The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Taka Ito - One of the best experts on this subject based on the ideXlab platform.
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physical and biological regulation of the soft tissue Carbon pump
AGUFM, 2006Co-Authors: Payal Parekh, Michael J Follows, Stephanie Dutkiewicz, Taka ItoAbstract:[1] We examine the relationship between aeolian iron deposition, ocean circulation, and atmospheric CO2 in the context of a global ocean circulation and biogeochemistry model with a coupled atmospheric reservoir of CO2. In common with previous models we find only a small reduction of atmospheric pCO2 in response to an enhanced aeolian iron source consistent with Last Glacial Maximum conditions. We show this to be due to a combination of limiting factors including control of deep ocean iron concentrations by complexation to an organic ligand, regional compensation in changes to export production, and the maintenance of high preformed nutrient concentrations in deep water formation regions. We also demonstrate a significant sensitivity of atmospheric pCO2 to changes in the residual mean overturning circulation of the Southern Ocean dominated by its regulation of the accumulation of Biogenic Carbon in the deep ocean. Although it is not enough to explain the full drawdown of pCO2 to glacial levels, a reduction in overturning can lead to significant reduction in atmospheric pCO2, providing mechanistic basis for the control by ‘‘vertical mixing’’ inferred from box models. Citation: Parekh, P., M. J. Follows, S. Dutkiewicz, and T. Ito (2006), Physical and biological regulation of the soft tissue Carbon pump, Paleoceanography, 21, PA3001, doi:10.1029/2005PA001258.
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physical and biological regulation of the soft tissue Carbon pump
Paleoceanography, 2006Co-Authors: Payal Parekh, Michael J Follows, Stephanie Dutkiewicz, Taka ItoAbstract:[1] We examine the relationship between aeolian iron deposition, ocean circulation, and atmospheric CO2 in the context of a global ocean circulation and biogeochemistry model with a coupled atmospheric reservoir of CO2. In common with previous models we find only a small reduction of atmospheric pCO2 in response to an enhanced aeolian iron source consistent with Last Glacial Maximum conditions. We show this to be due to a combination of limiting factors including control of deep ocean iron concentrations by complexation to an organic ligand, regional compensation in changes to export production, and the maintenance of high preformed nutrient concentrations in deep water formation regions. We also demonstrate a significant sensitivity of atmospheric pCO2 to changes in the residual mean overturning circulation of the Southern Ocean dominated by its regulation of the accumulation of Biogenic Carbon in the deep ocean. Although it is not enough to explain the full drawdown of pCO2 to glacial levels, a reduction in overturning can lead to significant reduction in atmospheric pCO2, providing mechanistic basis for the control by “vertical mixing” inferred from box models.
Richard B. Rivkin - One of the best experts on this subject based on the ideXlab platform.
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Biogenic Carbon and nitrogen export in a deep-convection region: simulations in the Labrador Sea
Deep Sea Research Part I: Oceanographic Research Papers, 2004Co-Authors: R.c. Tian, Richard B. Rivkin, Don Deibel, Alain F. VézinaAbstract:Abstract The Labrador Sea is a major sink of anthropogenic CO 2 due to deep-water formation in winter. To investigate the relative importance of different forms of export flux, we used a physical-biogeochemical model to simulate the vertical fluxes of particulate and dissolved Biogenic Carbon as a function of winter convection, food web dynamics and zooplankton vertical migration. The C:N ratio of these export fluxes was simulated based on trophic dynamics and bacterial activity. The model was run using winter convection and seasonal mixed layer evolution extracted from multi-year physical data collected in the central Labrador Sea. Comparisons between model output and data from the Labrador Sea and other systems indicate that the model provides a realistic picture of Carbon and nitrogen pools and fluxes. Our results suggest that on an annual basis, dissolved organic Carbon (DOC) export by deep, vertical convection is greater than that of the sinking flux of POC. Furthermore, the C:N ratio of exported dissolved organic matter (DOM) is higher than that of the particle sinking flux, resulting in 23% more Carbon exported than would be estimated if predictions were made from the Redfield ratio (e.g., 11.4 vs. 7.0 for DOM and particulate organic matter, respectively, at the bottom of the euphotic zone and 17.2 vs. 9.3 at 1000 m depth). The active export of Carbon by the respiration and mortality of migrating zooplankton amounts to 19% of sinking flux annually, but only 6% of total Carbon export because of the high rates of DOC export in deep-water formation regions. Our model simulations indicate that non-Redfield ratio DOC export characterizes the function of the biological pump in deep-water formation regions.
