Human-caused emissions of methane from the extraction and use of fossil fuels may have been “severely underestimated”, a new study suggests.
The research indicates that “natural” emissions of fossil methane, that seeps out of deeply-held reserves, make up a much smaller fraction of total methane emissions than previously thought.
This means that the levels of fossil methane in the atmosphere are likely being driven by the methane escaping as coal, oil and natural gas are mined, drilled and transported.
The implication is that methane emissions from fossil fuels are 25-40% higher than earlier estimates suggest, the lead researcher tells Carbon Brief.
The findings indicate that “the fossil-fuel industry is likely responsible for an even larger proportion of recent climate change than we previously thought”, a scientist not involved in the study tells Carbon Brief. However, there is also “greater opportunity” to cut emissions, she says, through “fixing leaks in natural gas extraction and distribution networks”.
Fossil methane
Methane is a potent greenhouse gas and is second only to CO2 in terms of how much it contributes to global warming.
Although more short-lived in the atmosphere than CO2, methane packs more of a warming punch – it is around 28-34 times (pdf) more powerful over a 100-year period (though there are other ways to compare methane’s warming impact with CO2).
There are two main types of methane: “biogenic”, produced from plants and animals, and “fossil”, which has been locked up underground for millions of years.
The new study, published in Nature, focuses on emissions of fossil methane. These are most commonly associated with the extraction and transport of fossil fuels – such as leaks from coal mining and flaring from oil and gas drilling – but they have “natural” sources as well.
There are four main ways that fossil methane escapes into the atmosphere naturally. These include onshore seeps (including oil and gas seeps, mud volcanoes and gas-bearing springs), submarine (offshore) seeps, “diffuse microseepage” from oil and gas-bearing sedimentary rocks, and geothermal and volcanic formations.
Close up of a methane bubble in a mud volcano, Qobustan, Azerbaijan. Credit :Hemis / Alamy Stock Photo
The new study suggests that the amount of methane being emitted in these natural ways has been overestimated.
Fingerprints
Scientists can analyse the precise makeup of methane molecules to determine their likely origin. Key to this is the “fingerprint” of carbon-14 (14C) – a naturally-occurring isotope of carbon, explains lead author Dr Benjamin Hmiel, a postdoctoral associate at the University of Rochester in New York state. He tells Carbon Brief:
“Fossil sources have been isolated from the atmosphere for a very long time – millions of years. Thus, all of the 14C has undergone natural radioactive decay and there are no 14C molecules left. Alternatively, biologic sources – such as wetlands, rice agriculture, cow burps – readily exchange their carbon with the atmosphere and contain a quantity of 14C similar to that of atmospheric CO2 at the time of emission.”
So, in short, scientists know when methane originated in deeply-held fossil sources because it has no carbon-14. This is known as “14C-free methane”
For their study, the researchers collected samples of air from ice cores drilled out of Greenland and Antarctic ice sheets. The ice traps tiny bubbles of air, built up in layers with new snowfall year after year. By cutting out a cylinder of ice down through the sheet, scientists can reconstruct a timeline of the makeup of the atmosphere going back thousands of years.
The new record spans around 1750-2013, which “captures the evolution of atmospheric 14CH4 [carbon-14 held in methane] since the pre-industrial era”, the paper says. By quantifying the ratio of fossil to biogenic methane in the air samples, the researchers reconstructed the signature of 14CH4 for more than 250 years.
The charts below show what is revealed by their new record. The upper chart shows the global concentration of methane in the atmosphere from mid-18th century, while the lower chart shows the reconstruction of 14CH4 (green line) in the atmosphere since 1850. The individual dots show the 14C measurements taken from ice cores at different sites.
Upper chart shows global CH4 mole fraction in parts per billion (ppb), reconstructed from ice core data. Lower chart shows a reconstructed history of atmospheric 14CH4 from the new study (green line). Dotted green line shows two standard deviation uncertainty range. Blue line shows 14CH4 signature from biogenic sources. Individual dots show measurements from specific ice cores. Source: Hmiel et al. (2020)
The lower chart shows how the 14C signature of methane emissions changed as the industrial revolution got underway. The concentration of atmospheric 14C declined as more 14C-free methane was emitted into the atmosphere.
