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Ampah JD, Jin C, Liu H, Afrane S, Adun H, Morrow D, Ho DT. Prioritizing Non-Carbon Dioxide Removal Mitigation Strategies Could Reduce the Negative Impacts Associated with Large-Scale Reliance on Negative Emissions. Environ Sci Technol 2024; 58:3755-3765. [PMID: 38285506 DOI: 10.1021/acs.est.3c06866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2024]
Abstract
Carbon dioxide removal (CDR) is necessary for reaching net zero emissions, with studies showing potential deployment at multi-GtCO2 scale by 2050. However, excessive reliance on future CDR entails serious risks, including delayed emissions cuts, lock-in of fossil infrastructure, and threats to sustainability from increased resource competition. This study highlights an alternative pathway─prioritizing near-term non-CDR mitigation and minimizing CDR dependence. We impose a 1 GtCO2 limit on global novel CDR deployment by 2050, forcing aggressive early emissions reductions compared to 8-22 GtCO2 in higher CDR scenarios. Our results reveal that this low CDR pathway significantly decreases fossil fuel use, greenhouse gas (GHG) emissions, and air pollutants compared to higher CDR pathways. Driving rapid energy transitions eases pressures on land (including food cropland), water, and fertilizer resources required for energy and negative emissions. However, these sustainability gains come with higher mitigation costs from greater near-term low/zero-carbon technology deployment for decarbonization. Overall, this work provides strong evidence for maximizing non-CDR strategies such as renewables, electrification, carbon neutral/negative fuels, and efficiency now rather than betting on uncertain future CDR scaling. Ambitious near-term mitigation in this decade is essential to prevent lock-in and offer the best chance of successful deep decarbonization. Our constrained CDR scenario offers a robust pathway to achieving net zero emissions with limited sustainability impacts.
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Affiliation(s)
- Jeffrey Dankwa Ampah
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
- State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China
| | - Chao Jin
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Haifeng Liu
- State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China
| | - Sandylove Afrane
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Humphrey Adun
- Energy Systems Engineering Department, Cyprus International University, Mersin 10, Haspolat-Lefkosa, Nicosia 99258, Turkey
| | - David Morrow
- Institute for Carbon Removal Law and Policy, American University, Washington, NW DC 20016, United States
| | - David T Ho
- Department of Oceanography, University of Hawaii at Ma̅noa, 1000 Pope Road, Honolulu, Hawaii 96822, United States
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2
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Buss W, Hasemer H, Ferguson S, Borevitz J. Stabilisation of soil organic matter with rock dust partially counteracted by plants. Glob Chang Biol 2024; 30:e17052. [PMID: 37994295 DOI: 10.1111/gcb.17052] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 10/28/2023] [Indexed: 11/24/2023]
Abstract
Soil application of Ca- and Mg-rich silicates can capture and store atmospheric carbon dioxide as inorganic carbon but could also have the potential to stabilise soil organic matter (SOM). Synergies between these two processes have not been investigated. Here, we apply finely ground silicate rock mining residues (basalt and granite blend) to a loamy sand in a pot trial at a rate of 4% (equivalent to 50 t ha-1 ) and investigate the effects of a wheat plant and two watering regimes on soil carbon sequestration over the course of 6 months. Rock dust addition increased soil pH, electric conductivity, inorganic carbon content and soil-exchangeable Ca and Mg contents, as expected for weathering. However, it decreased exchangeable levels of micronutrients Mn and Zn, likely related to the elevated soil pH. Importantly, it increased mineral-associated organic matter by 22% due to the supply of secondary minerals and associated sites for SOM sorption. Additionally, in the nonplanted treatments, rock supply of Ca and Mg increased soil microaggregation that subsequently stabilised labile particulate organic matter as organic matter occluded in aggregates by 46%. Plants, however, reduced soil-exchangeable Mg and Ca contents and hence counteracted the silicate rock effect on microaggregates and carbon within. We suggest this cation loss might be attributed to plant exudates released to solubilise micronutrients and hence neutralise plant deficiencies. The effect of enhanced silicate rock weathering on SOM stabilisation could substantially boost its carbon sequestration potential.
