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To achieve net-zero emissions by 2050, we need economic means of sequestering carbon dioxide (CO 2 ) and reducing greenhouse gas emissions (GHG). We analyze the sequestration potential of the Intermountain West (I-West) region, US, as a primary energy transition hub through analysis of wellbore retrofit potential and emission reduction in both fugitive gas abatement and flare gas. We selected the I-West region due to its abundant energy sources and oil and gas production legacy. Preliminary analysis hints that well retrofits can breathe new life into a well at a fraction of the cost of a new drill. With millions of potential candidates in the US, even a modest fraction (1% or less) suitable for retrofit could accelerate the shift to large-scale CO 2 sequestration. Fugitive gas, the unintentional release of wellbore gases such as methane, is a significant emissions source. Through conservative analysis, it is estimated that wellhead leakage alone may account for 5 million tonnes of carbon dioxide equivalent (CO 2 e) emissions. We conclude by assessing the CO 2 emissions from flaring, which is the burning of associated gas during well operations, conservative analysis indicates flaring contributes another 2 million tonnes of CO 2 emissions to the region. We find that with targeted retrofit and better controls on emissions sources, the I-West region can make a significant impact in the nation's push to become net-zero. This study outlines economic feasibility and actionable items to achieve the critical reductions in emissions and increases in sequestration necessary to attain net zero., 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., (Published by Elsevier Ltd.)

Consistent with the increasing environmental interest, the clean energy transition is highly critical to achieving decarbonization targets. Also, energy security has become an important topic under the shadow of the energy crisis,. Accordingly, countries have been trying to stimulate clean energy use to preserve the environment and ensure energy security. So, considering the leading role of economic size and volume of energy use, the study examines the USA to define whether energy transition helps decrease energy security risk (ESR) and curb CO 2 emissions. So, the study applies a disaggregated level analysis by performing quantile-based models for the period from 2001/Q1 through 2022/Q4. The results demonstrate that (i) the energy transition index decreases environmental ESR at higher quantiles and reliability ESR at lower and middle quantiles, whereas it is not beneficial in declining economic and geopolitical ESR; (ii) energy transition curbs CO 2 emissions in building and transport sectors at lower quantiles, whereas it does not help decrease CO 2 emissions in industrial and power sectors; (iii) energy transition is mostly ineffective on ESR, whereas it is highly effective in curbing CO 2 emissions in all sectors except for transport across various quantiles as time passes; (iv) the results differ according to the aggregated and disaggregated levels; (v) the results are consistent across main and alternative models. Hence, the study highlights the dominant effect of energy transition in curbing sectoral CO 2 emissions rather than easing ESR. Accordingly, the study discusses various policy implications for the USA., 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 Elsevier Ltd. All rights reserved.)

The article reports on the proposal publishing companies to becoming entirely carbon neutral and reduce its carbon emission in the U.S. Hearst Corp. plans to consider the implications for their magazines after the calculation on the amount of carbon dioxide emissions produced in the process of publishing. On the other hand, Time Inc. announced that it had asked their paper suppliers to reduce their greenhouse gas emissions by 20 percent by 2012.

Air-sea carbon dioxide (CO2) fluxes have recently been reported for the US South Atlantic Bight (SAB), a low-latitude shallow continental shelf bordered landward by abundant salt marshes and rivers. In this study, influences of terrestrial inputs on sea surface partial pressure of CO2 (pCO2) in the SAB are quantified. After re- moving pCO2 variations due to the annual temperature cycle and air-sea gas ex- change from the in situ pCO2, temperature and gas exchange corrected (TG-corrected) pCO2 is derived. Contributions from the river, marsh, and continental shelf to the TG-corrected pCO2 are then calculated. Findings show that CO2 contributions from the river [ΔpCO2 (river)] are highest close to the coast and decrease with distance off-shore. For example, ΔpCO2 (river) was up to 30 µatm on the inner shelf but averaged only 0--3 µatm on the outer shelf during January and March 2005. CO2 contributions from salt marshes [ΔpCO2 (marsh)] show similar spatial and seasonal distributions as ΔpCO2 (river), with the magnitude of ΔpCO2 (marsh) being about three times as high as that of ΔpCO2 (river). CO2 contributions from within the shelf [ΔpCO2 (shelf)] are highest among the three components. Compared to ΔpCO2 (river) and ΔpCO2 (marsh), ΔpCO2 (shelf) show the smallest onshore-offshore gradients. Despite large uncertainties, this study clearly demonstrates the importance of terrestrial impacts on coastal ocean CO2 distribution. [ABSTRACT FROM AUTHOR]

The article discusses a study on the use of SCIAMACHY WFM-DOAS XCO2 to determine errors related to reduction of scattering. The study develops a new version of the retrieval algorithm (WFMDv2.2) to enhance the quality of the SCIAMACHY XCO2 data product. It validates the new XCO2 data using ground-based observations from the Total Carbon Column Observing Network (TCCON). It also compares NOAA's global CO2 modelling and assimilation system CarbonTracker.

The limited available evidence about effects of high CO2 and acidification of our oceans on fish suggests that effects will differ across fish species, be subtle, and interact with other stressors. An experimental framework was implemented that includes the use of (1) multiple marine fish species of relevance to the northeastern USA that differ in their ecologies including spawning season and habitat; (2) a wide yet realistic range of environmental conditions (i.e., concurrent manipulation of CO2 levels and water temperatures), and (3) a diverse set of response variables related to fish sensitivity to elevated CO2 levels, water temperatures, and their interactions. This report is on an array of early life-history responses of summer flounder (Paralichthys dentatus), an ecologically and economically important flatfish of this region, to a wide range of pH and CO2 levels. Survival of summer flounder embryos was reduced by 50% below local ambient conditions (7.8 pH, 775ppmpCO2) when maintained at the intermediate conditions (7.4 pH, 1860ppmpCO2), and by 75% below local ambient when maintained at the most acidic conditions tested (7.1 pH, 4715ppmpCO2). This pattern of reduced survival of embryos at higher CO2 levels was consistent among three females used as sources of embryos. Sizes and shapes of larvae were altered by elevated CO2 levels with longer larvae in more acidic waters. This pattern of longer larvae was evident at hatching (although longer hatchlings had less energy reserves) to midway through the larval period. Larvae from the most acidic conditions initiated metamorphosis at earlier ages and smaller sizes than those from more moderate and ambient conditions. Tissue damage was evident in older larvae (age 14 to 28 d post-hatching) from both elevated CO2 levels. Damage included liver sinusoid dilation, focal hyper-plasia on the epithelium, separation of the trunk muscle bundles, and dilation of the liver sinusoids and central veins. Cranial-facial features were affected by CO2 levels that changed with ages of larvae. Skeletal elements of larvae from ambient CO2 environments were comparable or smaller than those from elevated CO2 environments when younger (14d and 21 d post-hatching) but larger at older ages (28 d). The degree of impairment in the early life-stages of summer flounder due to elevated CO2 levels suggests that this species will be challenged by ocean acidification in the near future. Further experimental comparative studies on marine fish are warranted in order to identify the species, life-stages, ecologies, and responses that are most sensitive to increased levels of CO2 and acidity in near-future ocean waters, and a strategy is proposed for achieving these goals. [ABSTRACT FROM AUTHOR]

