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In a 2017 press release, Don’t blame cattle – it’s humans who caused methane levels to skyrocket., Robert Howarth, Professor of Ecology and Evolutionary Biology at Cornell University claims that there was a recent surge in global methane emissions, that it had been falsely attributed to cattle farming, but that fossil fuels were the correct source.

“Several papers over the past 18 months have concluded that fossil fuels may not be cause of the latest surge in methane. However, there is very strong evidence that these papers are wrong. Several of the papers have concluded that an increase in emissions from cows and cattle is the cause. This conclusion conflicts strongly with the satellite data, which shows that the increase in global methane emissions over the past decade has come mostly from the United States: numbers of cows and cattle have decreased in the U.S. over this decade, and so this cannot be the cause.

“By far, the most likely cause of the increase in my opinion is from shale gas and shale oil, as the increase in emissions from the U.S. indicated by the satellite data coincides closely in time with the shale gas revolution. No other major change in activities over this time period in the U.S. makes any real sense.

Was there a surge in global methane emissions in 2017? Was it caused by cattle farming, fossil fuel consumption or other sources?

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You ask ‘Was there a surge in global methane emissions in 2017? Was it caused by cattle farming, fossil fuel consumption or other sources?’ The first partial quotes (below) are dated 2020:

“The atmosphere does not suggest that anything has slowed down for methane emissions in the last two years,” Rob Jackson, an environmental scientist at Stanford University and co-author of both studies, tells Science News. “If anything, it’s possibly speeding up.” Per Science News, the concentration of methane in Earth’s atmosphere increased from 1,857 parts per billion in 2017 to 1,875 parts per billion in 2019, according to NOAA.

Global emissions of the potent greenhouse gas methane hit an all-time high in 2017, according to a pair of new studies released this week by researchers with the Global Carbon Project. Agriculture, landfill waste and fossil fuel production are driving the sharp increase in methane emissions from human activities

Human activities were responsible for more than half of the methane emissions seen from 2000 to 2017, according to the research. Overall, agriculture contributed two-thirds of humanity’s share of emissions of the colorless gas while fossil fuels were responsible for most of the remaining third. Emissions of methane from agriculture and fossil fuels rose nearly 11 and 15 percent, respectively, compared to their 2000 to 2006 averages.

Source: https://www.smithsonianmag.com/smart-news/world-methane-emissions-hit-new-high-180975362/#:~:text=Per%20Science%20News%2C%20the%20concentration,in%202019%2C%20according%20to%20NOAA.

The second report, from Earth Observatory, NASA, found that global emissions of methane totalled 576 million metric tons per year for the 2008 to 2017 decade—a 9% increase compared to the previous decade. Although emissions briefly stabilized between 2000 and 2006, there was rapid growth from 2008–2017.

“The increase was primarily fuelled by human activities—especially agriculture and fossil fuels,” explained Benjamin Poulter, a NASA scientist and coordinator of the wetland methane emissions estimates for the Global Carbon Project. “The specific activities that we linked to the biggest increases were raising livestock, coal mining, waste disposal in landfills, and gas and oil production.”

Across the study years, wetlands contributed 30 percent of global methane emissions, with oil, gas, and coal activities accounting for 20 percent. Agriculture, including enteric fermentation and manure management, made up 24 percent of emissions, and landfills comprised 11 percent. Sixty-four percent of emissions came from tropical regions of South America, Asia, and Africa, with temperate regions accounting for 32 percent and the Arctic contributing 4 percent.

Source: https://earthobservatory.nasa.gov/images/146978/methane-emissions-continue-to-rise

Main Points regarding methane from agriculture and fossil fuels: Agriculture contributed two-thirds of humanity’s share of emissions of methane while fossil fuels were responsible for most of the remaining third. Emissions of methane from agriculture and fossil fuels rose nearly 11 and 15 percent, respectively, compared to their 2000 to 2006 averages. Agricultural emissions come primarily from livestock such as cattle and sheep, which burp methane as a result of how they digest their food. In the fossil fuel sector, methane is released by coal mining and leaks from oil and gas wells, pipelines as well as gas stoves in peoples’ homes.

Conclusion: From the two sources I found it would appear that there has been an increase in methane, mainly from cattle farming. However, I suspect there may be other reports that come to a different point of view.

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  • Great first contribution! Welcome. So, is it fair to summarise like so? There has been an increase. In absolute terms, more of the increase has come from cattle farming than fossil-fuels. However, fossil fuels have slightly increased their percentage of the contributions to methane.
    – Oddthinking
    Commented Jan 7, 2023 at 1:17
  • @Oddthinking - yes, that would be a fair summary. The reason I did not post a conclusion like that (in response to the specific question re comparing cattle farming with fossil fuel consumption and other sources) is my lack of scientific comprehension. Should I now post such a summary?
    – Lesley
    Commented Jan 7, 2023 at 10:54
  • Up to you. A short summary can help some people, but don't make any statements you don't feel you can stand behind.
    – Oddthinking
    Commented Jan 7, 2023 at 16:21

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