Uncertainty drives carbon ambition, even as deployment potential still at some remove
2021; Elsevier BV; Volume: 7; Issue: 11 Linguagem: Inglês
10.1016/j.chempr.2021.10.011
ISSN2451-9308
AutoresDanny Broberg, Caroline P. Normile, Addison K. Stark,
Tópico(s)Atmospheric and Environmental Gas Dynamics
ResumoIn the October issue of Joule, Grant et al. explore how uncertainties in three CDR pathways (BECCS, DACCS, and afforestation/reforestation) can be incorporated into integrated assessment models, resulting in an additional 10 gigatons of CO2e requiring mitigation by 2030. This finding underscores the importance of accelerating CDR research, design, and development. In the October issue of Joule, Grant et al. explore how uncertainties in three CDR pathways (BECCS, DACCS, and afforestation/reforestation) can be incorporated into integrated assessment models, resulting in an additional 10 gigatons of CO2e requiring mitigation by 2030. This finding underscores the importance of accelerating CDR research, design, and development. Main TextIntegrated assessment models (IAMs) are widely used tools for informing policy making and have been central to the results of reports by the Intergovernmental Panel on Climate Change. In recent years, these models have helped clarify the important role that carbon dioxide removal (CDR) deployment will play in complementing emissions reduction efforts as nations address climate change.IAMs serve to optimize economic and technological decision making to achieve emissions reduction targets. Despite their complexity, IAMs currently lack the social and political dimensions1Doukas H. Nikas A. González-Eguino M. Arto I. Anger-Kraavi A. From integrated to integrative: Delivering on the Paris Agreement.Sustainability. 2018; 10: 2299Crossref Scopus (57) Google Scholar that would more effectively represent the uncertainties underlying policy decisions. One example of this limitation is how IAMs may reflect a given trajectory to reaching net-zero greenhouse gas emissions. While one trajectory may minimize costs among a variety of decarbonization pathways—with assumptions about cost declines following innovation and deployment—real-world deployment requires federal and state policy advances at a time when there is wide uncertainty about future innovation and cost reduction capabilities.This uncertainty applies to the future of implementation of CDR approaches. In last month’s issue of Joule, Grant et al.2Grant N. Hawkes A. Mittal S. Gambhir A. The policy implications of an uncertain carbon dioxide removal potential. Joule, 2021Abstract Full Text Full Text PDF Scopus (6) Google Scholar conduct a unique survey of the “feasible potential” for CDR deployment from experts in the field and use the results to produce a probability distribution for CDR deployment uncertainty in their own IAM through stochastic optimization. By differentiating “feasible potential” from the “technical” or “sustainable” potentials, they aim to account for important considerations surrounding cost-reductions and technology readiness produced by innovation, institutional barriers for deployment, and other social, environmental, or governance issues that may influence the ultimate deployment of a given CDR method.Grant et al. use this unique approach to estimate an additional 10 gigatons of CO2e that may require mitigation by 2030, when accounting for CDR uncertainty. The authors further argue that this justifies massive ambition surrounding CDR innovation in the coming decade. In short: technical innovation can help narrow the range of uncertainty for policymakers.The CDR approaches explored by Grant et al. are in very different stages of technological development or deployment. These approaches include bioenergy with carbon capture and storage (BECCS), direct air capture with carbon storage (DACCS), and afforestation/reforestation (AR). Other burgeoning forms of CDR and storage—including direct ocean capture, soil carbon sequestration, and enhanced mineralization—also show tremendous potential but are not the focus of Grant et al.Each of the pathways examined by Grant et al. have unique challenges, but technological innovations have the potential to enable tremendous CDR deployment. We explore several possible ways to further enable global-scale deployment of CDR technologies and better validate stored carbon to decrease the associated uncertainties of projected feasible potentials for CDR deployment of BECCS, DACCS, AR, and other approaches (see Figure 1).Policy momentum and public support for mechanical removal of carbon through direct air capture (DAC) has accelerated tremendously over the past decade, with the Swiss company Climeworks commencing operation of the world’s largest DAC project, “Orca”, outside of Reykjavik in September 2021. The 4,000 