Search

Assessments of greenhouse gas (GHG) emissions in managed areas are facing various challenges. A non-flow-through, non-steady-state (NFT-NSS) chamber coupled to a frame permanently inserted into the landfilled substrates is a standard method for quantifying GHG emissions in managed areas, such as pulp and paper mill sludge (PPMS) landfill sites. Frequent measurements are needed to minimize uncertainties on GHG emission factors at the landfill site scale. However, maintaining a frame inserted into the substrates for a long time period is often impossible due to landfilling management operations. Therefore, GHG measurements using NFT-NSS chambers placed directly on substrates' surface could be an interesting option. Our objectives were to determine the relationships between CO 2 , CH 4 , and N 2 O fluxes measured with (F + ) and without (F-) a frame inserted in the substrates' surface and to develop correction factors for fluxes measured without a frame. Measurements were made at different PPMS landfill sites in the province of Québec, Canada. Stronger GHG flux relationships were observed at the provincial (across sites) than the specific site scale: the variance in GHG fluxes from F- chambers explained up to 80 % of variance in fluxes from F + chambers. The measured CO 2 , CH 4 , and N 2 O fluxes in F- chambers were on average 53, 78, and 63 % lower, respectively, than those estimated by the models at provincial scale. The correction factors developed with this approach could greatly extend the number of sites where in situ GHG measurements can be done and would help refining GHG inventories at the provincial and national levels., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Recycling is a commonly acknowledged strategy to reduce the environmental impacts linked to primary resource exploitation. Large regional variations can be observed in recycling processes' parameters, like efficiency, energy mix and treatment of rejects. Life-cycle assessment (LCA) is widely used to evaluate the environmental impacts of recycling processes, but existing studies are neither harmonized nor sufficient to provide a comprehensive geographical and technological coverage of recycling processes. The purpose of this research is to develop an efficient and iterative approach for the parametrized generation of semi-automated regionalized life-cycle inventories that take into account technological and geographical variabilities in the recycling sector. The regionalization framework is then applied to create a parametrized paper recycling regionalization tool. This tool is used in the results section to compare the national climate change impacts of recycling three paper grades. Results show a significant global warming impact variability between countries for recycled graphic paper (0.36 to 2.25 kg CO 2 -Eq/kg wastepaper recycled), newsprint (0.27 to 1.84 kg CO 2 -Eq/kg wastepaper recycled) and corrugated cardboard (0.28 to 1.68 kg CO 2 -Eq/kg wastepaper recycled) productions. A regionalized LCA of the international recycling of the mixed wastepaper exported from Quebec's (Canada) sorting centers is also performed with the tool and compared to the non-regionalized mixed wastepaper recycling process available in the ecoinvent database. Only nine midpoint ReCiPe impact categories remain environmentally advantageous compared to virgin paper production when applying the regionalization methodology, compared to sixteen when using the ecoinvent process, illustrating how regionalization can substantially influence LCA results., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Applying a mixed frequency vector autoregressive (MF-VAR) approach, we examine relationships between CO 2 emissions and economic growth from 1970Q1 to 2019Q4 among G7 countries. We incorporate primary energy consumption as a control variable, to avoid any bias from an omitted variable. Our empirical results, using forecast error variance decomposition and a Granger causality check, suggest that MF-VAR exhibits better explanatory ability over the more commonly used VAR model employing single frequency data. Results from LF-VAR exhibit a feedback loop connecting economic expansion and emissions of CO 2 with one-way Granger causality from primary energy consumption to growth of the economies studied. MF-VAR model results also indicate that, in G7 countries, economic expansion exhibits a one-way causal link to CO 2 emissions in Canada, UK, and US cases. Interestingly, MF-VAR shows feedback between economic expansion and primary energy use in Germany, while LF-VAR quantifies the link from economic growth to CO 2 emissions in Canada and from CO 2 to economic growth in the UK. Results raise implications for the G7 samples' policymakers., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The ecological footprint has currently become a highly popular environmental performance indicator. It provides the basis for setting goals, identifying options for action, and tracking progress toward stated goals. Because the examination of the existence of convergence is important for the climate change protection of the earth, the convergence of ecological footprint and its subcomponents are a major concern for scholars and policymakers. To this end, this study aims to investigate the stochastic convergence of ecological footprint and its subcomponents. We employ the recently developed Hepsag (2021) unit root test that allows nonlinearity and smooth structural change simultaneously to study stochastic convergence in per-capita ecological footprint over the period 1961-2018 for the most polluting countries. The results provide mixed evidence of the presence of stochastic convergence in conventional unit root tests such as ADF, KPSS and Fourier KPSS. According to the Hepsag (2021) unit root test results for all countries, built-up land footprint converges except Australia, Malaysia, Poland, and Turkey. Carbon footprint converges for Indonesia, Malaysia, Mexico, South Africa, Thailand, Turkey, the UK, and the USA. Cropland footprint converges for Australia, Canada, China, France, Indonesia, Italy, Japan, Korea, Malaysia, Mexico, Poland, South Africa, the UK, and Vietnam. Fishing grounds footprint converges in Brazil, France, Germany, Indonesia, Italy, Mexico, South Africa, and Vietnam. Forest product footprint converges in Australia, Canada, France, Germany, India, Korea, Mexico, Poland, Turkey, and Vietnam. Grazing land footprint converges in Canada, France, India, Indonesia, Japan, Korea, Poland, South Africa, Thailand, and Vietnam. And lastly, the total ecological footprint converges in Canada, France, Korea, Malaysia, Mexico, South Africa, the UK, and the USA., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Energy is unquestionably necessary for economic progress; nevertheless, it also produces CO 2 emissions, which are the primary cause of climate change and environmental degradation. Renewable energy, which consists of non-carbohydrate energy sources that do not or seldom emit emissions, can assist the accomplishment of both ecological sustainability and sustainable development in this respect. Against this background, this paper takes into account political risk and assesses the impact of renewable energy use on CO 2 emissions in Canada from 1990 to 2018 controlling economic growth and trade globalization. The present research utilized an innovative dynamic ARDL method that overcomes the limitations of the ARDL method. The results revealed significant evidence of cointegration. In the long run, we established that a surge in economic growth, political risk, renewable energy use, and trade globalization mitigates environmental degradation. Furthermore, the outcomes of the frequency domain causality disclosed that in the long term, economic growth, political risk, renewable energy use, and trade globalization can predict CO 2 emissions in Canada. Since the political stability in Canada has helped to attract foreign firms to invest. Therefore, ensuring political stability will bring in more foreign investment, forcing the Canadian government to take its climate crisis problem more seriously., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Carbon dioxide removal (CDR) technologies, such as direct air carbon capture and storage (DACCS), will be critical in limiting the rise of the average global temperature over the next century. Scaling up DACCS technologies requires the support of a complex array of policies and infrastructure across multiple overlapping policy areas, such as climate, energy, technology innovation and resource management. While the literature on DACCS and other CDR technologies acknowledges the path-dependent nature of policy development, it has tended to focus on abstract policy prescriptions that are not rooted in the specific political, social and physical (infrastructural) context of the implementing state. To address this gap, this paper provides a country-level study of the emerging DACCS policy regime in Canada. Drawing on the existing literature that identifies idealized (acontextual) policy objectives that support DACCS development and effective regulation, we identify the actionable policy objectives across six issue domains: general climate mitigation strategies; energy and resource constraints; carbon storage and transport regulation and infrastructure; financing scale-up and supporting innovation; removal and capture technology availability and regulation; and addressing social acceptability and public interest. Using a database of Canadian climate policies (n = 457), we identify policies within the Canadian (federal and provincial) policy environment that map to the idealized policy objectives within each of these domains. This exercise allows us to analyze how key policy objectives for DACCS development are represented within the Canadian system, and enables us to identify potential niches, and landscape influences within the system, as well as gaps and potential barriers to the system transition process. This paper contributes to our understanding of national DACCS policy development by providing a framework for identifying components of the DAC system and linking those components to desired policy outcomes and may provide a basis for future cross-country comparisons of national-level DACCS policy. [ABSTRACT FROM AUTHOR]