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Affiliation(s)
- Wolfram Buss
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Heath Hasemer
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Scott Ferguson
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Justin Borevitz
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
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Reershemius T, Kelland ME, Jordan JS, Davis IR, D'Ascanio R, Kalderon-Asael B, Asael D, Suhrhoff TJ, Epihov DZ, Beerling DJ, Reinhard CT, Planavsky NJ. Initial Validation of a Soil-Based Mass-Balance Approach for Empirical Monitoring of Enhanced Rock Weathering Rates. Environ Sci Technol 2023; 57:19497-19507. [PMID: 37961896 DOI: 10.1021/acs.est.3c03609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Enhanced rock weathering (ERW) is a promising scalable and cost-effective carbon dioxide removal (CDR) strategy with significant environmental and agronomic co-benefits. A major barrier to large-scale implementation of ERW is a robust monitoring, reporting, and verification (MRV) framework. To successfully quantify the amount of carbon dioxide removed by ERW, MRV must be accurate, precise, and cost-effective. Here, we outline a mass-balance-based method in which analysis of the chemical composition of soil samples is used to track in situ silicate rock weathering. We show that signal-to-noise issues of in situ soil analysis can be mitigated by using isotope-dilution mass spectrometry to reduce analytical error. We implement a proof-of-concept experiment demonstrating the method in controlled mesocosms. In our experiment, a basalt rock feedstock is added to soil columns containing the cereal crop Sorghum bicolor at a rate equivalent to 50 t ha-1. Using our approach, we calculate rock weathering corresponding to an average initial CDR value of 1.44 ± 0.27 tCO2eq ha-1 from our experiments after 235 days, within error of an independent estimate calculated using conventional elemental budgeting of reaction products. Our method provides a robust time-integrated estimate of initial CDR, to feed into models that track and validate large-scale carbon removal through ERW.
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Affiliation(s)
- Tom Reershemius
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut 06511, United States
| | - Mike E Kelland
- Leverhulme Centre for Climate Change Mitigation, School of Biosciences, University of Sheffield, Sheffield S10 2TN, U.K
| | - Jacob S Jordan
- Porecast Research, Lawrence, Kansas 66049, United States
| | - Isabelle R Davis
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut 06511, United States
- School of Ocean and Earth Science, University of Southampton Waterfront Campus, Southampton SO14 3ZH, U.K
| | - Rocco D'Ascanio
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut 06511, United States
| | - Boriana Kalderon-Asael
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut 06511, United States
| | - Dan Asael
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut 06511, United States
| | - T Jesper Suhrhoff
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut 06511, United States
- Yale Center for Natural Carbon Capture, Yale University, New Haven, Connecticut 06511, United States
| | - Dimitar Z Epihov
- Leverhulme Centre for Climate Change Mitigation, School of Biosciences, University of Sheffield, Sheffield S10 2TN, U.K
| | - David J Beerling
- Leverhulme Centre for Climate Change Mitigation, School of Biosciences, University of Sheffield, Sheffield S10 2TN, U.K
| | - Christopher T Reinhard
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Noah J Planavsky
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut 06511, United States
- Yale Center for Natural Carbon Capture, Yale University, New Haven, Connecticut 06511, United States
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Haque F, Khalidy R, Chiang YW, Santos RM. Constraining the Capacity of Global Croplands to CO 2 Drawdown via Mineral Weathering. ACS Earth Space Chem 2023; 7:1294-1305. [PMID: 37492628 PMCID: PMC10364810 DOI: 10.1021/acsearthspacechem.2c00374] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Revised: 05/22/2023] [Accepted: 05/23/2023] [Indexed: 07/27/2023]
Abstract