tons CO2/year that this facility is drawing down is a drop in the bucket relative to the gigaton scale necessary for addressing climate change. Reaching this scale requires major cost reductions. For solid adsorbent approaches like the one demonstrated by Climeworks, adsorbent costs are more than 70% of the total capital expenditure and operating expenses costs. Moreover, experience from amine-based solid sorbents used in conventional carbon capture plants suggests that these solids degrade and break down over time.4NASEM(National Academies of Sciences, Engineering, and Medicine). Negative emissions technologies and reliable sequestration: a research agenda. The National Academies Press, 2019Google Scholar The potential to scale-up unique industrial sorbents that maximize CO2 uptake, reducing costs, and increasing sorbent lifetimes remains an active area of research.5McQueen N. Vaz Gomes K. McCormick C. Blumanthal K. Pisciotta M. Wilcox J. A review of direct air capture (DAC): scaling up commercial technologies and innovating for the future. Progress in Energy, 2021Google Scholar Competition with liquid solvent approaches, which operate at substantially higher temperatures, or an entire departure from the standard pressure or vacuum swing paradigms (such as through moisture-swing or electro-swing approaches) remain attractive pathways as well.Carbonate weathering and DOC are other areas ripe for innovation. Carbonation is a natural process that can store CO2 at scale, but a major bottleneck is access to alkali substances like Mg− or Ca− that readily want to react in the presence of CO2. Enhanced weathering in agricultural landscapes is also receiving increased attention for its potential climate and ecosystem benefits.6Beerling D.J. Kantzas E.P. Lomas M.R. Wade P. Eufrasio R.M. Renforth P. Sarkar B. Andrews M.G. James R.H. Pearce C.R. et al.Potential for large-scale CO2 removal via enhanced rock weathering with croplands.Nature. 2020; 583: 242-248https://doi.org/10.1038/s41586-020-2448-9Crossref PubMed Scopus (131) Google Scholar Used as a soil amendment, rock dust is applied to croplands, where it supports carbon sequestration in soils while also releasing nutrients that are critical to plant growth, such as calcium, magnesium, potassium, and phosphorus.Another emerging CDR pathway that falls outside the scope of Grant et al. is ocean-based CDR via kelp and seaweed sinking. Ocean-based CDR offers a blue-sky (or blue-sea, in this case) opportunity to increase total CDR potential by expanding our portfolio of removal approaches beyond just terrestrial systems. Ocean-based natural CDR has the potential to provide a pathway for dissolving atmospheric CO2 in the ocean at gigaton scale for costs below $50/ton. Naturally occurring macroalgae already play a significant role in the global carbon cycle, with more than 173 TgC/year sequestered by their growth and natural sinking.7Sclarsic, S.M.H. (2021). A bioengineering roadmap for negative emissions technologies. Masters thesis, (Massachusetts Institute of Technology).Google Scholar There has been recent public and private investment in the cultivation and sinking of macroalgae for direct CDR to the deep ocean floor (below 1,000 m) where the carbon is effectively permanently removed from the biosphere for >1,000 years. Recently the US Department of Energy’s ARPA-E MARINER program funded research and testing of large-scale kelp farming, and a number of private companies are working to develop the systems necessary to scale kelp-sinking to the gigaton per year scale, but open research questions remain.8Temple J. Companies hoping to grow carbon-sucking kelp may be rushing ahead of the science.https://www.technologyreview.com/2021/09/19/1035889/kelp-carbon-removal-seaweed-sinking-climate-change/Date: 2021Google Scholar Biochemical engineering approaches could be employed to further optimize seaweed species to increase negative buoyancy, faster growth, and relative carbon content of species for sinking applications.Beyond innovation in CDR technologies themselves, advances are also needed to support enhanced monitoring and verification of removals. This is especially true of terrestrial carbon storage and sequestration. At large scales, the carbon cycle is relatively well-constrained. We know, for example, that the global terrestrial biosphere sequesters some 30% of global emissions. However, monitoring land-based CDR at higher spatial and temporal resolutions is limited by measurement and sensing challenges, and quantifying land-based CDR at the plot level remains expensive, time-consuming, and labor intensive.9USGCRPSecond State of the Carbon Cycle Report (SOCCR2): A Sustained Assessment Report. U.S. Global Change Research Program, 2018Google Scholar This is especially true for below-ground carbon stocks. While above-ground carbon stocks, such as those in trees, shrubs, and grasses, can be passively monitored at scale via remote sensing (e.g., NASA Global Ecosystem Dynamics Investigation Lidar),10Dubayah R. Blair J.B. Goetz S. Fatoyinbo L. Hansen M. Healey S. Hofton M. Hurtt G. Kellner J. Luthcke S. Armston J. et al.The Global Ecosystem Dynamics Investigation: High-resolution laser ranging of the Earth’s forests and topography.Science of Remote Sensing. 