Over the past two decades, numerous developed and developing nations have witnessed a remarkable shift from manufacturing-based economies to those that center around the service sector. This development has led to a staggering growth in the consumption of energy-intensive goods, and Canada has not been immune to this trend. Despite being home to abundant energy reserves, the country's economic expansion has manifestly relied on prodigious energy consumption. Within this context of symbiotic energy-economic growth, this study investigates the empirical relationship between energy consumption and economic growth using Canadian time-series data from 1980 to 2020. In doing so, this paper offers a vital contribution to the development of theoretical frameworks within the sphere of endogenous growth. Besides, to arrive at empirical findings, a model known as the autoregressive distributed lag (ARDL) model, renowned for its ability to discern both short- and long-term coefficients, is employed. The results reveal that economic growth has a significant positive long-run effect on energy consumption and other explanatory variables. All variables other than trade openness demonstrate a positive relationship with economic growth in the short run. From Toda-Yamamoto causality test, it is evident that there exist bidirectional causal links between economic growth and energy consumption and between economic growth and financial development. Several unidirectional causalities were also observed for other variables. Based on these findings, it is recommended that Canada boosts its investment in energy infrastructure, especially in rural and backward regions, to deliver necessary energy services. An optimal trade-off between Canada's vast energy resources and economic growth can perhaps be achieved by minimizing the disparity in access to energy services across all parts of the country. Other policy implications are discussed., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This paper aims to capture the effect of environmentally related taxes on environmental quality in Canada while controlling economic growth, financial development, and energy consumption over the period of 1990Q1 to 2020Q4. The present study employs novel econometric approaches, namely, the nonlinear autoregressive distributed lag (N-ARDL) test and the gradual shift causality (GS-C) test. The outcomes of the study reveal that (i) there is long-run cointegration equation between environmental taxes (E-TAX), carbon dioxide emissions (CO 2 E), economic growth (ECG), financial development (FD), and primary energy consumption (PREC); (ii) E-TAX causes to decrease in environmental degradation in Canada; (iii) PREC and ECG increase (and cause) environmental degradation in Canada; and (iv) financial development also positively affect the environmental sustainability. This effort may also be of great importance for policymakers and decision-makers to better understand the factors of environmental degradation for developing effective tax policies that will alleviate human impacts and contribute to reducing environmental degradation., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Across Canada's boreal forest, disturbances from in situ oil sands mining, including well‐pads, significantly impact vast areas of the landscape. The creation of well‐pads requires removal of vegetation and placement of mineral fill, which essentially stops any carbon (C) sequestration on the once peatland ecosystem. It is important that, once no longer in use, these well‐pads are restored as long‐term C (peat) accumulation is what defines peatland ecosystem. However, little is known about the recovery of greenhouse gas exchange post‐restoration of these features. We studied a decommissioned well‐pad located in a treed poor fen that was restored using three soil adjustment treatments (SATs): (1) complete mineral fill removal (Peat‐Dec); (2) partial pad removal and burial under peat layer (BUPL); and (3) mixing mineral and peat by inversion (Mixed‐P‐M). The recreated peat surface was revegetated with donor peatland species using the moss layer transfer technique (MLTT). The objectives of this paper were to (1) quantify plot‐scale seasonal carbon dioxide (CO2) and methane (CH4) exchange of the SATs, 2–4 years post‐restoration compared to reference sites and (2) determine the influence of several environmental variables on CO2 and CH4 exchange. All SATs proved effective in recreating a soil surface needed to support peatland vegetation as shown by similar rates of net ecosystem exchange (NEE). Equally, both types of vegetation reintroduced led this site on a trajectory toward functioning as a net C sink. [ABSTRACT FROM AUTHOR]