Terrestrial enhanced weathering of alkaline silicate minerals is a promising climate change mitigation strategy with the potential to limit the global temperature rise. The formation and accumulation of pedogenic carbonate and bicarbonate in soils/subsoils and groundwater offers a large sink for C storage; the amount of soil inorganic carbon (SIC) presently held within soils has been estimated to be 720-950 Gt of C. These values can be augmented by the addition of a variety of calcium and magnesium silicates via enhanced weathering. While the concept of the application of finely milled silicate rocks for faster weathering rates is well established, there has been limited discussion on the role of local climate, natural SIC content (i.e., the SIC innately present in the soil), and soil pH (among other important agronomic factors) on silicate weathering when applied to croplands, especially in view that the aim is to establish terrestrial enhanced weathering as a carbon dioxide removal (CDR) strategy on a global scale. In this work, we emphasized the importance of soil pH and soil temperature on silicate weathering and looked to estimate an upper limit of (i.e., constrain) the global capacity until the year 2100 for enhanced rock weathering (ERW) to draw down CO2 in the form of accumulated pedogenic carbonate or soluble bicarbonate. We assessed the global spatial distribution of cropland soil pH, which serves as a proxy for local innate SIC; annual rate of pluvial (rainfall) precipitation; and soil temperature, and found that the potential CO2 drawdown difference between faster and slower weathering silicates is narrower in Asia, Africa, and South America, while the gap is larger for Europe, North America, and Oceania.
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Affiliation(s)
- Fatima Haque
- School
of Engineering, University of Guelph, Guelph, Ontario N1G 2W1, Canada
- Department
of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Reza Khalidy
- School
of Engineering, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Yi Wai Chiang
- School
of Engineering, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Rafael M. Santos
- School
of Engineering, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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Foteinis S, Campbell JS, Renforth P. Life Cycle Assessment of Coastal Enhanced Weathering for Carbon Dioxide Removal from Air. Environ Sci Technol 2023; 57:6169-6178. [PMID: 37011253 PMCID: PMC10116589 DOI: 10.1021/acs.est.2c08633] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 03/16/2023] [Accepted: 03/16/2023] [Indexed: 06/19/2023]
Abstract
Coastal enhanced weathering (CEW) is a carbon dioxide removal (CDR) approach whereby crushed silicate minerals are spread in coastal zones to be naturally weathered by waves and tidal currents, releasing alkalinity and removing atmospheric carbon dioxide (CO2). Olivine has been proposed as a candidate mineral due to its abundance and high CO2 uptake potential. A life cycle assessment (LCA) of silt-sized (10 μm) olivine revealed that CEW's life-cycle carbon emissions and total environmental footprint, i.e., carbon and environmental penalty, amount to around 51 kg CO2eq and 3.2 Ecopoint (Pt) units per tonne of captured atmospheric CO2, respectively, and these will be recaptured within a few months. Smaller particle sizes dissolve and uptake atmospheric CO2 even faster; however, their high carbon and environmental footprints (e.g., 223 kg CO2eq and 10.6 Pt tCO2-1, respectively, for 1 μm olivine), engineering challenges in comminution and transportation, and possible environmental stresses (e.g., airborne and/or silt pollution) might restrict their applicability. Alternatively, larger particle sizes exhibit lower footprints (e.g., 14.2 kg CO2eq tCO2-1 and 1.6 Pt tCO2-1, respectively, for 1000 μm olivine) and could be incorporated in coastal zone management schemes, thus possibly crediting CEW with avoided emissions. However, they dissolve much slower, requiring 5 and 37 years before the 1000 μm olivine becomes carbon and environmental net negative, respectively. The differences between the carbon and environmental penalties highlight the need for using multi-issue life cycle impact assessment methods rather than focusing on carbon balances alone. When CEW's full environmental profile was considered, it was identified that fossil fuel-dependent electricity for olivine comminution is the main environmental hotspot, followed by nickel releases, which may have a large impact on marine ecotoxicity. Results were also sensitive to transportation means and distance. Renewable energy and low-nickel olivine can minimize CEW's carbon and environmental profile.
