Global assessment of oil and gas methane ultra-emitters Lauvaux, T; Giron, C; Mazzolini, M ...
Science (American Association for the Advancement of Science),
2022-Feb-04, 2022-02-04, 20220204, Letnik:
375, Številka:
6580
Journal Article
Recenzirano
Odprti dostop
Methane emissions from oil and gas (O&G) production and transmission represent a considerable contribution to climate change. These emissions comprise sporadic releases of large amounts of methane ...during maintenance operations or equipment failures not accounted for in current inventory estimates. We collected and analyzed hundreds of very large releases from atmospheric methane images sampled by the TROPOspheric Monitoring Instrument (TROPOMI) between 2019 and 2020. Ultra-emitters are primarily detected over the largest O&G basins throughout the world. With a total contribution equivalent to 8 to 12% (~8 million metric tons of methane per year) of the global O&G production methane emissions, mitigation of ultra-emitters is largely achievable at low costs and would lead to robust net benefits in billions of US dollars for the six major O&G-producing countries when considering societal costs of methane.
The Aliso Canyon gas storage facility near Porter Ranch, California, produced a large accidental CH4 release from October 2015 to February 2016. The Hyperion imaging spectrometer on board the EO-1 ...satellite successfully detected this event, achieving the first orbital attribution of CH4 to a single anthropogenic superemitter. Hyperion measured shortwave infrared signatures of CH4 near 2.3 microns at 0.01 micron spectral resolution and 30 meter spatial resolution. It detected the plume on three overpasses, mapping its magnitude and morphology. These orbital observations were consistent with measurements by airborne instruments. We evaluate Hyperion instrument performance, draw implications for future orbital instruments, and extrapolate the potential for a global survey of CH4 superemitters.
The Los Angeles megacity, which is home to more than 40% of the population in California, is the second largest megacity in the United States and an intense source of anthropogenic greenhouse gases ...(GHGs). Quantifying GHG emissions from the megacity and monitoring their spatiotemporal trends are essential to be able to understand the effectiveness of emission control policies. Here we measure carbon dioxide (CO2) and methane (CH4) across the Los Angeles megacity using a novel approach - ground-based remote sensing from a mountaintop site. A Fourier transform spectrometer (FTS) with agile pointing optics, located on Mount Wilson at 1.67 km above sea level, measures reflected near-infrared sunlight from 29 different surface targets on Mount Wilson and in the Los Angeles megacity to retrieve the slant column abundances of CO2, CH4 and other trace gases above and below Mount Wilson. This technique provides persistent space- and time-resolved observations of path-averaged dry-air GHG concentrations, XGHG, in the Los Angeles megacity and simulates observations from a geostationary satellite. In this study, we combined high-sensitivity measurements from the FTS and the panorama from Mount Wilson to characterize anthropogenic CH4 emissions in the megacity using tracer-tracer correlations. During the period between September 2011 and October 2013, the observed XCH4 : XCO2 excess ratio, assigned to anthropogenic activities, varied from 5.4 to 7.3 ppb CH4 (ppm CO2)-1, with an average of 6.4 plus or minus 0.5 ppb CH4 (ppm CO2)-1 compared to the value of 4.6 plus or minus 0.9 ppb CH4 (ppm CO2)-1 expected from the California Air Resources Board (CARB) bottom-up emission inventory. Persistent elevated XCH4 : XCO2 excess ratios were observed in Pasadena and in the eastern Los Angeles megacity. Using the FTS observations on Mount Wilson and the bottom-up CO2 emission inventory, we derived a top-down CH4 emission of 0.39 plus or minus 0.06 Tg CH4 year-1 in the Los Angeles megacity. This is 18-61% larger than the state government's bottom-up CH4 emission inventory and consistent with previous studies.
Acute myeloid leukemias (AMLs) are a heterogeneous group of diseases that are sustained by relatively rare leukemia-initiating cells (LICs) that exhibit diverse genetic and phenotypic properties. AML ...heterogeneity presents a major challenge to development of targeted therapies, and effective treatment will require targeting of common molecular drivers of AML maintenance. The orphan nuclear receptors NR4A1 and NR4A3 are potent tumor suppressors of AML. They are silenced in all human AML LICs, irrespective of patient cytogenetics, and their deletion in mice leads to postnatal AML development. In the current report, we address the tumor-suppressive mechanisms and therapeutic potential of NR4As for AML intervention. We show that rescue of either NR4A1 or NR4A3 inhibits the leukemogenicity of AML cells in vivo and reprograms a subset of gene signatures that distinguish primary human LICs from normal hematopoietic stem cells (HSCs), irrespective of subtype. Central to NR4A reprogramming is the acute suppression of an LIC submodule that includes the transcriptional repression of MYC. Additionally, we show that upregulation of MYC is an acute preleukemic consequence of NR4A deletion and that MYC suppression functionally contributes to NR4A antileukemic effects. Collectively, these results identify NR4As as novel targets for AML therapeutic intervention and reveal molecular targets of NR4A tumor suppression, including the suppression of MYC.