This paper investigates the relationships among the important process parameters that impact Post-combustion Carbon Capture (PCC) carbon dioxide (C O 2) separation. A better understanding of the complex relationships among those parameters can support optimization and performance enhancement of the separation process. Being able to precisely predict the process parameters will enable the operator to determine the current state of the process, forecast any potential changes or events, and adjust process parameters to enhance the plant's performance. With the objective of studying the process parameters' correlations in the amine-based PCC process, we modeled the multi-year historical production data of the Clean Energy Technologies Research Institute (CETRi) (formerly known as the International Test Center for PCC or ITC) in Regina, Saskatchewan, Canada, using a Decision Forest approach. The model validation process revealed that the Decision Forest model produced higher predictive accuracy than previous efforts. The Decision Forest models we developed also represent knowledge about the importance of parameters involved in the capture process, and such knowledge is useful for further optimization of the capture process in the future. • Modeling the parameters of the Carbon Capture process with machine learning (ML). • The ML models used Decision Forest with Gradient Boosting and Oblique Split. • The ML models achieved superior predictive accuracy compared to past efforts. • The ML models support interpretability by visualizing weights and prediction paths. [ABSTRACT FROM AUTHOR]

• New carbon-sequestration geosystem paradigm proposed for screening CO 2 repositories. • Deposition, burial history 1st-order controls on repository attributes, traps, etc. • Genetic understanding of geology enables property prediction away from data control. • Case-study application to heavily industrialized region of onshore Canada. In this paper, I propose a new geoscience paradigm for evaluating potential carbon-sequestration targets. I introduce the term carbon-sequestration geosystem to study and describe portions of sedimentary basins where all the geologic components necessary for the safe and long-term storage of CO 2 are present. The purpose of this type of analysis, most appropriately applied at a basin-screening stage, is to derive a holistic, genetic, and predictive understanding of the geology – the depositional systems, structural setting and other factors that are direct controls on storage, injectivity, potential for induced seismicity, and other critical factors. To illustrate the concepts, I present a re-evaluation of the geologic carbon-sequestration options in Southern Ontario (Canada) where business and environmental needs, mostly associated with hard-to-abate industries, require urgent action. Legacy wireline-logs, core, and outcrop data are the main data sources available in this onshore setting. The results of this new, independent study are broadly similar to those of previous studies: the Cambrian section, a saline aquifer, is the most likely candidate to be a CO 2 repository. However, the methodology used identified several issues (e.g., stratigraphic heterogeneity, proximity to basement) that will need addressing by targeted data collection and/or analysis before site-selection for a test should be undertaken. [ABSTRACT FROM AUTHOR]

