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”.
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.
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.
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”.
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”.
‘Unique and exceptional’
“This paper is important,” says Prof Rob Jackson, professor of Earth system science at Stanford University and chair of the Global Carbon Project. Jackson, who was not involved in the study, tells Carbon Brief:
“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.”
An award-winning photographer tells you how to take pictures of the night sky – CBC.ca
Dave Brosha is a professional photographer who, over the last 15 years, has taken highly stunning pictures of the Canadian wilderness.
It was when he was living in Yellowknife — before he pursued photography full time — that he first became interested in pointing his lens toward the skies.
“Yellowknife is known as one of the best areas on the planet for displays of the aurora borealis,” he said. “I found myself outside many, many nights under the stars.”
Since then Brosha has been short-listed multiple times for the Astronomy Photography of the Year Awards, and in 2010 he was the first runner-up in the category of land and space.
Now that he’s based in P.E.I., he splits his time between doing commercial assignments and teaching photography to people across Canada and in other parts of the world.
Every summer, he holds a workshop on the Island with his colleague, Paul Zizka, on sunset and nighttime photography that features astrophotography, the art of capturing a picture of an object in space.
“There’s people that are more into deep-space photography, actually photographing the galaxies and close-ups of planets and stars and stuff like that,” Brosha said. “But to me, astrophotography is really just going out into the world once the light disappears and just exploring the beauty of that.”
Though his workshop just ended, Brosha took some time to tell CBC what beginners need to know to get into this hobby, which he says at its most barebones doesn’t require more than a fairly basic DSLR camera or a good smartphone — not even a fancy location.
“My favourite nighttime photographs have always just kind of come in my own backyard. I don’t have to drive anywhere, and it’s right there,” he said.
“Whether exploring star trails or aurora borealis or Milky Way photographs, or just being able to go outside in your own backyard, it’s [all] pretty wonderful.
“It helps to live in the countryside.”
Switching to manual
All good nighttime photographers — and all good photographers in general — must have a firm grasp on the concept of exposure. That’s the amount of light that’s allowed to reach the camera sensor. A picture that’s underexposed is one that looks too dark.
“You have to understand the principles of capturing very small amounts of light over a longer time. So you have to know how to be able to operate your camera to capture those miniscule bits of light,” Brosha said. “It really forces you to slow down and think.”
For starters, that means ditching your camera’s auto settings.
“You can’t really shoot night photography effectively in just auto mode. You have to learn the exposure triangle,” he said. “It takes a little bit of work, for sure. But the rewards are tremendous.”
Keep it steady
The longer the camera’s shutter remains open, the larger the amount of light the camera takes in. As such, in a night photography environment, it’s common to see shutter speeds of over 20 to 30 seconds.
But a slow shutter speed means the camera is very sensitive to any motion.
That’s great if you’re trying to capture the movement of celestial bodies such as when taking a “star trail” photograph, but even a slight movement could lead to blurry images.
Brosha said that for long exposures, it’s important to keep your camera steady. That means a good tripod is almost a must.
“If all else fails, I’ve improvised by propping my camera up on a solid surface,” Brosha said. “Using a timer on your camera rather than pressing your shutter also helps reduce camera shake.”
Check your ISO
Cranking up the ISO allows for more light to get in the camera at the expense of quality.
That could compensate for a faster shutter speed when capturing a moving object, such as when trying to capture the outlines of bright northern lights.
And having both a slow shutter speed and a high ISO could lead to highly detailed images of the night sky, such as this self-portrait with the Milky Way as a backdrop. It was taken with a 3200-ISO, and a 30-second shutter speed.
“When you go out there, and you even just let your eyes adjust for the dark, and you’re out there an hour, it’s remarkable how much more you see. The camera can take that even further,” Brosha said. “[It] picks up so much more.”
Brosha said that other than avoiding pouring rain, there are no real “ideal” conditions as to when to venture out, and that all types of weather can lead to interesting pictures.
“Cloudy? Reflected light pollution can actually look interesting in a long exposure. Full moon? Not the best conditions for shooting the Milky Way, but great conditions for being able to see your foregrounds,” he said.
A pitch-black night is a prime setting for taking pictures of stars. And if you’re looking to take a picture of the northern lights, you better look, well, north.
“It’s generally easier to photograph on the North Shore, when the aurora borealis is predicted. So that’s what I would probably recommend to people,” Brosha said.
Go out there and shoot
Brosha said that astrophotography may look intimidating on the surface, but that it’s not as complicated as most people might think.
“All you have to grasp to begin is the concept of long exposure. And that usually I find for people is something that they can get the hang of pretty quickly. It just takes a little bit of practice,” he said.
Once you got that nailed down, Brosha said you can get really creative with it. And the setting allows for that.
“Every time you turn on a light, like a flashlight, your eyes kind of lose the adjustment to the nighttime that you’ve gained,” he said.
“So you really try to function with as little light as possible. And so everything becomes slower and more deliberate.”
Plus, Brosha said, it’s a fine excuse to go outdoors.
It's once again time for the Perseids, one of the best meteor showers of the year – CBC News
Each August, Earth plows through a thick trail of debris left over from a passing comet. The result: A spectacular night of meteors lighting up the sky.
One of the best and most anticipated meteor showers of the year is the Perseids, which takes place from mid-July to the end of August. But peak viewing — where you’ll get a chance to see the most meteors — falls on the night of Aug. 12-13 this year, according to the International Meteor Organization.