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sensitivity of Biogenic Carbon export to ocean climate in the labrador sea a deep water formation region
Global Biogeochemical Cycles, 2003Co-Authors: Rucheng Tian, Alain F. Vézina, Don Deibel, Richard B. RivkinAbstract:[1] We used a physical-biogeochemical model to examine the sensitivity of Biogenic Carbon export to ocean climate in the Labrador Sea, a subpolar, deep-water formation region. Documented changes in winter mixed layer depth between the late 1960s and the mid-1990s were used to construct scenarios of weak, moderate, and strong winter convection that drive the biogeochemical model. The model simulations suggest that the total Biogenic Carbon export (particle sinking flux + DOC export) is higher under strong winter convection (e.g., during the early 1990s) than under weak winter convection (e.g., during the late 1960s), by � 70% axcross the 200-m isobath and nearly double at 500 m and 1000 m depth. These large variations in total Biogenic Carbon export are essentially due to the response of DOC export to ocean climate conditions. Sensitivity analyses indicate that the variations in DOC export from the euphotic zone are due to the impact of the convection regime on the development of the microbial food web and on the bacterial consumption of DOC in surface waters. Although DOC downward fluxes within the mesopelagic zone (below � 500 m) are largely controlled by physical processes, the effect of convection on microbial dynamics can potentially amplify the year-to-year variations in the transport of DOC to the deep ocean due to convection. INDEX TERMS: 4215 Oceanography: General: Climate and interannual variability (3309); 4255 Oceanography: General: Numerical modeling; 4806 Oceanography: Biological and Chemical: Carbon cycling; 4840 Oceanography: Biological and Chemical: Microbiology; KEYWORDS: sensitivity analyses, Carbon export, ocean climate, microbial food web, deep-water formation, Labrador Sea
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Biogenic Carbon cycling in the upper ocean effects of microbial respiration
Science, 2001Co-Authors: Richard B. Rivkin, Louis LegendreAbstract:Food-web processes are important controls of oceanic Biogenic Carbon flux and ocean-atmosphere Carbon dioxide exchange. Two key controlling parameters are the growth efficiencies of the principal trophic components and the rate of Carbon remineralization. We report that bacterial growth efficiency is an inverse function of temperature. This relationship permits bacterial respiration in the euphotic zone to be computed from temperature and bacterial production. Using the temperature-growth efficiency relationship, we show that bacterial respiration generally accounts for most community respiration. This implies that a larger fraction of assimilated Carbon is respired at low than at high latitudes, so a greater proportion of production can be exported in polar than in tropical regions. Because bacterial production is also a function of temperature, it should be possible to compute euphotic zone heterotrophic respiration at large scales using remotely sensed information.
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export of Biogenic Carbon and structure and dynamics of the pelagic food web in the gulf of st lawrence part 1 seasonal variations
Deep-sea Research Part Ii-topical Studies in Oceanography, 2000Co-Authors: C Savenkoff, Richard B. Rivkin, Alain F. Vézina, Louis Legendre, Suzanne Roy, Bert Klein, Connie Lovejoy, J C Therriault, C Berube, Jeaneric TremblayAbstract:Abstract The seasonal changes in photosynthetic production, respiration, sinking flux of organic Carbon, and food web structure are described in the Gulf of St. Lawrence over a two-year period during the Canadian Joint Global Ocean Flux Study (JGOFS) program. The results show contrasts in net metabolism between periods of low (winter and spring) and high (summer and fall) vertical stability. The winter–spring period was associated with an autotrophic pelagic food web: predominance of large phytoplankton cells, large zooplankton, and high herbivorous potential transfers towards the zooplankton. The stratified summer-fall period was associated with a heterotrophic food web: dominance of small phytoplankton cells, replacement of the size class occupied by large phytoplankton with large heterotrophic dinoflagellates and ciliates, smaller zooplankton, and dominance of omnivorous transfers towards the zooplankton. Despite differences in algal size and composition as well as in size structure of the trophic compartments between winter–spring and summer–fall, the particulate organic Carbon fluxes observed at 50 m depth was quantitatively similar during these two periods. Even though winter photosynthetic production was relatively low, the high chlorophyll a concentration, the size structure of the trophic compartments, and the high contribution of large phytoplankton cells (mainly diatoms) to biological activity were similar to those observed during the spring and could explain the high heterotrophic biomass observed during winter.
