Methane / Natural Gas Leakage

Qin, Yue, Mi Zhou, Da Pan, Zbigniew Klimont, Daniel B. Gingerich, Denise L. Mauzerall, Lei Zhao, Gang He, and Jeffrey M. Bielicki. “Environmental Consequences of Potential Strategies for China to Prepare for Natural Gas Import Disruptions.” Environmental Science & Technology (2021).Abstract
Worldwide efforts to switch away from coal have increased the reliance on natural gas imports for countries with inadequate domestic production. In preparing for potential gas import disruptions, there have been limited attempts to quantify the environmental and human health impacts of different options and incorporate them into decision-making. Here, we analyze the air pollution, human health, carbon emissions, and water consumption impacts under a set of planning strategies to prepare for potentially fully disrupted natural gas imports in China. We find that, with China’s current natural gas storage capacity, compensating for natural gas import disruptions using domestic fossil fuels (with the current average combustion technology) could lead up to 23,300 (95% CI: 22,100–24,500) excess premature deaths from air pollution, along with increased carbon emissions and aggravated water stress. Improving energy efficiency, more progressive electrification and decarbonization, cleaner fossil combustion, and expanding natural gas storage capacity can significantly reduce the number of excess premature deaths and may offer opportunities to reduce negative carbon and water impacts simultaneously. Our results highlight the importance for China to increase the domestic storage capacity in the short term, and more importantly, to promote a clean energy transition to avoid potentially substantial environmental consequences under intensifying geopolitical uncertainties in China. Therefore, mitigating potential negative environmental impacts related to insecure natural gas supply provides additional incentives for China to facilitate a clean and efficient energy system transition.
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Ocko, Ilissa B., T Sun, D Shindell, M. Oppenheimer, AN Hristov, S.W. Pacala, DL Mauzerall, Y Xu, and SP Hamburg. “Acting rapidly to deploy readily available methane mitigation measuresby sector can immediately slow global warming.” Environmental Research Letters (2021).Abstract
Methane mitigation is essential for addressing climate change, but the value of rapidly implementing available mitigation measures is not well understood. In this paper, we analyze the climate benefits of fast action to reduce methane emissions as compared to slower and delayed mitigation timelines. We find that the scale up and deployment of greatly underutilized but available mitigation measures will have significant near-term temperature benefits beyond that from slow or delayed action. Overall, strategies exist to cut global methane emissions from human activities in half within the next ten years and half of these strategies currently incur no net cost. Pursuing all mitigation measures now could slow the global-mean rate of near-term decadal warming by around 30%, avoid a quarter of a degree Centigrade of additional global-mean warming by midcentury, and set ourselves on a path to avoid more than half a degree Centigrade by end of century. On the other hand, slow implementation of these measures may result in an additional tenth of a degree of global- mean warming by midcentury and 5% faster warming rate (relative to fast action), and waiting to pursue these measures until midcentury may result in an additional two tenths of a degree Centigrade by midcentury and 15% faster warming rate (relative to fast action). Slow or delayed methane action is viewed by many as reasonable given that current and on-the-horizon climate policies heavily emphasize actions that benefit the climate in the long-term, such as decarbonization and reaching net-zero emissions, whereas methane emitted over the next couple of decades will play a limited role in long-term warming. However, given that fast methane action can considerably limit climate damages in the near-term, it is urgent to scale up efforts and take advantage of this achievable and affordable opportunity as we simultaneously reduce carbon dioxide emissions.
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Pan, Da, Lei Tao, Kang Sun, Levi M. Golston, David J. Miller, Tong Zhu, Yue Qin, Yan Zhang, Denise L. Mauzerall, and Mark A. Zondlo. “Methane emissions from natural gas vehicles in China.” Nature Communications 11 (2020).Abstract
Natural gas vehicles (NGVs) have been promoted in China to mitigate air pollution, yet our measurements and analyses show that NGV growth in China may have significant negative impacts on climate change. We conducted real-world vehicle emission measurements in China and found high methane emissions from heavy-duty NGVs (90% higher than current emission limits). These emissions have been ignored in previous emission estimates, leading to biased results. Applying our observations to life-cycle analyses, we found that switching to NGVs from conventional vehicles in China has led to a net increase in greenhouse gas (GHG) emissions since 2000. With scenario analyses, we also show that the next decade will be critical for China to reverse the trend with the upcoming China VI standard for heavy-duty vehicles. Implementing and enforcing the China VI standard is challenging, and the method demonstrated here can provide critical information regarding the fleet-level CH4 emissions from NGVs.
