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Despite the growing unconventional natural gas production industry in northeastern British Columbia, Canada, few studies have explored the air quality implications on human health in nearby communities. Researchers who have worked with pregnant women in this area have found higher levels of volatile organic compounds (VOCs) in the indoor air of their homes associated with higher density and closer proximity to gas wells. To inform ongoing exposure assessments, this study develops land use regression (LUR) models to predict ambient air pollution at the homes of pregnant women by using natural gas production activities as predictor variables. Using the existing monitoring network, the models were developed for three temporal scales for 12 air pollutants. The models predicting monthly, bi-annual, and annual mean concentrations explained 23%–94%, 54%–94%, and 73%–91% of the variability in air pollutant concentrations, respectively. These models can be used to investigate associations between prenatal exposure to air pollutants associated with natural gas production and adverse health outcomes in northeastern British Columbia. [Display omitted] • Assessing exposure to hydraulic fracturing is hindered by sparse air quality monitors. • Developed LUR models using air quality data and oil and gas production data. • Used LUR models to predict ambient air pollution concentrations. • Concentrations can be used to assess health outcomes and environmental justice. [ABSTRACT FROM AUTHOR]

• Evaluated pathways to reduce metal use & GHG emissions from US EV batteries (LIBs). • US will face metal supply constraints when transitioning to fully electric fleet. • Cumulative 2020–2050 battery production GHG emissions range from 1.3 to 1.6 gt CO 2 e. • Differences in use-phase due to LIB weight can surpass 20% of LIB production GHGs. • Aggressive PHEV penetration has GHG benefits with less critical material use. We evaluated the battery material demand and GHG emissions implications from high EV and very aggressive Plug-in Hybrid EV (PHEV) penetration rates for the U.S. light-duty vehicle fleet from 2020 to 2050. If the U.S. relies primarily on EV deployment to decarbonize passenger transport, there are potentially significant supply constraints over the next decade, particularly for cobalt, lithium, and nickel. Very aggressive PHEV deployment has the potential to reduce GHGs and with ∼80% lower demand on critical metals. Recycling can play a major role reducing metal demand in the long-term but until 2035, shifting to an iron-based battery cathode reduces critical metal use by more than recycling would but with higher charging emissions due to increased weight. Increasing recycling, shifting battery chemistry, and adopting low-carbon electricity for battery production can avoid 250 million tonnes CO 2 e in cumulative GHG emissions from 2020 to 2050 (equivalent to 15% of U.S. transportation sector's 2020 GHG emissions). [ABSTRACT FROM AUTHOR]

Reducing embodied greenhouse gas (GHG) emissions in the construction of buildings is increasingly recognized as necessary to meet medium- and long-term climate targets. The focus of efforts to reduce embodied GHG have been on using lower GHG intensity materials through material switching (e.g., wood vs concrete buildings) or changing the manufacturing of materials to reduce their GHG intensity (e.g., blast oxygen furnace to electric arc furnace in steel manufacturing). There has been much less attention directed toward the potential to reduce embodied GHG emissions by reducing the amount of material used for the construction of buildings. This study estimates the embodied GHG emission intensity of single-family dwellings (SFD) in Toronto, Canada, Perth, Australia, and Luzon, Philippines using a carbon neutral approach (excluding biogenic carbon) and focusing on the product stage (A1-A3). This examines the main drivers of embodied GHG emissions and quantifies the pathways to reduce embodied GHG emissions of SFDs. The mean embodied GHG emission intensities of SFDs vary across locations with differences driven by construction type and in upstream manufacturing of materials. The mean embodied GHG emission intensities in studied SFDs are 137 kg CO 2 eq/m2 for Toronto, 190 kg CO 2 eq/m2 for Perth, and 313 kg CO 2 eq/m2 for Luzon. Monte Carlo simulation and principal component regression show that the variation in embodied GHG emission intensity within the studied cases is dominated by material quantities with less influence from material GHG intensity. Structural light-weighting, more intensive use of buildings, and very low material GHG factors collectively are shown to have the potential to reduce embodied emissions by 45%–60%. Strategies tested illustrated that savings on the order of 20% are readily available through more intensive use and structural lightweighting. Aggressive changes in energy sources and material manufacturing would take longer to achieve but could deliver another 22%–37% in emissions reductions. • Product stage embodied GHG emissions of single-family dwellings are calculated using a carbon neutral approach. • Product stage embodied GHG emissions of single-family dwellings vary between locations. • Material intensity drives the variance in embodied GHG emissions of single-family dwellings. • Cascading design and material pathways can halve embodied GHG emissions of single-family dwellings. [ABSTRACT FROM AUTHOR]

