The publication highlights of this week relate to direct air capture, enhanced rock weathering, ocean alkalinity enhancement, bioenergy with carbon capture and storage and forestation.
Applicability of Adsorbents in Direct Air Capture (DAC): Recent Progress and Future Perspectives
Abstract
Carbon capture, utilization, and storage (CCUS) has been considered as an approach to mitigate CO2 emissions to achieve a net-zero target as indicated in the Paris Climate Agreement. Nevertheless, over 50% of global CO2 emissions stem from distributed sources; the incorporation of negative emission technologies (NETs) is required. Direct air capture (DAC) is recognized as one of the feasible NETs offering flexibility in installation location. This review primarily focuses on the utilization of solid sorbents, which demonstrate lower energy consumption and higher CO2/N2 selectivity compared to alternative methods (cryogenic distillation and amine scrubbing). It provides a comprehensive analysis of the performance of nonporous and nanoporous adsorbents relevant to DAC applications. Among these, amine-appended adsorbents are the key for the DAC process due to the strong affinity between CO2 and amine at low partial pressure, as highlighted in the literature. Last but not least, the future direction and the practical feasibility of the sorbent-based DAC process will be discussed to allow more effective analysis of adsorbent performance, especially in the context of the repetitive adsorption/desorption cycling process.
Chuah, C. et al. (2025) Applicability of Adsorbents in Direct Air Capture (DAC): Recent Progress and Future Perspectives 64 (8) Industrial & Engineering Chemistry Research 4117-4147.
Read the full paper here: Applicability of Adsorbents in Direct Air Capture (DAC): Recent Progress and Future Perspectives I Industrial & Engineering Chemistry Research.
Enhanced Rock Weathering Promotes Soil Organic Carbon Accumulation: A Global Meta-Analysis Based on Experimental Evidence
Abstract
Enhanced rock weathering (ERW) has emerged as a promising carbon dioxide removal (CDR) strategy with the potential to modulate soil carbon sequestration, yet empirical assessments of its impacts remain limited. Here, we address this knowledge gap through a global meta-analysis synthesizing 74 publications. Synthesized results from field experiments showed that crushed rock amendment increased soil organic carbon (SOC), mineral-associated organic carbon, and particulate organic carbon by an average of up to 3.8%, 6.1%, and 7.5%, respectively, with no significant impact on dissolved organic carbon and soil inorganic carbon. SOC accrual was driven by elevated soil exchangeable Ca, increased microbial biomass, and improved soil structure, with local climate regulating these responses. Machine learning simulations of global croplands revealed pronounced site dependency in ERW impacts on SOC, which was positive in low-latitude (warm and humid) regions (40° N–30° S) but negative in high-latitude (cold and dry) regions. Additionally, the effects of ERW on SOC are dose- and duration-dependent. Our simulations indicated that application amounts of 50–500 g m−2 are optimal for maximizing SOC sequestration, with positive effects diminishing and negative impacts intensifying beyond this range. This empirical synthesis confirms the efficacy of ERW—particularly when Ca-rich silicate rocks in—promoting SOC sequestration and long-term CO2 sequestration. Maximizing the CDR potential of ERW requires integrating site-specific climatic and edaphic characteristics with optimized application amounts and duration. Our findings provide insights critical for balancing the costs and benefits of rock weathering for CDR and highlight the importance of ERW as a sustainable strategy for soil carbon management and climate change mitigation.
Xu, T. et al. (2025) Enhanced Rock Weathering Promotes Soil Organic Carbon Accumulation: A Global Meta-Analysis Based on Experimental Evidence 31 (9) Global Change Biology.
Read the full paper here: Enhanced Rock Weathering Promotes Soil Organic Carbon Accumulation: A Global Meta-Analysis Based on Experimental Evidence I Global Change Biology.