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export of Biogenic Carbon and structure and dynamics of the pelagic food web in the gulf of st lawrence part 2 inverse analysis
Deep-sea Research Part Ii-topical Studies in Oceanography, 2000Co-Authors: Alain F. Vézina, Richard B. Rivkin, Suzanne Roy, Bert Klein, C Savenkoff, J C Therriault, Louis LegendreAbstract:Abstract The effects of the structure and dynamics of the pelagic food web on the export of organic Carbon from the euphotic zone (BC export) are poorly understood. In this paper, we use inverse methods to calculate trophic flows and BC export during two contrasting seasonal regimes in the Gulf of St. Lawrence, Canada. The inverse estimates take into account forms of export other than sinking particles, such as downward mixing of dissolved and suspended particulate organic Carbon. The inverse analysis shows that the ratio of BC export to primary production ( E / P ) is ca. 0.70 for the winter–spring period (November–April), which is characterized by weak stratification, high primary production, and high abundance of large phytoplankton cells (>5 μm). The E / P declines to between 0 and 0.4, depending on the model used, during the summer–fall period (May–October), which is characterized by strong stratification, low production, and dominance of small phytoplankton cells. The higher export relative to production during winter–spring primarily results from the export of detritus, particularly dissolved organic Carbon (DOC), by physical processes. Direct sinking of the larger phytoplankton cells plays a minor role. Conversely, the small export from the summer–fall food web appears to result primarily from reduced grazing activity and DOC production. Herbivory by microbial grazers (flagellates, dinoflagellates and ciliates) dominates consumption of phytoplankton throughout the year and is a significant trophic link to the mesozooplankton. In contrast, transfer of recycled DOC through bacteria and the microbial grazers is a less significant source of Carbon for the larger consumers.
Payal Parekh - One of the best experts on this subject based on the ideXlab platform.
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physical and biological regulation of the soft tissue Carbon pump
AGUFM, 2006Co-Authors: Payal Parekh, Michael J Follows, Stephanie Dutkiewicz, Taka ItoAbstract:[1] We examine the relationship between aeolian iron deposition, ocean circulation, and atmospheric CO2 in the context of a global ocean circulation and biogeochemistry model with a coupled atmospheric reservoir of CO2. In common with previous models we find only a small reduction of atmospheric pCO2 in response to an enhanced aeolian iron source consistent with Last Glacial Maximum conditions. We show this to be due to a combination of limiting factors including control of deep ocean iron concentrations by complexation to an organic ligand, regional compensation in changes to export production, and the maintenance of high preformed nutrient concentrations in deep water formation regions. We also demonstrate a significant sensitivity of atmospheric pCO2 to changes in the residual mean overturning circulation of the Southern Ocean dominated by its regulation of the accumulation of Biogenic Carbon in the deep ocean. Although it is not enough to explain the full drawdown of pCO2 to glacial levels, a reduction in overturning can lead to significant reduction in atmospheric pCO2, providing mechanistic basis for the control by ‘‘vertical mixing’’ inferred from box models. Citation: Parekh, P., M. J. Follows, S. Dutkiewicz, and T. Ito (2006), Physical and biological regulation of the soft tissue Carbon pump, Paleoceanography, 21, PA3001, doi:10.1029/2005PA001258.
