for input about what role it could play in coordinating research related to carbon removal—i.e. “negative emissions”—solutions. Below is my letter to Dr. Michael Kuperberg, Executive Director of the USGCRP, in response to this request for comment.


January 30, 2016

Dear Dr. Kuperberg,

Thank you in advance for the opportunity to comment on the latest update to the USGCRP strategic plan for 2012-2021. I am writing to address the request for comments about “climate intervention” research (Page 22, lines 31-42), with a particular focus on how the USGCRP can design their research coordination efforts around “carbon removal” (also called “carbon dioxide removal” or “CDR”) most effectively.

I recommend that the USGCRP address carbon removal in the following four ways:

  1. Completely separate discussion on carbon removal and albedo modification, as carbon removal research is best governed in conjunction with—and with the same strong safeguards and governance—as conventional climate mitigation research.
  2. Identify and communicate what research the US Government is pursuing today that is related to carbon removal.
  3. Coordinate carbon removal research efforts across agencies to ensure knowledge is shared effectively and swiftly.
  4. Assist in the coordination of the development and demonstration of carbon removal solutions.

Recommendation 1: Completely separate discussion on carbon removal and albedo modification, as carbon removal research is best governed in conjunction with—and with the same strong safeguards and governance—as conventional climate mitigation research.

It would be misleading to characterize carbon removal research as “climate intervention.” Importantly, the aim and objective of carbon removal is not climate intervention. Instead, carbon removal aims to reduce historical human influence on the climate system by decreasing the amount of excess carbon dioxide in the atmosphere—essentially reversing the influence of anthropogenic greenhouse gas (GHG) emissions. In this regard, carbon removal approaches share a common purpose with conventional climate mitigation technologies, which also seek to reduce human influence on the climate system (by reducing future anthropogenic GHG emissions). In fact, the IPCC defines “mitigation” as “an anthropogenic intervention to reduce the sources or enhance the sinks of greenhouse gases” [emphasis added].

Given the shared objective of carbon removal and mitigation approaches, research into carbon removal should proceed in conjunction with other climate change mitigation research—and with the same set of strong safeguards and governance that would apply to this research. There are significant risks, uncertainties, and challenges surrounding most carbon removal solutions, but these risks are similar in nature and scope to the risks of conventional climate mitigation approaches. Strict governance and ethical consideration is needed of carbon removal and of conventional mitigation approaches, and research programs should consider the issues surrounding carbon removal and conventional climate mitigation using the same criteria.

In contrast, the purpose of albedo modification technologies is to introduce a new form of human influence on the climate system by altering the amount of sunlight absorbed by the Earth. This difference in purpose from carbon removal and mitigation, as well as the novel risks and uncertainties introduced by this new type of climate influence, will require separate governance and ethics considerations. Again, carbon removal approaches need strict and thorough governance and ethical consideration, but the type of governance questions for carbon removal are of a nature best addressed in conjunction with conventional climate mitigation approaches, not in conjunction with albedo modification approaches. Given the divergence between carbon removal and albedo modification approaches, I recommend removing any language in the USGCRP’s update to the strategic plan that combines research efforts of albedo modification and carbon removal approaches.

Recommendation 2: Identify and communicate what research the US Government is pursuing today that is related to carbon removal.

Despite the large role that many climate models suggest carbon removal solutions can play in meeting climate goals, it remains very difficult to identify what research the US Government is pursuing today in relation to carbon removal. To address this situation, I recommend that the USGCRP endeavor to produce a cross-cutting report that identifies all of the research that the US Government is pursuing related to carbon removal (including research into climate mitigation solutions that hold carbon removal potential), and update this report at regular intervals. Communicating what work the US is doing related to carbon removal to policymakers around the world will help foster the global cooperation needed to meet international climate goals.

Recommendation 3: Coordinate carbon removal research efforts across agencies to ensure knowledge is shared effectively and swiftly.

Carbon removal approaches span many industries (including energy, agriculture, and forestry), and thus research into this topic falls under the jurisdiction of a number of Federal agencies. Because of the USGCRP’s comprehensive membership, it is ideally positioned to help each agency set priorities for their own research in a way that reduces duplicative efforts. Some of the key areas where the USGCRP can coordinate carbon removal research across agencies include:

  1. Soliciting external stakeholder input on research priorities. The USGCRP can work with organizations such as the National Academy of Sciences and other leading academic institutions to help identify research priorities for USGCRP member agencies that have the greatest impact on addressing uncertainties and mitigating risks associated with carbon removal and related mitigation solutions.
  2. Advancing multi-sector climate systems modeling. The USGCRP can help foster interagency collaboration to strengthen climate models by improving linkages between terrestrial sequestration approaches and impacts to land and food prices, water and nutrient availability, and land use change (both direct and indirect).
  3. Developing the science needed for measurement and verification of carbon removal projects. The USGCRP’s Carbon Cycle Science Interagency Working Group can work with practitioners developing and regulating carbon removal projects to understand what additional science is needed to measure and verify GHG sequestration projects reliably, and can help direct Agency funding to address the most pressing obstacles. The USGCRP can also engage working groups to help develop science-based accounting standards for various carbon removal approaches.
  4. Researching materials science for better carbon capture. The USGCRP can coordinate the research into materials science to improve our ability to capture CO2 from the atmosphere.

Recommendation 4: Assist in the coordination of the development and demonstration of carbon removal solutions.

Development and demonstration of carbon removal solutions are needed in addition to basic science and research to inform policy related to carbon removal. However, the mandate of the USGCRP does not include solution development and demonstration at this time, and there is no organization analogous to the Climate Change Technology Program (CCTP) of the George W. Bush Administration that is responsible for cross-agency collaboration and coordination of climate solution development and demonstration. To address this issue, the USGCRP can work with the Administration to implement an official CCTP analog that includes carbon removal solutions, and/or collaborate with White House and Congressional officials in an ad hoc manner to ensure that carbon removal solutions development priorities align with USGCRP research activities and priorities, and that solution development efforts are informed by the best science available from the work of the USGCRP.


