Discrepancy between simulated and observed ethane and propane
levels explained by underestimated fossil emissions

Dalsøren, S. B.; Myhre, Gunnar; Hodnebrog, Øivind; Myhre, Cathrine Lund; Stohl, Andreas; Pisso, Ignacio; Schwietzke, Stefan; Höglund-Isaksson, Lena; Helmig, Detlev; Reimann, Stefan; Sauvage, S.; Schmidbauer, Norbert; Read, Katie A.; Carpenter, Lucy J.; Lewis, Alastair C.; Punjabi, Shalini; Wallasch, Markus

doi:10.1038/s41561-018-0073-0

Cited by 77 publications

(81 citation statements)

References 81 publications

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“…We find that to achieve good agreement with airborne propane observations, we need to scale the NEI2011 inventory by a factor of 10. This large correction is consistent with recent work by Dalsøren et al (), who found that simulated propane was roughly 2–5 times too low near U.S. oil and gas sources even after increasing propane emissions by a factor of 3. Our final simulations use the scaled Turner et al () emissions globally, overwritten over the United States with NEI2011 emissions scaled by a factor of 10.…”

Section: Model Descriptionsupporting

confidence: 92%

“…Tzompa‐Sosa et al () showed that ethane distributions simulated using these emissions capture the seasonal and spatial distributions seen in surface and aircraft observations from around the world. RONO 2 sensitivity to recent changes in ethane emissions driven by oil and gas extraction (Dalsøren et al, ; Helmig et al, ; Helmig et al, ) is discussed in section .…”

Section: Model Descriptionmentioning

confidence: 99%

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Methyl, Ethyl, and Propyl Nitrates: Global Distribution and Impacts on Reactive Nitrogen in Remote Marine Environments

et al. 2018

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Alkyl nitrates (RONO 2 ) are important components of tropospheric reactive nitrogen that serve as reservoirs for nitrogen oxides (NO x ≡ NO + NO 2 ). Here we implement a new simulation of atmospheric methyl, ethyl, and propyl nitrate chemistry in a global chemical transport model (GEOS-Chem). We show that the model can reproduce the spatial and seasonal variability seen in a 20-year ensemble of airborne observations. Methyl nitrate accounts for 17 Gg N globally, with maxima over the tropical Pacific and Southern Ocean. Propyl nitrate is enhanced in continental boundary layers, but its global impact (6 Gg N) is limited by a short lifetime (8 days vs. 26 days for methyl nitrate and 14 days for ethyl nitrate) that inhibits long-range transport. Ethyl nitrate has the smallest impact of the three species (4 Gg N). We find that methyl nitrate is the dominant form of reactive nitrogen (NO y ) in the Southern Ocean marine boundary layer, where its addition to the model corrects a large NO y underestimate in austral winter relative to recent aircraft data. RONO 2 serve as a small net NO x source to the marine troposphere, except in the northern midlatitudes where the continental outflow is enriched in precursors that promote NO x loss via RONO 2 formation. Recent growth in NO x emissions from East Asia has enhanced the role of RONO 2 as a source of NO x to the remote free troposphere. This relationship implies projected future NO x emissions growth across the southern hemisphere may further enhance the importance of RONO 2 as a NO x reservoir.Plain Language Summary Nitrogen in the atmosphere has many impacts on atmospheric chemistry, including affecting how polluted the air is. Many nitrogen-containing gases are released over polluted areas and are quickly broken down-staying far away from remote areas like the ocean. In this paper, we investigate a group of nitrogen gases (called alkyl nitrates) that break down more slowly and so stay in the atmosphere long enough to be transported to the otherwise pollution-free remote Pacific Ocean. These gases are also created naturally in the ocean and then make their way into the atmosphere, changing the atmospheric chemistry over the ocean. We use 20 years of measurements collected from aircraft, combined with a computer model, to determine the abundance and impacts of alkyl nitrates. We find that the smallest alkyl nitrates are particularly important over the Southern Ocean, where there are few other sources of nitrogen. We show that alkyl nitrates are playing an increasingly important role over the remote oceans because of recent growth in East Asian air pollution. This relationship implies that these gases may have a stronger influence on atmospheric chemistry over remote ocean areas in future if anticipated pollution growth in Africa, South America, and Southeast Asia is realised.