In the pursuit of mitigating the performance gap between model-predicted thermal comfort and measurements of perceived thermal comfort, recent studies have investigated the multi-domain nature of thermal comfort and IEQ. This paper presents an update to a recent work that applied Bayesian logistic regression to examine possible independent correlations between perceived thermal comfort of building occupants and metrics of indoor environmental quality (IEQ) such as CO 2 concentrations. The prior work made use of the COPE dataset, a 20-year-old field database of objective and subjective IEQ measurements collected from approximately 800 occupants of open-plan offices in large Canadian and US cities. This study updates that work with a new IEQ field study of 141 workstations carried out at the University of British Columbia across 2019 and 2020. In addition, a new, hierarchical (multi-level) Bayesian logistic regression model is formulated and applied. The new results not only increase the credibility of observing measurements of CO 2 concentrations to improve predictions of thermal satisfaction in the original COPE dataset, but that the credibility of this evidence is strengthened on the addition of the new data. At indoor temperatures of 23.5 °C, the probability of an occupant feeling thermally satisfied at measured CO 2 levels of 550 ppm was 0.62 [0.54 - 0.69, 95% CrI]. This decreased to 0.28 [0.17-0.42, 95% CrI] at 750 ppm. This study does not suggest these observations are generalizable outside the COPE and UBC datasets, nor does it suggest that CO 2 must be affecting occupants physiologically or psychologically to cause these observations. However, it is suggested that CO 2 levels may remain overlooked as a contextual, or latent variable for the real-time prediction of perceived thermal comfort in buildings. For instance, prior research has observed a relationship between indoor CO 2 levels and perceived air quality as well as a relationship between multiple perceptual factors of IEQ, such as air quality and thermal comfort. If the findings of this paper continue to be found in future studies, measurements of CO 2 concentrations may be used to improve the accuracy of thermal comfort prediction models. The core recommendation for future work is therefore to expand measurements in future thermal comfort field studies to include, at least, measurements of indoor CO 2 levels. A greater dataset is needed to determine whether the findings of this study are possibly universally applicable, and/or whether knowledge of indoor CO 2 concentrations may improve personalized models of thermal comfort that are building- and context-specific. • A new IEQ field study of office workers in Canada adds 141 samples to a prior dataset. • The newly collected IEQ database is publicly accessible as part of this publication. • The data is applied to a new hierarchical Bayesian logistic regression model. • Indoor CO 2 levels are found to credibly improve predictions of thermal satisfaction. • Increases in CO 2 levels correlate to observed decreases in thermal satisfaction. [ABSTRACT FROM AUTHOR]

The Neoproterozoic St Honoré carbonatite complex is one of three currently mined niobium deposits. In these and most other carbonatite-hosted niobium deposits, pyrochlore is the principal ore mineral. Four major pyrochlore-bearing rock types are observed in the St Honoré complex, namely, biotitite, magnetite-biotite rock, apatitite and carbonatite. The textural relationships among the different rock types and within each rock type are extremely complex, as are the textures and crystal chemistry of the pyrochlore. Compositionally, there are two major types of pyrochlore. Type-1 is enriched in Ta, U, Zr, Sr, Th, Fe, REE and Cl and Type-2 is a Ca-Na-F-rich pyrochlore, with proportions of other elements close to or below their detection limits. Type-1 pyrochlore is yellow- to red-brown and, in many cases, displays oscillatory zoning. This variety occurs most commonly in the cores of crystals in apatitite, where it has its highest concentrations of the elements listed above. It also is observed in biotitite, but the proportions of the above elements are much lower. Type-2 pyrochlore is light to dark brown and, generally, does not exhibit oscillatory zoning. It forms overgrowths on Type-1 pyrochlore in apatitite and biotitite, and occurs as large crystals in the magnetite-biotite rock (Type-1 pyrochlore is not present in this rock). We propose that Type-1 pyrochlore crystallised from a highly evolved, fluid-undersaturated carbonatitic magma, whereas Type-2 pyrochlore crystallised from a carbonatitic magma that had undergone fluid exsolution, which depleted the magma in elements that tend to partition preferentially into aqueous fluids, i.e., U, Sr, Fe, REE, Ba and Cl. The processes that governed the evolution of the carbonatitic magma (which was mantle-derived and introduced in numerous small batches) and crystallisation of pyrochlore at St Honoré were biotitisation (by the magma), crystallisation of calcite and aqueous fluid exsolution. Biotitisation of the host syenite consumed MgO, H 2 O and CO 2 from each magma batch (the CO 2 was released as a gas), leading to the crystallisation of Type-1 pyrochlore in biotitite. This process also locally increased the CaO content of the magma to a level sufficient to saturate it with calcite, leaving a residual phoscoritic magma that crystallised the most Ta-U-enriched variety of Type-1 pyrochlore. Exsolution of the aqueous fluid occurred as a result of prolonged crystallisation and/or pressure release and led to the crystallisation of Type-2 pyrochlore. The evolution of each of the magma batches was different and depended on the extent of biotitisation, on whether calcite crystallised, and on the timing of fluid exsolution. As the two types of pyrochlore and their temporal relationship have been described for many carbonatite complexes, the hypotheses presented in this paper are likely also applicable to the genesis of pyrochlore in these other complexes. [ABSTRACT FROM AUTHOR]

