This week’s publication highlights relate to carbon removal with enhanced root systems, direct air capture, forestation and enhanced rock weathering.
Removing Atmospheric CO2 through Mass Scaleup of Crops with Enhanced Root Systems
Abstract
The Intergovernmental Panel on Climate Change estimates that societies may need to remove 5–16 GtCO2 from the atmosphere annually to reach global net-zero CO2 emissions within this century. Yet there has been little analysis of how quickly carbon dioxide removal (CDR) strategies could scale to meet this expected need. We develop a new integrated modeling approach for assessing scalability that combines insights from the history of analogous technological revolutions with information about the efficacy and specific constraints of CDR strategies. We illustrate our approach with genetically enhanced crops that grow larger roots and, in turn, increase soil carbon. Unlike many CDR technologies whose deployment will be slowed by the need for novel and costly infrastructures, history suggests that crop innovations can scale rapidly in countries that admit them. Within 13 years of first deployment, diffusion of enhanced crops could peak and remove 0.9–1.2 GtCO2 yr–1—about 7 times larger than all CO2 offsets supplied today to the global voluntary offsets market. Upscaling depends on policy and politics, as they affect the total land area on which carbon-absorbing crops are allowed. Early scaling could allow crop engineering to play an outsized role in a portfolio of CDR strategies that, overall, scales to IPCC-like levels of carbon removal, even though carbon storage in soils is less permanent than geological storage.
Dias, D. et al. (2025) Removing Atmospheric CO2 through Mass Scaleup of Crops with Enhanced Root Systems 20 (054004) Environmental Research Letters.
Read the full paper here: Removing Atmospheric CO2 through Mass Scaleup of Crops with Enhanced Root Systems I Environmental Research Letters.
Nanomaterials for Direct Air Capture of CO2: Current State of the Art, Challenges and Future Perspectives
Abstract
Direct Air Capture (DAC) is emerging as a critical climate change mitigation strategy, offering a pathway to actively remove atmospheric CO2. This comprehensive review synthesizes advancements in DAC technologies, with a particular emphasis on the pivotal role of nanostructured solid sorbent materials. The work critically evaluates the characteristics, performance, and limitations of key nanomaterial classes, including metal–organic frameworks (MOFs), covalent organic frameworks (COFs), zeolites, amine-functionalized polymers, porous carbons, and layered double hydroxides (LDHs), alongside solid-supported ionic liquids, highlighting their varied CO2 uptake capacities, regeneration energy requirements, and crucial water sensitivities. Beyond traditional temperature/pressure swing adsorption, the review delves into innovative DAC methodologies such as Moisture Swing Adsorption (MSA), Electro Swing Adsorption (ESA), Passive DAC, and CO2-Binding Organic Liquids (CO2 BOLs), detailing their unique mechanisms and potential for reduced energy footprints. Despite significant progress, the widespread deployment of DAC faces formidable challenges, notably high capital and operational costs (currently USD 300–USD 1000/tCO2), substantial energy demands (1500–2400 kWh/tCO2), water interference, scalability hurdles, and sorbent degradation. Furthermore, this review comprehensively examines the burgeoning global DAC market, its diverse applications, and the critical socio-economic barriers to adoption, particularly in developing countries. A comparative analysis of DAC within the broader carbon removal landscape (e.g., CCS, BECCS, afforestation) is also provided, alongside an address to the essential, often overlooked, environmental considerations for the sustainable production, regeneration, and disposal of spent nanomaterials, including insights from Life Cycle Assessments. The nuanced techno-economic landscape has been thoroughly summarized, highlighting that commercial viability is a multi-faceted challenge involving material performance, synthesis cost, regeneration energy, scalability, and long-term stability. It has been reiterated that no single ‘best’ material exists, but rather a portfolio of technologies will be necessary, with the ultimate success dependent on system-level integration and the availability of low-carbon energy. The review paper contributes to a holistic understanding of cutting-edge DAC technologies, bridging material science innovations with real-world implementation challenges and opportunities, thereby identifying critical knowledge gaps and pathways toward a net-zero carbon future.
Simari, C. (2025) Nanomaterials for Direct Air Capture of CO2: Current State of the Art, Challenges and Future Perspectives 30 (14) Molecules.
Read the full paper here: Nanomaterials for Direct Air Capture of CO2: Current State of the Art, Challenges and Future Perspectives I Molecules.
Climate Mitigation Potential for Targeted Forestation After Considering Climate Change, Fires and Albedo
Abstract
Afforestation and reforestation, both of which refer to forestation strategies, are widely promoted as key tools to mitigate anthropogenic warming. However, the carbon sequestration potential of these efforts remains uncertain in satellite-based assessments, particularly when accounting for dynamic climate conditions, vegetation-climate feedback, fire-dominated disturbance, and the trade-offs associated with surface albedo changes. Leveraging a coupled Earth system model, we estimated that global forestation mitigates 31.3 to 69.2 Pg Ceq (carbon equivalent) during 2021–2100 under a sustainable shared socioeconomic pathway. Regionally, the highest carbon mitigation potential of forestation concentrates in tropical areas, while mid-high-latitude regions demonstrate higher heterogeneity, highlighting the need for region-specific strategies and further refinement of nature-based mitigation plans. Our findings underscore the importance of considering disturbances and minimizing adverse albedo changes when estimating the carbon mitigation potential of forestation initiatives. We also advocate for the development of consistent, high-resolution maps of suitable areas for targeted forestation, avoiding environmentally sensitive lands and potential conflicts with other human activities.