That’s when Earth moves through the thickest part of the debris left over from comet 109P/Swift-Tuttle, with tiny pieces of particles burning up in our atmosphere at 59 km/s.
Try this interactive map showing how Earth passes through the meteor shower:
Swift-Tuttle, which was first discovered in 1862 independently by both Lewis Swift and Horace Tuttle, makes an orbit of the sun every 133 years. The last time it was in our solar system was in 1992. Still, from all those trips around the sun, it’s left behind plenty of debris.
Some of this debris can be bigger than the normal grain-like particles and can create beautiful bolides, or bright fireballs that light up the sky.
How to see the meteors
Though the Perseids rarely disappoint, there is one thing to contend with this year that may hamper your viewing delight: the full moon.
With the moon lighting up the sky, that means that only the brightest of meteors will be visible. Fortunately, many Perseids tend to be quite bright anyway.
The Perseids are given their name for the constellation — Perseus. This is the point in the sky from which they seem to appear, called the radiant.
While some people like to look in the direction of the constellation, which rises in the northeast, it limits the number of meteors that can be seen, since they will have shorter tails. To see longer meteors (ie., with long tails), you don’t need to look directly up, but at more of an angle.
And the best thing about meteor showers is that you don’t need a telescope or binoculars, just your own eyes.
You can also keep an eye out for “earthgrazers,” meteors that skim Earth’s atmosphere and, as a result, leave a long trail behind them.
These are best viewed early in the night, when the sky is dark and the radiant is low in the east. They will be moving roughly from north to south.
To increase your chances of catching some bright meteors, you could head out ahead of the peak night of Aug. 12, or even in the days after, when the moon won’t be entirely full. Try to keep the moon behind you when stargazing to block out its glare.
Lot more <a href=”https://twitter.com/hashtag/Perseid?src=hash&ref_src=twsrc%5Etfw”>#Perseid</a> meteors on our cameras this morning <a href=”https://t.co/SAmtS7RL7k”>pic.twitter.com/SAmtS7RL7k</a>
Another hot tip is to try to lie down on a blanket or even on a beach lounge chair, otherwise your neck will get tired and ache from trying to look up.
Also, put away those phones as your eyes will need to become accustomed to the dark, something that can take anywhere from 30 minutes to an hour. And remember, the more stars you can see, the more faint meteors you will catch, so try to get to as dark a location as you can, away from city lights.
Patience is your friend, so try not to give up if you haven’t seen any meteors within a few minutes. Under ideal conditions, the Perseids can produce more than 100 meteors an hour, but don’t expect to see that many.
At this time of year, you can also catch a couple of planets: Jupiter will be low in the east and hard to miss, and Saturn will lie in the southeast.
People can also use free apps like StarWalk or SkyView (they have a night mode that displays in red in order to preserve your night vision) that allow you to hold your phone up to the sky to identify constellations, planets and more.
There’s always something to look at in the night sky, even if meteors aren’t providing a show.
Watch OSIRIS-REx's Complex Orbital Path Around Bennu in This Cool Animation – Universe Today
The OSIRIS-REx spacecraft conducted a two-year reconnaissance and sample collection at the asteroid Bennu, providing crucial data about the 500-meter-wide potentially hazardous rubble pile/space rock. When OSIRIS-REx arrived on Dec. 3, 2018, it needed some tricky navigation and precise maneuvers to make the mission work.
Experts at NASA Goddard’s Scientific Visualization Studio created an amazing visualization of the path the spacecraft took during its investigations. A short film called “A Web Around Asteroid Bennu” highlights the complexity of the mission, and the film is being shown at the SIGGRAPH computer graphics conference in Vancouver, British Columbia, Canada, a festival honoring standout works of computer animated storytelling.
Other films in the festival include Disney’s “Encanto” and Warner Brothers’ “The Batman.”
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Data visualizer Kel Elkins compiled the data for the film, which shows the web-like flight path for OSIRIS-REx, as well as the touch-and-go, or TAG, maneuver to collect the sample from the asteroid’s surface.
“I started working with the trajectory data in 2015,” Elkins said. “And when you first see an image of all the different maneuvers it looks like a rat’s nest. But it was really exciting to see these complicated maneuvers in 3D space.”
The video runs about four minutes in total, showing the flight path around Bennu from beginning to end in a single, continuous shot.
“From a trajectory and navigation perspective, the team really did things that have never been done before in planetary exploration,” said Mike Moreau, deputy project manager for OSIRIS-REx at NASA Goddard. “We flew the spacecraft closer to this object than any spacecraft has ever been flown before; we did maneuvers that were centimeters per second, or millimeters per second, in order to get the spacecraft exactly where it needed to be and to change its orbit.”
Taking their data visualization to the next level, Elkins and colleagues plan to release a 360-degree version of “A Web Around Asteroid Bennu” that wraps the video around the viewer, for an interactive experience on VR headsets, mobile devices, and online.
“As amazing as it is to see the trajectory in front of you in the original format, there’s something about putting the viewer in the middle of it and letting them look around,” Elkins said. “You’re in space and OSIRIS-REx is flying around you. We’re really excited to be able to publish this additional 360-degree view.”
OSIRIS-REx is currently on its way back towards Earth, and in September 2023, will drop off a sample in the Utah desert. Once the sample is retrieved, the spacecraft has been given a new mission, and it will be heading to one of the most infamous asteroids of them all, the potentially hazardous asteroid Apophis for an 18 month study. The mission will be renamed OSIRIS-APEX, which is short for OSIRIS-Apophis Explorer.
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