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In new ozone alert, a warning of harm to plants and to people – ‘We are on track to return to the maximum ethane levels we saw in the 1970s in only about three more years’

Tuesday, October 18, 2016 9:30
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Desdemona Despair

Ethane and propane trends at global monitoring sites. Mole fraction changes are indicated by the colour scale with marker size corresponding to the R2 of the fit multiplied by the fraction of available site data. Results from overlapping GGGRN flask and in situ measurements are shown in black. Graphic: Helmig, et al., 2016 / Nature Geoscience

By Jim Robbins
17 October 2016

(Yale e360) – For the last four years Jack Fishman, a professor of meteorology at St. Louis University, has guided the planting of five gardens in the Midwest, gardens that have a distinct purpose: to show the impacts of an invisible gas that is damaging and contributing to the premature death of forests, crops, and other plants — and also humans.

“The idea of the ozone garden is that it is a canary in the coal mine,” said Fishman, who recently planted one of the gardens at the Missouri Botanical Gardens. The snap beans, milkweed, coneflowers, and other plants that turn brown and sickly from exposure to ozone when it occurs at ground level, he said, are “natural bio-indicators showing this pollutant is harmful to anything that lives — a human, a squirrel, or plants. It's the only way to show the real-time impacts of something that's happening to our planet.”

The ozone crisis may fly under the radar compared to climate change, but it is entwined with that mother of all problems. And it’s nothing new for Fishman. He began studying ground-level ozone for NASA in 1977 and has been warning about its impacts since the 1980s. Ozone is highly toxic, even at very low concentrations. Over the last few decades, background levels have steadily increased, though pollution controls have brought down the highest concentrations in many places. And while what scientists know about the effects of ground-level ozone on life on earth is deadly serious, the subject is not all that well-researched — and what they don't know is potentially disastrous. […]

A major and growing source of ozone in the United States is oil and gas fields. There are 1.5 million oil and gas wells in the U.S. and ethane, butane, methane, and propane are among the ozone precursors released from pipes, inadvertently and purposefully, by oil and gas companies. Over the last 40 years, ethane levels had dropped by 60 percent. But a study published earlier this year in the journal Nature Geoscience found that much of that drop had been reversed in the last five years by emissions from oil and gas wells. “If this rate continues, we are on track to return to the maximum ethane levels we saw in the 1970s in only about three more years,” said Detlev Helmig, an atmospheric scientist at the University of Colorado, Boulder and an author of the study. [more]

In New Ozone Alert, A Warning Of Harm to Plants and to People

Histories of atmospheric ethane. Reconstructed 1950–2010 ethane history from firn air sampling at NEEM in Greenland3 with 2009.5 mean seasonally detrended atmospheric values at five Arctic sites for comparison. Graphic: Helmig, et al., 2016 / Nature Geoscience

By Jim Scott
13 June 2016

(UC Boulder) – Global emissions of ethane, an air pollutant and greenhouse gas, are on the uptick again, according to a new study led by the University of Colorado Boulder.

The team found that a steady decline of global ethane emissions following a peak in about 1970 ended between 2005 and 2010 in most of the Northern Hemisphere and has since reversed, said CU-Boulder Associate Research Professor Detlev Helmig, lead study author. Between 2009 and 2014, ethane emissions in the Northern Hemisphere increased by about 400,000 tons annually, the bulk of it from North American oil and gas activity, he said.

The decline of ethane and other non-methane hydrocarbons (NMHC) starting around 1970 is believed to be primarily due to better emission controls, said Helmig. The controls resulted in reduced emissions from oil and gas production, storage and distribution, as well as combustion exhaust from cars and trucks.

“About 60 percent of the drop we saw in ethane levels over the past 40 years has already been made up in the past five years,” said Helmig. “If this rate continues, we are on track to return to the maximum ethane levels we saw in the 1970s in only about three more years. We rarely see changes in atmospheric gases that quickly or dramatically.”

Ethane, propane and a host of other NMHCs are released naturally by the seepage of fossil carbon deposits, volcanic activity and wildfires, said Helmig. But human activities, which also include biomass burning and industrial use, constitute the most dominant source of the NMHCs worldwide.

“These human sources make up roughly three-quarters of the atmospheric ethane that is being emitted,” said Helmig.

The air samples for the study were collected from more than 40 sites around the world, from Colorado and Greenland to Germany, Switzerland, New Zealand and the Earth’s polar regions. More than 30,000 soda bottle-sized air containers were sampled at the National Oceanic and Atmospheric Administration’s (NOAA) Earth Systems Research Laboratory (ESRL) in Boulder over the past decade.

The study also showed that among the air sampling locations around the world, the largest increases in ethane and shorter-lived propane were seen over the central and eastern United States, areas of heavy oil and gas activity, said Helmig.

“We concluded that added emissions from U.S. oil and gas drilling have been the primary source for the atmospheric ethane trend reversal,” he said.

The study, published today in Nature Geoscience, also indicated that emissions of total NMHC in the Northern Hemisphere are now increasing by roughly 1.2 million tons annually.

The findings from the flask network, which INSTAAR and NOAA have been operating for more than 10 years, were supported by additional measurements showing very similar ethane behavior from a number of continuous global monitoring sites, he said.

A component of natural gas, ethane plays an important role in Earth’s atmosphere. As it breaks down near Earth’s surface it can create ground-based ozone pollution, a health and environmental risk.

Chemical models by the team show that the increase in ethane and other associated hydrocarbons will likely cause additional ground-based ozone production, particularly in the summer months, he said.

“Ethane is the second most significant hydrocarbon emitted from oil and gas after methane,” said Helmig. “Other studies show on average there is about 10 times as much methane being emitted by the oil and gas industry as ethane.”

There is high interest by scientists in methane since it is a strong greenhouse gas, said Helmig. The new findings on ethane increases indicate there should be more research on associated methane emissions.

Other CU-Boulder co-authors on the study included INSTAAR graduate student Samuel Rossabi and researcher Jacques Hueber. The paper also included scientists from NOAA, the National Center for Atmospheric Research in Boulder and institutes in Germany, England, Switzerland, Belgium and New Zealand.

Global ethane concentrations rising again, study finds

ABSTRACT: Non-methane hydrocarbons such as ethane are important precursors to tropospheric ozone and aerosols. Using data from a global surface network and atmospheric column observations we show that the steady decline in the ethane mole fraction that began in the 1970s1, 2, 3 halted between 2005 and 2010 in most of the Northern Hemisphere and has since reversed. We calculate a yearly increase in ethane emissions in the Northern Hemisphere of 0.42 (±0.19) Tg yr−1 between mid-2009 and mid-2014. The largest increases in ethane and the shorter-lived propane are seen over the central and eastern USA, with a spatial distribution that suggests North American oil and natural gas development as the primary source of increasing emissions. By including other co-emitted oil and natural gas non-methane hydrocarbons, we estimate a Northern Hemisphere total non-methane hydrocarbon yearly emission increase of 1.2 (±0.8) Tg yr−1. Atmospheric chemical transport modelling suggests that these emissions could augment summertime mean surface ozone by several nanomoles per mole near oil and natural gas production regions. Methane/ethane oil and natural gas emission ratios could suggest a significant increase in associated methane emissions; however, this increase is inconsistent with observed leak rates in production regions and changes in methane’s global isotopic ratio.

Reversal of global atmospheric ethane and propane trends largely due to US oil and natural gas production

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