Liang, S. et al. (2025) Climate Mitigation Potential for Targeted Forestation After Considering Climate Change, Fires and Albedo 11 (15) Science Advances.
Read the full paper here: Climate Mitigation Potential for Targeted Forestation After Considering Climate Change, Fires and Albedo I Science Advances.
Incorporating Enhanced Rock Weathering into Sustainable Forest Management
Abstract
Enhanced rock weathering (ERW) can be implemented in managed forests that use selective harvesting through trail networks for carbon dioxide removal (CDR) while improving soil health by neutralizing excess acidity and restoring base cations. Wollastonite-rich rock powder (Wo = 28.4 wt% and D50 = 350 μm) was applied using a tractor and spreader from a trail in Haliburton Forest, Ontario, Canada, to evaluate the practicability and challenges of incorporating ERW into silviculture practices. The intended amendment dosage of 5 t/ha aimed to replace soil Ca losses due to historic acidic deposition. Based on trail networks mapped in Haliburton Forest and a spreading width of 12 m, 85 % of the forest area could potentially be amended, assuming no overlapping areas. Spreading of 5 t/ha over the annually harvested area (∼700 ha) has a maximum potential to sequester 1120–1270 t CO2/yr based on the CDR potential of the amendment (377–427 kg CO2/t), calculated using its bulk geochemical composition. Assuming the same trail coverage as in Haliburton Forest and a dosage of 5 t/ha wollastonite-rich amendment, managed forests undergoing selection harvest in the United States and Canada have a maximum potential to sequester 4.5–5.1 Mt CO2/yr. The CDR rate of forest ERW requires field-based monitoring and life-cycle assessments. This application test successfully showed the technical feasibility of incorporating ERW into forest management via trail networks. However, it also demonstrated considerable spatial heterogeneity in dosages (0.8–6.7 t/ha), varying by proximity to trail centers, obstructions such as large trees, and overlapping applications in dense trail networks, which challenges the accuracy and verifiability of carbon credits generated. Selecting monitoring sites near trail centers and away from large obstructions and trail junctions will help ensure dosages are representative of the larger application. Furthermore, we recommend verifying dosages to avoid over- or under-estimating CDR in future forest ERW studies.
Guo, M. et al. (2025) Incorporating Enhanced Rock Weathering into Sustainable Forest Management 394 (127335) Journal of Environmental Management
Read the full paper here: Incorporating Enhanced Rock Weathering into Sustainable Forest Management I Journal of Environmental Management
Direct Air Capture of Carbon Dioxide: Advances, Feasibility and Future Directions
Abstract
Direct air capture technologies have gained prominence as vital tools for atmospheric carbon dioxide removal, with four major categories, namely liquid solvent-based, solid sorbent-based, electrochemical, and emerging hybrid systems, demonstrating varying degrees of maturity and feasibility. Liquid solvent-based direct air capture, including systems using potassium hydroxide, amines, and advanced ionic liquids or deep eutectic solvents, benefits from high CO2 reactivity and established chemical regeneration processes, but faces limitations from high thermal energy demands, solvent degradation, and environmental handling concerns. Solid sorbent-based systems, such as those utilizing amine-functionalized materials or metal-organic frameworks, offer low-temperature regeneration and modular designs, yet often suffer from variable adsorption capacity under different humidity levels and degradation over multiple cycles. Electrochemical direct air capture is a rapidly advancing field that uses redox-active materials or ion-exchange membranes to reversibly bind and release CO2 using electrical energy. These systems enable operation under ambient conditions with high selectivity and reduced thermal input, though challenges persist in terms of redox material stability and scalability. Other emerging methods, such as cryogenic, photocatalytic, mineralization-based, and biological direct air capture, offer innovative pathways to reduce energy use or permanently sequester CO2, but remain at early developmental stages. While significant advances have improved energy efficiency, cost-effectiveness, and operational stability across direct air capture technologies, further research is needed to enhance long-term material performance, develop low-cost, scalable reactor designs, and improve integration with renewable energy systems. Future studies should prioritize techno-economic assessments, lifecycle analysis, and hybrid approaches that combine the strengths of multiple direct air capture pathways to achieve cost-effective and durable carbon removal at gigaton scales.
Tang, K. (2025) Direct Air Capture of Carbon Dioxide: Advances, Feasibility and Future Directions 6 SCE.
Read the full paper here: Direct Air Capture of Carbon Dioxide: Advances, Feasibility and Future Directions I SCE.