Thank you again for considering these comments.


Noah Deich

Call for comments: Philanthropy Beyond Carbon Neutrality

Dear readers,

I am proud to announce that the Center for Carbon Removal has released a draft of our first major report, titled: “Philanthropy Beyond Carbon Neutrality: Unlocking the Potential of Carbon Removal Solutions.” (Available on the publications page of our website)

The report includes a deep exploration of why carbon removal is a critical piece of the climate solutions puzzle, as well as an analysis of how philanthropies can ignite action to develop carbon removal solutions. Our team has spent many months analyzing data on philanthropic grant-making to climate-related projects, interviewing climate and philanthropy stakeholders, and surveying the academic literature on carbon removal solutions. I'm also very grateful for all of the feedback we have received so far on earlier drafts of this report from our wonderful advisory board.

But the release of this draft is only a first step. To continue moving forward, we need your help.

We have opened this draft of our report to the public for comments, and we want all of your thoughts. No comment is too small or too big--we want to hear as many ideas as possible, so that the final draft of our report can provide the climate community with as valuable a resource as possible.

Our ask to the climate and philanthropy communities: how can we strengthen our philanthropy report to provide the climate community with as valuable a resource as possible?


There are two ways you can help us achieve this goal. First, please submit a comment through the form on our website (on the publications page). All comments are confidential unless you express otherwise—and we hope you will. Our intention is to respond to all of the comments we get, and we hope to get your approval to incorporate some of the comments directly in the final report. Second, please share this report with anyone else you think would be interested in sharing their thoughts—we want this report to reflect the input of as broad a community as possible.

At the Center for Carbon Removal, transparency and inclusiveness is one of our core values.

Transparency and Inclusiveness: We strive to engage and include the voices of a broad community of stakeholders involved in an open and rigorous debate on the most appropriate pathways for developing carbon removal solutions.
— Center for Carbon Removal: Core Value

Opening this draft of our report to the public before a final version is released is an important way for us to practice what we preach, and we hope that you engage in this effort with us.

Thank you in advance for your support, and I look forward to hearing everyone’s comments and to advancing the conversation on carbon removal as a climate solution.


Noah Deich

Executive Director |  Center for Carbon Removal

Recap: Oxford Conference on Carbon Removal

Background: The Oxford Martin School convened a “Greenhouse Gas Removal Conference” over the three days spanning September, 30 to October 2, 2015. Around 100 people from academia, industry, and NGOs attended to share updates on promising carbon removal research and innovation, and to discuss strategies for the field to gain the policy support it needs to flourish. Being one of, if not the only, conference dedicated to the concept of carbon removal, the event provided a good look into the state of the carbon removal field today. Here’s are the three most important things I took away from the event:

  Researchers from across the world gathered in Oxford for the Greenhouse Gas Removal Conference hosted by the Oxford Martin School.

Researchers from across the world gathered in Oxford for the Greenhouse Gas Removal Conference hosted by the Oxford Martin School.

1. Research and development of carbon removal solutions is progressing in a number of the carbon removal fields. For one, there was encouraging data presented by the community of researchers that are investigating ways to enhance the natural ability of silicate minerals to sequester carbon directly from the air. While there still were a number of presentations that relied on back-of-the-envelope calculations to suggest the potential of this technique for carbon removal, work such as that by Dutch researcher Francesc Montserrat is staring to show real laboratory-scale enhanced weathering processes actually doing what the scientists have suggested they will do.

In addition, the direct air capture (DAC) field is commercializing rapidly. Climeworks announced closing a commercial sales contract on a 1,000 t/yr plant in Germany, Carbon Engineering talked about getting close to inking commercial off-take contracts for solar fuels; Global Thermostat showed calculations showing how they could get below the $50/t price point for DAC CO2. The big caveat here is that DAC developers aren’t focusing on carbon removal in the short-term, as the markets for DAC sequestration aren't large enough. That said, many of the practitioners in the DAC companies that I spoke with expressed confidence that as soon as carbon prices (or other mechanisms for supporting carbon sequestration) rise considerably, DAC companies will have a clear path to delivering net-negative carbon emissions.

2. But there are still numerous uncertainties surrounding all of the carbon removal solutions, particularly around the sustainable scale potential. Biosequestration (e.g. reforestation, soil carbon sequestration, bioenergy with carbon capture and storage) still remains a highly uncertain prospect for carbon removal. Guy Lomax from the Nature Conservancy shared details of his most recent analysis that estimated that such biosequestration approaches are likely quite large, but not enormous – "you can't sequester the geosphere in the biosphere" was the quote that resonated the most with me from his talk. On the bioenergy with carbon capture front, scientists from Greenpeace and from DAC company Carbon Engineering alike shared the view that the sustainable biomass potential is likely constrained significantly,given the indirect land use considerations and potential competition for land with food crops. This view on biomass constraints doesn't seem to be shared with the climate modeling community: Andy Wiltshire from the UK Met Office shared that the average build out of bioenergy with carbon capture in modeling scenarios sequesters over 160 billion tons of carbon dioxide over the next century (equivalent to four times current emission levels today) -- which would involve bioenergy production on land larger than all of India.

 Tim Kruger moderates a panel discussion on biological carbon sinks at the Oxford Greenhouse Gas Removal Conference.

Tim Kruger moderates a panel discussion on biological carbon sinks at the Oxford Greenhouse Gas Removal Conference.

3. The policy and governance conversation around carbon removal is fairly advanced – likely much further advanced than the actual solutions are themselves. This is both a good and bad thing. On the one hand, these discussions are critical for thinking through potential future impacts of carbon removal and how to provide incentives to scale up carbon removal solutions in an appropriate and ethical manner. On the other hand, because there are still so many uncertainties as to which solutions are even going to be viable, these discussions are founded on numerous hypothetical situations and assumptions, making it difficult to extract the most relevant conclusions. This is reflected most in the conversations where carbon removal was still conflated with solar geoengineering, much to the detriment of the overall conversation.