This is “coincident with the timing of significant growth in the use of fossil fuels”, says Hmiel.
In contrast, the new record suggests that before 1870, “the quantity of natural fossil methane seepage is very small – no more than 1% of the total methane source today”, notes Hmiel.
Previous estimates put natural fossil methane emissions at around 40-60m tonnes of methane per year, the paper says. The new study finds they are more likely to be of the order of 1.6m tonnes per year, with a maximum of 5.4m tonnes per year. This suggests that natural emissions are “10 times smaller than previously thought”, says Hmiel.
Going nuclear
The chart above takes a dramatic turn around the middle of the 20th century. This is because of a complicating factor: nuclear technology.
There are two ways that the nuclear industry has affected the amount of 14C in the atmosphere. The first was nuclear-bomb testing above ground, which began in 1945 and added a substantial quantity of 14C into the air, explains Hmeil:
“This is known as the bomb pulse, which although the testing was outlawed via international treaties in 1963,…caused a major perturbation of the amount of 14C in the atmosphere, which complicates the simple segregation of ‘fossil’ and ‘biologic’ methane due to how quickly natural 14C levels changed in the atmosphere.”
This effect can be seen in the blue line in the earlier chart, which shows a huge spike in biogenic 14CH4 in the mid-20th century.
The BADGER, a 23 kiloton nuclear bomb tested on April 18, 1953, at the Nevada Test Site. Credit: Everett Collection Historical / Alamy Stock Photo
The second influence was from nuclear power plants, says Hmiel. Beginning in the 1970s, nuclear power added “a very small, yet globally quantifiable, amount of 14CH4”, he notes:
“This perturbation alters the 14CH4 signature we measure in the atmosphere today without significantly affecting the total quantity of methane that is part of our calculation in quantifying the fossil component of the source.”
The upshot of the nuclear influences is that the new 14C record is less reliable for assessing fossil methane after the middle of the 20th century, the researchers say.
However, because the level of natural seepage only changes on very long timescales – many thousands of years or more – says Hmiel, it “is not expected to have changed over the last 250 years”.
‘Severely underestimating’
The findings indicate that “almost all fossil methane in the atmosphere today is from anthropogenic emissions originating from the extraction and use of fossil fuels”, Hmiel says.
This suggests that previous “bottom-up” inventories – which estimate methane figures by multiplying the number of sources (such as livestock, natural gas operations and landfills) by their likely emissions – “are severely underestimating” emissions from fossil fuels, says Hmiel.
Human-caused fossil methane emissions are likely to have been underestimated by 38-58m tonnes per year, the paper concludes – equivalent to about 25-40% of recent estimates.
Other research has also suggested that bottom-up methane inventories are not fully taking into account methane emissions from oil-and-gas infrastructure. Yet, ironically, the short-lived plateau in rising atmospheric methane concentrations between the late 1990s and early 2000s (see earlier chart) has been linked to oil and gas industries in developed countries reducing “fugitive” emissions of escaping methane.
There is a positive side to this finding, says Hmiel:
“Simply put, if the emissions from anthropogenic sources are larger than we thought, then that puts more of the emissions under our domain and agency. Whereas humanity has little control over ‘natural’ emissions as they were going to occur anyway.”
For example, he adds, if “the emissions are coming from oil-and-gas production, then by enacting regulations to force the industry to institute at least improved reporting of them – or better yet, reducing them – then we can limit the emissions of methane to the atmosphere and the warming they cause”.
“It’s possible we’ve overestimated methane emissions from natural geologic seeps. If so, fossil-fuel activities are even worse for climate and the environment than we thought.”
However, there are still “many things” that need to be checked, he adds:
“We need more measurements at natural geologic seeps right now. We need to check the modelling and isotopic assumptions behind the paper’s conclusions, too. Both should happen quickly.”
