Preindustrial 14CH4 indicates greater anthropogenic fossil CH4 emissions.

Atmospheric methane (CH4) is a potent greenhouse gas, and its mole fraction has more than doubled since the preindustrial era1. Fossil fuel extraction and use are among the largest anthropogenic sources of CH4 emissions, but the precise magnitude of these contributions is a subject of debate2,3. Carbon-14 in CH4 (14CH4) can be used to distinguish between fossil (14C-free) CH4 emissions and contemporaneous biogenic sources; however, poorly constrained direct 14CH4 emissions from nuclear reactors have complicated this approach since the middle of the 20th century4,5. Moreover, the partitioning of total fossil CH4 emissions (presently 172 to 195 teragrams CH4 per year)2,3 between anthropogenic and natural geological sources (such as seeps and mud volcanoes) is under debate; emission inventories suggest that the latter account for about 40 to 60 teragrams CH4 per year6,7. Geological emissions were less than 15.4 teragrams CH4 per year at the end of the Pleistocene, about 11,600 years ago8, but that period is an imperfect analogue for present-day emissions owing to the large terrestrial ice sheet cover, lower sea level and extensive permafrost. Here we use preindustrial-era ice core 14CH4 measurements to show that natural geological CH4 emissions to the atmosphere were about 1.6 teragrams CH4 per year, with a maximum of 5.4 teragrams CH4 per year (95 per cent confidence limit)-an order of magnitude lower than the currently used estimates. This result indicates that anthropogenic fossil CH4 emissions are underestimated by about 38 to 58 teragrams CH4 per year, or about 25 to 40 per cent of recent estimates. Our record highlights the human impact on the atmosphere and climate, provides a firm target for inventories of the global CH4 budget, and will help to inform strategies for targeted emission reductions9,10.

Household Determinants of Liquified Petroleum Gas (LPG) as a Cooking Fuel in South West Cameroon.

Currently 70% of the population in Cameroon are reliant on solid fuel for cooking (90% in rural communities) and the associated household air pollution contributes to significant mortality and morbidity in the country. To address the problems of energy security, deforestation and pollution the government has developed a strategy (Masterplan) to increase use of liquified petroleum gas (LPG) as a cooking fuel from 12% to 58% by 2030. As a clean fuel scaled adoption of LPG has the potential to make significant positive impacts on population health. The LPG Adoption in Cameroon Evaluation (LACE) studies are assessing in the community (i) barriers and enablers for and (ii) local interventions to support, adoption and sustained use of LPG. A census survey conducted for LACE in rural and peri-urban regions of SW Cameroon provided an opportunity to investigate current fuel use patterns and factors associated with primary and exclusive use of LPG. A cross-sectional survey of 1577 households (1334 peri-urban and 243 rural) was conducted in March 2016 using standardised fuel use and household socio-demographic questions, administered by trained fieldworkers. Wood (40.7%) and LPG (51.1%) were the most frequently reported fuels, although the dominant fuels in rural and peri-urban communities were wood (81%) and LPG (58%) respectively. Fuel stacking was observed for the majority of LPG using households (91% of peri-urban and 99% of rural households). In rural homes, a higher level of education, access to sanitation and piped water and household wealth (income and asset ownership) were all significantly associated with LPG use (p < 0.05). In peri-urban homes, younger age, access to sanitation and piped water and increasing education were significantly associated with both any and exclusive use of LPG (p < 0.05). However, whilst household wealth was related to any LPG use, there was no relationship with exclusive use. Results from this census survey of a relatively well-established LPG market with lower levels of poverty and high levels of education than Cameroon as a whole, find LPG usage well below target levels set by the Cameroon government (58% by 2030). Fuel stacking is an issue for the majority of LPG using households. Whilst, as observed here, education, household wealth and socio-economic status are well recognised predictors of adoption and sustained use of clean modern fuels, it is important to consider factors across the whole LPG eco-system when developing policies to support their scaled expansion. A comprehensive approach is therefore required to ensure implementation of the Cameroon LPG Masterplan achieves its aspirational adoption target within its stated timeframe.

Adoption of Liquefied Petroleum Gas Stoves in Guatemala: A Mixed-Methods Study.