Wildfires are becoming more frequent due to the global climate change. Large amounts of greenhouse gases emitted by wildfires can lead to increases in extreme climate events. Accurately estimating the greenhouse gas carbon dioxide (CO2) emissions from wildfires is important for mitigation of climate change. In this paper, we develop a novel method to estimate wildfire CO2 emissions from the relationship between local CO2 emissions and XCO2 anomalies. Our method uses the WRF-Chem assimilation system from OCO-2 XCO2 retrievals which coupled with Data Assimilation Research Testbed (DART). To validate our results, we conducted three experiments evaluating the wildfire CO2 emissions over the conterminous United States. The four-month average wildfire emissions from July to October in 2015∼2018 were estimated at 4.408 Tg C, 1.784 Tg C, 1.514 Tg C and 2.873 Tg C, respectively. Compared to the average of established inventories CT2019B, FINNv1.5 and GFASv1.2 fire emissions, our estimates fall within one standard deviation, except for 2017 due to lacking of OCO-2 XCO2 retrievals. These results suggest that the regional carbon assimilation system, such as WRF-Chem/DART, using OCO-2 XCO2 retrievals has a great potential for accurately tracking regional wildfire emissions. [ABSTRACT FROM AUTHOR]

This investigation explores whether sustainable finance and renewable energy could facilitate U.S. carbon neutrality. We perform the time-varying parameter-stochastic volatility-vector auto-regression (TVP-SV-VAR) model to obtain the changing relations among U.S. sustainable finance (SF), renewable energy (RE) and carbon dioxide emission (CO2). The empirical outcomes reveal a short-term negative effect from RE to CO2, indicating that renewable energy consumption could promote U.S. carbon neutrality. This effect is asymmetrical, and it could be observed that RE increase has a greater effect on CO2 than RE reduction. Also, the development of sustainable finance could facilitate U.S. carbon neutrality, and the direct impact is longer and more significant than RE, but the indirect effect of SF on CO2 by influencing RE is hysteretic. Besides, the asymmetric effect reveals that the negative direct impact of SF increase on CO2 is smaller than SF reduction, and the latter's indirect effect is more rapid than the former. Against the backdrop of global warming and frequent extreme weather, the above conclusions have meaningful practical applications for the U.S. to achieve carbon neutrality targets through developing sustainable finance and renewable energy., 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.)

This paper based on quantile stochastic frontier framework constructs quantile eco-efficiency measures. Using the estimates from the quantile stochastic frontier, the eco-performance of the U.S. states for nitrogen oxides (NO X ), carbon dioxide (CO 2 ), and sulfur dioxide (SO 2 ) emissions is evaluated. A decoupling analysis involving the evaluation of the nonsynchronous change among states' economic output and environmental degradation levels is also performed. The findings suggest that U.S. states have followed a decoupling process among their GDP and emission levels over the period 1990-2017. In addition, a quantile eco-productivity change estimator is presented alongside with its main components (i.e. quantile eco-technical change and quantile eco-efficiency change). Our findings suggest that over the examined period states' eco-productivity levels have been improved driven both from their eco-technical and eco-efficiency change levels., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Over the last half century in the United States, the per-hectare volume of wood in trees has increased, but it is not clear whether this increase has been driven by forest management, forest recovery from past land uses, such as agriculture, or other environmental factors such as elevated carbon dioxide, nitrogen deposition, or climate change. This paper uses empirical analysis to estimate the effect of elevated carbon dioxide on aboveground wood volume in temperate forests of the United States. To accomplish this, we employ matching techniques that allow us to disentangle the effects of elevated carbon dioxide from other environmental factors affecting wood volume and to estimate the effects separately for planted and natural stands. We show that elevated carbon dioxide has had a strong and consistently positive effect on wood volume while other environmental factors yielded a mix of both positive and negative effects. This study, by enabling a better understanding of how elevated carbon dioxide and other anthropogenic factors are influencing forest stocks, can help policymakers and other stakeholders better account for the role of forests in Nationally Determined Contributions and global mitigation pathways to achieve a 1.5 degree Celsius target., (© 2022. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

The visual analysis of carbon neutrality research can help better understand the development of the research field and explore the difficulties and hot spots in the research, thus making contributions to "carbon emission reduction," environmental protection and human health. This paper makes a visual quantitative analysis of 2,819 research papers published in top international journals from 2008 to 2021 in the WOS core database. It is found that China, the United States, Britain, and Germany are leading the way in carbon neutrality research. The research hotspots are mainly divided into three dimensions: (1) biomass energy and the negative effects it might bring; (2) ways and methods of electrochemical reduction of carbon dioxide; (3) catalysts and catalytic environment. The research mainly went through the conceptual period of 1997-2007, the exploration period of bioenergy from 2008 to 2021, the criticized period of bioenergy sources from 2011 to 2013, and the carbon dioxide electroreduction period from 2013 to the present. In the future, the research direction of biomass energy is to find one kind of biomass energy source which can be stored in a low-carbon way, produced in large quantities at a low cost, and will not occupy forestland. The electrolysis of water to produce hydrogen and the synthesis of fuel with CO 2 are two major research directions at present, whose aims are to find the suitable catalyst and environment for the reaction. Besides, more research can be done on "carbon neutrality" policies so as to reduce carbon dioxide emissions from the source, develop a low-carbon economy and protect human health., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Mao, Zhu, Ju, Bao and Xu.)

The development of globalization has separated the production and consumption of products spatially, and the international trade of products has become a carrier of embodied carbon trade. This paper adopted the perspective of value-added trade to calculate the amount of embodied carbon trade of China from 2006 to 2015 and perform a structural decomposition analysis of the changes in China's embodied carbon trade. This study found that: (1) China's embodied carbon exports are much larger than its embodied carbon imports, and there are differences between countries. China imported the largest amount of embodied carbon from South Korea, and it exported the largest amount of embodied carbon to the United States. (2) The structural decomposition analysis shows that changes in the value-added carbon emission coefficient during the study period would have caused China's embodied carbon trade to decrease, and changes in value-added trade would have caused China's embodied carbon trade to increase. Therefore, countries trading with China need to strengthen their cooperation with China in energy conservation, emission reduction, and product trade. In order to accurately reflect China's embodied carbon trade, it is necessary to calculate embodied carbon trade from the perspective of value-added trade., Competing Interests: The authors have declared that no competing interests exist.