Evaluating Ocean Alkalinity Enhancement as a Carbon Dioxide Removal Strategy in the North Sea
Abstract
Ocean alkalinity enhancement (OAE) is a climate mitigation strategy aimed at increasing the ocean’s capacity to absorb and store atmospheric CO2. The effect of OAE depends significantly on local physical and biogeochemical conditions, underscoring the importance of selecting optimal locations for alkalinity addition. Using a regional coupled physical-biogeochemical-carbon model, we examine OAE responses in the North Sea, including CO2 uptake potential, enhanced carbon storage and cross-shelf export, and the associated changes in the carbonate chemistry. Alkalinity is continuously added as a surface flux in three distinct regions of the North Sea. Our simulations show that the Norwegian Trench and the Skagerrak serve as sinks for added alkalinity, reducing its interaction with the atmosphere. Alkalinity addition along shallow eastern coasts results in a higher CO2 uptake efficiency (∼0.79 mol CO2 uptake per mol alkalinity addition) than offshore addition in ship-accessible areas (∼0.66 mol CO2 uptake per mol alkalinity addition) as offshore alkalinity is more susceptible to deep-ocean loss. Long-term carbon storage, measured by excess carbon accumulation in deep ocean and cross-shelf export below permanent pycnoclines, is similar across the three scenarios and accounts for less than 10 % of total excess CO2 uptake. The smallest changes in pH occur when alkalinity is added offshore with effects nearly an order of magnitude lower than alkalinity addition in the shallow German Exclusive Economic Zone where pH increases from 8.1 to 8.4. The model’s resolution (∼4.5 km in coastal areas) limits its ability to capture rapid, localized carbonate responses, leading to a nearly 10-fold underestimation of chemical perturbations. Thus, finer-scale models are needed to accurately assess near-source alkalinity impacts.
Liu, F. et al. (2025) Evaluating Ocean Alkalinity Enhancement as a Carbon Dioxide Removal Strategy in the North Sea 22 Biogeosciences 3699-3719.
Read the full paper here: Evaluating Ocean Alkalinity Enhancement as a Carbon Dioxide Removal Strategy in the North Sea I Biogeosciences.
Comparative Performance Analysis of Bioenergy with Carbon Capture and Storage (BECCS) Technologies
Abstract
This study presents a comprehensive performance assessment of combustion-based options for Bioenergy with Carbon Capture and Storage (BECCS), widely regarded as key enablers of future climate neutrality. From 972 publications (2000–2025), 16 sources are identified as providing complete data. Seven technologies are considered: Calcium Looping (CaL), Chemical Looping Combustion (CLC), Hot Potassium Carbonate (HPC), low-temperature solvents (mainly amine-based), molten sorbents, Molten Carbonate Fuel Cells (MCFCs), and oxyfuel. First- and second-law efficiencies are reported for 53 bioenergy configurations (19 reference plants without carbon capture and 34 BECCS systems). Performance is primarily evaluated via the reduction in second-law (exergy) efficiency and the Specific Primary Energy Consumption per CO2 Avoided (SPECCA), both relative to each configuration’s reference plant. MCFC-based systems perform best, followed by CLC; molten sorbents and oxyfuel also show very good performance, although each is documented by a single source. Low-temperature solvents span a wide performance range—from poor to competitive—highlighting the heterogeneity of this category; HPC performs in line with the average of low-temperature solvents. CaL exhibits modest efficiency penalties alongside appreciable energy costs of CO2 capture, a counterintuitive outcome driven by the high performance of the benchmark plants considered in the definition of SPECCA. To account for BECCS-specific features (multiple outputs and peculiar fuels), a dedicated evaluation framework with a revised SPECCA formulation is introduced.
Cretarola, C. et al. (2025) Comparative Performance Analysis of Bioenergy with Carbon Capture and Storage (BECCS) Technologies 18 (18) Energies.
Read the full paper here: Comparative Performance Analysis of Bioenergy with Carbon Capture and Storage (BECCS) Technologies I Energies.
Amplified Local Cooling Effects of Forestation in Warming Europe
Abstract
Forests exhibit local cooling or warming effects compared to adjacent openlands through biophysical processes. These temperature effects are predicted by earth system models to evolve in response to climate change. However, such temporal patterns remain unconstrained by observations and have not been detected in historical records. Here, by comparing the satellite observations of spatially nearby forests and openlands over the last two decades, we quantify temporal trends in local land surface temperature (LST) effects of forest change in Europe. During winter, the daytime warming effect of potential forestation weakens and reverses to cooling (−0.142 K/decade) with decreasing snow cover, as forests show less pronounced surface darkening trends than openlands. During summer, the daytime cooling effect intensifies (−0.188 K/decade) because forests remain more physiologically and hydrologically resilient to increasing soil dryness. These negative trends are broadly supported by state-of-the-art earth system models, though substantial inter-model variability persists. Given continued climate change, we emphasize the need to consider the dynamics of biophysical effects when comprehensive forest-related climate policies are formed.
Li, Y. et al. (2025) Amplified Local Cooling Effects of Forestation in Warming Europe 16 (8412) Nature Communications.
Read the full paper here: Amplified Local Cooling Effects of Forestation in Warming Europe I Nature Communications.