There has been an alarming uptick in atmospheric methane in recent years, following a flattening of concentrations from 2000 to around 2007
Just from livestock methane emissions, study’s revisions resulted in 11 percent more methane in a recent year than previously estimated– not the biggest contributor to the annual methane budget in the atmosphere, but it may be the biggest contributor to increases in the atmospheric budget over recent years
When it comes to climate change, we know where the most important warming agent — carbon dioxide — is coming from….But the second-most potent greenhouse warming agent — the hard-hitting, if short-lived, gas known as methane — presents more of a mystery. There has clearly been an alarming uptick in atmospheric methane in recent years, following a flattening of concentrations from 2000 to around 2007. But the cause of this particular pattern has been hotly debated, with some blaming the fracked natural gas boom (natural gas is primarily composed of methane) and others pointing to causes such as agriculture.
Now, new research published Thursday in the journal Carbon Balance and Management …. point the finger at agriculture once again. And more specifically, at cattle and other livestock.
“Just from livestock methane emissions, our revisions resulted in 11 percent more methane in a recent year than what we were previously estimating,” said Julie Wolf, lead author of the study who completed the work while a postdoc at the institute and now works at the Department of Agriculture. “It’s not the biggest contributor to the annual methane budget in the atmosphere, but it may be the biggest contributor to increases in the atmospheric budget over recent years…
….Cows and other ruminant animals release methane into the atmosphere as a result of a process called “enteric fermentation” — a technical term that basically refers to the digestive chemistry in the animals’ stomachs. As the Environmental Protection Agency explains, the methane produced in this process “is exhaled or belched by the animal and accounts for the majority of emissions from ruminants.”
Furthermore, the animals’ waste also fills the atmosphere with methane depending on how it is handled, meaning that “manure management” is categorized as a separate source of methane emissions….
Our results suggest that livestock methane emissions, while not the dominant overall source of global methane emissions, may be a major contributor to the observed annual emissions increases over the 2000s to 2010s.
… The study, originally published in the journal PLoS Genetics last year, showed that a cow’s genetics determine which microbes populate its gut — and some of those microbes produce the methane that eventually makes its way into the atmosphere…
… It turned out that the different groups differed in the amounts of methane they emitted — by a lot. “The highest [group emitted] 200 grams per day, and the lowest [group’s] methane emission was at 140 grams per day. So there is a large difference,” says Rainer Roehe, the lead author on the study and a geneticist at Scotland’s Rural College.
Roehe says the different diets made a difference in how much methane the cows emitted, but when they ranked the cow families based on how much gas they were expelling, the least gassy family emitted the least methane no matter what they ate. On the flipside, the cows in the family that gave off the most gas were still the biggest offenders regardless of what they were eating. Roehe says that suggests genetics is playing a big role in shaping which microbes exist in any individual cow’s gut and is the reason why some cows belch and fart less than others….
Conclusion: The recent call for improved management of grazing systems as part of an international climate change mitigation strategy is critical, particularly in light of many existing beef LCAs [life cycle assessments] that have concluded that beef cattle produced in grazing systems are a particularly large sources of GHG emissions. To identify the best opportunities to reduce GHG emissions from beef production, a systems approach that considers the potential to increase soil C and reduce ecosystem-level GHG emissions is essential. Using a combination of on-farm collected data, literature values, and IPCC Tier 1 methodology, we generated an LCA that indicates highly-managed grass-ﬁnished beef systems in the Upper Midwestern United States can mitigate GHG emissions through SCS while contributing to food provisioning at stocking rates as high as 2.5 AU ha-1. From this data, we conclude that well-managed grazing and grass-ﬁnishing systems in environmentally appropriate settings can positively contribute to reducing the carbon footprint of beef cattle, while lowering overall atmospheric CO2 concentrations.
Measurements over Canada’s Mackenzie River Basin suggest that thawing permafrost is starting to free greenhouse gases long trapped in oil and gas deposits.
The conclusion of the authors: The warming climate triggers not only the natural production of biogenic methane, it can also lead to stronger emissions of fossil gas. This contributes significantly to the permafrost-carbon-climate feedback
Global warming may be unleashing new sources of heat-trapping methane from layers of oil and gas that have been buried deep beneath Arctic permafrost for millennia.As the Earth’s frozen crust thaws, some of that gas appears to be finding new paths to the surface through permafrost that’s starting to resemble Swiss cheese in some areas, scientists said.
In a study [see below] released today, the scientists used aerial sampling of the atmosphere to locate methane sources from permafrost along a 10,000 square-kilometer swath of the Mackenzie River Delta in northwestern Canada, an area known to have oil and gas desposits.
Deeply thawed pockets of permafrost, the research suggests, are releasing 17 percent of all the methane measured in the region, even though the emissions hotspots only make up 1 percent of the surface area, the scientists found.
In those areas, the peak concentrations of methane emissions were found to be 13 times higher than levels usually caused by bacterial decomposition—a well-known source of methane emissions from permafrost—which suggests the methane is likely also coming from geological sources, seeping up along faults and cracks in the permafrost, and from beneath lakes.