Conclusion: The impact of events like this will hopefully be to stimulate further research and collaboration – building the networks necessary for growth of the field. What’s needed now is to expand the conversation to involve new voices, scale up research, and get deployments happening. To this point, my favorite presentations was from Ned Garnett from the UK's Natural Environment Research Council, who shared his advice on how to get this research funded, telling the audience:

  • Don’t just identify the problem, identify the innovative carbon removal research needed to address the problem;
  • Identify any international development angles to carbon removal, as these are seen as higher priority in funders' minds today;
  • Find independent forums to deliver advice; and 
  • It is critical to have a competitive process for awarding research grants in this field

Bottom line: a very interesting three days of carbon removal conversation in Oxford, and I look forward to more conferences in the future to continue to track the progress of the field and see how it grows over time.


What "Deep Decarbonization" Tells us about Carbon Removal

Here's a common question we hear at the Center for Carbon Removal: if it is technically feasible to prevent climate change without carbon removal (i.e. climate solutions capable of removing and sequestering carbon dioxide that has accumulated in the atmosphere), why bother investing any time and capital to develop carbon removal solutions?

This is the exact question begged by the findings of the Deep Decarbonization Pathways Project (DDPP), a collaboration among climate and energy experts from 16 countries representing around 75% of global greenhouse gas emissions. The recently-released 2015 DDPP synthesis report found that:

  1. "Deep decarbonization of today’s highest emitting economies is technically achievable and can accommodate expected economic and population growth." In other words, it is possible to invest in the clean energy technologies that would prevent global mean temperatures from rising more than 2C by 2050.
  2. "All deep decarbonization pathways incorporate “three pillars” of energy system transformation: energy efficiency and conservation, decarbonizing electricity and fuels, and switching end uses to low-carbon supplies." That is, carbon removal solutions are not included in the DDPP projections.
  3. "Deep decarbonization accommodates the energy services needed to meet countries’ economic growth targets and social priorities."
 The DDPP analysis shows that achieving deep decarbonization by 2050 is possible without carbon removal, but it doesn't argue against developing carbon removal solutions in parallel. 

The DDPP analysis shows that achieving deep decarbonization by 2050 is possible without carbon removal, but it doesn't argue against developing carbon removal solutions in parallel. 

Just because it is possible to achieve deep decarbonization without carbon removal solutions, however, doesn't mean that it still isn't highly valuable to develop carbon removal solutions today. Here's a few reasons why:

  • The limit used to define "dangerous climate change" in the DDPP analysis may be too high. The DDPP analysis defines dangerous climate change as a mean global temperature increase of 2C compared to pre-industrial averages. However, many leading climate experts have suggested that 1.5C is a more reasonable limit. Using a limit lower than 2C requires even more aggressive decarbonization, which in turn makes carbon removal solutions increasingly important. It's also worth noting that whatever temperature limit the international community eventually defines as acceptable, it is a limit, not a goal—it is always best to stay as far below that limit as possible, and carbon removal can only help with that effort.
  • Even though deep decarbonization is technically feasible, political constraints may prevent decarbonization from happening as quickly as is needed. As David Roberts asked in his recent Vox article, "if [curtailing climate change] makes so much economic sense, why are we not [curtailing it]? Why, when study after study has found that we ought to be acting aggressively to transition to clean energy, does actual movement in that direction remain tentative, halting, incremental, and insufficient?" The answer is: politics. If society proves unable to overcome the political constituencies allied against decarbonization, then decarbonization is likely to proceed too slowly to prevent temperature increases above 2C. In this event, carbon removal solutions will be necessary to reduce atmospheric CO2 concentrations back to acceptable levels. And if carbon removal solutions take decades to become commercially viable, then research and development efforts have to begin now to ensure these solutions are ready in the future when they might be necessary.
  • Carbon removal solutions may help build political will to decarbonize more quickly. The more carbon removal solutions that exist, the more tools companies and governments have for fighting climate change. Developing carbon removal solutions, then, can enable greater political commitments to deep decarbonization—even if carbon removal solutions only become a small portion of the overall effort to decarbonize.

Taken collectively, these reasons make a strong case to invest in developing carbon removal solutions today alongside GHG emission abatement approaches today, even though carbon removal isn't technically necessary for deep decarbonization. 

Bonus section for Direct Air Capture month: The DDPP analysis has interesting implications for the direct air capture (DAC) field. The large-scale build out of intermittent renewable generation resources (listed as one of the three "pillars" of the DDPP analysis) holds the potential to create market conditions where DAC systems could thrive. Because DAC systems can turn on and off relatively quickly, they hold the potential to utilize inexpensive energy generated in peak sun/wind periods, while avoiding expensive energy charges during peak demand periods by pausing operation, reducing their overall operating costs substantially. 

Clean technology research and development is critical for curtailing climate change. But is it enough?

A number of leaders in the energy/climate field, from Bill Gates to a group of British climate experts, have recently called for governments across the world to significantly increase spending on research and development (R&D) for clean energy technologies. Implicit in many of these calls for R&D, however, is the misleading idea that the climate change problem can be solved mainly by investments in clean technology R&D. Take the Global Apollo Project report, for example:

"One thing would be enough to [make energy clean]: if clean energy became less costly to produce than energy based on coal, gas or oil. Once this happened, the coal, gas and oil would simply stay in the ground."