Inland waters are hotspots of greenhouse gas (GHG) cycling, with small water bodies particularly active in the production and consumption of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). However, wetland ponds are being replaced rapidly by small constructed reservoirs in agricultural regions, yet it is unclear whether these two water body types exhibit similar physical, chemical, and environmental controls of GHG content and fluxes. Here, we compared the content and regulatory mechanisms of all three major GHGs in 20 pairs of natural wetland ponds and constructed reservoirs in Canada's largest agricultural region. Carbon dioxide content was associated primarily with metabolic indicators in both water body types; however, primary production was paramount in reservoirs, and heterotrophic metabolism a stronger correlate in wetland ponds. Methane concentrations were correlated positively with eutrophication of the reservoirs alone, while competitive inhibition by sulfur‐reducing bacteria may have limited CH4 in both waterbody types. Contrary to expectations, N2O was undersaturated in both water body types, with wetlands being a significantly stronger and more widespread N2O sink. Varying regulatory processes are attributed to differences in age, depth, morphology, and water‐column circulation between water body types. These results suggest that natural and constructed water bodies should be modeled separately in regional GHG budgets. Plain Language Summary: Small inland water bodies, ponds and reservoirs, are hotspots of greenhouse gas (GHG) production. However, modern farming practices replace natural wetlands by artificial reservoirs, without consideration on the effects on landscape GHG fluxes. Here we measured concentrations and controls of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) in locally‐paired wetland ponds and agricultural reservoirs and found that while GHG concentrations were similar in the two waterbody types, underlying mechanisms differed, owing to the differences in shape, depth, and age of individual water bodies. Shallower wetland ponds were typically more fully mixed, exhibited more oxygen at depth, and had higher nutrients and organic carbon concentrations reflecting their ages. Findings suggest that the balance between wetland drainage and reservoir construction may have a pronounced effect on regional budgets of GHG fluxes, particularly in the face of forthcoming climate changes. Key Points: CO2 content was associated with metabolism; primary production in reservoirs, but bacterial respiration in wetlandsCH4 concentrations were correlated positively with either eutrophication (reservoirs) or competitive inhibition of methanogenesis (both)N2O undersaturation was ubiquitous, but wetlands were stronger and more widespread N2O sinks [ABSTRACT FROM AUTHOR]

[Display omitted] • Post-plasma constriction of a CO 2 microwave plasma enhances conversion and energy efficiency. • Increased performance is the result of enhanced molecular transport from the plasma region. • 3D CFD simulations showed that the constriction encourages product retention, which results in increased performance. Transforming CO 2 into value-added chemicals is crucial to realizing a carbon–neutral economy, and plasma-based conversion, a Power-2-X technology, offers a promising route to realizing an efficient and scalable process. This paper investigates the effects of post-plasma placement of a converging–diverging nozzle in a vortex-stabilized 2.45 GHz CO 2 microwave plasma reactor to increase energy efficiency and conversion. The CDN leads to a 21 % relative increase in energy efficiency (31 %) and CO 2 conversion (13 %) at high flow rates and near-atmospheric conditions. The most significant performance improvement was seen at low flow rates and sub-atmospheric pressure (300 mbar), where energy efficiency was 23 % and conversion was 28 %, a 71 % relative increase over conditions without the CDN. Using CFD simulations, we found that the CDN produces a change in the flow geometry, leading to a confined temperature profile at the height of the plasma, and forced extraction of CO to the post-CDN region. [ABSTRACT FROM AUTHOR]