2020; 1: 100002Crossref Google Scholar quantifying below-ground baselines and monitoring changes requires data on mineral-organic matter interactions, soil microbiology and chemistry, environmental conditions, and other variables to inform models, project productivity rates, and estimate residence time of the soil carbon. But emerging research is tackling this challenge. For example, the ARPA-E Systems for Monitoring and Analytics for Renewable Transportation Fuels from Agricultural Resources and Management (SMARTFARM) program is supporting validation technology with the goal of increasing resolution and certainty of soil organic carbon monitoring in order to inform new crediting mechanisms. The program is advancing commercial tools to directly measure fluxes of carbon, exploring integration of drone-captured digital imagery and eddy covariance data into networked systems, and fostering innovation in reliable soil carbon measurement at depth.Emissions mitigation remains the priority in addressing climate change, but the scientific consensus now tells us that carbon removal has an essential role to play in meeting climate goals. The pace and magnitude of CDR deployment is highly variable in the literature, and Grant et al. demonstrate with stochastic optimization that this uncertainty can result in an additional 10 GtCO2e that needs to be mitigated by 2030. Their result illustrates the dual conclusions that (1) further climate ambition is needed for driving down emissions in the coming decade and (2) CDR innovation may yield significant dividends and accelerate our pathway to net-zero. Main TextIntegrated assessment models (IAMs) are widely used tools for informing policy making and have been central to the results of reports by the Intergovernmental Panel on Climate Change. In recent years, these models have helped clarify the important role that carbon dioxide removal (CDR) deployment will play in complementing emissions reduction efforts as nations address climate change.IAMs serve to optimize economic and technological decision making to achieve emissions reduction targets. Despite their complexity, IAMs currently lack the social and political dimensions1Doukas H. Nikas A. González-Eguino M. Arto I. Anger-Kraavi A. From integrated to integrative: Delivering on the Paris Agreement.Sustainability. 2018; 10: 2299Crossref Scopus (57) Google Scholar that would more effectively represent the uncertainties underlying policy decisions. One example of this limitation is how IAMs may reflect a given trajectory to reaching net-zero greenhouse gas emissions. While one trajectory may minimize costs among a variety of decarbonization pathways—with assumptions about cost declines following innovation and deployment—real-world deployment requires federal and state policy advances at a time when there is wide uncertainty about future innovation and cost reduction capabilities.This uncertainty applies to the future of implementation of CDR approaches. In last month’s issue of Joule, Grant et al.2Grant N. Hawkes A. Mittal S. Gambhir A. The policy implications of an uncertain carbon dioxide removal potential. Joule, 2021Abstract Full Text Full Text PDF Scopus (6) Google Scholar conduct a unique survey of the “feasible potential” for CDR deployment from experts in the field and use the results to produce a probability distribution for CDR deployment uncertainty in their own IAM through stochastic optimization. By differentiating “feasible potential” from the “technical” or “sustainable” potentials, they aim to account for important considerations surrounding cost-reductions and technology readiness produced by innovation, institutional barriers for deployment, and other social, environmental, or governance issues that may influence the ultimate deployment of a given CDR method.Grant et al. use this unique approach to estimate an additional 10 gigatons of CO2e that may require mitigation by 2030, when accounting for CDR uncertainty. The authors further argue that this justifies massive ambition surrounding CDR innovation in the coming decade. In short: technical innovation can help narrow the range of uncertainty for policymakers.The CDR approaches explored by Grant et al. are in very different stages of technological development or deployment. These approaches include bioenergy with carbon capture and