UAA Inventory: Greenhouse Gas Emissions From Transportation

As a signatory of the American College and University Presidents Climate Commitment, UAA has agreed to conduct an inventory of its greenhouse gas (GHG) emissions. This inventory serves as a baseline against which to measure the effectiveness of GHG emissions reduction projects. To fulfill the Commitment UAA agreed to conduct an inventory of its Scope 1 and 2 emissions, as well as some Scope 3 emissions. In addition to signing the Presidents Climate Commitment, UAA signed the Talloires Declaration in April 2004. The Talloires Declaration is a statement of principles and practices for using higher education to promote sustainability. Scope 1 emissions are defined as direct GHG emissions occurring from sources that are owned or controlled by the institution. Scope 2 emissions are indirect emissions generated in the production of energy purchased by the institution. Scope 3 emissions are indirect emissions that are the consequence of the activities of the institution, but occur from sources not owned or controlled by the institution. Pursuant to the Commitment, this study estimates the levels of two types of Scope 3 GHG emissions – commuting by students and employees, and university-funded air travel. Scope 1 and Scope 2 GHG emissions are being estimated in a separate study. Two models were developed and used: a UAA commuter model and a UAA air travel model.Office of Sustainability, University of Alaska Anchorag

Recent and future trends in synthetic greenhouse gas radiative forcing

Atmospheric measurements show that emissions of hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons are now the primary drivers of the positive growth in synthetic greenhouse gas (SGHG) radiative forcing. We infer recent SGHG emissions and examine the impact of future emissions scenarios, with a particular focus on proposals to reduce HFC use under the Montreal Protocol. If these proposals are implemented, overall SGHG radiative forcing could peak at around 355 mW m[superscript −2] in 2020, before declining by approximately 26% by 2050, despite continued growth of fully fluorinated greenhouse gas emissions. Compared to “no HFC policy” projections, this amounts to a reduction in radiative forcing of between 50 and 240 mW m[superscript −2] by 2050 or a cumulative emissions saving equivalent to 0.5 to 2.8 years of CO2 emissions at current levels. However, more complete reporting of global HFC emissions is required, as less than half of global emissions are currently accounted for.Natural Environment Research Council (Great Britain) (Advanced Research Fellowship NE/I021365/1)United States. National Aeronautics and Space Administration (Upper Atmospheric Research Program Grant NNX11AF17G)United States. National Oceanic and Atmospheric Administratio

Assessing the climate impacts of Chinese dietary choices using a telecoupled global food trade and local land use framework

Global emissions trajectories developed to meet the 2⁰C temperature target are likely to rely on the widespread deployment of negative emissions technologies and/or the implementation of substantial terrestrial carbon sinks. Such technologies include afforestation, carbon capture and storage (CCS) and bioenergy with carbon capture and storage (BECCS), but mitigation options for agriculture appear limited. For example, using the Global Calculator tool (http://www.globalcalculator.org/), under a 2⁰C pathway, the ‘forests and other land use’ sector is projected to become a major carbon sink, reaching -15 GtCO2e yr-1 by 2050, compared to fossil emissions of 21 GtCO2e yr-1. At the same time, rates of agricultural emissions remain static at about 6 GtCO2e yr-1, despite increasing demands for crop and livestock production to meet the forecast dietary demands of the growing and increasingly wealthy global population. Emissions in the Global Calculator are sensitive to the assumed global diet, and particularly to the level and type of meat consumption, which in turn drive global land use patterns and agricultural emissions. Here we assess the potential to use a modified down-scaled Global Calculator methodology embedded within the telecoupled global food trade framework, to estimate the agricultural emissions and terrestrial carbon stock impacts in China and Brazil, arising from a plausible range of dietary choices in China. These dietary choices are linked via telecoupling mechanisms to Brazilian crop production (e.g. Brazilian soy for Chinese animal feed provision) and drive land and global market dynamics. ‘Spill-over’ impacts will also be assessed using the EU and Malawi as case studies