Empirical studies of the EKC hypothesis may be very sensitive to datasets, specifications, and functional forms. The aim of this paper is to investigate the long-run relationship among CO 2 emissions, real GDP, and energy consumption using a panel of 9 advanced economies from 1870 to 2008 using both parametric and semi-parametric additive models. While at the panel level the results provide support to the Environmental Kuznets Curve (EKC) only in the post-1950s period, at the individual country level the inverted U-shaped relationship between CO 2 and real GDP is validated for a subset of countries only. However, when a semi-parametric regression framework is applied an inverse U-shaped pattern becomes clear for all countries of the sample, except Canada. Empirical findings indicate that relaxing the restrictions associated with parametric regression models may be critical for the question of investigating the existence of the EKC. • Panel data results provide support to the EKC only in the post-1950s period. • Semi-parametric regressions reveal an inverse U-shaped pattern for all countries, except Canada • An effective policy to reduce CO 2 emissions should encourage innovation activities in low-emission technologies. [ABSTRACT FROM AUTHOR]

The carbon (C) dynamics of northern peatlands are sensitive to hydrological changes owing to ecohydrological feedbacks. We quantified and evaluated the impact of water level variations in a beaver pond (BP) on the CO2 flux dynamics of an adjacent, raised Sphagnum–shrub-dominated bog in southern Canada. We applied the CoupModel to the Mer Bleue bog, where the hydrological, energy and CO2 fluxes have been measured continuously for over 20 years. The lateral flow of water from the bog to the BP was estimated by the hydraulic gradient between the peatland and the BP's water level and the vertical profile of peat hydraulic conductivity. The model outputs were compared with the measured hydrological components, CO2 flux and energy flux data (1998–2019). CoupModel was able to reproduce the measured data well. The simulation shows that variation in the BP water level (naturally occurring or due to management) influenced the bog net ecosystem exchange (NEE) of CO2. Over 1998–2004, the BP water level was 0.75 to 1.0 m lower than during 2017–2019. Simulated net CO2 uptake was 55 gCm-2yr-1 lower during 1998–2004 compared to 2017–2019 when there was no BP disturbance, which was similar to the differences in measured NEE between those periods. Peatland annual NEE was well correlated with water table depth (WTD) within the bog, and NEE also shows a linear relation with the water level at the BP, with a slope of - 120 gCO2-Cm-2yr-1m-1. The current modelling predicts that the bog may switch from CO2 sink to source when the BP water levels drop lower than ∼ 1.7 m below the peat surface at the eddy covariance (EC) tower, located on the bog surface 250 m from the BP. This study highlights the importance of natural and human disturbances to adjacent water bodies in regulating the net CO2 uptake function of northern peatlands. [ABSTRACT FROM AUTHOR]

Biomass burning is an important and changing component of global and hemispheric carbon cycles. Boreal forest fires in Russia and Canada are significant sources of the greenhouse gases carbon dioxide (CO2) and methane (CH4). The influence of carbon monoxide (CO) on the greenhouse effect is practically absent; its main absorption bands of 4.6 and 2.3 μm are far away from the climatically important spectral regions. Meanwhile, CO concentrations in fire plumes are closely related to CO2 and CH4 emissions from fires. On the other hand, satellite measurements of CO are much simpler than those of the aforementioned gases. The Atmospheric Infrared Sounder (AIRS) operating in the Thermal IR spectral region has provided a satellite-based CO data set since October 2002. This satellite data allow to estimate CO emissions from biomass burning north of 30° N using a simple two-box mass-balance model. These results correlate closely with independently estimated CO emissions from the GFED4c bottom-up database. In 2021, both estimate record high emissions throughout the preceding two decades, double the annual emissions compared to previous periods. There have been two years with extremely high emissions (2003 and 2021) but for the rest of the data, an upward trend with a rate of 3.6 ± 2.2 Tg CO yr−2 (4.8 ± 2.7% yr−1) was found. A similar rate of CO emissions can be seen in the GFED4c data. [ABSTRACT FROM AUTHOR]