storage (BECCS), direct air capture with carbon storage (DACCS), and afforestation/reforestation (AR). Other burgeoning forms of CDR and storage—including direct ocean capture, soil carbon sequestration, and enhanced mineralization—also show tremendous potential but are not the focus of Grant et al.Each of the pathways examined by Grant et al. have unique challenges, but technological innovations have the potential to enable tremendous CDR deployment. We explore several possible ways to further enable global-scale deployment of CDR technologies and better validate stored carbon to decrease the associated uncertainties of projected feasible potentials for CDR deployment of BECCS, DACCS, AR, and other approaches (see Figure 1).Policy momentum and public support for mechanical removal of carbon through direct air capture (DAC) has accelerated tremendously over the past decade, with the Swiss company Climeworks commencing operation of the world’s largest DAC project, “Orca”, outside of Reykjavik in September 2021. The 4,000 tons CO2/year that this facility is drawing down is a drop in the bucket relative to the gigaton scale necessary for addressing climate change. Reaching this scale requires major cost reductions. For solid adsorbent approaches like the one demonstrated by Climeworks, adsorbent costs are more than 70% of the total capital expenditure and operating expenses costs. Moreover, experience from amine-based solid sorbents used in conventional carbon capture plants suggests that these solids degrade and break down over time.4NASEM(National Academies of Sciences, Engineering, and Medicine). Negative emissions technologies and reliable sequestration: a research agenda. The National Academies Press, 2019Google Scholar The potential to scale-up unique industrial sorbents that maximize CO2 uptake, reducing costs, and increasing sorbent lifetimes remains an active area of research.5McQueen N. Vaz Gomes K. McCormick C. Blumanthal K. Pisciotta M. Wilcox J. A review of direct air capture (DAC): scaling up commercial technologies and innovating for the future. Progress in Energy, 2021Google Scholar Competition with liquid solvent approaches, which operate at substantially higher temperatures, or an entire departure from the standard pressure or vacuum swing paradigms (such as through moisture-swing or electro-swing approaches) remain attractive pathways as well.Carbonate weathering and DOC are other areas ripe for innovation. Carbonation is a natural process that can store CO2 at scale, but a major bottleneck is access to alkali substances like Mg− or Ca− that readily want to react in the presence of CO2. Enhanced weathering in agricultural landscapes is also receiving increased attention for its potential climate and ecosystem benefits.6Beerling D.J. Kantzas E.P. Lomas M.R. Wade P. Eufrasio R.M. Renforth P. Sarkar B. Andrews M.G. James R.H. Pearce C.R. et al.Potential for large-scale CO2 removal via enhanced rock weathering with croplands.Nature. 2020; 583: 242-248https://doi.org/10.1038/s41586-020-2448-9Crossref PubMed Scopus (131) Google Scholar Used as a soil amendment, rock dust is applied to croplands, where it supports carbon sequestration in soils while also releasing nutrients that are critical to plant growth, such as calcium, magnesium, potassium, and phosphorus.Another emerging CDR pathway that falls outside the scope of Grant et al. is ocean-based CDR via kelp and seaweed sinking. Ocean-based CDR offers a blue-sky (or blue-sea, in this case) opportunity to increase total CDR potential by expanding our portfolio of removal approaches beyond just terrestrial systems. Ocean-based natural CDR has the potential to provide a pathway for dissolving atmospheric CO2 in the ocean at gigaton scale for costs below $50/ton. Naturally occurring macroalgae already play a significant role in the global carbon cycle, with more than 173 TgC/year sequestered by their growth and natural sinking.7Sclarsic, S.M.H. (2021). A bioengineering roadmap for negative emissions technologies. Masters thesis, (Massachusetts Institute of Technology).Google Scholar There has been recent public and private investment in the cultivation and sinking of macroalgae for direct CDR to the deep ocean floor (below 1,000 m) where the carbon is effectively permanently removed from the biosphere for >1,000 years. Recently the US Department of Energy’s ARPA-E MARINER program funded research and testing of large-scale kelp farming, and a number of private companies are working to develop the systems necessary to scale kelp-sinking to the gigaton per year scale, but open research questions remain.8Temple J. Companies hoping to grow carbon-sucking kelp may be rushing ahead of the science.https://www.technologyreview.com/2021/09/19/1035889/kelp-carbon-removal-seaweed-sinking-climate-change/Date: 