This paper provides a review and comparison of strategies to increase forest carbon, and reduce species losses for climate change mitigation and adaptation in the United States. It compares forest management strategies and actions that are taking place or being proposed to reduce wildfire risk and to increase carbon storage with recent research findings. International agreements state that safeguarding biodiversity and ecosystems is fundamental to climate resilience with respect to climate change impacts on them, and their roles in adaptation and mitigation. The recent Intergovernmental Panel on Climate Change report on impacts, mitigation, and adaptation found, and member countries agreed, that maintaining the resilience of biodiversity and ecosystem services at a global scale is "fundamental" for climate mitigation and adaptation, and requires "effective and equitable conservation of approximately 30 to 50% of Earth's land, freshwater and ocean areas, including current near-natural ecosystems." Our key message is that many of the current and proposed forest management actions in the United States are not consistent with climate goals, and that preserving 30 to 50% of lands for their carbon, biodiversity and water is feasible, effective, and necessary for achieving them. [ABSTRACT FROM AUTHOR]

A critical reason for China-United States trade friction is that China has a huge trade balance, especially the trade balance of goods. However, this huge trade balance is based on the results of official statistics and does not reflect the real economic benefits and environmental costs embodied in China-US trade, where both refer to trade in value-added and embodied CO 2 emission costs, respectively. This paper calculates the trade in value-added and carbon emission transfer between China and the United States based on the World Input-Output Database. Results demonstrate that: (1) Gross trade statistics seriously overestimate China's benefits in China-US trade. The China-US trade surplus, based on gross trade statistics, is 20% higher than when based on trade in value-added accounting. (2) In China-US bilateral trade, China mainly adopts the trade model of importing intermediate products and exporting final products，whereas the United States mainly adopts the trade model of importing final products and exporting intermediate products. China's exports to the United States contain many of value-added in Korea, Taiwan, and Japan. (3) From 2000 through 2014, China maintained a large surplus of CO 2 emissions exports to the United States, and China paid a huge environmental cost in its trade with the United States. (4) In China-US trade, China's environmental costs per unit value-added is 3.02 times that of the United States., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In this paper, we analyze how carbon emissions affect the selection of transportation modes and social welfare by using a two-stage Stackelberg gaming model. Based on this model, the government’s optimal carbon-emission tax scheme and the company’s optimal transportation mode and production decisions are explored. We find that: 1) whether or not the transport carbon-emission tax can increase social welfare depends on the relationships among the social cost of carbon (SCC), the transportation mode shifting threshold (TMST), and the biggest carbon-emission tax that a company can afford (BCRA); 2) a greater SCC implies a higher probability of improving social welfare via imposing transportation carbon-emission tax; and 3) a smaller TMST or BCRA yields a higher probability of improving social welfare when a carbon-emission tax is imposed. Further study shows that imposing a carbon-emission tax on the product with a higher production cost, a bigger product volume, or a bigger product density can increase the probability of improving social welfare. [ABSTRACT FROM PUBLISHER]

The U.S. Clean Power Plan stipulates a state-specific performance-based CO2 emission standard, delegating states with considerable flexibility for using either a tradable performance-based or a mass-based permit program. This paper analyzes these two standards under imperfect competitive. We limit our attention to (1) short-run analyses and (2) a situation in which all states are subject to the same type of standard. We show that while the cross-subsidy inherent in the performance- based standard might effectively reduce power prices, it could also inflate energy consumption. A dominant firm with a relatively clean endowment under the performance-based standard would be able to manipulate the electricity market as well as to elevate permit prices, which might worsen market outcomes compared to its mass-based counterpart. On the other hand, the "cross-subsidy" could be the dominant force leading to a higher social welfare if the leader has a relatively dirty endowment. [ABSTRACT FROM AUTHOR]

By using space-based measurements of the column-averaged dry air mole fraction of carbon dioxide (XCO2) from the Orbiting Carbon Observatory-2 (OCO-2) and CO and NO2 from the Tropospheric Monitoring Instrument (TROPOMI), this study investigates the seasonal variation in the characteristics of CO2, CO, and NO2 across major states in the United States. Beyond correlating these trends with natural factors, significant emphasis is placed on human activities, including heating demands, energy usage, and the impacts of the COVID-19 pandemic. Concentration enhancements in observations influenced by anthropogenic emissions from urban regions relative to background values are calculated to estimate gas emissions. Our investigation reveals a strong correlation between NO2 and CO2 emissions, as evidenced by a correlation coefficient (r) of 0.75. Furthermore, we observe a correlation of 0.48 between CO2 and CO emissions and a weaker correlation of 0.37 between CO and NO2 emissions. Notably, we identify the NO2 concentration as a reliable indicator of CO2 emission levels, in which a 1% increase in NO2 concentration corresponds to a 0.8194% (±0.0942%) rise in annual mean CO2 emissions. Enhancement ratios among NO2, CO, and XCO2 are also calculated, uncovering that high ΔNO2: ΔXCO2 ratios often signify outdated industrial structures and production technologies, while low ΔCO: ΔXCO2 ratios are linked to states that utilize clean energy sources. This approach offers a deeper understanding of the effect of human activities on atmospheric gas concentrations, paving the way for more effective environmental monitoring and policy-making. [ABSTRACT FROM AUTHOR]

Abstract: Proper understanding of the determinants of household CO2 emissions is essential for a shift to sustainable lifestyles. This paper explores the impacts of date of birth and income on household CO2 emissions in France and in the USA. Direct CO2 emissions of French and American households are computed from consumer budget surveys, over the 1980–2000 time period. Age Period Cohort estimators are used to isolate the generational effect on CO2 emissions — i.e. the specific effect of date of birth, independent of the age, the year and other control variables. The paper shows that French 1935–55 cohorts have a stronger tendency to emit CO2 than their predecessors and followers. The generational effect is explained by the fact that over their lifespan, French baby boomers are better off than other generations and live in energy and carbon inefficient dwellings. In the USA, the absence of a generational effect on CO2 emissions can be explained by the fact that intergenerational income inequalities are weaker than in France. Persistence of the generational effect once income and housing type is controlled for in France can be explained by the difficulty for French 1935–55 cohorts to adapt to sober energy consumption patterns. [Copyright &y& Elsevier]

This paper reviews the Validation Phase (Phase II) of the Department of Energy's Regional Carbon Sequestration Partnerships initiative. In 2003, the U.S. Department of Energy created a nationwide network of seven Regional Carbon Sequestration Partnerships (RCSP) to help determine and implement the technology, infrastructure, and regulations most appropriate to promote carbon sequestration in different regions of the nation. The objectives of the Characterization Phase (Phase I) were to characterize the geologic and terrestrial opportunities for carbon sequestration; to identify CO(2) point sources within the territories of the individual partnerships; to assess the transportation infrastructure needed for future deployment; to evaluate CO(2) capture technologies for existing and future power plants; and to identify the most promising sequestration opportunities that would need to be validated through a series of field projects. The Characterization Phase was highly successful, with the following achievements: established a national network of companies and professionals working to support sequestration deployment; created regional and national carbon sequestration atlases for the United States and portions of Canada; evaluated available and developing technologies for the capture of CO(2) from point sources; developed an improved understanding of the permitting requirements that future sequestration activities will need to address as well as defined the gap in permitting requirements for large scale deployment of these technologies; created a raised awareness of, and support for, carbon sequestration as a greenhouse gas (GHG) mitigation option, both within industry and among the general public; identified the most promising carbon sequestration opportunities for future field tests; and established protocols for project implementation, accounting, and management. Economic evaluation was started and is continuing and will be a factor in project selection. During the Validation Phase, the seven regional partnerships will put the knowledge learned during the Characterization Phase into practice through field tests that will validate carbon sequestration technologies that are best suited to their respective regions of the country. These tests will verify technologies developed through DOE's core R&D effort and enable implementation of CO(2) sequestration on a large scale, should that become necessary. Pilot projects will have a site-specific focus to test technology; assess formation storage capacity and injectivity; validate and refine existing CO(2) formation models used to determine the transport and fate of CO(2) in the formation; demonstrate the integrity of geologic seals to contain CO(2); validate monitoring, mitigation, and verification (MMV) technologies; define project costs and compare costs of alternatives; assess potential operational and long-term storage risks; address regulatory requirements; and engage and evaluate public acceptance of sequestration technologies. Field validation tests involving both sequestration in geologic formations and terrestrial sequestration are being developed. The results from the Validation Phase will help to confirm the estimates made during the Characterization Phase and will be used to update the regional atlases and NatCarb. Answers to many questions about the effectiveness and safety of carbon sequestration technologies will be instrumental in planning for a Deployment Phase, in which large volume tests will be planned to further sequestration as an option that can mitigate GHG emissions in the United States.