• Important variabilities exist in material intensities of single-family dwellings within and between locations. • The choice of functional unit changes the perception of which location has more efficient building material use. • House size is a strong predictor of overall material use. • Foundations and exterior walls consume the most materials in houses but in different ratios across geographical locations. This study examines variability in material use in single-family dwellings within and between three different locations (Toronto, Perth, and Luzon). It investigates how the use of different functional units changes the perception of what buildings are more materially efficient and which location has the more materially efficient home building norms. Material intensities for 80 single- family dwellings in the three locations form the foundational data for the paper. Important variabilities exist in the material intensities of the single-family dwellings and change with the functional unit selected (e.g., 7–23% for 1 m2 functional unit). Toronto single-family dwellings appear to be one of the least material intensive when presented per 1 m2 floor area but become the most material intensive when presented per 1 building and 1 bedroom with the opposite for Luzon. Housing size is the most effective explainer of overall material use with foundations and walls consuming the most materials but in different ratios across the three locations. [ABSTRACT FROM AUTHOR]

While bioenergy plays a key role in strategies for increasing renewable energy deployment, studies assessing greenhouse gas (GHG) emissions from forest bioenergy systems have identified a potential trade-off of the system with forest carbon stocks. Of particular importance to national GHG inventories is how trade-offs between forest carbon stocks and bioenergy production are accounted for within the Agriculture, Forestry and Other Land Use (AFOLU) sector under current and future international climate change mitigation agreements. Through a case study of electricity produced using wood pellets from harvested forest stands in Ontario, Canada, this study assesses the implications of forest carbon accounting approaches on net emissions attributable to pellets produced for domestic use or export. Particular emphasis is placed on the forest management reference level (FMRL) method, as it will be employed by most Annex I nations in the next Kyoto Protocol Commitment Period. While bioenergy production is found to reduce forest carbon sequestration, under the FMRL approach this trade-off may not be accounted for and thus not incur an accountable AFOLU-related emission, provided that total forest harvest remains at or below that defined under the FMRL baseline. In contrast, accounting for forest carbon trade-offs associated with harvest for bioenergy results in an increase in net GHG emissions (AFOLU and life cycle emissions) lasting 37 or 90 years (if displacing coal or natural gas combined cycle generation, respectively). AFOLU emissions calculated using the Gross-Net approach are dominated by legacy effects of past management and natural disturbance, indicating near-term net forest carbon increase but longer-term reduction in forest carbon stocks. Export of wood pellets to EU markets does not greatly affect the total life cycle GHG emissions of wood pellets. However, pellet exporting countries risk creating a considerable GHG emissions burden, as they are responsible for AFOLU and bioenergy production emissions but do not receive credit for pellets displacing fossil fuel-related GHG emissions. Countries producing bioenergy from forest biomass, whether for domestic use or for export, should carefully consider potential implications of alternate forest carbon accounting methods to ensure that potential bioenergy pathways can contribute to GHG emissions reduction targets. [ABSTRACT FROM AUTHOR]

While bioenergy plays a key role in strategies for increasing renewable energy deployment, studies assessing greenhouse gas (GHG) emissions from forest bioenergy systems have identified a potential trade-off of the system with forest carbon stocks. Of particular importance to national GHG inventories is how trade-offs between forest carbon stocks and bioenergy production are accounted for within the Agriculture, Forestry and Other Land Use (AFOLU) sector under current and future international climate change mitigation agreements. Through a case study of electricity produced using wood pellets from harvested forest stands in Ontario, Canada, this study assesses the implications of forest carbon accounting approaches on net emissions attributable to pellets produced for domestic use or export. Particular emphasis is placed on the forest management reference level (FMRL) method, as it will be employed by most Annex I nations in the next Kyoto Protocol Commitment Period. While bioenergy production is found to reduce forest carbon sequestration, under the FMRL approach this trade-off may not be accounted for and thus not incur an accountable AFOLU-related emission, provided that total forest harvest remains at or below that defined under the FMRL baseline. In contrast, accounting for forest carbon trade-offs associated with harvest for bioenergy results in an increase in net GHG emissions (AFOLU and life cycle emissions) lasting 37 or 90 years (if displacing coal or natural gas combined cycle generation, respectively). AFOLU emissions calculated using the Gross-Net approach are dominated by legacy effects of past management and natural disturbance, indicating near-term net forest carbon increase but longer-term reduction in forest carbon stocks. Export of wood pellets to EU markets does not greatly affect the total life cycle GHG emissions of wood pellets. However, pellet exporting countries risk creating a considerable GHG emissions burden, as they are responsible for AFOLU and bioenergy production emissions but do not receive credit for pellets displacing fossil fuel-related GHG emissions. Countries producing bioenergy from forest biomass, whether for domestic use or for export, should carefully consider potential implications of alternate forest carbon accounting methods to ensure that potential bioenergy pathways can contribute to GHG emissions reduction targets. [ABSTRACT FROM AUTHOR]