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Riddick, SN, DL Mauzerall+, MA Celia, M Kang, and K Bandilla. “Variability observed over time in methane emissions from abandoned oil and gas wells.” International Journal of Greenhouse Gas Control 100 (2020).Abstract
Recent studies have reported methane (CH4) emissions from abandoned oil and gas wells across the United States and the United Kingdom. These emissions can reach hundreds of kg CH4 per year per well and are important to include in greenhouse gas emission inventories and mitigation strategies. Emission estimates are generally based on single,  short-term measurements that assume constant emission rates over both short (hours) and longer (months/years) time periods. To investigate this assumption, we measure CH4  missions from 18 abandoned oil and gas wells in the USA and the UK continuously over 24 h and then make repeat 24 -h measurements at a single site over 12 months. While the lack of historical records for these wells makes it impossible to determine the underlying leakage-pathways, we observed that CH4 emissions at all wells varied over 24 h (range 0.2-81,000 mg CH4 hr−1) with average emissions varying by a factor of 18 and ranging from factors of 1.1–142. We did not find a statistically significant relationship between the magnitude of emissions and variability or that variability is correlated with temperature, relative humidity or atmospheric pressure. The results presented here suggest high CH4 emission events tend to be short-lived, so short-term (< 1 h) sampling is likely to miss them. Our findings present the dynamic nature of CH4 emissions from abandoned oil and gas wells which should be considered when planning measurement methodologies and developing greenhouse gas inventories/mitigation strategies. Incorporation of these temporal dynamics could improve national greenhouse gas emissions inventories.
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Riddick, SN, DL Mauzerall+, MA Celia, G Allen, M Kang, and JC Riddick. “The calibration and deployment of a low-cost methane sensor.” Atmospheric Environment 230 (2020).Abstract
Since 1850 the atmospheric mixing ratio of methane (CH4), a potent greenhouse gas, has doubled. This increase is directly linked to an escalation in emissions from anthropogenic sources. An inexpensive means to identify and monitor CH4 emission sources and evaluate the efficacy of mitigation strategies is essential. However, sourcing reliable, low-cost, easy-to-calibrate sensors that are fit for purpose is challenging. A recent study showed that CH4 mixing ratio data from a low-power, low-cost CH4 sensor (Figaro TGS2600) agreed well with CH4 mixing ratios measured by a high precision sensor at mixing ratios between 1.85 ppm and 2 ppm. To investigate, as a proof of concept, if this low-cost sensor could be used to measure typical ambient CH4 mixing ratios, we operated a TGS2600 in conjunction with a Los Gatos Ultra-portable Greenhouse Gas Analyzer (UGGA) in controlled laboratory conditions. We then explored the sensor's long-term reliability by deploying the TGS2600 near an onshore gas terminal to calculate emissions from May to July 2018. Our initial studies showed that previously published linear algorithms could not convert TGS2600 output to CH4 mixing ratios measured by the UGGA. However, we derived a non-linear empirical relationship that could be used to reliably convert the output of a TGS2600 unit to CH4 mixing ratios over a range of 1.85–5.85 ppm that agree to a high-precision instrument output to ±0.01 ppm. Our study showed that the TGS2600 could be used to continuously measure variability in CH4 mixing ratios from 1.82 to 5.40 ppm for three months downwind of the gas terminal. Using a simplified Gaussian Plume approach, these mixing ratios correspond to an emission flux range of 0–238 g CH4 s−1, with average emission of 9.6 g CH4 s−1 from the currently active North Terminal and 1.6 g CH4 s−1 from the decommissioned South Terminal. Our work here demonstrates the feasibility of utilizing a low-cost sensor to detect methane leakage at concentrations close to ambient background levels, as long as the device is routinely calibrated with an accurate reference instrument. Having a widely deployed network of such low-cost CH4 sensors would allow improved identification, monitoring and mitigation of a variety of CH4 emissions.
