University of Rochester
Methane is a powerful greenhouse gas and large contributor to global warming. Methane emissions to the atmosphere have increased by approximately 150 percent over the past three centuries, but it has been difficult for researchers to determine exactly where these emissions originate; heat-trapping gases like methane can be emitted naturally, as well as from human activity.
University of Rochester researchers Benjamin Hmiel, a postdoctoral associate in the lab of Vasilii Petrenko, a professor of earth and environmental sciences, and their collaborators, measured methane levels in ancient air samples and found that scientists have been vastly underestimating the amount of methane humans are emitting into the atmosphere via fossil fuels. In a paper published in Nature, the researchers indicate that reducing fossil fuel use is a key target in curbing climate change.
“Placing stricter methane emission regulations on the fossil fuel industry will have the potential to reduce future global warming to a larger extent than previously thought,” Hmiel says.
TWO TYPES OF METHANE
Methane is the second largest anthropogenic–originating from human activity–contributor to global warming, after carbon dioxide. But, compared to carbon dioxide, as well as other heat-trapping gases, methane has a relatively short shelf-life; it lasts an average of only nine years in the atmosphere, while carbon dioxide, for instance, can persist in the atmosphere for about a century. That makes methane an especially suitable target for curbing emission levels in a short time frame.
“If we stopped emitting all carbon dioxide today, high carbon dioxide levels in the atmosphere would still persist for a long time,” Hmiel says. “Methane is important to study because if we make changes to our current methane emissions, it’s going to reflect more quickly.”
Methane emitted into the atmosphere can be sorted into two categories, based on its signature of carbon-14, a rare radioactive isotope. There is fossil methane, which has been sequestered for millions of years in ancient hydrocarbon deposits and no longer contains carbon-14 because the isotope has decayed; and there is biological methane, which is in contact with plants and wildlife on the planet’s surface and does contain carbon-14. Biological methane can be released naturally from sources such as wetlands or via anthropogenic sources such as landfills, rice fields, and livestock. Fossil methane, which is the focus of Hmiel’s study, can be emitted via natural geologic seeps or as a result of humans extracting and using fossil fuels including oil, gas, and coal.
Scientists are able to accurately quantify the total amount of methane emitted to the atmosphere each year, but it is difficult to break down this total into its individual components: Which portions originate from fossil sources and which are biological? How much methane is released naturally and how much is released by human activity?
“As a scientific community we’ve been struggling to understand exactly how much methane we as humans are emitting into the atmosphere,” says Petrenko, a coauthor of the study. “We know that the fossil fuel component is one of our biggest component emissions, but it has been challenging to pin that down because in today’s atmosphere, the natural and anthropogenic components of the fossil emissions look the same, isotopically.”
TURNING TO THE PAST
In order to more accurately separate the natural and anthropogenic components, Hmiel and his colleagues turned to the past, by drilling and collecting ice cores from Greenland. The ice core samples act like time capsules: they contain air bubbles with small quantities of ancient air trapped inside. The researchers use a melting chamber to extract the ancient air from the bubbles and then study its chemical composition.
Hmiel’s research focused on measuring the composition of air from the early 18th century–before the start of the Industrial Revolution–to the present day. Humans did not begin using fossil fuels in significant amounts until the mid-19th century. Measuring emission levels before this time period allows researchers to identify the natural emissions absent the emissions from fossil fuels that are present in today’s atmosphere. There is no evidence to suggest natural fossil methane emissions can vary over the course of a few centuries.
By measuring the carbon-14 isotopes in air from more than 200 years ago, the researchers found that almost all of the methane emitted to the atmosphere was biological in nature until about 1870. That’s when the fossil component began to rise rapidly. The timing coincides with a sharp increase in the use of fossil fuels.
The levels of naturally released fossil methane are about 10 times lower than previous research reported. Given the total fossil emissions measured in the atmosphere today, Hmiel and his colleagues deduce that the manmade fossil component is higher than expected–25-40 percent higher, they found.
CLIMATE CHANGE IMPLICATIONS
The data has important implications for climate research: if anthropogenic methane emissions make up a larger part of the total, reducing emissions from human activities like fossil fuel extraction and use will have a greater impact on curbing future global warming than scientists previously thought.
To Hmiel, that’s actually good news. “I don’t want to get too hopeless on this because my data does have a positive implication: most of the methane emissions are anthropogenic, so we have more control. If we can reduce our emissions, it’s going to have more of an impact.”
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This study was supported by the US National Science Foundation and the David and Lucille Packard Foundation.
As their previous Shibboliths fail the scientific test, the Alarmists simply move on to new Alarm Fields or dig up some Golden Oldies from the past. As things continue to get better it’s always worse than we thought.
If we are emitting far more methane than previously estimated, and if no one has already adjusted temperatures to match, then the conclusion is methane is far less dangerous than we thought… It can only account for a small amount of the observed warming but it takes far more of it.
If natural methane emissions are far less than we previously estimated, then cows are far less dangerous then we thought, and a thawing permafrost is far less dangerous then we thought.