Methane bubbles rising above a cold seep site. Methane bubbles flow in a small stream out of the sediment on an area of seafloor offshore Virginia north of Washington Canyon. Quill worms, anemones, patches of bacterial mat, pandalid shrimp, and a large red crab (Chaceon quinquedens) can be seen in and along the periphery of the seepage area. Credit: NOAA OKEANOS Explorer Program , 2013 ROV Shakedown and Field Trials
Dr Célia Sapart, a researcher at the Université Libre de Bruxelles who has previously published research on analysing natural and human-caused methane sources, says the new dataset is of “unique and of exceptional quality”.
However, mirroring the comments of Prof Jackson, she tells Carbon Brief that “partitioning between anthropogenic and natural – geological – fossil emissions remains extremely difficult” and so “denser and longer datasets” going back before 1850 would “be helpful to consolidate the quantitative conclusions of this paper in the future”.
Dr Heather Graven, a senior lecturer on the global carbon cycle at Imperial College London, says the findings indicate that “the fossil-fuel industry is likely responsible for an even larger proportion of recent climate change than we previously thought”. This means there is a “greater opportunity” to cut these emissions, she tells Carbon Brief:
“It’s critical that more effort is put into methane emissions mitigation, such as fixing leaks in natural gas extraction and distribution networks. And we need to monitor these mitigation efforts using atmospheric measurements, including measurements of radiocarbon in atmospheric methane like those made in this study.”
More than 40 trillion gallons of rain drenched the Southeast United States in the last week from Hurricane Helene and a run-of-the-mill rainstorm that sloshed in ahead of it — an unheard of amount of water that has stunned experts.
That’s enough to fill the Dallas Cowboys’ stadium 51,000 times, or Lake Tahoe just once. If it was concentrated just on the state of North Carolina that much water would be 3.5 feet deep (more than 1 meter). It’s enough to fill more than 60 million Olympic-size swimming pools.
“That’s an astronomical amount of precipitation,” said Ed Clark, head of the National Oceanic and Atmospheric Administration’s National Water Center in Tuscaloosa, Alabama. “I have not seen something in my 25 years of working at the weather service that is this geographically large of an extent and the sheer volume of water that fell from the sky.”
The flood damage from the rain is apocalyptic, meteorologists said. More than 100 people are dead, according to officials.
Private meteorologist Ryan Maue, a former NOAA chief scientist, calculated the amount of rain, using precipitation measurements made in 2.5-mile-by-2.5 mile grids as measured by satellites and ground observations. He came up with 40 trillion gallons through Sunday for the eastern United States, with 20 trillion gallons of that hitting just Georgia, Tennessee, the Carolinas and Florida from Hurricane Helene.
Clark did the calculations independently and said the 40 trillion gallon figure (151 trillion liters) is about right and, if anything, conservative. Maue said maybe 1 to 2 trillion more gallons of rain had fallen, much if it in Virginia, since his calculations.
Clark, who spends much of his work on issues of shrinking western water supplies, said to put the amount of rain in perspective, it’s more than twice the combined amount of water stored by two key Colorado River basin reservoirs: Lake Powell and Lake Mead.
Several meteorologists said this was a combination of two, maybe three storm systems. Before Helene struck, rain had fallen heavily for days because a low pressure system had “cut off” from the jet stream — which moves weather systems along west to east — and stalled over the Southeast. That funneled plenty of warm water from the Gulf of Mexico. And a storm that fell just short of named status parked along North Carolina’s Atlantic coast, dumping as much as 20 inches of rain, said North Carolina state climatologist Kathie Dello.
Then add Helene, one of the largest storms in the last couple decades and one that held plenty of rain because it was young and moved fast before it hit the Appalachians, said University of Albany hurricane expert Kristen Corbosiero.
“It was not just a perfect storm, but it was a combination of multiple storms that that led to the enormous amount of rain,” Maue said. “That collected at high elevation, we’re talking 3,000 to 6000 feet. And when you drop trillions of gallons on a mountain, that has to go down.”