2021Google Scholar Biochemical engineering approaches could be employed to further optimize seaweed species to increase negative buoyancy, faster growth, and relative carbon content of species for sinking applications.Beyond innovation in CDR technologies themselves, advances are also needed to support enhanced monitoring and verification of removals. This is especially true of terrestrial carbon storage and sequestration. At large scales, the carbon cycle is relatively well-constrained. We know, for example, that the global terrestrial biosphere sequesters some 30% of global emissions. However, monitoring land-based CDR at higher spatial and temporal resolutions is limited by measurement and sensing challenges, and quantifying land-based CDR at the plot level remains expensive, time-consuming, and labor intensive.9USGCRPSecond State of the Carbon Cycle Report (SOCCR2): A Sustained Assessment Report. U.S. Global Change Research Program, 2018Google Scholar This is especially true for below-ground carbon stocks. While above-ground carbon stocks, such as those in trees, shrubs, and grasses, can be passively monitored at scale via remote sensing (e.g., NASA Global Ecosystem Dynamics Investigation Lidar),10Dubayah R. Blair J.B. Goetz S. Fatoyinbo L. Hansen M. Healey S. Hofton M. Hurtt G. Kellner J. Luthcke S. Armston J. et al.The Global Ecosystem Dynamics Investigation: High-resolution laser ranging of the Earth’s forests and topography.Science of Remote Sensing. 2020; 1: 100002Crossref Google Scholar quantifying below-ground baselines and monitoring changes requires data on mineral-organic matter interactions, soil microbiology and chemistry, environmental conditions, and other variables to inform models, project productivity rates, and estimate residence time of the soil carbon. But emerging research is tackling this challenge. For example, the ARPA-E Systems for Monitoring and Analytics for Renewable Transportation Fuels from Agricultural Resources and Management (SMARTFARM) program is supporting validation technology with the goal of increasing resolution and certainty of soil organic carbon monitoring in order to inform new crediting mechanisms. The program is advancing commercial tools to directly measure fluxes of carbon, exploring integration of drone-captured digital imagery and eddy covariance data into networked systems, and fostering innovation in reliable soil carbon measurement at depth.Emissions mitigation remains the priority in addressing climate change, but the scientific consensus now tells us that carbon removal has an essential role to play in meeting climate goals. The pace and magnitude of CDR deployment is highly variable in the literature, and Grant et al. demonstrate with stochastic optimization that this uncertainty can result in an additional 10 GtCO2e that needs to be mitigated by 2030. Their result illustrates the dual conclusions that (1) further climate ambition is needed for driving down emissions in the coming decade and (2) CDR innovation may yield significant dividends and accelerate our pathway to net-zero. Integrated assessment models (IAMs) are widely used tools for informing policy making and have been central to the results of reports by the Intergovernmental Panel on Climate Change. In recent years, these models have helped clarify the important role that carbon dioxide removal (CDR) deployment will play in complementing emissions reduction efforts as nations address climate change. IAMs serve to optimize economic and technological decision making to achieve emissions reduction targets. Despite their complexity, IAMs currently lack the social and political dimensions1Doukas H. Nikas A. González-Eguino M. Arto I. Anger-Kraavi A. From integrated to integrative: Delivering on the Paris Agreement.Sustainability. 2018; 10: 2299Crossref Scopus (57) Google Scholar that would more effectively represent the uncertainties underlying policy decisions. One example of this limitation is how IAMs may reflect a given trajectory to reaching net-zero greenhouse gas emissions. While one trajectory may minimize costs among a variety of decarbonization pathways—with assumptions about cost declines following innovation and deployment—real-world deployment requires federal and state policy advances at a time when there is wide uncertainty about future innovation and cost reduction capabilities. This uncertainty applies to the future of implementation of CDR approaches. In last month’s issue of Joule, Grant et al.2Grant N. Hawkes A. Mittal S. Gambhir A. The policy implications of an uncertain carbon dioxide removal potential. Joule, 2021Abstract Full Text Full Text PDF Scopus (6) Google Scholar conduct a unique survey of the “feasible potential” for CDR deployment from experts in the field and use the results