Methane in the Atmosphere Rises

R B Jackson, M Saunois, P Bousquet , J G Canadell, B Poulter, A R Stavert , P Bergamaschi, Y Niwa , A Segers and A Tsuruta: Increasing anthropogenic methane emissions arise equally from agricultural and fossil fuel sources, Environ. Res. Lett. 15 (2020) 071002 https://iopscience.iop.org/article/10.1088/1748-9326/ab9ed2/pdf.


As you have probably heard or read the lock downs associated with the Covid-19 pandemic has reduced global carbon emissions, albeit temporarily. However, Scientists at the Stanford’s School of Earth Energy and Environmental Sciences believe it is unlikely that methane levels in the environment have seen the same reduction because many of the sources of methane have continued unabated. The paper cited above tells the story or rising methane levels. Methane levels in the atmosphere have risen since 2000. We care about methane because climate scientists estimate that the gas is responsible for about one quarter of the global warming that has happened since industrialization.

According to the paper cited above the amount of methane in Earth’s atmosphere continues to rise. Concentrations of methane now exceed 1875 parts per billion, about 2.5 times as much as was in the atmosphere in the 1850s. The researchers synthesized all known data about methane from the US EPA’s emissions inventories, atmospheric measurements, and models to assemble a global “methane budget” that details which processes add the gas to the atmosphere and which remove it.

 

from the Global Carbon Project

According to their study, wetlands contributed 30% of global methane emissions, with oil, gas, and coal activities accounting for 20%. Agriculture, including enteric fermentation (cow belching), manure management, and rice cultivation, made up 24% of emissions, and landfill gas contributed 11%. Sixty-four percent of methane emissions came from the tropical regions of South America, Asia, and Africa, with temperate regions accounting for 32% and the Arctic contributing 4%.

Methane emissions rose most sharply in Africa and the Middle East; China; and South Asia and Oceania. Each of these three regions increased emissions by an estimated 10 to 15 million tons per year during the study period. The United States followed behind, increasing methane emissions by 4.5 million tons, mostly due to more natural gas drilling, distribution and consumption.Europe was the only region where methane emissions decreased over the study period, attributed to reductions chemical manufacturing and growing food more efficiently with better management of manure and landfills. 

According to Dr. Jackson and his colleagues, curbing methane emissions will require reducing fossil fuel use and controlling fugitive emissions such as leaks from pipelines and wells, as well as changes to the way we feed cattle, grow rice and eat. “We’ll need to eat less meat and reduce emissions associated with cattle and rice farming,” Dr. Jackson said, “and replace oil and natural gas in our cars and homes.”

Rob Jackson is Stanford’s Michelle and Kevin Douglas Provostial Professor. Dr. Jackson and his lab examine the many ways people affect the Earth.  They're currently examining the effects of climate change and droughts on forest and grassland ecosystems. They are also working to measure and reduce greenhouse gas emissions through the Global Carbon Project (globalcarbonproject.org), which Jackson chairs; examples of new research Rob leads include establishing a global network of methane tower measurements at more than 80 sites worldwide and measuring and reducing methane emissions from oil and gas wells, city streets, and homes and buildings.

Their work has real practical applications for reducing the emission of greenhouse gases, though he admits Human driven emissions are in many ways easier to pin down than those from natural sources.