The fact that these storms hit the mountains made everything worse, and not just because of runoff. The interaction between the mountains and the storm systems wrings more moisture out of the air, Clark, Maue and Corbosiero said.
North Carolina weather officials said their top measurement total was 31.33 inches in the tiny town of Busick. Mount Mitchell also got more than 2 feet of rainfall.
Before 2017’s Hurricane Harvey, “I said to our colleagues, you know, I never thought in my career that we would measure rainfall in feet,” Clark said. “And after Harvey, Florence, the more isolated events in eastern Kentucky, portions of South Dakota. We’re seeing events year in and year out where we are measuring rainfall in feet.”
Storms are getting wetter as the climate change s, said Corbosiero and Dello. A basic law of physics says the air holds nearly 4% more moisture for every degree Fahrenheit warmer (7% for every degree Celsius) and the world has warmed more than 2 degrees (1.2 degrees Celsius) since pre-industrial times.
Corbosiero said meteorologists are vigorously debating how much of Helene is due to worsening climate change and how much is random.
For Dello, the “fingerprints of climate change” were clear.
“We’ve seen tropical storm impacts in western North Carolina. But these storms are wetter and these storms are warmer. And there would have been a time when a tropical storm would have been heading toward North Carolina and would have caused some rain and some damage, but not apocalyptic destruction. ”
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It’s a dinosaur that roamed Alberta’s badlands more than 70 million years ago, sporting a big, bumpy, bony head the size of a baby elephant.
On Wednesday, paleontologists near Grande Prairie pulled its 272-kilogram skull from the ground.
They call it “Big Sam.”
The adult Pachyrhinosaurus is the second plant-eating dinosaur to be unearthed from a dense bonebed belonging to a herd that died together on the edge of a valley that now sits 450 kilometres northwest of Edmonton.
It didn’t die alone.
“We have hundreds of juvenile bones in the bonebed, so we know that there are many babies and some adults among all of the big adults,” Emily Bamforth, a paleontologist with the nearby Philip J. Currie Dinosaur Museum, said in an interview on the way to the dig site.
She described the horned Pachyrhinosaurus as “the smaller, older cousin of the triceratops.”
“This species of dinosaur is endemic to the Grand Prairie area, so it’s found here and nowhere else in the world. They are … kind of about the size of an Indian elephant and a rhino,” she added.
The head alone, she said, is about the size of a baby elephant.
The discovery was a long time coming.
The bonebed was first discovered by a high school teacher out for a walk about 50 years ago. It took the teacher a decade to get anyone from southern Alberta to come to take a look.
“At the time, sort of in the ’70s and ’80s, paleontology in northern Alberta was virtually unknown,” said Bamforth.
When paleontogists eventually got to the site, Bamforth said, they learned “it’s actually one of the densest dinosaur bonebeds in North America.”
“It contains about 100 to 300 bones per square metre,” she said.
Paleontologists have been at the site sporadically ever since, combing through bones belonging to turtles, dinosaurs and lizards. Sixteen years ago, they discovered a large skull of an approximately 30-year-old Pachyrhinosaurus, which is now at the museum.
About a year ago, they found the second adult: Big Sam.
Bamforth said both dinosaurs are believed to have been the elders in the herd.
“Their distinguishing feature is that, instead of having a horn on their nose like a triceratops, they had this big, bony bump called a boss. And they have big, bony bumps over their eyes as well,” she said.
“It makes them look a little strange. It’s the one dinosaur that if you find it, it’s the only possible thing it can be.”
The genders of the two adults are unknown.
Bamforth said the extraction was difficult because Big Sam was intertwined in a cluster of about 300 other bones.
The skull was found upside down, “as if the animal was lying on its back,” but was well preserved, she said.
She said the excavation process involved putting plaster on the skull and wooden planks around if for stability. From there, it was lifted out — very carefully — with a crane, and was to be shipped on a trolley to the museum for study.
“I have extracted skulls in the past. This is probably the biggest one I’ve ever done though,” said Bamforth.
“It’s pretty exciting.”
This report by The Canadian Press was first published Sept. 25, 2024.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