“One thing would be enough to make it happen: if clean energy became less costly to produce than energy based on coal, gas or oil. Once this happened, the coal, gas and oil would simply stay in the ground.”
— A Global Apollo Program to Combat Climate Change

While the statement above is true -- and while more publicly funded R&D into all greenhouse gas abatement strategies (including carbon removal) is almost certainly a positive thing -- focusing exclusively on this "one thing" to fight climate change is likely sub-optimal for a number of reasons:

  1. First, there is another way to keep fossil fuels in the ground: regulation. Governments can either impose taxes on carbon-intensive fuels, or simply restrict their use outright. In fact, such regulation would likely spur significant private-sector R&D into clean energy technologies, in the end accomplishing similar (or even deeper) cost reductions for clean energy technologies as compared to cost reductions from public-sector R&D efforts. Most governments have done a poor job of regulating carbon emissions to date -- and have found that climate regulation garners less political support than clean energy R&D -- but smart climate regulation is too valuable a tool to shelve for a focus only on R&D.
  2. Second, a focus on clean energy R&D buries the importance of a key variable in the fight against climate change: time. Cost reductions for clean energy technologies can take significant amounts of time -- event with massive R&D pushes. And we don't have time to wait for R&D to reduce the costs of clean energy, raising the importance of complementary strategies to reduce emissions.
  3. Third, the fact that not all fossil fuels cost the same amount to produce increases the challenges for clean energy systems. Take the oil supply curve, below, for example:

For clean energy to out-compete all supplies of oil on price alone, they can't just get below the current price of oil -- they will have to get below the lowest-cost oil supplies, which are very cheap. This level of cost reduction is hopefully possible to accomplish with massive investments in R&D, but there is significant risk that such cost reductions will not happen at the pace needed to curtail climate change. One strategy to reduce this challenge is to make the cost of these inexpensive fossil resources through smart regulation. Alternatively, policies that encourage the development and deployment of carbon removal systems could enable us to meet climate goals even if R&D efforts to reduce costs of clean energy systems didn't result in prices low enough to displace all carbon emissions.

The bottom line:

While something like a Global Apollo program for clean energy (and for other climate change abatement strategies too) is almost certainly a good idea, society risks moving too slowly to curtail climate change by focusing primarily on R&D. Instead, pursuing parallel policy pathways that increase the cost of extracting and using carbon-intensive fuels alongside clean technology R&D efforts can help ensure that we decarbonize as swiftly as needed to curtail climate change -- and that we do so in as economically-viable and sustainable a manner as possible. 

What climate scientists talk about when they talk about carbon removal

Last week, around 2,000 climate experts gathered at the Our Common Future Under Climate Change Conference hosted by a consortium of NGOs in advance of the upcoming UN COP21 climate negotiations. The idea of removing carbon dioxide from the atmosphere to create “negative emissions” was a hot topic of conversation at the Conference. Below, I’ve summarized my key takeaways about what scientists were saying about carbon removal at the Conference:

 Discussion on the main stage at the Our Common Future Under Climate Change Conference.

Discussion on the main stage at the Our Common Future Under Climate Change Conference.

Takeaway 1: Carbon removal is increasingly embedded in projections of what we will need to do in order to curtail climate change. The consensus documents from the conference state: “to limit warming to 2°C, emissions must be zero or even negative by the end of the 21st century.” Carbon removal solutions will be necessary to transform the economy to generate negative emissions, as more traditional climate mitigation strategies (such as renewable energy, energy efficiency, avoided deforestation, etc.) can only get us to zero emissions – not below zero. And it’s not just "below zero" emissions that we need carbon removal for, as carbon removal solutions also make up a significant component of many pathways for reducing greenhouse gas emissions by 40-70% by mid-century.

Takeaway 2: But…scientists still have many untested assumptions about deploying large-scale carbon removal projects. Today, carbon removal solutions have not been deployed at large scale. As a result, projections of large-scale carbon removal deployments rely on many untested assumptions (around cost, sustainability, scalability, etc.). For example, many projections that include carbon removal solutions involve the large-scale deployment of bioenergy systems, yet critical uncertainties remain around our estimates of:

  • The sustainable supply of bioenergy crops;
  • The ability for bioenergy crops to co-exist with growing demand for food; and
  • Public acceptance about underground carbon sequestration

The scientists working on carbon removal systems are the first to admit these limitations in their models. But unless these assumptions are stress-tested promptly, we risk setting climate policy in a direction that may end up ultimately infeasible and/or unsustainable.

Takeaway 3: Scientists are focusing on a narrow set of carbon removal solutions today. Most of the talk about carbon removal at the conference focused on bioenergy coupled with carbon capture and storage (BECCS, as it is referred to in the scientific community) and forestry solutions (such as reforesting degraded lands or planting new forests altogether). But innovators are also working on other carbon removal methods: direct air capture systems, agricultural techniques with the potential to sequester carbon in soils, and mining techniques that use minerals to sequester carbon directly from the atmosphere, for example. While these latter techniques might have even more uncertainties surrounding them than do bioenergy/forestry approaches, many scientists still think that it is worthwhile conducting further research on these systems to learn how they might broaden the portfolio of feasible, sustainable, and scalable carbon removal solutions in the future.

Takeaway 4: The scientific conversation on carbon removal is an implicit call for increased R&D for carbon removal solutions.

 Carbon removal is the elephant in the room for the climate change conversation: scientists are increasingly convinced we need carbon removal solutions, yet significant uncertainties remain as to what carbon removal solutions can scale in a sustainable, cost-effective way.

Carbon removal is the elephant in the room for the climate change conversation: scientists are increasingly convinced we need carbon removal solutions, yet significant uncertainties remain as to what carbon removal solutions can scale in a sustainable, cost-effective way.

In many regards, carbon removal is the elephant in the room in today’s climate change conversation. While scientists increasingly assume that carbon removal solutions will provide a critical component in the fight against climate change, they are quick to acknowledge that we aren’t researching and building carbon removal projects nearly as fast as needed to ensure we actually can remove carbon from the atmosphere at the scale needed. Implicit in this conversation is the need for more research and development across a full portfolio of carbon removal solutions – something that is critical for policymakers and climate negotiators to make explicit as soon as possible.

A busy week in Carbon Removal: February 8-15, 2015

The second week of February, 2015, proved to be a busy week in all things carbon dioxide removal (“CDR”). First and foremost, the National Academy of Sciences came out with an extensive report on CDR that garnered significant media attention (including my own). The full report is worth the read, but if you only read two lines, I'd recommend the following in terms of importance for the CDR field:

"Even if CDR technologies never scale up to the point where they could remove a substantial fraction of current carbon emissions at an economically acceptable price, and even if it took many decades to develop even a modest capability, CDR technologies still have an important role to play.”