In addition to national inventories of emissions of greenhouse gases, there are inventories for most, but not all, states constituting the United States. This paper analyzes the state inventories to see if reported emissions of carbon dioxide, methane, and nitrous oxide are additive. Considerable reanalysis of the state inventories is required before they can be added to yield a larger-scale inventory. Some specific sources were considered by some states but not by others. Estimation techniques evolved over time as inventories were produced, and there are instances of both double-counting (two states reporting the same emission) and omission (neither state reporting the same emission), where interstate transfers of energy or materials occurred. Nevertheless, the inventories, when adjusted for obvious double-counting or omissions, are probably approximately additive, although it is difficult to quantify the extent to which this is true.

Background: More than 90% of the cigarettes sold worldwide have a filter. Nearly all filters consist of a rod of numerous ( > 12 000) plastic-like cellulose acetate fibres. During high speed cigarette manufacturing procedures, fragments of cellulose acetate that form the mouthpiece of a filter rod become separated from the filter at the end face. The cut surface of the filter of nearly all cigarettes has these fragments. In smoking a cigarette in the usual manner, some of these fragments are released during puffing. In addition to the cellulose acetate fragments, carbon particles are released also from some cigarette brands that have a charcoal filter. Cigarettes with filters that release cellulose acetate or carbon particles during normal smoking conditions are defective., Objective: Specific goals were to review systematically the writings of tobacco companies to: (a) identify papers that would document the existence of defective filters; (b) characterise the extent of the defect; (c) establish when the defect became known; (d) determine whether the defect exists on cigarettes marketed currently; (e) assess the prevalence of the defect on cigarettes manufactured by different companies; (f) define whether the knowledge of the defect had been withheld by the tobacco company as confidential and not disclosed publicly; and (g) ascertain the feasibility of correcting or preventing the defect., Methods: Document searches utilised databases of the scientific literature, medical journals, chemical abstracts, US Patents, Tobacco Abstracts, papers presented at tobacco meetings and court documents., Results: Sixty one documents of Philip Morris, Inc were selected for study because they disclosed specifically the "fall-out" of cellulose acetate filter fibres and, for cigarettes with charcoal filters, carbon particles from cigarette filters. The term "fall-out" was defined in 1985 laboratory protocols of Philip Morris, Inc. as "loose fibers (or particles) that are drawn out of the filter during puffing of the cigarette". As early as 1957, the health concern of inhaling cellulose acetate fibres released from cigarette filters was addressed by Philip Morris, Inc. A 1962 document reported the results of laboratory tests conducted by Phillip Morris, Inc that compared the "fall-out" of cellulose acetate fibres from the filters of their cigarettes (Marlboro) and cigarettes of their competitor (Liggett & Meyers). A 1997 overview by Phillip Morris of documents addressing the "fallout of carbon particles and cellulose acetate fibers from filters" stated that they were "essentially routine reports" of cigarette filter assays, and referenced a "Filter Fallout" memo written in 1961-more than 40 years ago. Most likely these tests are being conducted presently as illustrated by a 1999 report that details the revisions of the "fall-out" protocol of Phillip Morris, Inc and reports the results of tests that measured the discharge of cellulose acetate fibres and silica gel from beta cigarettes with a new type of filter. Our analysis of the "fall-out" tests results presented in the 61 "fall-out" documents showed that filter fibres and carbon particles were discharged from the filters of all types of cigarettes tested. These cigarette types (n = 130) included both coded cigarettes and popular brand name cigarettes. No publications were found in the scientific literature of the "fall-out" studies. Thus, the results of the "fall-out" studies are thought to have been withheld as confidential to Philip Morris, Inc. We have identified also other companies that have tested recently cigarettes for defective filters. In addition, our searches have shown that simple, expedient, and inexpensive technologies for decontaminating cigarette filters of loose cellulose acetate fibres and particles from the cut surface of the filter have been developed and described in 1997 and 1998 US patents. What is more important is that these patents also define methods for preventing or reducing the broken plastic-like fibres that arise during cigarette making. Many US patents (n = 607; 1957 to 2001) have been awarded for cigarette filters. Some of these inventions describe novel materials and unique filtration schemes that would eliminate or minimise the discharge of filter materials into mainstream smoke., Conclusions: We have shown that: (a) the filter of today's cigarette is defective; (b) Philip Morris, Inc has known of this filter defect for more than 40 years; (c) the existence of this filter defect has been confirmed by others in independent studies; (d) many methods exist to prevent and correct the filter defect, but have not been implemented; and (e) results of investigations substantiating defective filters have been concealed from the smoker and the health community. The tobacco industry has been negligent in not performing toxicological examinations and other studies to assess the human health risks associated with regularly ingesting and inhaling non-degradable, toxin coated cellulose acetate fragments and carbon microparticles and possibly other components that are released from conventional cigarette filters during normal smoking. The rationale for harm assessment is supported by the results of consumer surveys that have shown that the ingestion or inhalation of cigarette filter fibres are a health concern to nearly all smokers.

Natural gas comprises about a quarter of the United States' energy use. It is more environmentally friendly than oil and coal due to lower carbon dioxide (CO2) emissions per unit, less costly per unit of energy and more readily available domestically in abundant supply. However, due to a number of barriers in the political, infrastructural, pricing and other arenas, the use of natural gas as a significant energy source in the United States has been limited. In our paper, we highlight the favorable qualities of natural gas and its benefits for the consumer, producer, and environment, having compared the costs of the various components of the natural gas business such as drilling and transport to that of coal and oil. Moreover, we touch upon the major issues that have prevented a more prevalent use of the gas, such as the fact that the infrastructure of natural gas is more costly since it is transported though pipelines whereas other energy sources such as oil and coal have flexible systems that use trains, trucks and ships. In addition, the powerful lobbies of the coal and oil businesses, along with the inertia in the congress to pass a national climate change bill further dampens incentives for these industries to invest in natural gas, despite its various attractive qualities. We also include discussions of policy proposals to incentive greater use of natural gas in the future. [ABSTRACT FROM AUTHOR]

We calculate the cost of a carbon dioxide constraint in the production of electricity by modeling the replacement of coal generators with natural gas generators. We find: First, replacing coal generators with natural gas generators is the most economical way to reduce carbon dioxide emissions by 20 percent. Second, replacing existing coal generation capacity with modern coal generation plants can only reduce total carbon dioxide by 5 percent. Third, the distribution of the efficiency of coal generators in the United States restricts the range over which carbon dioxide prices effectively manage the displacement of coal by gas. Fourth, the narrow range for the price of carbon dioxide creates the possibility that a market in carbon dioxide permits will result in high volatility in the market for electricity. Fifth, the carbon prices implied by the transition from coal to gas will have very little impact on transportation fuels. [ABSTRACT FROM AUTHOR]