We report the first water‐column dissolved methane data set from the Estuary and Gulf of St. Lawrence (EGSL). Per surface‐water methane concentration and sea‐to‐air flux, the upper estuary behaved like a typical shallow macrotidal estuary, while the lower estuary and the gulf resembled outer shelf seas and ocean slopes, respectively. The EGSL emitted 166.3 (71.5–214.4) × 106 mol CH4 year−1 to the atmosphere, representing 0.3% (0.1%–0.4%) of the total emission from global estuarine environments. A net production of 11.7 × 107 mol CH4 year−1 was required to sustain this emission. Methane distributions in the upper estuary were dominated by physical mixing, while those in the lower estuary and the gulf bore characteristic subsurface maxima and deep minima shedding light on the methane consumption and production pathways. Elevated but highly variable near‐bottom methane concentrations (10.4–695.3 nmol L−1) transpired over pockmarks on the seabed of the lower estuary, inferring an upward diffusive flux of up to ∼700 mmol CH4 m2 d−1. Hypoxia in the lower estuary bottom water had little influence on methane concentrations. Lab incubations yielded methane cycling rates from a net production of 0.0068 nmol L−1 d−1 to net consumption with turnover times of 33.3–263 days. Methane in the EGSL was isotopically enriched with 13C (δ13CCH4: −40.9‰ to −27.4‰ relative to Peedee Belemnite). This study reveals that the EGSL is a smaller proportional contributor to methane emission from estuarine environments and that complex physical‐biogeochemical interactions control methane cycling and isotopic composition in this vast estuarine system. Plain Language Summary: Methane is the second most important greenhouse gas after carbon dioxide. The ocean is a significant source of methane to the atmosphere, with a disproportionally higher share from estuarine and coastal environments. The Estuary and Gulf of St. Lawrence (EGSL) is the largest semi‐enclosed estuarine system in the world. However, methane concentrations and air‐sea fluxes in the EGSL are unknown to date and are thus absent in global‐ocean methane data compilations. We collected a multi‐season and multi‐year data set of methane from the water column of the EGSL to assess methane's distributions, air‐sea fluxes, sources, and cycling in this vast system. Surface‐water methane concentration decreases from the upper estuary to the lower estuary to the gulf. The distribution of methane in the upper is mainly controlled by the mixing of river water with seawater, while the distribution of methane in the lower estuary and the gulf, which are much deeper and wider than the upper estuary, is dictated by oceanic water mass composition and its interaction with different biogeochemical processes. The EGSL accounts for 0.3% of the total methane emission from global estuarine environments, which is a smaller proportional contribution on a per‐surface‐area basis. Key Points: Contrasting methane distributions and dynamics in different subregions of the Estuary and Gulf of St. LawrenceElevated, highly variable methane concentrations in bottom waters near pockmarks but no escape of pockmark methane to the atmosphereBoth methane concentrations and emission rates are at the lower bounds of global estuarine environments [ABSTRACT FROM AUTHOR]

First‐order streams flowing through peatlands receive, carry and transform large amounts of organic carbon, methane (CH4) and carbon dioxide (CO2) but remain poorly documented. The objectives of this study were to (a) identify the origins of CO2 and CH4 (thereafter C‐GHG for carbon greenhouse gases) in a peatland headwater stream, (b) determine the environmental factors driving C‐GHG export and emissions, and (c) quantify C‐GHG losses from this system and discuss its implications. Data were collected from eight sampling sites along a 3 km boreal peatland headwater stream (Eastern Canada) over the growing seasons 2019 and 2020. The studied stream was oversaturated in pCO2 [min: 2,044; max: 23,306 μatm] and pCH4 [14; 17,614 μatm]. A mass balance model showed that ∼81% of in‐stream CO2 originated from porewater seepage while the remaining 17% and 2% originated from in‐stream productivity and methane oxidation, respectively. Porewater seepage was concluded to be the primary source of CH4. Seasonal dissolved C‐GHG concentrations were negatively correlated with the peatland water table depth, suggesting an active release of carbon‐rich peat porewater during the base flow. Nevertheless, greater C‐GHG losses occurred during stormflow periods which acted as pulses with most of the C‐GHG being shunted downstream. The sum of C‐GHG export and emissions at our site was 8.08 gC m−2 y−1 with 86% being released to the atmosphere and 14% being exported downstream. Our study demonstrates that peatland headwater streams act as large sources of C‐GHG and that precipitation events and topography control the magnitude of the fluxes. Plain Language Summary: Headwater streams are the inceptive fragment of the river network where a substantial quantity of organic carbon is released from the surrounding substrate. This terrestrial organic carbon can also be transformed into greenhouse gases (GHGs) such as methane and carbon dioxide. In the stream, those GHG can be either consumed, emitted to the atmosphere, or exported downstream. However, the respective contribution of those pathways is unknown. We sampled a stream draining a rain‐fed peatland in Eastern Canada to describe and quantify its carbon GHG dynamics. We found higher concentrations in this stream than in most headwater streams but the total carbon emissions and export were comparable. Peatland streams typically have a low velocity and gentle slope which minimizes atmospheric gas release. We also found that concentrations were greater during the low flow period, potentially because carbon‐rich porewater was released from the peat. However, greater export was reported during the few days of intense rain. The significance of this work is that GHG in headwater streams are spatially and temporally variable and controlled by the surrounding ecosystems, the intensity of rain events and the stream morphology. The inclusion of this variability will improve regional and global carbon budget estimates. Key Points: Porewater seepage accounted for 81% of the carbon dioxide (CO2) present in the stream, in‐stream production and methane (CH4) oxidation contributed to 17% and 2%86.5% of the dissolved CO2 and CH4 was emitted to the atmosphere rather than exported downstream due to gases oversaturation and slow flow46% of the CO2 and CH4 exported downstream occurred during the 10% period when water discharge rates were maximum, suggesting a pulse effect [ABSTRACT FROM AUTHOR]