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Section: Model Descriptionsupporting

confidence: 92%

Section: Model Descriptionmentioning

confidence: 99%

Methyl, Ethyl, and Propyl Nitrates: Global Distribution and Impacts on Reactive Nitrogen in Remote Marine Environments

et al. 2018

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“…Ethane (C 2 H 6 ) is the second most abundant hydrocarbon in the atmosphere after CH 4 . Ethane has an average atmospheric lifetime of roughly 2 mo due to reaction with the hydroxyl radical and a global emission rate estimated at 12 Tg·y −1 to 20 Tg·y −1 (10)(11)(12)(13)(14)(15)(16). Roughly two-thirds of global ethane emissions are related to human use of fossil fuel and biofuels (10).…”

Section: And References Therein)mentioning

confidence: 99%

Large changes in biomass burning over the last millennium inferred from paleoatmospheric ethane in polar ice cores

Nicewonger

Aydın

Prather

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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Biomass burning drives changes in greenhouse gases, climate-forcing aerosols, and global atmospheric chemistry. There is controversy about the magnitude and timing of changes in biomass burning emissions on millennial time scales from preindustrial to present and about the relative importance of climate change and human activities as the underlying cause. Biomass burning is one of two notable sources of ethane in the preindustrial atmosphere. Here, we present ice core ethane measurements from Antarctica and Greenland that contain information about changes in biomass burning emissions since 1000 CE (Common Era). The biomass burning emissions of ethane during the Medieval Period (1000–1500 CE) were higher than present day and declined sharply to a minimum during the cooler Little Ice Age (1600–1800 CE). Assuming that preindustrial atmospheric reactivity and transport were the same as in the modern atmosphere, we estimate that biomass burning emissions decreased by 30 to 45% from the Medieval Period to the Little Ice Age. The timing and magnitude of this decline in biomass burning emissions is consistent with that inferred from ice core methane stable carbon isotope ratios but inconsistent with histories based on sedimentary charcoal and ice core carbon monoxide measurements. This study demonstrates that biomass burning emissions have exceeded modern levels in the past and may be highly sensitive to changes in climate.

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“…This study builds on Höglund-Isaksson (2012) by extending the timeframe from 2030 to 2050, updating statistics for historical years to 2015, reflecting recent findings from the literature, and including several methodological improvements of emission estimations, e.g., for the oil and gas sectors (Höglund-Isaksson 2017, Dalsøren et al 2018) and waste and wastewater sectors . The extended timeframes of this study, to 2015 for historical emissions and to 2050 for future projections, allow for two important insights.…”

Section: Introductionmentioning

confidence: 99%

Technical potentials and costs for reducing global anthropogenic methane emissions in the 2050 timeframe –results from the GAINS model

Höglund-Isaksson

Gómez-Sanabria

Klimont

et al. 2020

Environ. Res. Commun.

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141

113

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Methane is the second most important greenhouse gas after carbon dioxide contributing to humanmade global warming. Keeping to the Paris Agreement of staying well below two degrees warming will require a concerted effort to curb methane emissions in addition to necessary decarbonization of the energy systems. The fastest way to achieve emission reductions in the 2050 timeframe is likely through implementation of various technical options. The focus of this study is to explore the technical abatement and cost pathways for reducing global methane emissions, breaking reductions down to regional and sector levels using the most recent version of IIASA's Greenhouse gas and Air pollution Interactions and Synergies (GAINS) model. The diverse human activities that contribute to methane emissions make detailed information on potential global impacts of actions at the regional and sectoral levels particularly valuable for policy-makers. With a global annual inventory for 1990-2015 as starting point for projections, we produce a baseline emission scenario to 2050 against which future technical abatement potentials and costs are assessed at a country and sector/technology level. We find it technically feasible in year 2050 to remove 54 percent of global methane emissions below baseline, however, due to locked in capital in the short run, the cumulative removal potential over the period 2020-2050 is estimated at 38 percent below baseline. This leaves 7.7 Pg methane released globally between today and 2050 that will likely be difficult to remove through technical solutions. There are extensive technical opportunities at low costs to control emissions from waste and wastewater handling and from fossil fuel production and use. A considerably more limited technical abatement potential is found for agricultural emissions, in particular from extensive livestock rearing in developing countries. This calls for widespread implementation in the 2050 timeframe of institutional and behavioural options in addition to technical solutions.

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Discrepancy between simulated and observed ethane and propane levels explained by underestimated fossil emissions

Cited by 77 publications

References 81 publications

Methyl, Ethyl, and Propyl Nitrates: Global Distribution and Impacts on Reactive Nitrogen in Remote Marine Environments

Methyl, Ethyl, and Propyl Nitrates: Global Distribution and Impacts on Reactive Nitrogen in Remote Marine Environments

Large changes in biomass burning over the last millennium inferred from paleoatmospheric ethane in polar ice cores

Technical potentials and costs for reducing global anthropogenic methane emissions in the 2050 timeframe –results from the GAINS model

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