Abstract
Methane and ethane are the most abundant hydrocarbons in the atmosphere and they affect both atmospheric chemistry and climate. Both gases are emitted from fossil fuels and biomass burning, whereas methane (CH(4)) alone has large sources from wetlands, agriculture, landfills and waste water. Here we use measurements in firn (perennial snowpack) air from Greenland and Antarctica to reconstruct the atmospheric variability of ethane (C(2)H(6)) during the twentieth century. Ethane levels rose from early in the century until the 1980s, when the trend reversed, with a period of decline over the next 20 years. We find that this variability was primarily driven by changes in ethane emissions from fossil fuels; these emissions peaked in the 1960s and 1970s at 14-16 teragrams per year (1 Tg = 10(12) g) and dropped to 8-10 Tg yr(-1) by the turn of the century. The reduction in fossil-fuel sources is probably related to changes in light hydrocarbon emissions associated with petroleum production and use. The ethane-based fossil-fuel emission history is strikingly different from bottom-up estimates of methane emissions from fossil-fuel use, and implies that the fossil-fuel source of methane started to decline in the 1980s and probably caused the late twentieth century slow-down in the growth rate of atmospheric methane.
Highlights
Methane and ethane are the most abundant hydrocarbons in the atmosphere and they affect both atmospheric chemistry and climate
Ethane levels rose from early in the century until the 1980s, when the trend reversed, with a period of decline over the 20 years. We find that this variability was primarily driven by changes in ethane emissions from fossil fuels; these emissions peaked in the 1960s and 1970s at 14–16 teragrams per year (1 Tg 5 1012 g) and dropped to 8–10 Tg yr[21] by the turn of the century
The ethane atmospheric histories based on the WAIS-D and South Pole firn air measurements display the same trends for the period since 1950 (Fig. 1)
Summary
Recent decreases in fossil-fuel emissions of ethane and methane derived from firn air. Ethane is an organic trace gas that is primarily emitted to the atmosphere during mining, processing, transport and consumption of fossil fuels, during use of biofuels, and during biomass burning[4,5,6]. It acts as a precursor of ozone and carbon monoxide in the troposphere. Atmospheric histories based on South Pole firn air measurements are constrained for the past 80–90 years The ethane atmospheric histories based on the WAIS-D and South Pole firn air measurements display the same trends for the period since 1950 (Fig. 1). Mean annual ethane levels measured over Summit and South Pole are consistent with those at other high-latitude sites, indicating that the
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