Abstract
In the summer of 2020, the AVIRIS-NG airborne imaging spectrometer surveyed California’s Southern San Joaquin Valley and the South Bay (Los Angeles County) to identify anthropogenic methane ...(CH
4
) point source plumes, estimate emission rates, and attribute sources to both facilities and emission sectors. These flights were designed to revisit regions previously surveyed by the 2016–2017 California Methane Survey and to assess the socioeconomic responses of COVID-19 on emissions across multiple sectors. For regions flown by both the California Methane Survey and the California COVID campaigns, total CH
4
point source emissions from the energy and oil & natural gas sectors were 34.8% lower during the summer 2020 flights, however, emission trends varied across sector. For the energy sector, there was a 28.2% decrease driven by reductions in refinery emissions consistent with a drop in production, which was offset in part with increases from powerplants. For the oil & natural gas sector, CH
4
emissions declined 34.2% and significant variability was observed at the oilfield scale. Emissions declined for all but the Buena Vista and Cymric fields with an observed positive relationship between production and emissions. In addition to characterizing the short-term impact of COVID-19 on CH
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emissions, this study demonstrates the broader potential of remote sensing with sufficient sensitivity, spatial resolution, and spatio-temporal completeness to quantify changes in CH
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emissions at the scale of key sectors and facilities.
Urban Planning and State Reform Libertun de Duren, Nora R.
Journal of planning education and research,
04/2009, Letnik:
28, Številka:
3
Journal Article
Recenzirano
This article explores how the relationship between the economic activities of urban elites and the national economy explain the historical changes on the land uses of the urban periphery. It traces ...the social and economic paths that led Buenos Aires from an industrial hub to a sprawling city that juxtaposes gated communities and informal settlements. After a brief review that places this research within the literature on gated communities, the organization of the article follows the chronology of Argentina's national governments from 1976 until 1999. The article links the changes in national industrialization policies with the allocation of land for the development of gated communities in Buenos Aires's suburbs. The article concludes with an assessment of the effects these spatial changes had on the suburban polity.
Strong methane point source emissions generate large atmospheric concentrations that can be detected and quantified with infrared remote sensing and retrieval algorithms. Two standard and widely used ...retrieval algorithms for one class of observing platform, imaging spectrometers, include pixel-wise and column-wise approaches. In this study, we assess the performance of both approaches using the airborne imaging spectrometer (Global Airborne Observatory) observations of two extensive controlled-release experiments. We find that the column-wise retrieval algorithm is sensitive to the flight line length and can have a systematic low bias with short flight lines, which is not present in the pixel-wise retrieval algorithm. However, the pixel-wise retrieval is very computationally expensive, and the column-wise retrieval algorithms can produce good results when the flight line length is sufficiently long. Lastly, this study examines the methane plume detection performance of the Global Airborne Observatory with a column-wise retrieval algorithm and finds minimum detection limits of between 9 of 10 kg h−1 and 90 % probability of detection between 10 and 45 kg h−1. These results present a framework of rules for guiding proper concentration retrieval selection given conditions at the time of observation in order to ensure robust detection and quantification.
Gated communities have usually been studied from the perspective of the residents-their proclivities, economic status, and social ambitions. Moreover, these communities have also been associated with ...weakening states and market-led urbanization. What role do public institutions play in the development of gated communities?
This article examines the case of Buenos Aires, Argentina, where impoverished suburban municipalities have relied on gated communities as a local development strategy. Taking advantage of the decentralization of land use planning, municipalities with a high percentage of poor households have facilitated the development of gated communities as a way to increase local employment and real estate investment. As a consequence, these communities have been clustered in the poorest suburban municipalities, thus increasing social polarization within municipal boundaries and calling into question the effect of decentralization reforms on the formation of an inclusive, participatory polity.
Predicting species presence requires knowledge of detection of individuals, scale of model variables, model selection uncertainty, and spatial autocorrelation. Our objective was to incorporate recent ...modeling advances to predict potential habitat occupancy of northern bobwhite (Colinus virginianus). From 15 May—15 August 2008 and 2009, we conducted repeat-visit surveys at 360 sites within Delaware to sample presence of bobwhite. We randomly selected half the data to model scale-dependent relationships of bobwhite presence with metrics of landscape- and site-scale habitat composition and configuration. The final averaged habitat-occupancy model fit the remainder testing dataset with an area under the receiver operating characteristic curve value of 0.62. At the site scale, bobwhite presence was negatively related to interspersion and juxtaposition of early successional habitat (ESH; grassland and shrubland), ESH to forest edge density, and agriculture to forest edge density, though relative effect sizes were weak to moderate after accounting for model selection uncertainty. At the landscape scale, bobwhite presence was negatively related to patch cohesion of human development within 2.5 km and positively related to patch cohesion of ESH within 2.0 km, with both variables exerting strong effects. Bobwhite presence was also weakly and positively related to percentage of shrubland habitat within 1.0 km of the sampling point. We applied our habitat occupancy model to map the predicted presence of breeding bobwhite within the Delmarva Peninsula, USA. The modeling results and distribution map will provide guidance to State and Federal private land management programs in the Mid-Atlantic to identify where habitat management efforts will be most effective. Our methodology can also serve as a basis for future habitat modeling of bobwhite and other grassland—shrubland species across their range.
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