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physical and biological regulation of the soft tissue Carbon pump
Paleoceanography, 2006Co-Authors: Payal Parekh, Michael J Follows, Stephanie Dutkiewicz, Taka ItoAbstract:[1] We examine the relationship between aeolian iron deposition, ocean circulation, and atmospheric CO2 in the context of a global ocean circulation and biogeochemistry model with a coupled atmospheric reservoir of CO2. In common with previous models we find only a small reduction of atmospheric pCO2 in response to an enhanced aeolian iron source consistent with Last Glacial Maximum conditions. We show this to be due to a combination of limiting factors including control of deep ocean iron concentrations by complexation to an organic ligand, regional compensation in changes to export production, and the maintenance of high preformed nutrient concentrations in deep water formation regions. We also demonstrate a significant sensitivity of atmospheric pCO2 to changes in the residual mean overturning circulation of the Southern Ocean dominated by its regulation of the accumulation of Biogenic Carbon in the deep ocean. Although it is not enough to explain the full drawdown of pCO2 to glacial levels, a reduction in overturning can lead to significant reduction in atmospheric pCO2, providing mechanistic basis for the control by “vertical mixing” inferred from box models.
Louis Legendre - One of the best experts on this subject based on the ideXlab platform.
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Biogenic Carbon cycling in the upper ocean effects of microbial respiration
Science, 2001Co-Authors: Richard B. Rivkin, Louis LegendreAbstract:Food-web processes are important controls of oceanic Biogenic Carbon flux and ocean-atmosphere Carbon dioxide exchange. Two key controlling parameters are the growth efficiencies of the principal trophic components and the rate of Carbon remineralization. We report that bacterial growth efficiency is an inverse function of temperature. This relationship permits bacterial respiration in the euphotic zone to be computed from temperature and bacterial production. Using the temperature-growth efficiency relationship, we show that bacterial respiration generally accounts for most community respiration. This implies that a larger fraction of assimilated Carbon is respired at low than at high latitudes, so a greater proportion of production can be exported in polar than in tropical regions. Because bacterial production is also a function of temperature, it should be possible to compute euphotic zone heterotrophic respiration at large scales using remotely sensed information.
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export of Biogenic Carbon and structure and dynamics of the pelagic food web in the gulf of st lawrence part 1 seasonal variations
Deep-sea Research Part Ii-topical Studies in Oceanography, 2000Co-Authors: C Savenkoff, Richard B. Rivkin, Alain F. Vézina, Louis Legendre, Suzanne Roy, Bert Klein, Connie Lovejoy, J C Therriault, C Berube, Jeaneric TremblayAbstract:Abstract The seasonal changes in photosynthetic production, respiration, sinking flux of organic Carbon, and food web structure are described in the Gulf of St. Lawrence over a two-year period during the Canadian Joint Global Ocean Flux Study (JGOFS) program. The results show contrasts in net metabolism between periods of low (winter and spring) and high (summer and fall) vertical stability. The winter–spring period was associated with an autotrophic pelagic food web: predominance of large phytoplankton cells, large zooplankton, and high herbivorous potential transfers towards the zooplankton. The stratified summer-fall period was associated with a heterotrophic food web: dominance of small phytoplankton cells, replacement of the size class occupied by large phytoplankton with large heterotrophic dinoflagellates and ciliates, smaller zooplankton, and dominance of omnivorous transfers towards the zooplankton. Despite differences in algal size and composition as well as in size structure of the trophic compartments between winter–spring and summer–fall, the particulate organic Carbon fluxes observed at 50 m depth was quantitatively similar during these two periods. Even though winter photosynthetic production was relatively low, the high chlorophyll a concentration, the size structure of the trophic compartments, and the high contribution of large phytoplankton cells (mainly diatoms) to biological activity were similar to those observed during the spring and could explain the high heterotrophic biomass observed during winter.
