Inverse modeling and mapping US air quality influences of inorganic PM_(2.5) precursor emissions using the adjoint of GEOS-Chem

Influences of specific sources of inorganic PM_(2.5) on peak and ambient aerosol concentrations in the US are evaluated using a combination of inverse modeling and sensitivity analysis. First, sulfate and nitrate aerosol measurements from the IMPROVE network are assimilated using the four-dimensional variational (4D-Var) method into the GEOS-Chem chemical transport model in order to constrain emissions estimates in four separate month-long inversions (one per season). Of the precursor emissions, these observations primarily constrain ammonia (NH_3). While the net result is a decrease in estimated US~NH_3 emissions relative to the original inventory, there is considerable variability in adjustments made to NH_3 emissions in different locations, seasons and source sectors, such as focused decreases in the midwest during July, broad decreases throughout the US~in January, increases in eastern coastal areas in April, and an effective redistribution of emissions from natural to anthropogenic sources. Implementing these constrained emissions, the adjoint model is applied to quantify the influences of emissions on representative PM_(2.5) air quality metrics within the US. The resulting sensitivity maps display a wide range of spatial, sectoral and seasonal variability in the susceptibility of the air quality metrics to absolute emissions changes and the effectiveness of incremental emissions controls of specific source sectors. NH_3 emissions near sources of sulfur oxides (SO_x) are estimated to most influence peak inorganic PM_(2.5) levels in the East; thus, the most effective controls of NH_3 emissions are often disjoint from locations of peak NH_3 emissions. Controls of emissions from industrial sectors of SO_x and NO_x are estimated to be more effective than surface emissions, and changes to NH_3 emissions in regions dominated by natural sources are disproportionately more effective than regions dominated by anthropogenic sources. NOx controls are most effective in northern states in October; in January, SO_x controls may be counterproductive. When considering ambient inorganic PM_(2.5) concentrations, intercontinental influences are small, though transboundary influences within North America are significant, with SO_x emissions from surface sources in Mexico contributing almost a fourth of the total influence from this sector

Moderate emissions grandfathering

Emissions grandfathering holds that a history of emissions strengthens an agent’s claim for future emission entitlements. Though grandfathering appears to have been influential in actual emission control frameworks, it is rarely taken seriously by philosophers. This article presents an argument for thinking this an oversight. The core of the argument is that members of countries with higher historical emissions are typically burdened with higher costs when transitioning to a given lower level of emissions. According to several appealing views in political philosophy (utilitarianism, egalitarianism, prioritarianism, and sufficientarianism) they are therefore entitled to greater resources, including emission entitlements, than those in similar positions but with lower emissions. This grandfathering may play an especially important role in allocating emission entitlements among rich countries

Carbon Emissions Pinch Analysis (CEPA) for emissions reduction in the New Zealand electricity sector

Carbon Emissions Pinch Analysis (CEPA) is a recent extension of traditional thermal and mass pinch analysis to the area of emissions targeting and planning on a macro-scale (i.e. economy wide). This paper presents an extension to the current methodology that accounts for increased demand and a carbon pinch analysis of the New Zealand electricity industry while illustrating some of the issues with realising meaningful emissions reductions. The current large proportion of renewable generation (67% in 2007) complicates extensive reduction of carbon emissions from electricity generation. The largest growth in renewable generation is expected to come from geothermal generation followed by wind and hydro. A four fold increase in geothermal generation capacity is needed in addition to large amounts of new wind generation to reduce emissions to around 1990 levels and also meet projected demand. The expected expansion of geothermal generation in New Zealand raises issues of GHG emissions from the geothermal fields. The emissions factors between fields can vary by almost two orders of magnitude making predictions of total emissions highly site specific

Cities, traffic, and CO2: A multidecadal assessment of trends, drivers, and scaling relationships

Emissions of CO2 from road vehicles were 1.57 billion metric tons in 2012, accounting for 28% of US fossil fuel CO2 emissions, but the spatial distributions of these emissions are highly uncertain. We develop a new emissions inventory, the Database of Road Transportation Emissions (DARTE), which estimates CO2 emitted by US road transport at a resolution of 1 km annually for 1980-2012. DARTE reveals that urban areas are responsible for 80% of on-road emissions growth since 1980 and for 63% of total 2012 emissions. We observe nonlinearities between CO2 emissions and population density at broad spatial/temporal scales, with total on-road CO2 increasing nonlinearly with population density, rapidly up to 1,650 persons per square kilometer and slowly thereafter. Per capita emissions decline as density rises, but at markedly varying rates depending on existing densities. We make use of DARTE's bottom-up construction to highlight the biases associated with the common practice of using population as a linear proxy for disaggregating national- or state-scale emissions. Comparing DARTE with existing downscaled inventories, we find biases of 100% or more in the spatial distribution of urban and rural emissions, largely driven by mismatches between inventory downscaling proxies and the actual spatial patterns of vehicle activity at urban scales. Given cities' dual importance as sources of CO2 and an emerging nexus of climate mitigation initiatives, high-resolution estimates such as DARTE are critical both for accurately quantifying surface carbon fluxes and for verifying the effectiveness of emissions mitigation efforts at urban scales.https://doi.org/10.1073/pnas.1421723112Published versio

