Associations among particulate matter, hazardous air pollutants and methane emissions from the Aliso Canyon natural gas storage facility during the 2015 blowout

Non-Fossil Methane Emissions Mitigation From Agricultural Sector and Its Impact on Sustainable Development Goals

The agriculture sector contributes to ∼40% of methane emissions globally. Methane is also 28 times (Assessment Report 5) more potent greenhouse gas than CO2. In this study, we assess the impact of measures for mitigating methane emissions from the agricultural sector on the achievement of all the 17 United Nations’ Sustainable Development Goals (SDGs). A keyword literature review was employed that focused on finding the synergies and trade-offs with non-fossil methane emissions from the agricultural sector and respective SDGs’ targets. The results were in broad consensus with the literature aimed at finding the relationship between SDGs and measures targeting climate change. There is a total of 88 synergies against eight trade-offs from the 126 SDGs’ targets that were assessed. It clearly shows that measures to mitigate methane emissions from the agricultural sector will significantly help in achieving the SDGs. Since agriculture is the primary occupation and the source of income in developing countries, it can further be inferred that methane mitigation measures in developing countries will play a larger role in achieving SDGs. Measures to mitigate methane emissions reduce poverty; diversify the source of income; promote health, equality, education, sanitation, and sustainable development while providing energy and resource security to the future generations.

Global trade network and CH4 emission outsourcing

The intensifying globalization contributes to the anthropogenic methane (CH₄) emissions outsourcing, a strong greenhouse gas and harmful air pollutant, through the increasingly complex global trade network. However, the CH₄ flow patterns embodied in global traded goods and services have not been interpreted from the perspective of a complex network. In this paper, we integrate global CH₄ emission inventory from the EDGAR (the Emission Database for Global Atmospheric Research) databases, global multi-regional input-output model from the GTAP database, and complex network analysis to reveal the structural characteristics of the global CH₄ flow network (GCFN). In the GCFN, more than one quarter of the global anthropogenic CH₄ emissions in 2014 are associated with international trade. The top 20 economies contribute to about 70% of the total embodied CH₄ emission flows. The GCFNs mainly consist of tripartite patterns centered on China, the USA and Russia. Some emerging countries, such as Thailand and Brazil, also exhibit dominated positions in different kinds of GCFNs. Moreover, the core-periphery structure of the GCFN confirms the existence of a few hub economies associated with a large amount of CH₄ emissions. The results emphasize the multinational cooperation on global CH₄ emission mitigation, and well-focused mitigation policies should be implemented on some key economies.

Climate Justice and California's Methane Superemitters: Environmental Equity Assessment of Community Proximity and Exposure Intensity

Methane superemitters emit non-methane copollutants that are harmful to human health. Yet, no prior studies have assessed disparities in exposure to methane superemitters with respect to race/ethnicity, socioeconomic status, and civic engagement. To do so, we obtained the location, category (e.g., landfill, refinery), and emission rate of California methane superemitters from Next Generation Airborne Visible/Infrared Imaging Spectrometer (AVIRIS-NG) flights conducted between 2016 and 2018. We identified block groups within 2 km of superemitters (exposed) and 5-10 km away (unexposed) using dasymetric mapping and assigned level of exposure among block groups within 2 km (measured via number of superemitter categories and total methane emissions). Analyses included 483 superemitters. The majority were dairy/manure (n = 213) and oil/gas production sites (n = 127). Results from fully adjusted logistic mixed models indicate environmental injustice in methane superemitter locations. For example, for every 10% increase in non-Hispanic Black residents, the odds of exposure increased by 10% (95% confidence interval (CI): 1.04, 1.17). We observed similar disparities for Hispanics and Native Americans but not with indicators of socioeconomic status. Among block groups located within 2 km, increasing proportions of non-White populations and lower voter turnout were associated with higher superemitter emission intensity. Previously unrecognized racial/ethnic disparities in exposure to California methane superemitters should be considered in policies to tackle methane emissions.

Changes in neighborhood air quality after idling of an urban oil production site

Oil and gas development is occurring in urban, densely populated neighborhoods; however, the impacts of these operations on neighborhood air quality are not well characterized. In this research, we leveraged ambient air monitoring adjacent to an oil and gas production site in Los Angeles, California during active and idle periods. This study analyzed continuous methane (CH4) and non-methane hydrocarbon (NMHC) measurements, together with triggered grab samples and 24 hour integrated canister samples collected by the South Coast Air Quality Management District. Ambient air pollutant levels and trends were evaluated during active and idle well operations to assess changes in neighborhood air quality after the suspension of oil and gas production. We find that mean concentrations of methane, NMHC, benzene, toluene, ethylbenzene, xylenes, styrene, n-hexane, n-pentane, ethane, and propane decreased following the stop in production activities. Using a source apportionment approach, we observed that the "natural gas" drilling source contributed 23.7% to the total VOCs measured during the active phase, and only 0.6% to the total measured VOCs in the idle phase. Near urban oil and gas production sites, residents may face poorer air quality due to the oil and gas activities which may pose adverse health and environmental risks among proximate communities.