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export of Biogenic Carbon and structure and dynamics of the pelagic food web in the gulf of st lawrence part 2 inverse analysis
Deep-sea Research Part Ii-topical Studies in Oceanography, 2000Co-Authors: Alain F. Vézina, Richard B. Rivkin, Suzanne Roy, Bert Klein, C Savenkoff, J C Therriault, Louis LegendreAbstract:Abstract The effects of the structure and dynamics of the pelagic food web on the export of organic Carbon from the euphotic zone (BC export) are poorly understood. In this paper, we use inverse methods to calculate trophic flows and BC export during two contrasting seasonal regimes in the Gulf of St. Lawrence, Canada. The inverse estimates take into account forms of export other than sinking particles, such as downward mixing of dissolved and suspended particulate organic Carbon. The inverse analysis shows that the ratio of BC export to primary production ( E / P ) is ca. 0.70 for the winter–spring period (November–April), which is characterized by weak stratification, high primary production, and high abundance of large phytoplankton cells (>5 μm). The E / P declines to between 0 and 0.4, depending on the model used, during the summer–fall period (May–October), which is characterized by strong stratification, low production, and dominance of small phytoplankton cells. The higher export relative to production during winter–spring primarily results from the export of detritus, particularly dissolved organic Carbon (DOC), by physical processes. Direct sinking of the larger phytoplankton cells plays a minor role. Conversely, the small export from the summer–fall food web appears to result primarily from reduced grazing activity and DOC production. Herbivory by microbial grazers (flagellates, dinoflagellates and ciliates) dominates consumption of phytoplankton throughout the year and is a significant trophic link to the mesozooplankton. In contrast, transfer of recycled DOC through bacteria and the microbial grazers is a less significant source of Carbon for the larger consumers.
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Fluxes of Biogenic Carbon in the Southern Ocean: Roles of large microphagous zooplankton
Journal of Marine Systems, 1998Co-Authors: Jacques Le Fèvre, Louis Legendre, Richard B. RivkinAbstract:The Southern Ocean is an extreme environment, where waters are permanently cold, a seasonal ice cover extends over large areas, and the solar energy available for photosynthesis is severely restricted, either by vertical mixing to considerable depths or, especially south of the Antarctic Circle, by prolonged seasonal periods of low or no irradiance. Such conditions would normally lead to low productivity and a water column dominated by recycling processes involving microbial components of pelagic communities but this does not seem to be the case in the Southern Ocean, where there is efficient export to large apex predators and deep waters. This paper investigates the role of large microphagous zooplankton (salps, krill, and some large copepods) in the partitioning of Biogenic Carbon among the pools of short- and long-lived organic Carbon and sequestered Biogenic Carbon. Large microphagous zooplankton are able to ingest microbial-sized particles and thus repackage small, non-sinking particles into both metazoan biomass and large, rapidly sinking faeces. Given the wide spatio-temporal extent of microbial trophic pathways in the Southern Ocean, large zooplankton that are omnivorous or able to ingest small food particles have a competitive advantage over herbivorous zooplankton. Krill efficiently transfer Carbon to a wide array of apex predators and their faecal pellets are exported to depth during occasional brief sedimentation episodes in spring time. Salps may be a significant link towards some fish (directly) and other apex predators (indirectly) and, at some locations (especially in offshore waters) and time, they may account for most of the downward flux of Biogenic Carbon. Large copepods are a trophic link towards fish and at least one whale species, and their grazing activity generally impedes the export of organic particles to depth. As a-result, Biogenic Carbon is channelled mainly towards apex predators and episodically into the deep ocean. Without these original interactions, Antarctic waters might well be dominated by microbial components and recycling processes instead of active export from the generally small primary producers towards large apex predators.
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vertical flux of Biogenic Carbon in the ocean is there food web control
Science, 1996Co-Authors: Richard B. Rivkin, Louis Legendre, Don Deibel, Suzanne Roy, Jeaneric Tremblay, Bert Klein, Kenneth Crocker, Norman Silverberg, Connie Lovejoy, Fabrice MespleAbstract:Models of Biogenic Carbon (BC) flux assume that short herbivorous food chains lead to high export, whereas complex microbial or omnivorous food webs lead to recycling and low export, and that export of BC from the euphotic zone equals new production (NP). In the Gulf of St. Lawrence, particulate organic Carbon fluxes were similar during the spring phytoplankton bloom, when herbivory dominated, and during nonbloom conditions, when microbial and omnivorous food webs dominated. In contrast, NP was 1.2 to 161 times greater during the bloom than after it. Thus, neither food web structure nor NP can predict the magnitude or patterns of BC export, particularly on time scales over which the ocean is in nonequilibrium conditions.