Abstract: Optimization of combined cooling, heating, and power (CCHP) systems operation commonly focuses only on energy cost. Different algorithms have been developed to attain optimal utilization of CCHP units by minimizing the energy cost in CCHP systems operation. However, other outcomes resulting from CCHP operation such as primary energy consumption and emission of pollutants should also be considered during CCHP systems evaluation as one would expect these outcomes can be subject to regulation. This paper presents an optimization of the operation of CCHP systems for different climate conditions based on operational cost, primary energy consumption (PEC), and carbon dioxide emissions (CDE) using an optimal energy dispatch algorithm. The results for the selected cities demonstrate that in general there is not a common trend among the three optimization modes presented in this paper since optimizing one parameter may reduce or increase the other two parameters. The only cities that show reduction of PEC while also reducing the CDE are Columbus, MS; Minneapolis, MN; and Miami, FL. For these cities the operational cost always increases when compared to the reference case consisting of using a vapor/compression cycle for cooling and natural gas for heating. On the other hand, for San Francisco and Boston, CCHP systems increase the CDE. In general, if CCHP systems increase the cost of operation, as long as energy savings and reduction of emissions are guaranteed, the implementation of these systems should be considered. [Copyright &y& Elsevier]

A simulation model based on satellite observations of monthly vegetation cover from the Moderate Resolution Imaging Spectroradiometer (MODIS) was used to estimate monthly carbon fluxes in terrestrial ecosystems of the conterminous United States over the period 2001–04. Predicted net ecosystem production (NEP) flux for atmospheric CO2 in the United States was estimated as annual net sink of about +0.2 Pg C in 2004. Regional climate patterns were reflected in the predicted annual NEP flux from the model, which showed extensive carbon sinks in ecosystems of the southern and eastern regions in 2003–04, and major carbon source fluxes from ecosystems in the Rocky Mountain and Pacific Northwest regions in 2003–04. As demonstrated through tower site comparisons, net primary production (NPP) modeled with monthly MODIS enhanced vegetation index (EVI) inputs closely resembles both the measured high- and low-season carbon fluxes. Modeling results suggest that the capacity of the NASA Carnegie Ames Stanford Approach (CASA) model to use 8-km resolution MODIS EVI data to predict peak growing season uptake rates of CO2 in irrigated croplands and moist temperate forests is strong. [ABSTRACT FROM AUTHOR]

Economic analyses of climate change policies frequently focus on reductions of energy-related carbon dioxide emissions via market-based, economy-wide policies. The current course of environment and energy policy debate in the United States, however, suggests an alternative outcome: sector-based and/or inefficiently designed policies. This paper uses a collection of specialized, sector-based models in conjunction with a computable general equilibrium model of the economy to examine and compare these policies at an aggregate level. We examine the relative cost of different policies designed to achieve the same quantity of emission reductions. We find that excluding a limited number of sectors from an economy-wide policy does not significantly raise costs. Focusing policy solely on the electricity and transportation sectors doubles costs, however, and using non-market policies can raise cost by a factor often. These results are driven in part by, and are sensitive to, our modeling of pre-existing tax distortions. [ABSTRACT FROM AUTHOR]

With electric generation responsible for 41 percent of U.S anthropogenic carbon dioxide (CO2) emissions from energy use, development of clean energy sources is essential if the United States is to reduce release of greenhouse gases and slow global warming. Many proponents of sustainable energy anticipate that electric generation from renewable sources would thrive in a deregulated market, driven by consumer demand for “green” energy and the end of incentives to build large central power plants under the cost-plus profits guaranteed by state utility commissions. This paper examines the flaws in this expectation. After reviewing the highly cyclical nature of U.S. energy policy making in recent decades, the study links the ineffectiveness of policy with the institutional setting. Under electric utility market restructuring, renewable energy generation (wind, biomass, solar, geothermal, and small-scale hydro) must overcome barriers such as price distortions, lack of storage capability, discriminatory transmission system access, and the end of linked utility rate hikes guaranteed to cover the additional expense of renewable generation. In the absence of strong federal leadership, the state commitment to renewable energy has been uneven under utility restructuring. Moreover, nuclear power—the other leading alternative to fossil fuel use—is beset by serious problems. Only renewable energy options offer long-term hope for sustainability. Along these lines, green marketing, renewable portfolio standards, system benefit charges, carbon taxes, public power, “Community Choice,” and production credits—all based on recent U.S. and European experience—are critically examined and recommendations made for changing course. At present, during this highly fluid period of utility restructuring, and absent more forceful regulation and demand management, it is dubious whether U.S. electricity market reform can encourage sufficient conversion to renewable energy to stem a rising tide of greenhouse gas emissions. [ABSTRACT FROM AUTHOR]

Increase in the use of conservation practices by agriculture in the United States will enhance soil organic carbon and potentially increase carbon sequestration. This, in turn, will decrease the net emission of carbon dioxide. A number of studies exist that calibrate the contribution of various individual, site-specific conservation practices on changes in soil organic carbon. There is a general absence, however, of a comprehensive effort to measure objectively the contribution of these practices including conservation tillage, the Conservation Reserve Program, and conservation buffer strips to an change in soil organic carbon. This paper fills that void. After recounting the evolution of the use of the various conservation practices, it is estimated that organic carbon in the soil in 1998 in the United States attributable to these practices was about 12.2 million metric tons. By 2008, there will be an increase of about 25%. Given that there is a significant potential for conservation practices to lead to an increase in carbon sequestration, there are a number of policy options that can be pursued. [ABSTRACT FROM AUTHOR]

International water resources have been a source of contention in many parts of the world over the last few decades and such conflicts may grow in frequency and severity as future climatic changes alter the quantity or quality of limited water resources. Indeed, some future climatic changes appear inevitable due to growing atmospheric concentrations of carbon dioxide and other trace gases. Unless mechanisms for incorporating climatic changes into water agreement can be worked out, these changes may provoke further frictions and conflicts. One region with a history of political conflict over shared water resources is the Colorado River Basin in the United States and Mexico. While past disagreements over water have mostly been resolved, future climatic changes that adversely affect the existing hydrologic regime of the basin cannot be discounted. This paper examines the possibility that future long-term climatic changes may exacerbate shortages in the Colorado River. Political conflicts and tensions that arise from reductions in water supply in both the United States and Mexico are evaluated and discussed, together with recommendations for incorporating the issue of climatic change into existing international treaties and agreements. [ABSTRACT FROM AUTHOR]

Using CO2 data from the Atmospheric Infrared Sounder (AIRS), it is found for the first time that the mid-tropospheric CO2 concentration is ~1 part per million by volume higher during dry years than wet years over the southwestern USA from June to September. The mid-tropospheric CO2 differences between dry and wet years are related to circulation and CO2 surface fluxes. During drought conditions, vertical pressure velocity from NCEP2 suggests that there is more rising air over most regions, which can help bring high surface concentrations of CO2 to the mid-troposphere. In addition to the circulation, there is more CO2 emitted from the biosphere to the atmosphere during droughts in some regions, which can contribute to higher concentrations of CO2 in the atmosphere. Results obtained from this study demonstrate the significant impact of droughts on atmospheric CO2 and therefore on a feedback cycle contributing to greenhouse gas warming. It can also help us better understand atmospheric CO2, which plays a critical role in our climate system. [ABSTRACT FROM AUTHOR]