Interference Phenomena in Medium Induced Radiation

We consider the interference pattern for the medium-induced gluon radiation produced by a color singlet quark-antiquark antenna embedded in a QCD medium with size $L$ and `jet quenching' parameter $\hat q$. Within the BDMPS-Z regime, we demonstrate that, for a dipole opening angle $\theta_{q\bar q} \gg\theta_c\equiv {2}/{\sqrt{\hat q L^3}}$, the interference between the medium--induced gluon emissions by the quark and the antiquark is suppressed with respect to the direct emissions. This is so since direct emissions are delocalized throughout the medium and thus yield contributions proportional to $L$ while interference occurs only between emissions at early times, when both sources remain coherent. Thus, for \tqq \gg\theta_c, the medium-induced radiation is the sum of the two spectra individually produced by the quark and the antiquark, without coherence effects like angular ordering. For \tqq \ll\theta_c, the medium--induced radiation vanishes.Comment: 4 pages, 2 figures; Proceedings of the "Quark Matter 2011" conferenc

Molecular Tracers of Filamentary CO Emission Regions Surrounding the Central Galaxies of Clusters

Optical emission is detected from filaments around the central galaxies of clusters of galaxies. These filaments have lengths of tens of kiloparsecs. The emission is possibly due to heating caused by the dissipation of mechanical energy and by cosmic ray induced ionisation. CO millimeter and submillimeter line emissions as well as H$_{2}$ infrared emission originating in such filaments surrounding NGC~1275, the central galaxy of the Perseus cluster, have been detected. Our aim is to identify those molecular species, other than CO, that may emit detectable millimeter and submillimeter line features arising in these filaments, and to determine which of those species will produce emissions that might serve as diagnostics of the dissipation and cosmic ray induced ionisation. The time-dependent UCL photon-dominated region modelling code was used in the construction of steady-state models of molecular filamentary emission regions at appropriate pressures, for a range of dissipation and cosmic ray induced ionisation rates and incident radiation fields.HCO$^+$ and C$_2$H emissions will potentially provide information about the cosmic ray induced ionisation rates in the filaments. HCN and, in particular, CN are species with millimeter and submillimeter lines that remain abundant in the warmest regions containing molecules. Detections of the galaxy cluster filaments in HCO$^{+}$, C$_{2}$H, and CN emissions and further detections of them in HCN emissions would provide significant constraints on the dissipation and cosmic ray induced ionisation rates.Comment: 11 pages, 3 figures, 3 tables, accepted in A&

Development of a low-maintenance measurement approach to continuously estimate methane emissions: a case study

The chemical breakdown of organic matter in landfills represents a significant source of methane gas (CH4). Current estimates suggest that landfills are responsible for between 3% and 19% of global anthropogenic emissions. The net CH4 emissions resulting from biogeochemical processes and their modulation by microbes in landfills are poorly constrained by imprecise knowledge of environmental constraints. The uncertainty in absolute CH4 emissions from landfills is therefore considerable. This study investigates a new method to estimate the temporal variability of CH4 emissions using meteorological and CH4 concentration measurements downwind of a landfill site in Suffolk, UK from July to September 2014, taking advantage of the statistics that such a measurement approach offers versus shorter-term, but more complex and instantaneously accurate, flux snapshots. Methane emissions were calculated from CH4 concentrations measured 700 m from the perimeter of the landfill with observed concentrations ranging from background to 46.4 ppm. Using an atmospheric dispersion model, we estimate a mean emission flux of 709 μg m−2 s−1 over this period, with a maximum value of 6.21 mg m−2 s−1, reflecting the wide natural variability in biogeochemical and other environmental controls on net site emission. The emissions calculated suggest that meteorological conditions have an influence on the magnitude of CH4 emissions. We also investigate the factors responsible for the large variability observed in the estimated CH4 emissions, and suggest that the largest component arises from uncertainty in the spatial distribution of CH4 emissions within the landfill area. The results determined using the low-maintenance approach discussed in this paper suggest that a network of cheaper, less precise CH4 sensors could be used to measure a continuous CH4 emission time series from a landfill site, something that is not practical using far-field approaches such as tracer release methods. Even though there are limitations to the approach described here, this easy, low-maintenance, low-cost method could be used by landfill operators to estimate time-averaged CH4 emissions and their impact downwind by simultaneously monitoring plume advection and CH4 concentrations