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Kang, Mary, Denise L. Mauzerall+, Daniel Z. Ma, and Michael A. Celia. “Reducing methane emissions from abandoned oil and gas wells: Strategies and costs.” Energy Policy 132 (2019): 594-601.Abstract
Well plugging, the main strategy for reducing methane emissions from millions of unplugged abandoned oil and gas (AOG) wells in the U.S. and abroad, is expensive and many wells remain unplugged. In addition, plugging does not necessarily reduce methane emissions and some categories of plugged wells are high emitters. We analyze strategies and costs of five options for reducing methane emissions from high-emitting AOG wells - those which are unplugged and plugged/vented gas wells. The five options are: plugging without gas venting, plugging with gas venting and flaring, plugging with gas venting and usage, gas flaring only, and gas capture/usage only. Average plugging costs ($37,000 per well) can be justified by the social cost of methane, which considers air quality, climate, and human/ecosystem impacts. Savings as measured by natural gas prices and alternative energy credits can offset low plugging costs (<$15,400 per well) but are not large enough to offset average plugging costs. Nonetheless, reducing methane emissions from AOG wells is a cost-effective strategy for addressing climate change that has comparable costs to some current greenhouse gas mitigation options and can produce co-benefits such as groundwater protection. Therefore, we recommend including the mitigation of AOG wells in climate and energy policies in the U.S., Canada, and other oil-and-gas-producing regions.
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Riddick, Stuart N., Denise L. Mauzerall+, Michael Celia, Neil R. P. Harris, Grant Allen, Joseph Pitt, John Staunton-Sykes, et al.Methane emissions from oil and gas platforms in the North Sea.” Atmospheric Chemistry and Physics 19, no. 15 (2019): 9787–9796. Publisher's VersionAbstract
Since 1850 the concentration of atmospheric methane (CH4), a potent greenhouse gas, has more than doubled. Recent studies suggest that emission inventories may be missing sources and underestimating emissions. To investigate whether offshore oil and gas platforms leak CH4during normal operation, we measured CH4 mole fractions around eight oil and gas production platforms in the North Sea which were neither flaring gas nor offloading oil. We use the measurements from summer 2017, along with meteorological data, in a Gaussian plume model to estimate CH4 emissions from each platform. We find CH4 mole fractions of between 11 and 370 ppb above background concentrations downwind of the platforms measured, corresponding to a median CH4 emission of 6.8 g CH4 s−1 for each platform, with a range of 2.9 to 22.3 g CH4 s−1. When matched to production records, during our measurements individual platforms lost between 0.04 % and 1.4 % of gas produced with a median loss of 0.23 %. When the measured platforms are considered collectively (i.e. the sum of platforms' emission fluxes weighted by the sum of the platforms' production), we estimate the CH4 loss to be 0.19 % of gas production. These estimates are substantially higher than the emissions most recently reported to the National Atmospheric Emission Inventory (NAEI) for total CH4 loss from United Kingdom platforms in the North Sea. The NAEI reports CH4 losses from the offshore oil and gas platforms we measured to be 0.13 % of gas production, with most of their emissions coming from gas flaring and offshore oil loading, neither of which was taking place at the time of our measurements. All oil and gas platforms we observed were found to leak CH4 during normal operation, and much of this leakage has not been included in UK emission inventories. Further research is required to accurately determine total CH4 leakage from all offshore oil and gas operations and to properly include the leakage in national and international emission inventories.
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Riddick, Stuart N., Denise L. Mauzerall+, Michael A. Celia, Mary Kang, Kara Bressler, Christopher Chu, and Caleb D. Gum. “Measuring methane emissions from abandoned and active oil and gas wells in West Virginia.” Science of the Total Environment 651, no. 2 (2019): 1849-1856.Abstract
Recent studies have reported methane (CH4) emissions from abandoned and active oil and gas infrastructure across the United States, where measured emissions show regional variability. To investigate similar phenomena in West Virginia, we measure and characterize emissions from abandoned and active conventional oil and gas wells. In addition, we reconcile divergent regional CH4 emissions estimates by comparing our West Virginia emissions estimates with those from other states in the United States. We find the CH4 emission factors from 112 plugged and 147 unplugged wells in West Virginia are 0.1 g CH4 h−1 and 3.2 g CH4 h−1, respectively. The highest emitting unplugged abandoned wells in WV are those most recently abandoned, with the mean emission of wells abandoned between 1993 and 2015 of 16 g CH4 h−1 compared to the mean of those abandoned before 1993 of 3 × 10−3 g CH4 h−1. Using field observations at a historic mining area as a proxy for state-wide drilling activity in the late 19th/early 20th century, we estimate the number of abandoned wells in WV at between 60,000 and 760,000 wells. Methane emission factors from active conventional wells were estimated at 138 g CH4 h−1. We did not find an emission pattern relating to age of wells or operator for active wells, however, the CH4 emission factor for active conventional wells was 7.5 times larger than the emission factor used by the EPA for conventional oil and gas wells. Our results suggest that well emission factors for active and abandoned wells can vary within the same geologic formation and may be affected by differences in state regulations. Therefore, accounting for state-level variations is critical for accuracy in greenhouse gas emissions inventories, which are used to guide emissions reduction strategies.