Sooo…I guess we can all relax now.
Don’t relax too much.
Or else there will be more methane released.
Not again … “This study was supported by the US National Science Foundation.”
They are also doing great job of unnecessarily scaring our kids … https://wattsupwiththat.com/2019/09/03/a-teacher-friendly-guide-to-climate-alarmism/
Sorry, the NSF is no longer credible.
Did they previously underestimate the number of vegans?
It was inevitable.
The climate debate has become what it was always going to be.
A fart in a thunderstorm.
What’s cute about little children is how they fart when they laugh.
Can’t have that anymore I guess.
The occasional cortex is right – we should eat them.
Several numbers used by the EPA in the past are demonstrable wrong.
Upland soil is listed as a 30tg methane sink. This is wrong. Upland soil
contributes natural gas to the atmosphere. It enters the soil from
below, upwelling from deep in the earth. In soil which has adequate
moisture, the natural gas is oxidized by microbes, contributing CO2
to the atmosphere, so the upland topsoil as a sink is more than 100%
wrong. When methane hits the atmosphere, it rises.
On cattle, first of all, they do not fart. They belch. Then you would
have to subtract the buffalo contribution because humans removed
that source from the US. The tall grass which once covered the US
plains would die and rot, contributing methane or CO2 to the
atmosphere if not eaten by ruminants or prairie dogs. The grass
frequently burned, again contributing CO2 and other gasses.
The same upwelling natural gas on rice farms is eaten by the microbial
culture when the paddies are not flooded. When they are flooded, the
water causes the natural gas to rise faster than the culture can consume
it. Is the upwelling natural gas a human contribution? If flooding land is
a human contribution, then all natural gas upwelling from any reservoir
is a human contribution, less the CO2 contributed by the top soil.
NASA, in their study released January 20, 2020, says that CO2 in that
atmosphere has a cooling effect.
https://principia-scientific.org/carbon-dioxide-is-a-cooling-gas-according-to-nasa/
The subject is very complicated and errors abound.
I’m a little confused about the impact of methane. Isn’t it a relatively unstable molecule that will turn into CO2 and water in the atmosphere relatively quickly?
They are confused too, WonkotheSane. About a great many things.
https://www.youtube.com/watch?v=Nembr1ZeRc8
The effect of methane is very small, partly, as others mention, because its absorption spectrum overlaps with water, which dominates.
And even if it was significant then, as you rightly point out, its short lifetime in the atmosphere means that we could fairly easily reverse any significant changes actually caused by us in the event of it being a problem. This is what the alarmists don’t like to acknowledge or discuss: The ability to wait and see that it might not be a problem blows their “we must act now” claims out of the water. Once everybody realizes that we can, and are, discovering that there is no immediate threat, then the game is up.
Can someone explain how Greenland Ice Cores can exist from 200 years ago when today is supposed to be hotter than it was 200 years ago? Obviously the Medieval Warming would have caused previous Glaciers to melt in the Arctic and especially Greenland Glaciers. So the Methane would have increased in the Atmosphere. But with a 9 year life would have broken down before the LIA Glaciers formed over 300 years ago and 200 year old Glaciers wouldn’t exist with our current Modern Warming.
John,
Greenland cores are taken at the top of the inland ice, which is several thousands of meters thick, thus much colder. Ice melt is very rare (once in 100 years) on the summit, that is not a problem.
Greenland ice only melts at the edges which are far lower, thus relative warmer.
The 9 years breakdown is on a continuous stream of methane, thus when it gets hotter, more CH4 is continuously emitted and levels go up, even when they also break down at the same speed.
Once enclosed in ice, the air bubbles don’t change in CH4/air composition, as there is no huge biological or chemical activity to do that.
For CO2, Greenland ice is not suitable, as frequent volcanic ash from nearby Iceland reacts with carbonate dust from sea salts and can produce CO2 in situ. For CH4, one hasn’t found similar problems.
Anthropocentric underestimations, speculations, misunderstandings as in models and predictions. Nature, however, is unimpressed, and there is cooling, and there is warming, and there is unremarkable, albeit highly variable, change.
Let me guess.
Because “NASA Flights Detect Millions of Arctic Methane Hotspots” then, because Man has detected what has always been there, Man is responsible for the always-there-but-not noticed-methane-sources because an SUV or two used in launching the NASA flights used fossil fuels?
Is that the logic?
(My head hurts. Maybe I’ll go chew on some willow bark.)
If human methane contributions are vastly underestimated, then that extra methane should be showing up in the atmosphere.
Where is it?
A substantial percentage of it seems to be trapped in my exes new husbands couch cushion.
MarkW,
Here they are:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/law_dome_ch4.jpg
and recent direct measurements:
https://www.esrl.noaa.gov/gmd/dv/iadv/
Choose Mauna Loa (or any other station)
Carbon cycle gases
CH4
and submit…
Wasn’t science already settled?