Oil and gas exploration has resulted in over 300,000 km of linear disturbances, known as seismic lines, throughout boreal peatlands across Canada. Sites are left with altered hydrologic and topographic conditions that prevent tree re-establishment. Restoration efforts have concentrated on tree recovery through mechanical mounding to re-create microtopography and support planted tree seedlings to block sightlines and deter the use of lines by wolves, but little is known about the impact of seismic line disturbance or restoration on peatland carbon cycling. This study looked at two mounding treatments and compared summer growing season carbon dioxide and methane fluxes to untreated lines and natural reference areas of a wooded fen in the first two years post-restoration. We found no significant differences in net ecosystem CO2 exchange, but untreated seismic lines were slightly more productive than natural reference areas and mounding treatments. Both restoration treatments increased ecosystem respiration, decreased net productivity by 6–21 g CO2 m−2 d−1, and created areas of increased methane emissions, including an increase in the contribution of ebullition, of up to 2000 mg CH4 m−2 d−1 over natural and untreated lines. Further research on this site to assess the longer-term impacts of restoration, as well as application on other sites with varied conditions, will help determine if these restoration practices are effective at restoring carbon cycling. [ABSTRACT FROM AUTHOR]

Area burned, number of fires, seasonal fire severity, and fire season length are all expected to increase in Canada, with largely unquantified ecosystem feedbacks. However, there are few observational studies measuring ecosystem-scale biogeochemical (e.g., carbon dioxide exchanges) and biophysical (e.g., energy partitioning) properties during smoke episodes and hence assessing responses of gross primary production (GPP) to changes in incoming diffuse photosynthetically active radiation (PAR). In this study, we leveraged two long-term eddy covariance measurement sites in forest and wetland ecosystems to study four smoke episodes, which happened at different times and differed in length, over 4 different years (2015, 2017, 2018, and 2020). We found that the highest decrease in shortwave irradiance due to smoke was about 50 % in July and August but increased to about 90 % when the smoke arrived in September. When the smoke arrived in the later stage of summer, impacts on sensible and latent heat fluxes were very different than the earlier ones. Smoke generally increased the diffuse fraction (DF) from ∼ 0.30 to ∼ 0.50 and turned both sites into stronger carbon dioxide (CO2) sinks with increased GPP up to ∼ 18 % and ∼ 7 % at the forest and wetland site, respectively. However, when DF exceeded 0.80 as a result of dense smoke, both ecosystems became net CO2 sources as total PAR dropped to low values. The results suggest that this kind of natural experiment is important for validating future predictions of smoke–productivity feedbacks. [ABSTRACT FROM AUTHOR]

Carbon capture, utilization, and storage (CCUS) is an attractive technology for the decarbonization of global energy systems. However, its early development stage makes impact assessment difficult. Moreover, rising popularity in carbon pricing necessitates the development of a methodology for deriving carbon abatement costs that are harmonized with the price of carbon. We develop, using a combined bottom-up analysis and top-down learning curve approach, a levelized cost of carbon abatement (LCCA) model for assessing the true cost of emissions mitigation in CCUS technology under carbon pricing mechanisms. We demonstrate our methodology by adapting three policy scenarios in Canada to explore how the implementation of CO2-to-diesel technologies could economically decarbonize Canada's transportation sector. With continued policy development, Canada can avoid 932 MtCO2eq by 2075 at an LCCA of CA$209/tCO2eq. Technological learning, low emission hydroelectricity generation, and cost-effective electricity prices make Quebec and Manitoba uniquely positioned to support CO2-to-diesel technology. The additional policy supports beyond 2030, including an escalating carbon price, CO2-derived fuel blending requirements, or investment in low-cost renewable electricity, which can accelerate market diffusion of CO2-to-diesel technology in Canada. This methodology is applicable to different jurisdictions and disruptive technologies, providing ample foci for future work to leverage this combined technology learning + LCCA approach. [ABSTRACT FROM AUTHOR]