Abstract: An important consideration in forest management to mitigate climate change is the balance between forest carbon (C) storage and ecological sustainability. We explore the effects of management strategies on tradeoffs between forest C stocks and ecological sustainability under five scenarios, three of which included management and two scenarios which provide baselines emulating the natural forest. Managed forest scenarios were: (a) Protection (PROT), i.e., management by suppression of natural disturbance and harvest exclusion; (b) Harvest at a higher rate removing all sustainably available wood (HHARV); (c) Harvest at the lower historical average rate of harvest, AHARV. Both harvest scenarios reflected current forest management practices in the study area, including suppression of natural disturbance and a large (>20% of total) forest area reserved from harvest. Scenarios (d) and (e) simulated “natural” forest with unsuppressed fire at higher (NDH) or lower (NDL) levels and no harvest. Ecological sustainability was evaluated using a coarse filter approach where forest age class and tree species composition were indicators of condition. The study area encompassed 3.4 million hectares of forest in northeastern Ontario at the interface between the temperate hardwood and boreal forest zones. Future forest condition for each scenario was modeled using a timber supply model (SFMM), and C stored in forests and wood products were estimated using the FORCARB-ON model. Forest protection (PROT) resulted in greatest forest C stocks, especially in the near term, but was within 95% of its maximum, becoming saturated within 30years. Harvesting (HHARV and AHARV) resulted in less forest C stock compared to PROT, however, after 100years of adding C in wood products to that in regenerating forests total C storage was equivalent or greater than forest C with PROT. In contrast, removing management (NDH and NDL) decreased C relative to any of the management regimes, though in NDL the decrease was delayed for 30years compared to HHARV. Forest sustainability measured by similarity to natural forest age class was superior with HHARV and AHARV compared to PROT, although no management regime produced a fully natural result. PROT in particular largely lacked younger age classes. All management regimes produced species composition that was near or within the range of natural variation. This analysis provides an example of the types of tradeoffs that can be considered in evaluating the contribution of forests to climate change mitigation, either in a commercial forestry context or in an approach based on protected areas. [Copyright &y& Elsevier]

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• Material intensities within single-family dwellings have coefficients of variation ranging from 13% to 160%. • Concrete basements are the largest driver of material use by mass and building envelope by volume. • Zoning ordinances incentivize high MI construction. • Understanding the variability in MI facilitates communication of its impacts on LCA findings, bottom-up MFA or circular economy studies, and similar. The need to reduce resource use in the built environment is widely recognized, but quantitative understanding of material use in buildings is limited, especially at neighbourhood and city scales. Existing bottom-up material inventories largely rely on typology-based methods, using representative buildings with little quantification of variability in material use. They also typically focus on advancing material replacement or recycling with less attention to reducing material use. This paper quantifies the material intensity of 40 single-family wood framed dwellings in Toronto, Canada. Design and construction drawings from the Toronto Committee of Adjustment and local building codes were used to estimate material quantities for each building. The variability in material use and intensity is explored per building, floor area and number of bedrooms and the largest drivers determined to identify opportunities for building design modifications to meaningfully reduce material intensity. Variability in the quantities of construction materials used within the single-family dwellings studied is large, with coefficients of variation ranging from 13% up to 160%. Concrete basements are the largest driver of material use by mass (mean 56% of total material mass) and building envelope insulation by volume (37%). This paper advances our understanding of the range of material intensities within a single building type in one city and the largest drivers of material use within single-family dwellings. This provides valuable information for including variability in typology approaches to bottom-up urban material intensity and insights for policy/design pathways for reducing material use in single-family dwellings. [ABSTRACT FROM AUTHOR]