“If carbon removal technologies are to be viable, it is critical now to embark on a research program to lower the technical barriers to efficacy and affordability while remaining open to new ideas, approaches and synergies.”

Second, a great article was published in Nature Climate Change on the potential for bioenergy with carbon capture and storage ("bio-CCS") to generate net-negative electricity for the Western US. A summary of the report is available from UC Berkeley, and the research has garnered considerable outside media coverage. The biomass fuel supply curve developed by the report's authors is particularly interesting, and suggests that 100MM+ ton CDR from bio-CCS is possible in the western US largely from waste and residue feedstocks (which hold the potential to be more sustainable than dedicated feedstocks, assuming wastes aren't valued for other competing uses...).

Supply curve of available solid biomass post-2030.

Above: Biomass supply curve in Western US from Nature Climate Change "Biomass enables the transition to a carbon-negative power system across western North America"

Third, the AAAS Annual Meeting hosted a session titled, “Going Negative: Removing Carbon Dioxide From the Atmosphere” that looked into a wide range of CDR-related issues. The highlights from the session included:

  • Pete Smith from the University of Aberdeen kicked off the session with the conclusion that there is no magic bullet for CDR – pros and cons exist for all approaches – and that more RD&D is needed to develop viable CDR approaches. In addition, Pete noted that sustainability will be critical for developing CDR solutions, and that a negative emission technology strategy will have to develop hand in hand with food-, water-, and biodiversity-security strategies.
  • Jen Wilcox from Stanford summarized some of the key findings from the NAS report on CDR. One of the more interesting results she highlighted was from a paper she authored that estimated the amount of CDR potential in the existing fly ash, cement kiln dust, and iron/steel slag industries today -- which could present low-hanging fruit for turning today's industrial wastes into valuable inputs for tomorrow's CDR process (even though the study finds that such industrial sources represent about 0.1% of total US emissions). More importantly, Jen highlighted that CDR and CCS technologies share a number of open research questions, and could benefit from an overlapping research agenda.
  • Peter Byck from ASU presented his video Soil Carbon Cowboys and discussed the exciting scientific research his team is planning to conduct to assess the potential of adaptive management practices of livestock rearing. And Lisamarie Windham-Myers from the USGS shared her work with soil carbon sequestration, highlighting groups like the Marin Carbon Project
  • The final two presentations of the session, from Ken Caldeira of Carnegie Institution for Science  and Jae Edmonds of Joint Global Change Research Institute, provided an interesting point of conclusion for the session. In particular, Jae's work showed that integrated assessment models of energy systems enthusiastically build bio-CCS projects as a means to decarbonize the energy sector. Bio-CCS (as well as its cousin direct air capture and sequestration, or "DACS") are highly industrial systems, which contrast greatly to the ranching and "carbon farming" techniques highlighted by Peter and Lisa Marie in the previous two sessions. The industrial CDR approaches lag far behind the biological approaches in terms of early enthusiasm outside of the academic community, and it will be critical for these industrial approaches to find an enthusiastic supporter base in industry (or elsewhere) for them to gain traction and meet the promise identified in the integrated assessment models.

Fourth and finally, interesting CCS innovations were on display at the ARPA-E conference in DC. Such innovations from ARPA-E programs like IMPACCT will prove critical for enabling both fossil and bioenergy CCS projects in the future. CCS was only a small fraction of the overall ARPA-E conference, and the session dedicated to CCS focused on the nascent market for utilizing CO2 in industrial applications. I am hopeful that the ARPA-E conferences in the future will highlight more innovations with shared CDR applications, including direct air capture, gasification, and thermochemical biomass conversion technologies.

Recap and Commentary: National Academy of Sciences Report on Carbon Removal

Earlier today, the National Academy of Sciences (“NAS”) released a comprehensive study dedicated to carbon dioxide removal (“CDR”). To date, CDR has largely been relegated to the fringes of the conversation on climate change, despite the fact that major reports from the IPCC and the UN Environment Program have noted that CDR will likely be critically important for preventing climate change. Two factors have likely contributed to CDR’s position on the sideline for the climate conversation:

  1. CDR solutions have historically been conflated with the too-risky/speculative-to-even-research Albedo Modification (formerly Solar Radiation Management) “geoengineering” techniques
  2. Most CDR solutions cost more than other greenhouse gas (“GHG”) abatement approaches (e.g. solar, wind, energy efficiency, avoided deforestation, etc.), leaving little economic incentive for CDR approaches to develop organically.

The release of the NAS report takes important steps towards reducing both of these barriers for CDR to enter the mainstream climate change conversation. First, the NAS released two distinct reports – one on CDR and the other on Albedo Modification – with language explicitly stating that these two categories of “climate interventions” should not be analyzed together. Second, the report unequivocally endorses expanded R&D funding into CDR approaches, in hopes that such funding will enable the eventual commercialization of these CDR approaches.

The NAS analysis stops before identifying the necessary R&D required for developing and commercializing CDR solutions. But this report has hopefully cleared the way for this conversation to happen – along with the many other mainstream policy and industry discussions necessary for the development of CDR solutions.

The NAS study is worth the full read, but I have pulled out a handful of key sentences and figures from the report, below, along with some commentary on their context to the overall conversation on CDR and preventing climate change:

The definition of CDR according to the NAS:

The NAS study defines CDR as:

Carbon Dioxide Removal (CDR)—intentional efforts to remove carbon dioxide from the atmosphere, including land management strategies, accelerated weathering, ocean iron fertilization, biomass energy with carbon capture and sequestration (BECCS), and direct air capture and sequestration (DACS). CDR techniques complement carbon capture and sequestration (CCS) methods that primarily focus on reducing CO2 emissions from point sources such as fossil fuel power plants.”

Under the umbrella of CDR, the NAS identifies two broad classes of CDR approaches:

1. “Some carbon dioxide removal (CDR) strategies seek to sequester carbon in the terrestrial biosphere or the ocean by accelerating processes that are already occurring as part of the natural carbon cycle and which already remove significant quantities of CO2 from the atmosphere.”