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Qin, Yue, Fan Tong, Guang Yang, and Denise L. Mauzerall+. “Challenges of using natural gas as a carbon mitigation option in China.” Energy Policy 117 (2018): 457-462.Abstract
Under the Paris Agreement, China committed to peak its carbon dioxide emissions on or before 2030. Substituting natural gas for coal may facilitate it meeting this commitment. However, three major challenges may obstruct progress towards desired climate benefits from natural gas. 1) A fundamental price dilemma disincentivizing a coal-to-gas end-use energy transition: low city-gate gas prices discourage an increase in gas supplies while high end-use gas prices impede an increase in gas demand. 2) Insufficient and constrained access to natural gas infrastructure hinders connections between gas supplies and end-users, and obstructs a balance in seasonal supply and demand. 3) Methane leakage from the natural gas industry compromises the direct greenhouse gas emission reductions from combustion. To address these challenges, government and industry must work together to facilitate natural gas market reform, increase investment in natural gas infrastructure, and control methane emissions.
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Qin, Yue, Lena Höglund-Isaksson, Edward Byers, Kuishuang Feng, Fabian Wagner, Wei Peng, and Denise L. Mauzerall+. “Air quality-carbon-water synergies and trade-offs in China's natural gas industry.” Nature Sustainability 1 (2018): 505-511.Abstract
Both energy production and consumption can simultaneously affect regional air quality, local water stress and the global climate. Identifying the air quality–carbon–water interactions due to both energy sources and end-uses is important for capturing potential co-benefits while avoiding unintended consequences when designing sustainable energy transition pathways. Here, we examine the air quality–carbon–water interdependencies of China’s six major natural gas sources and three end-use gasfor-coal substitution strategies in 2020. We find that replacing coal with gas sources other than coal-based synthetic natural gas (SNG) generally offers national air quality–carbon–water co-benefits. However, SNG achieves air quality benefits while increasing carbon emissions and water demand, particularly in regions that already suffer from high per capita carbon emissions and severe water scarcity. Depending on end-uses, non-SNG gas-for-coal substitution results in enormous variations in air quality, carbon and water improvements, with notable air quality–carbon synergies but air quality–water trade-offs. This indicates that more attention is needed to determine in which end-uses natural gas should be deployed to achieve the desired environmental improvements. Assessing air quality–carbon–water impacts across local, regional and global administrative levels is crucial for designing and balancing the co-benefits of sustainable energy development and deployment policies at all scales.
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Qin, Yue, Ryan Edwards, Fan Tong, and Denise L. Mauzerall+. “Can Switching from Coal to Shale Gas Bring Net Carbon Reductions to China?Environmental Science & Technology (2017). Publisher's VersionAbstract
To increase energy security and reduce emissions of air pollutants and CO2from coal use, China is attempting to duplicate the rapid development of shale gas that has taken place in the United States. This work builds a framework to estimate the lifecycle greenhouse gas (GHG) emissions from China’s shale gas system and compares them with GHG emissions from coal used in the power, residential, and industrial sectors. We find the mean lifecycle carbon footprint of shale gas is about 30–50% lower than that of coal in all sectors under both 20 year and 100 year global warming potentials (GWP20 and GWP100). However, primarily due to large uncertainties in methane leakage, the upper bound estimate of the lifecycle carbon footprint of shale gas in China could be approximately 15–60% higher than that of coal across sectors under GWP20. To ensure net GHG emission reductions when switching from coal to shale gas, we estimate the breakeven methane leakage rates to be approximately 6.0%, 7.7%, and 4.2% in the power, residential, and industrial sectors, respectively, under GWP20. We find shale gas in China has a good chance of delivering air quality and climate cobenefits, particularly when used in the residential sector, with proper methane leakage control.