to produce a probability distribution for CDR deployment uncertainty in their own IAM through stochastic optimization. By differentiating “feasible potential” from the “technical” or “sustainable” potentials, they aim to account for important considerations surrounding cost-reductions and technology readiness produced by innovation, institutional barriers for deployment, and other social, environmental, or governance issues that may influence the ultimate deployment of a given CDR method. Grant et al. use this unique approach to estimate an additional 10 gigatons of CO2e that may require mitigation by 2030, when accounting for CDR uncertainty. The authors further argue that this justifies massive ambition surrounding CDR innovation in the coming decade. In short: technical innovation can help narrow the range of uncertainty for policymakers. The CDR approaches explored by Grant et al. are in very different stages of technological development or deployment. These approaches include bioenergy with carbon capture and storage (BECCS), direct air capture with carbon storage (DACCS), and afforestation/reforestation (AR). Other burgeoning forms of CDR and storage—including direct ocean capture, soil carbon sequestration, and enhanced mineralization—also show tremendous potential but are not the focus of Grant et al. Each of the pathways examined by Grant et al. have unique challenges, but technological innovations have the potential to enable tremendous CDR deployment. We explore several possible ways to further enable global-scale deployment of CDR technologies and better validate stored carbon to decrease the associated uncertainties of projected feasible potentials for CDR deployment of BECCS, DACCS, AR, and other approaches (see Figure 1). Policy momentum and public support for mechanical removal of carbon through direct air capture (DAC) has accelerated tremendously over the past decade, with the Swiss company Climeworks commencing operation of the world’s largest DAC project, “Orca”, outside of Reykjavik in September 2021. The 4,000 tons CO2/year that this facility is drawing down is a drop in the bucket relative to the gigaton scale necessary for addressing climate change. Reaching this scale requires major cost reductions. For solid adsorbent approaches like the one demonstrated by Climeworks, adsorbent costs are more than 70% of the total capital expenditure and operating expenses costs. Moreover, experience from amine-based solid sorbents used in conventional carbon capture plants suggests that these solids degrade and break down over time.4NASEM(National Academies of Sciences, Engineering, and Medicine). Negative emissions technologies and reliable sequestration: a research agenda. The National Academies Press, 2019Google Scholar The potential to scale-up unique industrial sorbents that maximize CO2 uptake, reducing costs, and increasing sorbent lifetimes remains an active area of research.5McQueen N. Vaz Gomes K. McCormick C. Blumanthal K. Pisciotta M. Wilcox J. A review of direct air capture (DAC): scaling up commercial technologies and innovating for the future. Progress in Energy, 2021Google Scholar Competition with liquid solvent approaches, which operate at substantially higher temperatures, or an entire departure from the standard pressure or vacuum swing paradigms (such as through moisture-swing or electro-swing approaches) remain attractive pathways as well. Carbonate weathering and DOC are other areas ripe for innovation. Carbonation is a natural process that can store CO2 at scale, but a major bottleneck is access to alkali substances like Mg− or Ca− that readily want to react in the presence of CO2. Enhanced weathering in agricultural landscapes is also receiving increased attention for its potential climate and ecosystem benefits.6Beerling D.J. Kantzas E.P. Lomas M.R. Wade P. Eufrasio R.M. Renforth P. Sarkar B. Andrews M.G. James R.H. Pearce C.R. et al.Potential for large-scale CO2 removal via enhanced rock weathering with croplands.Nature. 2020; 583: 242-248https://doi.org/10.1038/s41586-020-2448-9Crossref PubMed Scopus (131) Google Scholar Used as a soil amendment, rock dust is applied to croplands, where it supports carbon sequestration in soils while also releasing nutrients that are critical to plant growth, such as calcium, magnesium, potassium, and phosphorus. Another emerging CDR pathway that falls outside the scope of Grant et al. is ocean-based CDR via kelp and seaweed sinking. Ocean-based CDR offers a blue-sky (or blue-sea, in this case) opportunity to increase total CDR potential by expanding our portfolio of removal approaches beyond just terrestrial systems. Ocean-based natural CDR has the potential to provide a pathway for dissolving atmospheric CO2 in the ocean at gigaton scale for costs below $50/ton. Naturally