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Cox E, Spence E, Pidgeon N. Deliberating enhanced weathering: Public frames, iconic ecosystems and the governance of carbon removal at scale. Public Underst Sci 2022; 31:960-977. [PMID: 35916445 DOI: 10.1177/09636625221112190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Meeting goals for 'net zero' emissions may require the removal of previously emitted carbon dioxide from the atmosphere. One proposal, enhanced rock weathering, aims to speed up the weathering processes of rocks by crushing them finely and spreading them on agricultural land. Public perceptions of enhanced rock weathering and its wider social and environmental implications will be a critical factor determining its potential; we use six 2-day deliberative workshops in England, Wales and Illinois to understand public views. Consideration of enhanced rock weathering deployment in tropical countries led participants to frame it from a social justice perspective, which had been much less prevalent when considering Western agricultural contexts, and generated assumptions of increased scale, which heightened concerns about detrimental social and environmental impacts. Risk perceptions relating to 'messing with nature' became amplified when participants considered enhanced rock weathering in relation to 'iconic' environments such as the oceans and rainforest.
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Jariwala H, Haque F, Vanderburgt S, Santos RM, Chiang YW. Mineral-Soil-Plant-Nutrient Synergisms of Enhanced Weathering for Agriculture: Short-Term Investigations Using Fast-Weathering Wollastonite Skarn. Front Plant Sci 2022; 13:929457. [PMID: 35937370 PMCID: PMC9353033 DOI: 10.3389/fpls.2022.929457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 06/15/2022] [Indexed: 06/15/2023]
Abstract
Enhanced weathering is a proposed carbon dioxide removal (CDR) strategy to accelerate natural carbon sequestration in soils via the amendment of silicate rocks to agricultural soils. Among the suitable silicates (such as basalt and olivine), the fast-weathering mineral wollastonite (CaSiO3) stands out. Not only does the use of wollastonite lead to rapid pedogenic carbonate formation in soils, it can be readily detected for verification of carbon sequestration, but its weathering within weeks to months influences soil chemistry and plant growth within the same crop cycle of its application. This enables a variety of short-term experimental agronomic studies to be conducted to demonstrate in an accelerated manner what could take years to be observed with more abundant but slower weathering silicates. This study presents the results of three studies that were conducted to investigate three distinct aspects of wollastonite skarn weathering in soils in the context of both agricultural and horticultural plants. The first study investigated the effect of a wide range of wollastonite skarn dosages in soil (1.5-10 wt.%) on the growth of green beans. The second study provides insights on the role of silicon (Si) release during silicate weathering on plant growth (soybeans and lettuce). The third study investigated the effect of wollastonite skarn on the growth of spring rye when added to soil alongside a nitrogen-based coated fertilizer. The results of these three studies provide further evidence that amending soil with crushed silicate rocks leads to climate-smart farming, resulting in inorganic carbon sequestration, as well as better plant growth in agricultural (soybean and spring rye) and horticultural (green bean and lettuce) crops. They also demonstrate the value of working with wollastonite skarn as a fast-weathering silicate rock to accelerate our understanding of the mineral-soil-plant-nutrient synergism of enhanced weathering.
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Choi WJ, Park HJ, Cai Y, Chang SX. Environmental Risks in Atmospheric CO 2 Removal Using Enhanced Rock Weathering Are Overlooked. Environ Sci Technol 2021; 55:9627-9629. [PMID: 34184876 DOI: 10.1021/acs.est.1c02505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Affiliation(s)
- Woo-Jung Choi
- Department of Rural & Bio-Systems Engineering (BK 21), Chonnam National University, Gwangju 61186, Republic of Korea
| | - Hyun-Jin Park
- Department of Rural & Bio-Systems Engineering (BK 21), Chonnam National University, Gwangju 61186, Republic of Korea
| | - Yanjiang Cai
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou 311300, China
| | - Scott X Chang
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou 311300, China
- Department of Renewable Resources, University of Alberta, Edmonton, AB T6G 2E3, Canada
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