This paper studies the relationship between income inequality and carbon emissions in the United States between 1929 and 2019. We contribute to the literature by studying if and how the relationship has varied over time. To this end we estimate a band spectrum regression model and a smooth-varying coefficients model. Our results show that higher inequality was associated with lower emissions during the early part of the sample and higher emissions towards the end of the sample. • Whether the level of inequality affects carbon dioxide emssions is unclear. • We test the association between income inequalty and carbon dioxide emissions. • We find that the relationship varies over time. • Changes in consumption patterns may partially explain the time varying effects. [ABSTRACT FROM AUTHOR]

Streams and rivers are major sources of greenhouse gases (GHGs) to the atmosphere, as carbon and nitrogen are converted and outgassed during transport. Although our understanding of drivers of individual GHG fluxes has improved with numerous site‐specific studies and global‐scale compilations, our ability to parse out interrelated physical and biogeochemical drivers of gas concentrations is limited by a lack of consistently collected, temporally continuous samples of GHGs and their associated drivers. We present a first analysis of such a dataset collected by the National Ecological Observatory Network across 27 streams and rivers across ecoclimatic domains of the United States. Average concentrations of CO2 ranged from 36.9 ± 0.88 to 404 ± 33 μmol L−1, CH4 from 0.003 ± 0.0003 to 4.99 ± 0.72 μmol L−1, and N2O from 0.015 to 0.04 μmol L−1 and spanned ranges of previous global compilations. Both CO2 and CH4 were strongly affected by physical drivers including mean air temperature and stream slope, as well as by dissolved oxygen and total nitrogen concentrations. N2O was exclusively correlated with total nitrogen concentrations. Results suggested that potential for gas exchange dominated patterns in gas concentrations at the site level, but contributions of in‐stream aerobic and anaerobic metabolism, and groundwater also likely varied across sites. The highest gas concentrations as well as highest variability occurred in low‐gradient, warmer, and nonperennial systems. These results are a first step in providing unprecedented, continuous estimates of GHG flux constrained by temporally variable physical and biogeochemical drivers of GHG production. [ABSTRACT FROM AUTHOR]

The global carbon cycle is experiencing continued perturbations via increases in atmospheric carbon concentrations, which are partly reduced by terrestrial biosphere and ocean carbon uptake. Greenhouse gas satellites have been shown to be useful in retrieving atmospheric carbon concentrations and observing surface and atmospheric CO 2 seasonal-to-interannual variations. However, limited attention has been placed on using satellite column CO 2 retrievals to evaluate surface CO 2 fluxes from the terrestrial biosphere without advanced inversion models at low latency. Such applications could be useful to monitor, in near real time, biosphere carbon fluxes during climatic anomalies like drought, heatwaves, and floods, before more complex terrestrial biosphere model outputs and/or advanced inversion modelling estimates become available. Here, we explore the ability of Orbiting Carbon Observatory-2 (OCO-2) column-averaged dry air CO 2 (XCO 2) retrievals to directly detect and estimate terrestrial biosphere CO 2 flux anomalies using a simple mass-balance approach. An initial global analysis of surface–atmospheric CO 2 coupling and transport conditions reveals that the western US, among a handful of other regions, is a feasible candidate for using XCO 2 for detecting terrestrial biosphere CO 2 flux anomalies. Using the CarbonTracker model reanalysis as a test bed, we first demonstrate that a well-established mass-balance approach can estimate monthly surface CO 2 flux anomalies from XCO 2 enhancements in the western United States. The method is optimal when the study domain is spatially extensive enough to account for atmospheric mixing and has favorable advection conditions with contributions primarily from one background region. We find that errors in individual soundings reduce the ability of OCO-2 XCO 2 to estimate more frequent, smaller surface CO 2 flux anomalies. However, we find that OCO-2 XCO 2 can often detect and estimate large surface flux anomalies that leave an imprint on the atmospheric CO 2 concentration anomalies beyond the retrieval error/uncertainty associated with the observations. OCO-2 can thus be useful for low-latency monitoring of the monthly timing and magnitude of extreme regional terrestrial biosphere carbon anomalies. [ABSTRACT FROM AUTHOR]

This paper examines the asymmetry of changes in CO 2 emissions over business cycle recessions and expansions using yearly data from 1949 and monthly data from 1973 for the United States (US). In addition, decomposition analysis is applied to investigate the relative roles of various proximate contributing factors to observed changes in total and per capita CO 2 emissions and emissions intensity, over business cycle phases. The results suggest, inter alia , that aggregate emissions and emissions intensity reduce much faster in contractions than they increase in expansions. In addition, unlike the three previous expansions, in the most recent post-GFC US expansion, emissions per capita have continued to decline, and at a rate very similar to the rate of reduction in preceding contractions. This suggests the real possibility that the most recent contraction may have had an ongoing impact on the path of per capita emissions well beyond the immediate impact experienced during the contraction itself. [ABSTRACT FROM AUTHOR]

This paper describes a neonatal insert for use with the Hewlett-Packard Model 47210A capnometer airway adaptor. Dead space using this adaptor is 4.2 ml, which compares to 28.4 ml with the standard adaptor system and 4.0 ml with the pediatric Y-piece and endotracheal tube alone. Resistance was evaluated by plotting pressure drop-flow relationships. For oxygen flow rates used of up to seven L/min, the neonatal insert reduced the pressure drop as compared to both the standard adaptor and the pediatric Y-piece and endotracheal tube alone. Pressure drops were not very much larger than calculated theoretical values.

The multi-sector end-use energy model E3MC was used to analyze the energy and greenhouse gas emissions impact of adding a carbon tax to efficiency improvement standards for the residential sector in Canada and the USA. Compared to standards alone, the addition of the tax led to further residential emission reductions in Canada, but attenuated the residential emission reductions in the USA. Examination of the relative residential electricity:natural gas prices demonstrated that the different country impacts were due to an increase in relative prices in the USA, but a decrease in relative prices in Canada that led to opposite shifts in preference for electricity over natural gas in the residential sector. Markedly different impacts of the carbon tax on electricity prices was due to the predominance of hydroelectric power in Canada and coal-fired electric generation in the USA. [ABSTRACT FROM AUTHOR]

Abstract: The use of carbon dioxide (CO2) for enhanced oil recovery (EOR) is being tested for oil fields in the Illinois Basin, USA. While this technology has shown promise for improving oil production, it has raised some issues about the safety of CO2 injection and storage. The Midwest Geological Sequestration Consortium (MGSC) organized a Monitoring, Verification, and Accounting (MVA) team to develop and deploy monitoring programs at three EOR sites in Illinois, Indiana, and Kentucky, USA. MVA goals include establishing baseline conditions to evaluate potential impacts from CO2 injection, demonstrating that project activities are protective of human health and the environment, and providing an accurate accounting of stored CO2. This paper focuses on the use of MVA techniques in monitoring a small CO2 leak from a supply line at an EOR facility under real-world conditions. The ability of shallow monitoring techniques to detect and quantify a CO2 leak under real-world conditions has been largely unproven. In July of 2009, a leak in the pipe supplying pressurized CO2 to an injection well was observed at an MGSC EOR site located in west-central Kentucky. Carbon dioxide was escaping from the supply pipe located approximately 1 m underground. The leak was discovered visually by site personnel and injection was halted immediately. At its largest extent, the hole created by the leak was approximately 1.9 m long by 1.7 m wide and 0.7 m deep in the land surface. This circumstance provided an excellent opportunity to evaluate the performance of several monitoring techniques including soil CO2 flux measurements, portable infrared gas analysis, thermal infrared imagery, and aerial hyperspectral imagery. Valuable experience was gained during this effort. Lessons learned included determining (1) hyperspectral imagery was not effective in detecting this relatively small, short-term CO2 leak, (2) even though injection was halted, the leak remained dynamic and presented a safety risk concern during monitoring activities and, (3) the atmospheric and soil monitoring techniques used were relatively cost-effective, easily and rapidly deployable, and required minimal manpower to set up and maintain for short-term assessments. However, characterization of CO2 distribution near the land surface resulting from a dynamic leak with widely variable concentrations and fluxes was challenging. [Copyright &y& Elsevier]