Qin, Yue, Fabian Wagner, Noah Scovronick, Wei Peng, Junnan Yang, Tong Zhu, Kirk R. Smith, and Denise L. Mauzerall+. “Air quality, health, and climate implications of China's synthetic natural gas development.” Proceedings of the National Academy of Sciences of the United States of America 114, no. 19 (2017): 4887-4892.Abstract
Facing severe air pollution and growing dependence on natural gas imports, the Chinese government plans to increase coal-based synthetic natural gas (SNG) production. Although displacement of coal with SNG benefits air quality, it increases CO2 emissions. Due to variations in air pollutant and CO2 emission factors and energy efficiencies across sectors, coal replacement with SNG results in varying degrees of air quality benefits and climate penalties. We estimate air quality, human health, and climate impacts of SNG substitution strategies in 2020. Using all production of SNG in the residential sector results in an annual decrease of ∼32,000 (20,000 to 41,000) outdoor-air-pollutionassociated premature deaths, with ranges determined by the low and high estimates of the health risks. If changes in indoor/household air pollution were also included, the decrease would be far larger. SNG deployment in the residential sector results in nearly 10 and 60 times greater reduction in premature mortality than if it is deployed in the industrial or power sectors, respectively. Due to inefficiencies in current household coal use, utilization of SNG in the residential sector results in only 20 to 30% of the carbon penalty compared with using it in the industrial or power sectors. Even if carbon capture and storage is used in SNG production with today’s technology, SNG emits 22 to 40% more CO2 than the same amount of conventional gas. Among the SNG deployment strategies we evaluate, allocating currently planned SNG to households provides the largest air quality and health benefits with the smallest carbon penalties
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Kang, Mary, Shanna Christian, Michael A. Celia, Denise L. Mauzerall, Markus Bill, Alana R. Miller, Yuheng Chen, Mark E. Conrad, Thomas H. Darrah, and Robert B. Jackson. “Identification and characterization of high methane-emitting abandoned oil and gas wells.” Proceedings of the National Academy of Science (2016).Abstract
Recent measurements of methane emissions from abandoned oil/gas wells show that these wells can be a substantial source of methane to the atmosphere, particularly from a small proportion of highemitting wells. However, identifying high emitters remains a challenge. We couple 163 well measurements of methane flow rates; ethane, propane, and n-butane concentrations; isotopes of methane; and noble gas concentrations from 88 wells in Pennsylvania with synthesized data from historical documents, field investigations, and state databases. Using our databases, we (i) improve estimates of the number of abandoned wells in Pennsylvania; (ii) characterize key attributes that accompany high emitters, including depth, type, plugging status, and coal area designation; and (iii) estimate attribute-specific and overall methane emissions from abandoned wells. High emitters are best predicted as unplugged gas wells and plugged/vented gas wells in coal areas and appear to be unrelated to the presence of underground natural gas storage areas or unconventional oil/gas production. Repeat measurements over 2 years show that flow rates of high emitters are sustained through time. Our attribute-based methane emission data and our comprehensive estimate of 470,000–750,000 abandoned wells in Pennsylvania result in estimated state-wide emissions of 0.04–0.07 Mt (1012 g) CH4 per year. This estimate represents 5–8% of annual anthropogenic methane emissions in Pennsylvania. Our methodology combining new field measurements with data mining of previously unavailable well attributes and numbers of wells can be used to improve methane emission estimates and prioritize cost-effective mitigation strategies for Pennsylvania and beyond.
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Reid, Matthew C., Kaiyu Guan, Fabian Wagner, and Denise L. Mauzerall+. “Global Methane Emissions from Pit Latrines.” Environmental Science & Technology 48, no. 15 (2014): 8727-8734.Abstract
Pit latrines are an important form of decentralized wastewater management, providing hygienic and low-cost sanitation for approximately one-quarter of the global population. Latrines are also major sources of the greenhouse gas methane (CH4) from the anaerobic decomposition of organic matter in pits. In this study, we develop a spatially explicit approach to account for local hydrological control over the anaerobic condition of latrines and use this analysis to derive a set of country-specific emissions factors and to estimate global pit latrine CH4 emissions. Between 2000 and 2015 we project global emissions to fall from 5.2 to 3.8 Tg y−1 , or from ∼2% to ∼1% of global anthropogenic CH4 emissions, due largely to urbanization in China. Two and a half billion people still lack improved sanitation services, however, and progress toward universal access to improved sanitation will likely drive future growth in pit latrine emissions. We discuss modeling results in the context of sustainable water, sanitation, and hygiene development and consider appropriate technologies to ensure hygienic sanitation while limiting CH4 emissions. We show that low-CH4 on-site alternatives like composting toilets may be price competitive with other CH4 mitigation measures in organic waste sectors, with marginal abatement costs ranging from 57 to 944 $/ton carbon dioxide equivalents (CO2e) in Africa and 46 to 97 $/ton CO2e in Asia.