2. “Other CDR approaches involve capturing CO2 from the atmosphere and disposing of it by pumping it underground at high pressure”

A graphic that I’ve created to understand how these CDR pathways are related to each other and to non-CDR pathways is below:

CDR pathways 3
CDR pathways 3

Note 1: the NAS study includes ocean iron fertilization, which I haven’t included in the above graphic because “previous studies nearly all agree that deploying ocean iron fertilization at climatically relevant levels poses risks that outweigh potential benefits.” In contrast, no other CDR approaches in the NAS study are given that assessment, and many others are even given endorsements on the grounds that they "can often generate substantial co-benefits.”

Note 2: Including “Carbon Sequestration on Agricultural Lands “ as part of a “Climate Intervention: Carbon Dioxide Removal and Reliable Sequestration” (emphasis added) report is an important win for advocates of soil carbon sequestration: many geologic sequestration proponents have called into question the permanence of soil carbon sequestration as a major issue with these approaches, which the NAS report largely doesn't raise as an issue.

Note 3: I have included biochar in the above graphic, but the NAS does not, citing "literature [on biochar] is still limited, and the impacts of utilization on net greenhouse gas emissions are not well defined."

The NAS report unequivocally separates CDR from “Albedo Modification” techniques…

The NAS study notes,

Carbon Dioxide Removal and Albedo Modification (i.e., modification of the fraction of short-wavelength solar radiation reflected from Earth back into space) have traditionally been lumped together under the term “geoengineering” but are sufficiently different that they deserved to be discussed in separate volumes.”

Separating CDR from Albedo Modification has been in the works for a long time – and I am hopeful that this report will definitively end the discussion of whether CDR falls under the geoengineering umbrella.

The below table from the NAS report highlights a number of key differences between CDR and Albedo Modification proposals. I have added commentary in italics in each cell:

figure 1.2
figure 1.2

...and links CDR as an extension of other GHG mitigation approaches.

“As a society, we need to better understand the potential cost and performance of CDR strategies for the same reason that we need to better understand the cost and performance of emission mitigation strategies—they may be important parts of a portfolio of options to stabilize and reduce atmospheric concentrations of carbon dioxide”

The report clearly states that the first-best option for preventing climate change is stopping GHG emissions, and that neither the development of CDR approaches nor the development of Albedo Modification approaches will change this finding.

The report’s first recommendation is that

“efforts to address climate change should continue to focus most heavily on mitigating greenhouse gas emissions in combination with adapting to the impacts of climate change because these approaches do not present poorly defined and poorly quantified risks and are at a greater state of technological readiness.”

The report goes on to reiterate that

“there is no substitute for dramatic reductions in the emissions of CO2 and other greenhouse gases to mitigate the negative consequences of climate change, and concurrently to reduce ocean acidification.” And by “helping to bring light to this topic area, carbon dioxide removal technologies could become one more viable strategy for addressing climate change.”

Figure 1.4 visualizes this hierarchy of desirable climate responses nicely:

figure 1.4
figure 1.4

The deployment of CDR techniques is limited by their cost, not by their riskiness or likely effectiveness (as is the case for Albedo Modification approaches).

“Carbon dioxide removal strategies… are generally of lower risk and of almost certain benefit given what is currently known of likely global emissions trajectories and the climate change future. Currently, cost and lack of technical maturity are factors limiting the deployment of carbon dioxide removal strategies for helping to reduce atmospheric CO2 levels.”


“Absent some new technological innovation, large-scale CDR techniques have costs comparable to or exceeding those of avoiding carbon dioxide emissions by replacing fossil fuels with low-carbon energy sources.”

The solar energy field in the 1970s provides a decent analog to the CDR field today. That is, the potential benefits from CDR are as clear as the potential benefits from solar were back in the 70s. But like solar in the 70s, CDR will not be able to scale up overnight.

Only CDR approaches can generate net-negative emissions... so if we need to deploy net-negative emissions to prevent climate change, we will need to have viable/scalable CDR solutions.

“industrialized and industrializing societies have not collectively reduced the rate of growth of GHG emissions, let alone the absolute amount of emissions, and thus the world will experience significant and growing impacts from climate change even if rapid decarbonization of energy systems begins.”


“Although such estimates of future deployment of carbon-free energy sources indicate that it may be possible to achieve a decarbonized energy system, great uncertainties remain regarding the implementation of such scenarios due to factors such as costs, technology evolution, public policies, and barriers to deployment of new technologies (NRC, 2010b)”

NAS to science funding government agencies – Part 1: more CDR R&D, please.

“Recommendation 2: The Committee recommends research and development investment to improve methods of carbon dioxide removal and disposal at scales that would have a global impact on reducing greenhouse warming, in particular to minimize energy and materials consumption, identify and quantify risks, lower costs, and develop reliable sequestration and monitoring.”

And from later in the report:

“Developing the ability to capture climatically important amounts of CO2 from the atmosphere and sequester it reliably and safely on scales of significance to climate change requires research into how to make the more promising options more effective, more environmentally friendly, and less costly. At this early stage successful development also requires soliciting and encouraging new synergies and approaches to CDR. Such research investments would accelerate this development and could help avoid some of the greatest climate risks that the lack of timely emissions reduction may make inevitable. The Committee recognizes that a research program in CDR faces difficult challenges to create viable, scalable, and affordable techniques, but the Committee argues that the situation with human-induced climate change is critical enough (see Chapter 1) that these CDR techniques need to be explored to assess their potential viability and potential breakthrough technologies need to nurtured as they arise.”

NAS to science funding government agencies – Part 2: more CDR R&D from everyone, please.

 “Several federal agencies should have a role in defining and supporting CDR research and development. The Committee recommends a coordinated approach that draws upon the historical strength of the various agencies involved and uses existing coordination mechanisms, such as the U.S. Global Change Research Program, to the extent possible.”