Abstract: The Plains CO2 Reduction Partnership, one of the seven U.S. Department of Energy National Energy Technology Laboratory Regional Carbon Sequestration Partnerships, is conducting a carbon dioxide (CO2) huff ‘n’ puff (HnP) project in the Northwest McGregor oil field in North Dakota to determine the effects CO2 has on the productivity of the reservoir, wellbore integrity, and the carbonate formation into which the CO2 was injected. This paper outlines the approach and current observations derived from numerical modeling and laboratory simulations of potential geochemical reactions to evaluate the short-term risks for operations (e.g., porosity and permeability decrease) and long-term implications for CO2 storage via mineralization. The integration of data obtained during mineralogical analyses, fluid sampling, and laboratory experiments proved to be a key for the better understanding of the dynamic geochemical processes that happen in the reservoir after CO2 injection and was necessary for successful completion of the numerical modeling. Results of the numerical modeling suggest that the already acidic and highly saline environment (pH <4.5 and total dissolved solids ∼300,000 mg/kg) of the Northwest McGregor oil field should not experience any significant changes in mineralogy as a result of CO2 injection, especially in the near term, which correlates with the postinjection field geochemical analyses. [Copyright &y& Elsevier]

Relationships on interannual and interdecadal timescales among global mean air temperature, CO2 concentrations and fossil-fuel carbon emissions in four major developed countries (the United States, the United Kingdom, France, and Germany) were analyzed. On an interannual timescale, the United States fossil-fuel carbon emissions tend to increase during cold winters and decrease during warm winters, which is opposite to the situation in summer. On an interdecadal timescale, cold (warm) periods both in the United States and globally agree with high (low) periods of fossil-fuel carbon emissions, with the temperature variability leading by 5-7 years. The leading correlation on the interdecadal timescale and the asymmetry in seasonal correlation on the interannual timescale indicate that temperature variability is a possible cause of changes in fossil-fuel carbon emissions. [ABSTRACT FROM AUTHOR]

Southern forests contribute significantly to the carbon sink for the atmospheric carbon dioxide (CO2) associated with the anthropogenic activities in the United States. Natural disasters like hurricanes are constantly threatening these forests. Hurricane winds can have a destructive impact on natural vegetation and can adversely impact net primary productivity (NPP). Hurricane Katrina (23-30 August 2005), one of the most destructive natural disasters in history, has affected the ecological balance of the Gulf Coast. This study analyzed the impacts of different categories of sustained winds of Hurricane Katrina on NPP in Mississippi. The study used the Carnegie-Ames-Stanford Approach (CASA) model to estimate NPP by using remote sensing data. The results indicated that NPP decreased by 14% in the areas hard hit by category 3 winds and by 1% in the areas hit by category 2 winds. However, there was an overall increase in NPP, from 2005 to 2006 by 0.60 Tg of carbon, in Mississippi. The authors found that Pearl River, Stone, Hancock, Jackson, and Harrison counties in Mississippi faced significant depletion of NPP because of Hurricane Katrina. [ABSTRACT FROM AUTHOR]

Many energy systems models have sought to develop pathways for deep decarbonization of the global energy system. Most often, these pathways minimize system costs or greenhouse gas emissions; with few exceptions, they ignore the constraints imposed by political, social, and economic factors that slow transition processes, making them prone to producing implausible decarbonization pathways. This paper integrates a key socio-technical factor—social acceptance of low-carbon nuclear power—into an energy systems model to illustrate how it alters the optimal energy generation mix. The United States was chosen as the example, but the approach itself is designed to be general and applicable to any region of interest. An empirically grounded risk tolerance model is developed to characterize acceptance of nuclear power and estimate an upper-bound deployment limit for the technology. Illustrative scenarios are presented to improve our understanding of how the socio-technical constraints that exist in the real world can alter deep decarbonization pathways. The cost-optimal generation portfolio to achieve net zero CO 2 emissions by 2050 primarily relies on nuclear power. If risk tolerance concerns constrain nuclear deployment to socially acceptable levels, deep decarbonization scenarios are up to 11% more expensive than the reference scenario and require low-carbon options to be available and replace the reduced nuclear share. Results from this novel framework improve our representation of the effect of social acceptance on the adoption and diffusion of energy technologies. They also contribute to a growing literature that seeks to firmly embed the social sciences in climate and energy policy. • Plausible decarbonization pathways must also account for social constraints. • We combine a social risk tolerance model with an energy system optimization model. • We assess the role of social acceptance in constraining nuclear power's deployment. • Social acceptance limits nuclear's share by as much as 71% in CO 2 reduction pathways. • Decision-making can be strengthened with integration of socio-technical analyses. [ABSTRACT FROM AUTHOR]

Gross primary productivity (GPP) quantifies the amount of carbon dioxide (CO 2) fixed by plants through photosynthesis. Although as a key quantity of terrestrial ecosystems, there is a lack of high-spatial-and-temporal-resolution, real-time and observation-based GPP products. To address this critical gap, here we leverage a state-of-the-art vegetation index, near-infrared reflectance of vegetation (NIR V), along with accurate photosynthetically active radiation (PAR), to produce a SatelLite Only Photosynthesis Estimation (SLOPE) GPP product for the contiguous United States (CONUS). Compared to existing GPP products, the proposed SLOPE product is advanced in its spatial resolution (250 m versus >500 m), temporal resolution (daily versus 8 d), instantaneity (latency of 1 d versus >2 weeks) and quantitative uncertainty (on a per-pixel and daily basis versus no uncertainty information available). These characteristics are achieved because of several technical innovations employed in this study: (1) SLOPE couples machine learning models with MODIS atmosphere and land products to accurately estimate PAR. (2) SLOPE couples highly efficient and pragmatic gap-filling and filtering algorithms with surface reflectance acquired by both Terra and Aqua MODIS satellites to derive a soil-adjusted NIR V (SANIR V) dataset. (3) SLOPE couples a temporal pattern recognition approach with a long-term Cropland Data Layer (CDL) product to predict dynamic C4 crop fraction. Through developing a parsimonious model with only two slope parameters, the proposed SLOPE product explains 85 % of the spatial and temporal variations in GPP acquired from 49 AmeriFlux eddy-covariance sites (324 site years), with a root-mean-square error (RMSE) of 1.63 gC m -2 d -1. The median R2 over C3 and C4 crop sites reaches 0.87 and 0.94, respectively, indicating great potentials for monitoring crops, in particular bioenergy crops, at the field level. With such a satisfactory performance and its distinct characteristics in spatiotemporal resolution and instantaneity, the proposed SLOPE GPP product is promising for biological and environmental research, carbon cycle research, and a broad range of real-time applications at the regional scale. The archived dataset is available at 10.3334/ORNLDAAC/1786 (download page: https://daac.ornl.gov/daacdata/cms/SLOPE%5fGPP%5fCONUS/data/ , last access: 20 January 2021) (Jiang and Guan, 2020), and the real-time dataset is available upon request. [ABSTRACT FROM AUTHOR]