A Human Development Framework for CO2 Reductions

Although developing countries are called to participate in CO2 emission reduction efforts to avoid dangerous climate change, the implications of proposed reduction schemes in human development standards of developing countries remain a matter of debate. We show the existence of a positive and time-dependent correlation between the Human Development Index (HDI) and per capita CO2 emissions from fossil fuel combustion. Employing this empirical relation, extrapolating the HDI, and using three population scenarios, the cumulative CO2 emissions necessary for developing countries to achieve particular HDI thresholds are assessed following a Development As Usual approach (DAU). If current demographic and development trends are maintained, we estimate that by 2050 around 85% of the world's population will live in countries with high HDI (above 0.8). In particular, 300Gt of cumulative CO2 emissions between 2000 and 2050 are estimated to be necessary for the development of 104 developing countries in the year 2000. This value represents between 20% to 30% of previously calculated CO2 budgets limiting global warming to 2{\deg}C. These constraints and results are incorporated into a CO2 reduction framework involving four domains of climate action for individual countries. The framework reserves a fair emission path for developing countries to proceed with their development by indexing country-dependent reduction rates proportional to the HDI in order to preserve the 2{\deg}C target after a particular development threshold is reached. Under this approach, global cumulative emissions by 2050 are estimated to range from 850 up to 1100Gt of CO2. These values are within the uncertainty range of emissions to limit global temperatures to 2{\deg}C.Comment: 14 pages, 7 figures, 1 tabl

Effect of primary treatment and organic loading on methane emissions from horizontal subsurface flow constructed wetlands treating urban wastewater

Methane is emitted in horizontal subsurface flow constructed wetlands (HSSF CWs) during wastewater treatment. The objective of this work was to determine the influence of primary treatment and organic loading rate on methane emissions from constructed wetlands. To this aim, methane emissions from a HSSF CW pilot plant were measured using the closed chamber method. The effect of primary treatment was addressed by comparing emissions from wetlands receiving the effluent of an anaerobic (HUSB reactor) or a conventional settler as primary treatments. Alternatively, the effect of organic loading was addressed by comparing emissions from wetlands operated under high organic loading (52 g COD m (2) day (1)) and low organic loading (17 g COD m (2) day (1)). Results showed that methane emission rates were affected by the type of primary treatment and, to a lesser extent, by the organic loading applied. Accordingly, lower redox conditions and slightly higher organic loading of a wetland receiving the effluent of a HUSB reactor resulted in methane emissions twelve times higher than those of the wetland fed with primary settled wastewater. Moreover, systems subjected to three times higher organic loading than that recommended lead to higher methane emission rates, although high data variability resulted in no statistically significant differences.Peer ReviewedPostprint (published version

Effect of agricultural practices on N2O emissions from Malagasy soils

Emissions of nitrous oxide (N20) are of concern because of the role of this gas in the greenhouse effect. The agricultural practices may affect the rate of N20 emissions from soil. The work focuses on 2 contrasted practices in use in Malagasy Highlands, i.e. a direct seeding on cover crop residues (SD) and a hand ploughing without residue return to soil (HP). Regarding potential denitrification and in situ N20 emissions, no difference was shown between both practices. Other measurements are currently in progress to confirm/invalidate this preliminary result. (Résumé d'auteur

Effect of heating rate on gas emissions and properties of fired clay bricks and fired clay bricks incorporated with cigarette butts

In general, the firing process of clay bricks generates a range of gas emissions into the atmosphere. At high concentrations, these volatile emissions can be a serious source of environmental pollutions. The main purpose of this study was to evaluate the effect of different heating rates on gas emissions and properties during the firing of clay bricks and clay bricks incorporated with cigarette butts (CBs). In this investigation, four different heating rates were used: 0.7 °C min−1−1, 2 °C min−1, 5 °C min−1 and 10 °C min. The samples were fired in solid form from room temperature to 1050 °C. During the firing cycles, carbon monoxide, carbon dioxide, nitrogen oxides,hydrogen cyanide and chlorine emissions were measured at different heating rates. All bricks were also tested for their physical and mechanical properties including dry density, compressive strength, tensile strength, water absorption and initial rate of absorption. Results show that gas emissions were reduced significantly with higher heating rates (10 °C min) followed by 5 °C min−1−1 and 2 °C min for both types of brick samples. Higher heating rates also decrease the compressive strength and tensile strength value but demonstrate an insignificant effect on the water absorption properties respectively. In conclusion, a higher heating rate is preferable in terms of decreasing gas emissions and it is also able to produce adequate physical and mechanical properties especially for the CB brick