Annie Levasseur - One of the best experts on this subject based on the ideXlab platform.
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Temporally-differentiated Biogenic Carbon accounting of wood building product life cycles
SN Applied Sciences, 2021Co-Authors: Marieke Head, Annie Levasseur, Robert Beauregard, Michael Magnan, Werner A. Kurz, Manuele MargniAbstract:Although standards have identified temporary Carbon storage as an important element to consider in wood product LCAs, there has been no consensus on a methodology for its accounting. This work aims to improve the accounting of Carbon storage and fluxes in long-life wood products in LCA. Biogenic Carbon from harvested roundwood logs were tracked using the Carbon Budget Model Framework for Harvested Wood Products (CBMF-HWP). Carbon flows through wood product manufacturing, building life and end-of-life phases, and Carbon stocks and fluxes from harvest to the atmosphere were estimated. To cover the products commonly used in the Canadian building industry, a range of softwood products types, provinces and territories and building lifetimes were considered. In addition, policy scenarios were considered in order to model the effects of dynamic parameters through time as a policy target is reached. Most wood products have similar emissions profiles, though cross-laminated timber has higher sawmill emissions and oriented-strand board has higher initial post-demolition emissions. The region of construction is also predictive of the initial post-demolition emissions. Higher recycling rates shift materials from landfills into subsequent product systems, thus avoiding landfill emissions. Landfill decay rates are affected by climate and results in a large range of landfill emissions. The degree of postponement of end-of-life emissions is highly dependent upon the wood product type, region and building lifespan parameters. This work develops Biogenic Carbon profiles that allows for modelling dynamic cradle-to-grave LCAs of Canadian wood products.
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forestry Carbon budget models to improve Biogenic Carbon accounting in life cycle assessment
Journal of Cleaner Production, 2019Co-Authors: Marieke Head, Annie Levasseur, Robert Beauregard, Pierre Y. Bernier, Manuele MargniAbstract:Abstract Currently, wood and wood construction materials have limitations in how Carbon fluxes are accounted for in life cycle assessments. The Biogenic Carbon balance of wood is often considered to be neutral, meaning that the Carbon sequestered by biomass through photosynthesis is considered equal to the Carbon feedstock in wood that is eventually released throughout its life cycle. Several publications have recently shown that this assumption could lead to accounting errors. This research work aims to improve the Biogenic Carbon accounting of the forestry phase of the life cycle of softwood products. This involved specifically modelling Carbon fluxes as a function of tree species, growing conditions and forest management practices, from Canadian managed forests. A baseline natural forest scenario was run for 1000 years until the Carbon stocks were assumed to reach an approximate steady-state, followed immediately by a harvest scenario that was simulated for another 100 years. The ecosystem Carbon costs of the harvest activity were calculated for 117 species and region forest landscapes across Canada and expressed per cubic meter of harvested wood. Most landscapes showed net sequestration after 100 years of harvest history. Exceptions to this included outlier landscapes characterized by low average annual temperatures and precipitation where slightly positive values (net emissions) were found. The mean time to ecosystem cost neutrality for each species ranged from 16 to 60 years. Knowing the time since forest management has started on a particular forest landscape now enables managers to obtain an estimate of ecosystem Carbon cost per cubic meter of wood harvested for most of Canada's forests and commercial tree species. These ecosystem Carbon costs can be used to generate regionalized cradle-to-gate life cycle inventories for harvested wood products across Canada.