The Representative Concentration Pathway 2.6 (RCP2.6), which is broadly compatible with the Paris Agreement's temperature goal by 1.5–2°C, contains substantial reductions in agricultural non-CO2 emissions besides the deployment of Carbon Dioxide Removal (CDR). Failing to mitigate agricultural methane and nitrous oxide emissions could contribute to an overshoot of the RCP2.6 warming by about 0.4°C. We explore using additional CDR to offset alternative agricultural non-CO2 emission pathways in which emissions either remain constant or rise. We assess the effects on the climate of calculating CDR rates to offset agricultural emission under two different approaches: relying on the 100-year global warming potential conversion metric (GWP100) and maintaining effective radiative forcing levels at exactly those of RCP2.6. Using a reduced-complexity climate model, we find that the conversion metric leads to a systematic underestimation of needed CDR, reaching only around 50% of the temperature mitigation needed to remain on the RCP2.6 track. This is mostly because the metric underestimates, in the near term, forcing from short-lived climate pollutants such as methane. We test whether alternative conversion metrics, the GWP20 and GWP*, are more suitable for offsetting purposes, and found that they both lead to an overestimation of the CDR requirements. Under alternative agricultural emissions pathways, holding to RCP2.6 total radiative forcing requires up to twice the amount of CDR that is already included in the RCP2.6. We examine the costs of this additional CDR, and the effects of internalizing these in several agricultural commodities. Assuming an average CDR cost by $150/tCO2, we find increases in prices of up to 41% for beef, 14% for rice, and 40% for milk in the United States relative to current retail prices. These figures are significantly higher (for beef and rice) under a global scenario, potentially threatening food security and welfare. Although the policy delivers a mechanism to finance the early deployment of CDR, using CDR to offset remaining high emissions may well hit other non-financial constraints and can thus only support, and not substitute, emission reductions. [ABSTRACT FROM AUTHOR]

The article discusses the economic impact of the U.S. government's policy governing carbon dioxide pollution. Benefit-cost analysis has become an accepted tool for evaluation of government investment programs in natural resources. Given changing lifestyles, substantial future shifts in technologies and probabilities of drastic world political-social events, any quantitative measures of benefits or costs in 100 years are not subject to better than 2-4 orders of magnitude accuracy and may even switch sign. The carbon dioxide problem, from the standpoint of an economic perspective, has its most interesting elements in terms of intergenerational choice. The reason for it is the anticipated positive economic benefits accruing for several generations and the potential disastrous economic costs that may accrue to generations after that. A drier climate in the Northern Great Plains of the U.S. would cause an increase in the probability of crop failure in any one year. Expected utility of the future depends on available consumption in two possible states of the world. If climate change does not occur, output is a function of capital and fossil fuel availability. Depending on ethical beliefs, different decisions emerge for resolving the carbon dioxide issue.

The recent historical increase in energy-related CO 2 emissions globally have put the United States of America's (USA) transportation sector in the spotlight, courtesy of the significantly high pollutant emissions from this particular sector. Taking a cue from this, this paper follows sustainable development goals of the United Nations, and investigates the impact of biomass energy consumption, fossil fuel energy consumption, and economic growth (GDP) on carbon dioxide (CO 2) emissions in the transportation sector of the USA. In doing so, this study also employs the Gregory-Hansen cointegration, Hatemi-J cointegration, cointegration regression (FMOLS, DOLS, and CCR), and Spectral Breitung-Candelon causality test for the period between 1981Q1 and 2019Q4. The findings reveal that (i) a significant nonlinear cointegration among the environmental quality determinants is observed, using the threshold cointegration test. This test determines the structural breaks endogenously and combines two cointegration tests, namely the Gregory-Hansen Cointegration and Hatemi-J Cointegration tests; (ii) while the use of biomass energy consumption and real GDP have a negative effect on CO 2 emissions in the transportation sector, the rising fossil fuel energy consumption is associated with increasing the CO 2 emissions that are stemming from the transportation sector; (iii) in the long-run, biomass energy consumption, fossil fuel energy consumption, and real GDP cause CO 2 emissions to stem from the transportation sector in the USA at different frequency levels. In general, the current study offers policy insights for the transportation sector of the USA and other similar economies that replicate the same conditions. Image 1 • We explore the driving forces of CO 2 emissions in the transport sector for the USA. • We employ advanced time series econometric techniques for empirical analysis. • Biomass energy and real GDP help to mitigate CO 2 emissions in the transport sector. • Fossil fuel energy has a positive impact on CO 2 emissions in the transport sector. • All variables have a causative relationship with CO 2 emissions in the long-run. [ABSTRACT FROM AUTHOR]

The current energy portfolio of the United States is exposed to significant risk, which depends on the price volatility of the energy sources. This paper focuses on the composition of energy portfolios for the energy sector of the United States and possible solutions to optimize this investment. The study utilizes the modern portfolio theory mean-variance approach, a risk-return analysis, to compose the efficient frontier of portfolios in which the risk is minimized for a given return. The performance of each energy portfolio, consisting of oil, coal, natural gas, nuclear energy, and renewable energy, is measured using the Sharpe Ratio and compared to the existing portfolio. Using future prices of fuels and accounting for external costs, the study provides further evidence that the current energy portfolio of the United States is not efficient. In addition, the study shows how including the cost of pollution, measured by the intensity of carbon emissions, changes the energy source allocation within the portfolio by including less carbon-intensive substances. The study implies that further diversification of the energy sector by including investment in hydroelectric energy generation technologies may decrease our dependence on more volatile sources of energy and consequently reduce the possibility of energy supply interruption from commodity price volatility. This proposes that the government focus on implementing a strategy to facilitate the introduction of renewable energy into our energy portfolio. The shift away from an infrastructure heavily dependent on fossil fuels towards one with more investment in renewable energy can be achieved by granting subsidies for renewable energy technologies and by implementing appropriate emissions prices to account for external energy generation costs. [ABSTRACT FROM AUTHOR]

Greatly enhanced atmospheric carbon dioxide (CO2) levels relative to well-mixed marine air are observed during periods of offshore winds at coastal sensor platforms in Monterey Bay, California, USA. The highest concentrations originate from urban and agricultural areas, are driven by diurnal winds, and peak in the early morning. These enhanced atmospheric levels can be detected across a ~100km wide nearshore area and represent a significant addition to total oceanic CO2 uptake. A global estimate puts the added sea-air flux of CO2 from these greatly enhanced atmospheric CO2 levels at 25 million tonnes, roughly 1% of the ocean’s annual CO2 uptake. The increased uptake over the 100 km coastal swath is of order 20%, indicating a potentially large impact on ocean acidification in productive coastal waters. [ABSTRACT FROM AUTHOR]