occurring macroalgae already play a significant role in the global carbon cycle, with more than 173 TgC/year sequestered by their growth and natural sinking.7Sclarsic, S.M.H. (2021). A bioengineering roadmap for negative emissions technologies. Masters thesis, (Massachusetts Institute of Technology).Google Scholar There has been recent public and private investment in the cultivation and sinking of macroalgae for direct CDR to the deep ocean floor (below 1,000 m) where the carbon is effectively permanently removed from the biosphere for >1,000 years. Recently the US Department of Energy’s ARPA-E MARINER program funded research and testing of large-scale kelp farming, and a number of private companies are working to develop the systems necessary to scale kelp-sinking to the gigaton per year scale, but open research questions remain.8Temple J. Companies hoping to grow carbon-sucking kelp may be rushing ahead of the science.https://www.technologyreview.com/2021/09/19/1035889/kelp-carbon-removal-seaweed-sinking-climate-change/Date: 2021Google Scholar Biochemical engineering approaches could be employed to further optimize seaweed species to increase negative buoyancy, faster growth, and relative carbon content of species for sinking applications. Beyond innovation in CDR technologies themselves, advances are also needed to support enhanced monitoring and verification of removals. This is especially true of terrestrial carbon storage and sequestration. At large scales, the carbon cycle is relatively well-constrained. We know, for example, that the global terrestrial biosphere sequesters some 30% of global emissions. However, monitoring land-based CDR at higher spatial and temporal resolutions is limited by measurement and sensing challenges, and quantifying land-based CDR at the plot level remains expensive, time-consuming, and labor intensive.9USGCRPSecond State of the Carbon Cycle Report (SOCCR2): A Sustained Assessment Report. U.S. Global Change Research Program, 2018Google Scholar This is especially true for below-ground carbon stocks. While above-ground carbon stocks, such as those in trees, shrubs, and grasses, can be passively monitored at scale via remote sensing (e.g., NASA Global Ecosystem Dynamics Investigation Lidar),10Dubayah R. Blair J.B. Goetz S. Fatoyinbo L. Hansen M. Healey S. Hofton M. Hurtt G. Kellner J. Luthcke S. Armston J. et al.The Global Ecosystem Dynamics Investigation: High-resolution laser ranging of the Earth’s forests and topography.Science of Remote Sensing. 2020; 1: 100002Crossref Google Scholar quantifying below-ground baselines and monitoring changes requires data on mineral-organic matter interactions, soil microbiology and chemistry, environmental conditions, and other variables to inform models, project productivity rates, and estimate residence time of the soil carbon. But emerging research is tackling this challenge. For example, the ARPA-E Systems for Monitoring and Analytics for Renewable Transportation Fuels from Agricultural Resources and Management (SMARTFARM) program is supporting validation technology with the goal of increasing resolution and certainty of soil organic carbon monitoring in order to inform new crediting mechanisms. The program is advancing commercial tools to directly measure fluxes of carbon, exploring integration of drone-captured digital imagery and eddy covariance data into networked systems, and fostering innovation in reliable soil carbon measurement at depth. Emissions mitigation remains the priority in addressing climate change, but the scientific consensus now tells us that carbon removal has an essential role to play in meeting climate goals. The pace and magnitude of CDR deployment is highly variable in the literature, and Grant et al. demonstrate with stochastic optimization that this uncertainty can result in an additional 10 GtCO2e that needs to be mitigated by 2030. Their result illustrates the dual conclusions that (1) further climate ambition is needed for driving down emissions in the coming decade and (2) CDR innovation may yield significant dividends and accelerate our pathway to net-zero. The policy implications of an uncertain carbon dioxide removal potentialGrant et al.JouleOctober 20, 2021In BriefWe conduct an expert survey into the feasible level of carbon dioxide removal (CDR). Experts suggest that feasible CDR deployment could be large but remains highly uncertain. We explore the implications of this uncertainty for the critical decade of the 2020s. Uncertainty in the future CDR potential should encourage greater climate action in the 2020s, with deeper emissions cuts, accelerated renewables deployment, greater investment in low-carbon technology, and a faster phaseout of fossil fuels from the energy system. Full-Text PDF Open Archive
Referência(s)