Today, human sources are responsible for 60% of global methane emissions, coming primarily from the burning of fossil fuels, decomposition in landfills and the agriculture sector. Nearly a quarter of methane emissions can be attributed to agriculture, much of which is from raising livestock. Rice cultivation and food waste are also important sources of agricultural methane, as nearly a third of all food produced for human consumption is lost or wasted.
At NASA, scientists study the global methane budget to better understand the primary sources of methane emissions and how they contribute to climate change. In addition to the human sources, methane is also produced in natural settings. The greatest natural source of methane is wetlands, which contribute 30% of global methane emissions. Other natural sources of methane emissions include the oceans, termites, permafrost, vegetation and wildfires.
Atmospheric methane concentrations have more than doubled since the Industrial Revolution because of intensive use of oil, gas and coal, rising demand for beef and dairy products and increased production of food and organic waste. Although the increase in atmospheric methane concentrations slowed appreciably near the end of the 20th Century, concentrations have been increasing substantially since 2006, likely as a result of rising emissions from raising livestock, renewed reliance on natural gas and, in recent years, wetlands and global warming.
The Greenhouse Effect and Methane
Greenhouse gases, including methane, contribute to chemical reactions and climate feedbacks. The greenhouse gas molecules trap solar energy by acting like a thermal blanket. Energy from the sun is absorbed by Earth’s surface, though some of this energy is reflected into the atmosphere. The absorbed energy is also re-emitted at infrared wavelengths. Some of the reflected and re-emitted energy re-enters space, but the rest is trapped in the atmosphere by greenhouse gases. Over time, the captured heat warms our climate, increasing global temperatures.
Greenhouse gases in our atmosphere act like a blanket trapping heat from the Sun. This causes global temperatures to rise as the amount of greenhouse gases increases.Credits: NASA/Jesse Kirsch
The human-driven temperature increases can have an impact on methane released from natural sources. For example, permafrost can thaw naturally and emit methane into the atmosphere, but humans have increased the rate at which permafrost thaws due to human-caused warming.
Methane is the world’s second largest contributor to global warming, after carbon dioxide. Although carbon dioxide is more abundant than methane in the atmosphere, a single molecule of methane more effectively traps heat than a single molecule of carbon dioxide.
However, the lifetime of a molecule of methane is shorter than a molecule of carbon dioxide because of natural chemical processes that are quicker at scrubbing methane out of the atmosphere than carbon dioxide. This means that if methane emissions were to decline and the natural chemical scrubbing of methane maintained, atmospheric methane could decrease dramatically in just ten years. Decreasing the amount of methane put into the atmosphere could have a significant and nearly immediate impact on reducing the near-term effects of climate change and may contribute to keeping global temperature change below 2-degrees Celsius.
Why Cows Produce Methane
Cattle, such as dairy cows or beef cattle produce methane as a by-product of digestion. Cattle are ruminant animals, meaning they have specialized digestive systems that allow them to process foods that cannot be digested by humans and most other animals, like fresh grass and uncooked grain. When food enters a bovine’s stomach, it undergoes a process called enteric fermentation: microbes and bacteria partially break down the food particles, which then ferment in the part of the stomach called the rumen. As the food particles ferment, they produce methane. Every time cattle belch – and, to a smaller extent, flatulate – methane is expelled and enters the atmosphere, where it acts as a greenhouse gas.
Methane fast facts: Methane is responsible for 20% of global warming since the Industrial Revolution; In 2018, the food system contributed 33% of all human-caused GHG emissions; In 2015, livestock contributed to 10% of US methane emissions; Methane is about 30 times more potent than CO2 over the span of a century; Europe and the Arctic are the only two regions whose methane emissions decreased from 2000 to 2018; Atmospheric methane concentrations have more than doubled in the last 200 years.Credits: NASA/Jesse Kirsch
NASA’s Eyes on Methane
While methane concentrations are well observed, emissions have to be inferred based on a variety of factors. NASA scientists use a variety of methods to track methane emissions. To get the most accurate estimates possible, they use emissions inventories from countries around the world, simulate wetland methane emissions, and combine this with ground-based, airborne and satellite data using atmospheric models.
In California (and some other regions), researchers fly aircraft equipped with NASA’s Airborne Visible Infrared Imaging Spectrometer – Next Generation, or AVIRIS-NG, and collect highly calibrated data. This data is used in the California Methane Survey, a project jointly funded by NASA, the California Air Resources Board and the California Energy Commission to rapidly identify and report methane leaks.
In Alaska and Northwestern Canada, NASA researchers use satellites, aircraft and field research to better understand methane emissions from thawing permafrost as part of the Arctic Boreal and Vulnerability Experiment, or ABoVE. Researchers have discovered that carbon-rich permafrost is thawing at increasingly high rates, likely as a result of human-induced climate change, making the Arctic an important potential source of methane emissions. According to scientific estimates, this region’s soils store five times more carbon than has been emitted by all human activities in the last 200 years.