Household air pollution is the sixth leading risk factor for premature mortality in Guatemala. Households in Guatemala are gradually adopting liquefied petroleum gas (LPG) stoves, but a strong tradition of woodstove use persists. We conducted a mixed-methods study of LPG stove use in peri-urban Guatemala. We used knowledge, attitudes and practices surveys with 187 LPG stove owners who also used woodstoves to identify perceptions of stove and cooking practices. Barriers to sustained use of LPG stoves were evaluated through focus groups, participant observations with stove users, and key informant interviews with community leaders. Seven themes emerged that explain household decisions to use LPG stoves: (1) The "new technology" should be framed in terms of what the "old technology" lacks, (2) income is not a predictor of gas stove acquisition but may predict sustained use, (3) men are key decision-makers but messages about LPG do not target them, (4) when stoves are viewed as "prize possessions" they may not be used, (5) collective fear about gas stoves is not based on personal experience, but on "stories we hear," (6) sustained LPG use is hampered by two major factors, seasonally available wood and LPG retailers who are perceived as dishonest, and (7) wood fuel collection is a time to enjoy the company of friends and family and is not "drudgery." National policies should promote the use of clean cookstove technologies in peri-urban and rapidly urbanizing areas in Guatemala where LPG stoves are in use, but used intermittently, instead of the current plan to install 100,000 "improved" woodstoves by 2032. This could be done by improving dependable cylinder distribution services, targeting gas safety and promoting positive health messages that appeal to men, as well as women.

Liquified Petroleum Gas (LPG) Supply and Demand for Cooking in Northern Ghana.

Like many other countries, Ghana relies on biomass (mainly wood and charcoal) for most of its cooking needs. A national action plan aims to expand liquefied petroleum gas (LPG) access to 50% of the country's population by 2020. While the country's southern urban areas have made progress toward this goal, LPG use for cooking remains low in the north. The aim of this cross-sectional study was to characterize the current state of the LPG market in this area and examine opportunities and barriers to scale up LPG adoption. We interviewed 16 LPG suppliers (stove, cylinder, and fuel vendors) as well as 592 households in the Kassena-Nankana Districts (KND) of Ghana. We find large rural-urban differences in LPG uptake: less than 10% of rural households own LPG stoves compared with over half of urban households. Awareness of LPG is high across the region, but accessibility of fuel supply is highly limited, with just one refilling station located in the KND. Affordability is perceived as the main barrier to LPG adoption, and acceptability is also limited by widespread concerns about the safety of cooking with LPG. Transitioning to a cylinder recirculation model, and providing more targeted subsidies and credit options, should be explored to expand access to cleaner cooking in this region.

Efficient big data assimilation through sparse representation: A 3D benchmark case study in petroleum engineering.

Data assimilation is an important discipline in geosciences that aims to combine the information contents from both prior geophysical models and observational data (observations) to obtain improved model estimates. Ensemble-based methods are among the state-of-the-art assimilation algorithms in the data assimilation community. When applying ensemble-based methods to assimilate big geophysical data, substantial computational resources are needed in order to compute and/or store certain quantities (e.g., the Kalman-gain-type matrix), given both big model and data sizes. In addition, uncertainty quantification of observational data, e.g., in terms of estimating the observation error covariance matrix, also becomes computationally challenging, if not infeasible. To tackle the aforementioned challenges in the presence of big data, in a previous study, the authors proposed a wavelet-based sparse representation procedure for 2D seismic data assimilation problems (also known as history matching problems in petroleum engineering). In the current study, we extend the sparse representation procedure to 3D problems, as this is an important step towards real field case studies. To demonstrate the efficiency of the extended sparse representation procedure, we apply an ensemble-based seismic history matching framework with the extended sparse representation procedure to a 3D benchmark case, the Brugge field. In this benchmark case study, the total number of seismic data is in the order of [Formula: see text]. We show that the wavelet-based sparse representation procedure is extremely efficient in reducing the size of seismic data, while preserving the salient features of seismic data. Moreover, even with a substantial data-size reduction through sparse representation, the ensemble-based seismic history matching framework can still achieve good estimation accuracy.

More heat, less light! The resource curse & HIV/AIDS: A reply to Olivier Sterck.

We reported fairly robust results suggesting that resource rich countries did less well containing HIV/AIDS than resource poor states (de Soysa and Gizelis, 2013). We argued that public action to prevent the spread of disease was going to be weaker in resource rich states because rulers would have less incentive to fight disease. Olivier Sterck (this issue) criticizes our study on several grounds, arguing that resource rich states can provide anti-retroviral therapy (ART) and thereby fight the AIDS epidemic. He, however, finds no relationship between resource wealth and HIV/AIDS. We argue that his reanalyses do not fully address the theoretical association between resource wealth and the spread of HIV/AIDS and that his argument about ART is more wishful than a realistic expectation. Future research should probe more carefully why resource wealth has not been deployed more effectively for fighting disease-a point we can all agree on.