Other notes:

  • Page 25: We have to remove a lot of carbon to get back to preindustrial atmospheric CO2 concentration levels – “Reducing CO2 concentration by 1 ppm/yr would require removing and sequestering CO2 at a rate of about 18 GtCO2/yr; reducing CO2 concentrations by 100 ppm would require removing and sequestering a total of about 1800 GtCO2, or roughly the same amount of CO2 as was added to the atmosphere from 1750 to 2000.”
  • Page 26: an interesting history of CDR
  • Page 31: figure 2.2 comparing fossil CCS, DACS, and BECCS.
  • Page 39: Not good grades given to biochar for carbon sequestration purposes: “The residence time of biochar in situ is not well established (Gurwick et al., 2013). Although there has been research associated with the role biochar could play on carbon and nitrogen dynamics, the literature is still limited, and the impacts of utilization on net greenhouse gas emissions are not well defined (Gurwick et al., 2013).” and “Despite not being among the CDR approaches…”
  • Page 57: Interesting graph showing thermodynamics of DACS vs. other CCS approaches
  • Page 62: “In general seawater capture is much less technologically mature than air capture, so research in this area could yield potential benefits.”
  • Pages 72-81: Interesting summary of what characteristics of CDR approaches the NAS committee thought were most important.

In summary and conclusion, in two quotes:

“Even if CDR technologies never scale up to the point where they could remove a substantial fraction of current carbon emissions at an economically acceptable price, and even if it took many decades to develop even a modest capability, CDR technologies still have an important role to play.”


“If carbon removal technologies are to be viable, it is critical now to embark on a research program to lower the technical barriers to efficacy and affordability while remaining open to new ideas, approaches and synergies.”

ARPA-C: How an Advanced Research Projects Agency for Carbon could Catalyze Development of the CDR Field

It has recently become clear that "negative" emissions technologies will likely prove a critical component for preventing climate change. Take, for example, the following sentence from Chapter 6 of the IPCC's Working Group 3 latest Assessment Report on Climate Change:

"The large majority of scenarios produced in the literature that reach roughly 450 ppm CO2eq by 2100 are characterized by concentration overshoot facilitated by the deployment of carbon dioxide removal (CDR) technologies.”

CDR Scenarios
CDR Scenarios

Above: the majority of the scenarios that keep the planet below 2 degrees C of warming (blue line) involve billion+ tonne scale deployments of negative emissions AND full decarbonization of the economy by the end of the century [source].

While CDR technologies have been thrust into prominence in the climate change debate, a major problem remains: currently, no CDR technologies exist that are scientifically, technically, and economically proven at the billion+ tonne scale required to prevent climate change.

CDR approaches
CDR approaches

Above: lots of CDR approaches are under development, but none have clearly demonstrated the potential to provide negative emissions at the billion+ tonne scale in a sustainable and economically viable way.

What's more, CDR technologies will require significant amounts of investment not just in R&D but also in markets to support these technologies once they mature. And government agencies, philanthropies, and private businesses alike are failing to make these necessary investments today.

Solar PV chart
Solar PV chart

Above: Solar PV is just now beginning to be cost competitive with fossil energy -- its development has taken decades of R&D for both technologies and markets. Source: Bloomberg New Energy Finance.

So how might we remedy this market failure and kickstart the development of CDR technologies?

One way would be to create an "ARPA-C", or an Advanced Research Project Agency for Carbon. Right now, the private sector cannot find investment cases for CDR R&D, despite the fact that such investments would also generate immense social benefits -- making the CDR field ideal for publicly-funded applied R&D. If an ARPA-C could fund CDR projects that result in technology cost reductions, advances in innovative business models, and better measurement and verification tools for would-be carbon removers, it could set the stage for follow-on investment by private sector companies to bring the CDR field to scale.

A new ARPA-C would also be critical for giving the CDR field much needed boost in awareness. Right now existing ARPA agencies (including DARPA and ARPA-E) could fund a number of various CDR projects. But none of these existing agencies currently have the mandate to fund the full spectrum of CDR approaches that have been proposed (spanning the energy, agriculture, natural resources, manufacturing, and other sectors). Take ARPA-E's mandate, for example:

"The Advanced Research Projects Agency-Energy (ARPA-E) advances high-potential, high-impact energy technologies that are too early for private-sector investment..."

Thinking about CDR beyond just the energy sector is critical for the field to develop effectively -- and a dedicated ARPA-C would demonstrate the need to think about carbon removal in as systematic a manner as possible.

An ARPA-C wouldn't be without its challenges, however. Most importantly, ARPA-C would have to ensure that the goals it sets for itself are achievable. It is unlikely that many CDR approaches can develop into large-scale, commercially viable businesses within a few years -- the commercialization pathway will likely take a long time. To help generate some quicker wins, a potential ARPA-C wouldn't even necessarily have to fund technologies that are carbon negative today, as some of the companies with the greatest promise for negative emissions are only pursuing low-emissions (not negative-emissions) business models (like the direct air capture startup Climeworks, who has partnered with Audi to make carbon neutral synthetic diesel). If ARPA-C simply helps pave the pathway to a net negative carbon emitting economy, it would be a huge success in the fight against climate change.

And even a small ARPA-C (with a budget in the $100MM range) could have massive positive impacts for the CDR field. At this early stage, small projects have the potential to generate large returns in helping the field prioritize where to focus short-term investments.

So what is certain is that there is a great opportunity for an organization to kickstart the development of the CDR field today. And it's not hard to imagine a new ARPA-C leading the way.

What the McKinsey GHG Abatement Curve tells us about CDR

McKinsey Supply Curve
McKinsey Supply Curve

The CDR field has begun to emerge out of relative obscurity recently as scientists have grown more confident that we will need to remove carbon from the atmosphere to prevent climate change. But CDR is not a new concept. In fact, there are a handful of CDR approaches that have been hiding in plain sight. Take the following supply curve of GHG abatement options that the consultancy McKinsey has prepared.

The approaches highlighted in orange are all CDR techniques. So what does this chart tell us?