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

Conspicuously absent: shipping emissions in climate change policy

This repository item contains a single issue of Issues in Brief, a series of policy briefs that began publishing in 2008 by the Boston University Frederick S. Pardee Center for the Study of the Longer-Range Future.The 2015 Paris Climate Agreement relies on state actors to meet self-determined greenhouse gas emissions reduction targets by self-determined means. In this Issues in Brief, Rebecca Cowing explores the unique emissions reduction challenges posed by the integrated, multi-state nature of maritime shipping. Ninety percent of all international trade by volume is transported by ship, accounting for nearly three percent of global carbon dioxide emissions. While the world’s highest-emitting countries set goals to cap or reduce emissions in the near future, marine shipping emissions continue to rise, and are expected to account for 6-14 percent of the global share by 2050. Cowing explores the question of who “owns” shipping emissions and presents the four options under consideration for the past two decades for allocating those emissions to individual countries. She concludes that without a robust methodology for assigning responsibility of shipping emissions and the proper incentives for states to include these emissions in their national totals, it will be nearly impossible to meaningfully reduce emissions from the sector. Rebecca Cowing is a 2016 graduate of Boston University’s Pardee School of Global Studies with a Master’s in International Relations and Environmental Policy. Her master’s thesis examined the complexities of international maritime shipping and the difficulties surrounding the mitigation of the sector’s greenhouse gas emissions. She currently works for the World Wildlife Fund in the Chinese Markets division

Assessment of the Contribution of Traffic Emissions to the Mobile Vehicle Measured PM2.5 Concentration by Means of WRF-CMAQ Simulations

INE/AUTC 12.0

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

Coronal Thick Target Hard X Ray Emissions and Radio Emissions

Recently a distinctive class of hard X ray (HXR) sources located in the corona was found, which implies that the collisionally thick target model (CTTM) applies even to the corona. We investigated whether this idea can independently be verified by microwave radiations that have been known as the best companion to HXRs. The study is made for the GOES M2.3 class flare occurred on 2002 September 9 that were observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and the Owens Valley Solar Array (OVSA). Interpreting the observed energy dependent variation of HXR source size under the CTTM the coronal density should be as high as $5\times 10^{11}$ cm$^{-3}$ over the distance up to 12$"$. To explain the cut-off feature of microwave spectrum at 3 GHz, we however, need density no higher than $1\times 10^{11}$ cm$^{-3}$. Additional constraints need to be placed on temperature and magnetic field of the coronal source in order to reproduce the microwave spectrum as a whole. Firstly, a spectral feature called the Razin suppression requires the magnetic field in a range of 250--350 gauss along with high viewing angles around 75$^{\rm o}$. Secondly, to avoid excess fluxes at high frequencies due to the free-free emission that were not observed, we need a high temperature $\geq2\times 10^7$ K. These two microwave spectral features, Razzin suppression and free-free emissions, become more significant at regions of high thermal plasma density and are essential for validating and for determining additional parameters for the coronal HXR sources.Comment: APJ Letters, in pres

Carbon emissions pinch analysis (CEPA) for emissions reduction in the New Zealand electricity sector

Carbon Emissions Pinch Analysis (CEPA) is a recent extension of traditional thermal and mass pinch analysis to the area of emissions targeting and planning on a macroscale (i.e. economy wide). This paper presents a carbon pinch analysis of the New Zealand electricity industry and illustrates some of the issues with realising meaningful emissions reductions. The current large proportion of renewable generation sources (~67% in 2007) complicates wholesale emissions reductions. The biggest growth in renewable generation is expected to come from geothermal energy followed by wind and hydro. A four fold increase in geothermal generation capacity is needed in addition to large amounts of new wind generation to reduce emissions to around 1990 levels and also meet projected demand. The expected expansion of geothermal generation in New Zealand raises issues of GHG emissions from the geothermal fields. The emissions factors between fields can vary by almost two orders of magnitude making predictions of total emissions highly site specific