Natural resources and the spread of HIV/AIDS: Curse or blessing?

This paper answers two questions: "What impact have natural resources had on the spread of the HIV epidemic so far?" and "What role can natural resource rents play in order to finance the long-run response to HIV/AIDS?" Using a panel dataset covering 137 countries from 1990 until 2008, de Soysa and Gizelis (2013) provided evidence in Social Science & Medicine that oil-rich countries are more deeply affected by the HIV and TB epidemics. They concluded that government of resource-rich countries failed to implement effective public policies for dealing with the epidemics. In this paper, I show that their results are (1) not robust, (2) based on an inappropriate choice of dependent variable and (3) spurious because series are non-stationary. After correcting for these issues, I find no robust relationship between resource rents and the spread of HIV and TB. The paper concludes by emphasizing the potential of natural resources rents for financing the long-term liability brought about by the HIV/AIDS epidemic in sub-Saharan Africa.

Frac Sand Mines Are Preferentially Sited in Unzoned Rural Areas.

Shifting markets can cause unexpected, stochastic changes in rural landscapes that may take local communities by surprise. Preferential siting of new industrial facilities in poor areas or in areas with few regulatory restrictions can have implications for environmental sustainability, human health, and social justice. This study focuses on frac sand mining-the mining of high-quality silica sand used in hydraulic fracturing processes for gas and oil extraction. Frac sand mining gained prominence in the 2000s in the upper midwestern United States where nonmetallic mining is regulated primarily by local zoning. I asked whether frac sand mines were more commonly sited in rural townships without formal zoning regulations or planning processes than in those that undertook zoning and planning before the frac sand boom. I also asked if mine prevalence was correlated with socioeconomic differences across townships. After creating a probability surface to map areas most suitable for frac sand mine occurrence, I developed neutral landscape models from which to compare actual mine distributions in zoned and unzoned areas at three different spatial extents. Mines were significantly clustered in unzoned jurisdictions at the statewide level and in 7 of the 8 counties with at least three frac sand mines and some unzoned land. Subsequent regression analyses showed mine prevalence to be uncorrelated with land value, tax rate, or per capita income, but correlated with remoteness and zoning. The predicted mine count in unzoned townships was over two times higher than that in zoned townships. However, the county with the most mines by far was under a county zoning ordinance, perhaps indicating industry preferences for locations with clear, homogenous rules over patchwork regulation. Rural communities can use the case of frac sand mining as motivation to discuss and plan for sudden land-use predicaments, rather than wait to grapple with unfamiliar legal processes during a period of intense conflict.

Profiling of Indigenous Microbial Community Dynamics and Metabolic Activity During Enrichment in Molasses-Supplemented Crude Oil-Brine Mixtures for Improved Understanding of Microbial Enhanced Oil Recovery.

Anaerobic incubations using crude oil and brine from a North Sea reservoir were conducted to gain increased understanding of indigenous microbial community development, metabolite production, and the effects on the oil-brine system after addition of a complex carbon source, molasses, with or without nitrate to boost microbial growth. Growth of the indigenous microbes was stimulated by addition of molasses. Pyrosequencing showed that specifically Anaerobaculum, Petrotoga, and Methanothermococcus were enriched. Addition of nitrate favored the growth of Petrotoga over Anaerobaculum. The microbial growth caused changes in the crude oil-brine system: formation of oil emulsions, and reduction of interfacial tension (IFT). Reduction in IFT was associated with microbes being present at the oil-brine interphase. These findings suggest that stimulation of indigenous microbial growth by addition of molasses has potential as microbial enhanced oil recovery (MEOR) strategy in North Sea oil reservoirs.

Effect of temperature shock and inventory surprises on natural gas and heating oil futures returns.