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Kang, Mary, Cynthia M. Kanno, Matthew C. Reid, Xin Zhang, Denise L. Mauzerall, Michael A. Celia, Yuheng Chen, and Tullis C. Onstott. “Direct measurements of methane emissions from abandoned oil and gas wells in Pennsylvania.” Proceeding of the National Academy of Science (2014).Abstract
Abandoned oil and gas wells provide a potential pathway for subsurface migration and emissions of methane and other fluids to the atmosphere. Little is known about methane fluxes from the millions of abandoned wells that exist in the United States. Here, we report direct measurements of methane fluxes from abandoned oil and gas wells in Pennsylvania, using static flux chambers. A total of 42 and 52 direct measurements were made at wells and at locations near the wells (“controls”) in forested, wetland, grassland, and river areas in July, August, October 2013 and January 2014, respectively. The mean methane flow rates at these well locations were 0.27 kg/d/well, and the mean methane flow rate at the control locations was 4.5 × 10−6 kg/d/location. Three out of the 19 measured wells were high emitters that had methane flow rates that were three orders of magnitude larger than the median flow rate of 1.3 × 10−3 kg/d/well. Assuming the mean flow rate found here is representative of all abandoned wells in Pennsylvania, we scaled the methane emissions to be 4–7% of estimated total anthropogenic methane emissions in Pennsylvania. The presence of ethane, propane, and n-butane, along with the methane isotopic composition, indicate that the emitted methane is predominantly of thermogenic origin. These measurements show that methane emissions from abandoned oil and gas wells can be significant. The research required to quantify these emissions nationally should be undertaken so they can be accurately described and included in greenhouse gas emissions inventories.
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Fang, Yuanyuan, Vaishali Naik, Larry W. Horowitz, and Denise L. Mauzerall+. “Air pollution and associated human mortality: The role of air pollutant emissions, climate change and methane concentration increases from the preindustrial period to the present.” Atmospheric Chemistry Physics (2013).Abstract
Increases in surface ozone (O3) and fine particulate matter (≤ 2.5 µm aerodynamic diameter, PM2.5) are associated with excess premature human mortalities. We estimate changes in surface O3 and PM2.5 from pre-industrial (1860) to present (2000) and the global present-day (2000) premature human mortalities associated with these changes. We extend previous work to differentiate the contribution of changes in three factors: emissions of short-lived air pollutants, climate change, and increased methane (CH4) concentrations, to air pollution levels and associated premature mortalities. We use a coupled chemistry-climate model in conjunction with global population distributions in 2000 to estimate exposure attributable to concentration changes since 1860 from each factor. Attributable mortalities are estimated using health impact functions of long-term relative risk estimates for O3 and PM2.5 from the epidemiology literature. We find global mean surface PM2.5 and health-relevant O3 (defined as the maximum 6-month mean of 1-h daily maximum O3 in a year) have increased by 8 ± 0.16 µg m−3 and 30 ± 0.16 ppbv (results reported as annual average ±standard deviation of 10-yr model simulations), respectively, over this industrial period as a result of combined changes in emissions of air pollutants (EMIS), climate (CLIM) and CH4 concentrations (TCH4). EMIS, CLIM and TCH4 cause global population-weighted average PM2.5 (O3) to change by +7.5 ± 0.19 µg m−3 (+25 ± 0.30 ppbv), +0.4 ± 0.17 µg m−3 (+0.5 ± 0.28 ppbv), and 0.04 ± 0.24 µg m−3 (+4.3 ± 0.33 ppbv), respectively. Total global changes in PM2.5 are associated with 1.5 (95 % confidence interval, CI, 1.2–1.8) million cardiopulmonary mortalities and 95 (95 % CI, 44–144) thousand lung cancer mortalities annually and changes in O3 are associated with 375 (95 % CI, 129–592) thousand respiratory mortalities annually. Most air pollution mortality is driven by changes in emissions of short-lived air pollutants and their precursors (95 % and 85 % of mortalities from PM2.5 and O3 respectively). However, changing climate and increasing CH4 concentrations also contribute to premature mortality associated with air pollution globally (by up to 5 % and 15 %, respectively). In some regions, the contribution of climate change and increased CH4 together are responsible for more than 20 % of the respiratory mortality associated with O3 exposure. We find the interaction between climate change and atmospheric chemistry has influenced atmospheric composition and human mortality associated with industrial air pollution. Our study highlights the benefits to air quality and human health of CH4 mitigation as a component of future air pollution control policy.
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Mauzerall, Denise L.Methane Mitigation – Benefits for air quality, health, crop yields, and climate.” IGAC Newsletter (2011): 17-18. Full Text PDF