NASA researchers combine the data from missions like ABoVE and the California Methane Survey with their knowledge of how methane behaves in the atmosphere to create methane computer models. These models can help scientists and policy makers understand past, current, and future atmospheric methane patterns.
Paths Toward Reduced Methane Emissions
Researchers in a variety of fields have looked into potential solutions to decrease global methane emissions. For example, biogas systems reduce methane emissions by transforming waste from livestock, crops, water and food into energy. Biogas is produced through the same natural process that occurs in landfills to break down organic waste. However, biogas systems harness the gas that is produced and use it as a clean, renewable and reliable energy source rather than let it release into the atmosphere as a greenhouse gas.
A study led by Professor Ermias Kebreab from the University of California-Davis discovered that introducing a few ounces of seaweed into beef cattle diets could reduce their methane emissions by over 82%.
These types of technological – and biological – innovations may provide decision-makers, ranchers and others with more options for managing our future methane.
Credits: NASA/Jesse Kirsch/courtesy of Tracy Schohr
by Emily Fischer
NASA’s Earth Science News Team
Where in the infrared wavelengths are the absorption bands of this extremely powerful greenhouse gas?
NIST data is here. The abosrption is around 1300 wavenumbers/cm = 7.7 um, and 3000 wavenumbers = 3.3 um.
Thanks.
20% x 10% = 2%…Cows are responsible for 2% of global warming. Cows burp methane, methane photooxidizes to CO2 and water vapor, CO2 and water vapor plus sunlight make forage, cows eat forage….It’s rock-paper-scissors, and has been going on since ungulates evolved.
All enviropropaganda starts at some carefully chosen spot in a cycle and proceeds only far enough to make a point. Nasa, excellence in science.
Fixed that for you.
Of course, this relates to their “climate bullshit” arm, not to the part of NASA dedicated to space exploration, but never let a good excuse for more funding limit your “mission,” I suppose.
“Greenhouse gases in our atmosphere act like a blanket trapping heat from the Sun”. What complete non-scientific nonsense
Yes, especially when ten times as much couldn’t prevent the Earth from plunging into an ice age.
Beautiful how they even try to explain the greenhouse effect – and fail.
It is easy to scare people with things they cannot see. And, if people do see a cow burp, there is no conception of the scale of this in relation to the earth’s atmosphere.
How do you “burn fossil fuels” without burning the methane?
My guess is that they are referring to methane leakage during drilling operations. But not knowing what you are writing about is pretty typical for AGW alarmists.
Methane is the ultimate renewable biogas. When we burn it, we get energy from four hydrogen atoms for every carbon atom. We have had the technology to use it for years. Examples are burning it that is produced in waste treatment plants and industrial use of that , that is produced in land fills. Just think about the amount of energy could be produced by using the waste treatment technology at all the big hog farms instead of storing it in lagoons. Then there is the big fact that nature has already produced more methane than we can use in decades. We just need more pipelines.
“Atmospheric methane concentrations have more than doubled in the last 200 years.”
Was this corrected for the 50-75million buffalo no longer filling up the Great Plains, or the 10s of millions of grassland animals killed in Africa since the 19th century? Whales? Millions of hectares of wetlands drained, filled?
The big poker tell is always what they don’t tell you. Methane in the atmosphere is less than 2.0ppm (yes, two ppm)!!! Indeed, they report the amount in parts per billion – ppb because they are a bit embarrassed by the small amount. Why not tell us that in a shopper’s list of ‘facts about methane’ that you give.
The shift over to methane marks the beginning of terror among climate wroughters that CO2 may not be the ‘Control Knob’ for temperatures after all (Jim Inundation-of-Boiling-Seas Hansen and protegé Gavin Schmidt have recently admitted that models are running a way too hot and something has to be done about it!). Indeed, they opine that a 30yr cooling period can’t be ruled out.
If this is so, not only will the present 6 yr cooling deepen to extend the 18yr Dreaded Pause, but it will erase the 18yr warming stint -1980-1997, that created this multitrillion dollar false alarm in the first place and join up with the 35yr “Ice Age Cometh” cooling period. Then, unraveling the algorithms that pushed the 1930s-early 40s 20th Century high stand of temperatures down, 0.5°C, all of the modern warming period will have taken place prior to mid century, before CO2 became a Planetary Greening Agent.
Methane 30 times more powerful a GHG than CO2? No problem.
Termites are notorious methane generators. Very small yet the billions on the planet certainly add up.
Every carbon based life form that rots in an anaerobic environment ie smelly, damp compost bin or industrial scale rubbish tip produces methane. So does the North Atlantic rift which belches out methane from time to time.
Methane – yet another reason to drain the swamp.