  1. CDR isn't new.  McKinsey first produced this widely distributed chart in 2007. While CDR might not have been a concept that was widely known at the time, this chart shows that many CDR techniques were clearly on the radar of climate change analysts.
  2. CDR is relatively inexpensive. The handful of CDR abatement options considered here all are expected to cost less than 20 Euros / tCO2 by 2030 (note: this chart shows estimates for McKinsey's expected cost/potential of different GHG abatement options in 2030 -- not actual  costs/potential as they stand today).
  3. CDR Supply Needs
  4. The supply of CDR techniques is potentially quite large. The techniques considered by McKinsey are able to provide around 5 tCO2 per year, which could provide a significant fraction of the likely demand for CDR, as shown in the chart below:  Source: The Climate Institute
  5. CDR is a complement to mitigation -- not a competitor. Many worry that CDR will be used as an excuse to delay decarbonization of the economy. This chart shows that CDR isn't a substitute for decarbonization, but instead part of the portfolio of solutions we can deploy to minimize the overall costs of decarbonization.
  6. Only a small fraction of the CDR approaches that have been proposed are expected to be "viable" by 2030 according toMcKinsey. Many other CDR approaches besides the ones considered by McKinsey have been proposed, as shown below:
CDR Approach tree
CDR Approach tree

The McKinsey curve focused only on the orange box under the "biological removal" branch of proposed CDR approaches. I've constructed a supply curve of many of the prominent CDR options based off of data and estimates from the IPCC and the Virgin Earth Challenge, reproduced below:

CDR Supply Curve
CDR Supply Curve

Of note is that McKinsey only considered GHG abatement options that they expected would cost less than 80 Euros/tCO2 in 2030, whereas the full CDR supply curve includes a number of approaches well above that threshold. The cost estimates in the full CDR chart also are current estimates (not projections for 2030), and so are likely to come down in cost significantly by 2030 if significant R&D spending flows to these approaches.

6. McKinsey is bullish on the technical potential for "biological" carbon removal approaches. The science behind several of the proposed land management CDR approaches that McKinsey considers remains uncertain. The degree to which grassland management, for example, can sequester the amount of carbon McKinsey suggests still requires significant scientific analysis to confirm. It is certainly possible for McKinsey's supply estimates to be validated, but first considerable investment in basic science behind some of the CDR approaches is required.

Can CDR "piggyback" on existing carbon capture research programs?

Several CDR approaches would benefit substantially from advances in carbon capture technologies that were designed to capture emissions from fossil fuel resources. Direct air capture, bio-CCS , and even biochar systems, for example, could all benefit from technical advances in carbon capture systems. What's more, there seems to be renewed interest in Federally-funded carbon capture demonstrations in the US, as evidenced in part by this latest Request for Information from the Department of Energy (DOE) titled: "Testing advanced post-combustion carbon dioxide capture technologies at a large pilot scale." Today, however, CDR is largely  absent from the research and development agenda for carbon capture systems.

Pre-Combustion CO2 Capture

Above: The US National Carbon Capture Center focuses on "clean coal," but it might benefit substantially from broadening its focus to include CDR techniques such as bio-CCS and Direct Air Capture.

A shared research agenda between CDR and fossil CCS could benefitboth communities, most importantly by enabling each community to get more funding. If carbon capture technologies are seen as more broadly applicable and more important for the fight against climate change, it is more likely that these technologies will get greater research funding. Framing CCS technologies as more than "clean coal" by including bio-CCS, for example, could help increase political support for CCS projects.

Bottom line: it is in the interest of both the fossil CCS and CDR communities to coordinate research agendas to ensure that investments in both fields generate the greatest returns.

One of nature's oldest carbon capture devices is also one of its most prodigious

Scientific American has a great article on the ability of the fern-like plant species Azolla to sequester carbon dioxide from the atmosphere. The most amazing stat from the article to me is that:

"Azolla bloomed and died like this in cycles for roughly 1 million years," over which period of time carbon dioxide level "dropped from between 25,000 and 35,000 [parts per million] to between 15,000 and 16,000 ppm."


Azolla. Source: Scientific American

What's so amazing about this?

  1. How much CO2 was in the atmosphere. Humans start to feel drowsiness and reduced cognitive function at about 1000 ppm CO2.
  2. How long it took to draw down these CO2 levels to the <600ppm levels of the past 2.5 million years. 50 million years is a long time -- especially given that scientists predict that only 50 years of unabated emissions will cause CO2 concentrations to rise above the 600 ppm levels not seen in recorded human history.
  3. The fact that the biological systems are capable of sequestering massive amounts of CO2: 1 pmm of CO2 weighs roughly 2 billion tons.

What the latest UNSDSN report gets right - and wrong - about negative emissions

The UN Sustainable Development Solutions Network (UNSDSN) recently released an interim report on the "Pathways to Deep Decarbonization." This report acknowledges negative emissions might play a role in helping the world meet carbon emission goals, but came to the stance that:

"large-scale net negative emissions are still too uncertain to build into our country-level Deep Decarbonization Pathways (DDPs), even though we strongly support research programs that could make net negative emissions a future reality."

The UN is right that large-scale net negative emissions are quite uncertain. But I think the UN is overly pessimistic about the potential for negative emissions to contribute to sustainable decarbonization. The technology section on negative emission approaches in the report only includes two negative emission techniques:

"The popular placeholder for net negative emissions is the integration of biomass energy (BE) with CCS, both as technologies for electricity generation and biofuel production..."


"An alternative approach for net negative emissions would be the direct air capture of CO2 followed by geological storage."

Numerous other negative emission technologies have been proposed, many of which could also help the UNSDSN promote sustainable development across the world. For example, many holistic land management, afforestation, and biochar techniques could help improve agricultural productivity,  water security, and ecosystem health in addition to removing carbon from atmosphere.

Herders Field From Seth

Holistic Ranch Management in Africa. Source: Savory Institute

Palm OIl
Palm OIl

Sustainable Palm Oil Plantation in Indonesia. Source: WWF

I hope that the UNSDSN reconsiders the role that CDR can play in meeting deep decarbonization and other sustainable development goals when it issues its final report in 2015.