…A 2012 study made similar findings near the edge of permafrost areas and around melting glaciers. Now, there is more evidence that “the loss of permafrost and glaciers opens conduits for the release of geologic methane to the atmosphere, constituting a newly identified, powerful feedback to climate warming,” said the 2012 study’s author, Katey Walter Anthony, a permafrost researcher at the University of Alaska Fairbanks.
“Together, these studies suggest that the geologic methane sources will likely increase in the future as permafrost warms and becomes more permeable,” she said…. Since the study only covered two years, it doesn’t show long-term trends, but it makes a strong argument that there is significant methane escaping from trapped layers of oil and gas, Schuur said
Study in the Mackenzie Delta in Canada shows high amount of geological methane emission
The thawing permafrost soils in the Arctic regions might contribute to the greenhouse effect in two respects: on the one hand rising temperatures lead to higher microbial methane production close to the surface. On the other hand thawing subsurface opens increasingly pathways for old, geologic methane…
Katrin Kohnert, Andrei Serafimovich, Stefan Metzger, Jörg Hartmann, Torsten Sachs. Strong geologic methane emissions from discontinuous terrestrial permafrost in the Mackenzie Delta, Canada. Scientific Reports, 2017; 7 (1) DOI: 10.1038/s41598-017-05783-2
In a surprising victory for President Barack Obama’s environmental legacy, the Senate voted 51-49 on Wednesday to uphold an Obama-era climate change regulation to control the release of methane from oil and gas wells on public land….to repeal the 2016 Interior Department rule to curb emissions of methane, a powerful planet-warming greenhouse gas. Senators John McCain of Arizona, Lindsey Graham of South Carolina and Susan Collins of Maine, all Republicans who have expressed concern about climate change and backed legislation to tackle the issue, broke with their party to join Democrats and defeat the resolution.
The vote also was the first, and probably the only, defeat of a stream of resolutions over the last four months — pursued through the once-obscure Congressional Review Act — to unwind regulations approved late in the Obama administration…
…On Tuesday, Gwen Lachelt, a county commissioner from La Plata County, Colo., which sits near the Four Corners where the state abuts New Mexico, Utah and Arizona, buttonholed Mr. McCain in a Senate elevator to tell him that county residents have suffered from methane pollution drifting over from New Mexico, and she noted that the same pollution could affect his state.
“I’m not taking credit for swaying Senator McCain’s vote, but I told him that right across the state line from my county are 35,000 oil and gas wells in New Mexico,” she said. “We all share an airshed and the winds that bring methane pollution our way, and without this federal rule, I have no way as a county commissioner to protect the people in my county. In the Four Corners, we all live under the largest methane cloud.”…
A new study is one of the first in the world to show that tree trunks in upland forests actually emit methane rather than store it, representing a new, previously unaccounted source of this powerful greenhouse gas.
An important discovery surrounding plants used to feed livestock has been released by scientists. They report that plants growing in warmer conditions are tougher and have lower nutritional value to grazing livestock, potentially inhibiting milk and meat yields and raising the amount of methane released by the animals. Higher amounts of methane are produced when plants are tougher to digest — an effect of a warmer environment. Methane is a potent greenhouse gas, around 25 times better at trapping heat than carbon dioxide. More than 95% of the methane produced by cows comes from their breath through eructation (belching) as they “chew the cud.”
“Our research has shown that cultivating more nutritious plants may help us to combat the challenges of warmer temperatures. We are undertaking work at Kew to identify the native forage plants that are associated with high meat and milk production and less methane, attempting to increase their presence on the grazing landscape. We are also developing our models to identify regions where livestock are going to be exposed to reductions in forage quality with greater precision. It is going to be important to put plans in place to help those countries exposed to the most severe challenges from climate change to adapt to a changing world” said Dr Mark Lee.
Mark A. Lee, Aaron P. Davis, Mizeck G. G. Chagunda, Pete Manning. Forage quality declines with rising temperatures, with implications for livestock production and methane emissions. Biogeosciences, 2017; 14 (6): 1403 DOI: 10.5194/bg-14-1403-2017
Americans’ fondness for milk, yogurt, cheese and juicy burgers requires a huge livestock industry, with nearly 90 million head of cattle in the U.S. in any one year. All those cows mean significant methane emissions.
With estimates from the United Nations that methane accounts for 44 percent of all greenhouse gas emissions from livestock production, and new determination – including legislation in California – to reduce methane emissions from farms, we need to figure out how to quantify and then reduce those emissions….
California is taking its fight against global warming to the farm
By TERENCE CHEA, Associated Press Nov 29 2016
GALT, Calif. (AP) — California is taking its fight against global warming to the farm. The nation’s leading agricultural state is now targeting greenhouse gases produced by dairy cows and other livestock.
Despite strong opposition from farmers, Gov. Jerry Brown signed legislation in September that for the first time regulates heat-trapping gases from livestock operations and landfills. Cattle and other farm animals are major sources of methane, a greenhouse gas many times more potent than carbon dioxide as a heat-trapping gas. Methane is released when they belch, pass gas and make manure.
“If we can reduce emissions of methane, we can really help to slow global warming,” said Ryan McCarthy, a science advisor for the California Air Resources Board, which is drawing up rules to implement the new law.
Livestock are responsible for 14.5 percent of human-induced greenhouse gas emissions, with beef and dairy production accounting for the bulk of it, according to a 2013 United Nations report….