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Methodological challenges and developments in LCA of low energy buildings: Application to Biogenic Carbon and global warming assessment
Building and Environment, 2015Co-Authors: Marine Fouquet, Catherine Buhé, Sébastien Lasvaux, Bernard Souyri, Alexandra Lebert, Annie Levasseur, Manuele Margni, Monika WoloszynAbstract:In Europe, low energy buildings become common for new constructions and life cycle assessment (LCA) is increasingly used to assess their environmental performance. The overall objective of this study is to investigate known challenges related to buildings LCA such as Biogenic Carbon accounting and dynamic and prospective aspects, and to discuss how they affect LCA results for low energy buildings and what developments are still needed. Three single family houses built respectively with timber frame, concrete blocks cavity wall, and cast concrete are used as a case study, focusing on the global warming impact category.When Biogenic Carbon is addressed, the timber house is the less impacting choice, whether it is landfilled or burned at the end-of-life. The cavity wall house is the second most favourable option, and the cast concrete house is the worst one. In the case of landfilling for the timber house, the Biogenic Carbon balance is not neutral and worth to be considered. When a dynamic approach and specific prospective scenarios are considered, the ranking between houses stays the same, but the gaps between options vary e.g. the gap between the landfilled timber house and the cast concrete house vary from 40 % to 60 % when optimistic changes in the electricity mix are considered.Dynamic LCA allows for a more consistent analysis of emissions flows and global warming impacts over time. Prospective LCA could provide more relevant LCA results but increases uncertainty and could be used as sensitivity analysis for long life span buildings.
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Biogenic Carbon and temporary storage addressed with dynamic life cycle assessment
Journal of Industrial Ecology, 2013Co-Authors: Annie Levasseur, Manuele Margni, Pascal Lesage, Rejean SamsonAbstract:Summary A growing tendency in policy making and Carbon footprint estimation gives value to temporary Carbon storage in biomass products or to delayed greenhouse gas (GHG) emissions. Some life cycle-based methods, such as the British publicly available specification (PAS) 2050 or the recently published European Commission's International Reference Life Cycle Data System (ILCD) Handbook, address this issue. This article shows the importance of consistent consideration of Biogenic Carbon and timing of GHG emissions in life cycle assessment (LCA) and Carbon footprint analysis. We use a fictitious case study assessing the life cycle of a wooden chair for four end-of-life scenarios to compare different approaches: traditional LCA with and without consideration of Biogenic Carbon, the PAS 2050 and ILCD Handbook methods, and a dynamic LCA approach. Reliable results require accounting for the timing of every GHG emission, including Biogenic Carbon flows, as soon as a benefit is given for temporarily storing Carbon or delaying GHG emissions. The conclusions of a comparative LCA can change depending on the time horizon chosen for the analysis. The dynamic LCA approach allows for a consistent assessment of the impact, through time, of all GHG emissions (positive) and sequestration (negative). The dynamic LCA is also a valuable approach for decision makers who have to understand the sensitivity of the conclusions to the chosen time horizon.
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key issues and options in accounting for Carbon sequestration and temporary storage in life cycle assessment and Carbon footprinting
International Journal of Life Cycle Assessment, 2013Co-Authors: Miguel Brandao, Annie Levasseur, Miko U F Kirschbaum, Bo Pedersen Weidema, Annette Cowie, Susanne Vedel Jorgensen, Michael Zwicky Hauschild, David Pennington, Kirana ChomkhamsriAbstract:Purpose Biological sequestration can increase the Carbon stocks of non-atmospheric reservoirs (e.g. land and land-based products). Since this contained Carbon is sequestered from, and retained outside, the atmosphere for a period of time, the concentration of CO2 in the atmosphere is temporarily reduced and some radiative forcing is avoided. Carbon removal from the atmosphere and storage in the biosphere or anthroposphere, therefore, has the potential to mitigate climate change, even if the Carbon storage and associated benefits might be temporary. Life cycle assessment (LCA) and Carbon footprinting (CF) are increasingly popular tools for the environmental assessment of products, that take into account their entire life cycle. There have been significant efforts to develop robust methods to account for the benefits, if any, of sequestration and temporary storage and release of Biogenic Carbon. However, there is still no overall consensus on the most appropriate ways of considering and quantifying it.