“Methane is the second largest anthropogenic–originating from human activity–contributor to global warming, after carbon dioxide. But, compared to carbon dioxide, as well as other heat-trapping gases, methane has a relatively short shelf-life; it lasts an average of only nine years in the atmosphere, while carbon dioxide, for instance, can persist in the atmosphere for about a century. That makes methane an especially suitable target for curbing emission levels in a short time frame.”
After the nuclear test ban treaty, the C14 level fell to normal in 9 years.
Chris Hoff,
One can’t compare the removal of the excess 14CO2 from the nuclear tests with the removal of any excess 12CO2 or methane.
In 1960 at the peak of 14CO2 from the bomb tests, what did go into the deep oceans was the isotopic composition of that year, what returned out of the deep oceans was the composition of ~1000 years ago, long before human intervention.
That made that in 1960 for 12CO2 some 97.5% returned the same year as was absorbed, but for 14CO2 that was only 45%. Therefore the decay rate of any excess 14CO2 is 2-3 times faster that for 12CO2.
For CH4 that plays no role, as the removal of CH4 is a chemical one in the higher troposphere which transforms CH4 in CO2 and water.
One of the side-effects of a plant-free diet for humans is less flatulence.
Far less flatulence.
Just sayin’…….. 🙂
Are you aware of beans?
Oh sure…everyone knows they are good for the heart.
But, the more you eat…
From the article…
“But, compared to carbon dioxide, as well as other heat-trapping gases…”
Stopped reading right there. Pure BS article.
0.00017% of the atmosphere drives climate for a planet??
All these wonderful studies of the multiple effects of CH4 on global warming also studiously neglect the fact that methane is measured in ppb and CO2 is measured in ppm. I haven’t referred to this study for a while but it seems it may be time again…
https://ams.confex.com/ams/Annual2006/techprogram/paper_100737.htm
Measurements of the Radiative Surface Forcing of Climate
W.F.J. Evans, North West Research Associates, Bellevue, WA; and E. Puckrin
You’ll have to open the Extended Abstract PDF to view all the info I will reference, I apologize but I’ ve never mastered linking to a PDF in one of these comments.
The study is a spectral analysis of DW radiation to the surface to measure the contribution of the various component gases of the atmosphere. The point apparently being to prove increasing GE by comparing measured data to modeled data of the past to show an increase in DWR, which they sorta did, if not very robustly.
The reason I bring up this work in this context is that throughout the study the DWR measurements for CH4 rarely show more than a little over 1W/m2 when the total DWR ranged from about 150-170W/m2 in the winter to 270 -300W/m2 in the summer. My point is that under almost any foreseeable scenario CH4
will remain a rounding error level factor in the GHE.
This study has stuck with me over the years because it was largely responsible for turning me from an agnostic to a total skeptic on CO2. A little more than half way down the study there are two graphs, one of winter measurements and the other of summer values. The winter numbers show CO2 providing about 25% of
total DWR in the cold dry air of the subarctic, which matches the canonical value usually offered. What I found quite revealing was that when the weather was warmer and moister during the summer the CO2 contribution to total DWR dropped to only 2-4%. When you look at DWR to the surface data across the planet and over the year, you find that for most of the planet, over most of the year the fact that H2O completely dominates CO2 is a completely viable hypothesis.
When I first encountered this I naively assumed this technique would become an instant sensation given what I saw as the terrific potential to provide the type of data necessary to actually solve some of these climate controversies we face. Sadly, although it has been nearly a quarter-century since the original fieldwork for this study was done the technique has been little copied, although I must admit it’s been several years since I’ve done a serious search for it. My more conspiratorial side wonders if there is someone out there who doesn’t want the information that this technique could provide getting out to the public.
“Methane emitted by humans vastly underestimated, researchers find”
That’ll be due to the silent emissions.
The first sentence was as far as I got before moving to the comments.
Methane is a powerful greenhouse gas and large contributor to global warming.
Gerry, England February 21, 2020 at 5:45 am
The first sentence was as far as I got before moving to the comments.
Only one of the several lies that the other side repeats over and over and over again.
I have calculated the contributions of GH gases including methane. It is not impossible. The water content is not a problem, because its average amount is very well known. It is good enough to know the annual average concentrations globally.
It is true that the absorptions peaks of methane overlap very badly with water. That is the reason why its contribution is insignificant as I showed.
“Methane emitted by humans vastly underestimated, researchers find”
They must not have studied what happens when a persons emits some on a crowded bus in Wintertime.
This seems like utter nonsense.
The NOAA monitors methane levels in the atmosphere. If the emissions are so much higher, why is this not being detected by the NOAA’s global network of monitoring stations?
https://www.esrl.noaa.gov/gmd/ccgg/trends_ch4/#global_growth
Note that methane levels have been climbing since 2004, with a spike starting 2013. This might be fracking, but might not since methane levels have fluctuated in a band for the duration of NOAA’s monitoring.
It’s perfectly natural that methane is a by-product of the production of Bull-…., well, you know.
(If you don’t know, a hint. You wouldn’t want to grabit.)
What if a researcher farted while setting up his atmospheric methane detecting apparatus. How many skewed results could be inside all these studies.