The aim of this paper is to examine the impact of temperature shock on both near-month and far-month natural gas and heating oil futures returns by extending the weather and storage models of the previous study. Several notable findings from the empirical studies are presented. First, the expected temperature shock significantly and positively affects both the near-month and far-month natural gas and heating oil futures returns. Next, significant temperature shock has effect on both the conditional mean and volatility of natural gas and heating oil prices. The results indicate that expected inventory surprises significantly and negatively affects the far-month natural gas futures returns. Moreover, volatility of natural gas futures returns is higher on Thursdays and that of near-month heating oil futures returns is higher on Wednesdays than other days. Finally, it is found that storage announcement for natural gas significantly affects near-month and far-month natural gas futures returns. Furthermore, both natural gas and heating oil futures returns are affected more by the weighted average temperature reported by multiple weather reporting stations than that reported by a single weather reporting station.

[Remedy for shortage or risk for national security? The search for oil in Switzerland]. / Lösung für das Knappheitsproblem oder nationales Risiko? Auf Erdölsuche in der Schweiz.

Over several decades, geologists, entrepreneurs, politicians, and public authorities dealt with a potential petroleum occurrence in Switzerland. They provided scientific expertise, granted concessions, invested capital and sank bore holes. Although the endeavour was never successful economically, it reveals how closely related geopolitical situations and the exploitation of natural resources were. This article investigates the search for crude oil in Switzerland from the 1930s until the 1960s, combining a history of science and technology perspective with a history of the political regulations and economic considerations concerning the extractive industry. It traces the changing fears and hopes about potential oil occurrences in Switzerland: From an investment to overcome future shortages, to the risk of imperial desires if oil would be found in abundance.

A novel algorithm combining finite state method and genetic algorithm for solving crude oil scheduling problem.

A hybrid optimization algorithm combining finite state method (FSM) and genetic algorithm (GA) is proposed to solve the crude oil scheduling problem. The FSM and GA are combined to take the advantage of each method and compensate deficiencies of individual methods. In the proposed algorithm, the finite state method makes up for the weakness of GA which is poor at local searching ability. The heuristic returned by the FSM can guide the GA algorithm towards good solutions. The idea behind this is that we can generate promising substructure or partial solution by using FSM. Furthermore, the FSM can guarantee that the entire solution space is uniformly covered. Therefore, the combination of the two algorithms has better global performance than the existing GA or FSM which is operated individually. Finally, a real-life crude oil scheduling problem from the literature is used for conducting simulation. The experimental results validate that the proposed method outperforms the state-of-art GA method.

New hydrocarbon degradation pathways in the microbial metagenome from Brazilian petroleum reservoirs.

Current knowledge of the microbial diversity and metabolic pathways involved in hydrocarbon degradation in petroleum reservoirs is still limited, mostly due to the difficulty in recovering the complex community from such an extreme environment. Metagenomics is a valuable tool to investigate the genetic and functional diversity of previously uncultured microorganisms in natural environments. Using a function-driven metagenomic approach, we investigated the metabolic abilities of microbial communities in oil reservoirs. Here, we describe novel functional metabolic pathways involved in the biodegradation of aromatic compounds in a metagenomic library obtained from an oil reservoir. Although many of the deduced proteins shared homology with known enzymes of different well-described aerobic and anaerobic catabolic pathways, the metagenomic fragments did not contain the complete clusters known to be involved in hydrocarbon degradation. Instead, the metagenomic fragments comprised genes belonging to different pathways, showing novel gene arrangements. These results reinforce the potential of the metagenomic approach for the identification and elucidation of new genes and pathways in poorly studied environments and contribute to a broader perspective on the hydrocarbon degradation processes in petroleum reservoirs.

Oil, Gas and Conflict: A Mathematical Model for the Resource Curse.

Oil and natural gas are highly valuable natural resources, but many countries with large untapped reserves suffer from poor economic and social-welfare performance. This conundrum is known as the resource curse. The resource curse is a result of poor governance and wealth distribution structures that allow the elite to monopolize resources for self-gain. When rival social groups compete for natural resources, civil unrest soon follows. While conceptually easy to follow, there have been few formal attempts to study this phenomenon. Thus, we develop a mathematical model that captures the basic elements and dynamics of this dilemma. We show that when resources are monopolized by the elite, increased exportation leads to decreased domestic production. This is due to under-provision of the resource-embedded energy and industrial infrastructure. Decreased domestic production then lowers the marginal return on productive activities, and insurgency emerges. The resultant conflict further displaces human, built, and natural capital. It forces the economy into a vicious downward spiral. Our numerical results highlight the importance of governance reform and productivity growth in reducing oil-and-gas-related conflicts, and thus identify potential points of intervention to break the downward spiral.