Astronomers Spot Comet in Solar System’s Main Asteroid Belt

Oct 5, 2021 by News Staff 

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(248370) 2005 QN137 is the eighth main-belt asteroid, out of more than half a million asteroids in the main belt, confirmed to not only be active, but to have been active on more than one occasion.

These images show the main-belt comet (248370) 2005 QN137. Image credit: Hsieh et al., arXiv: 109.14822.

(248370) 2005 QN173 was discovered to be active on July 7, 2021 in data obtained by the Asteroid Terrestrial-Impact Last Alert System (ATLAS) survey telescope.

On that date, the object was at a heliocentric distance of 2.39 AU (astronomical units), and exhibited a thin, straight dust tail.

“This behavior strongly indicates that its activity is due to the sublimation of icy material,” said Dr. Henry Hsieh, senior scientist at the Planetary Science Institute.

“As such, it is considered a so-called main-belt comet, and is one of just about 20 objects that have currently been confirmed or are suspected to be main-belt comets, including some that have only been observed to be active once so far.”

“2005 QN173 can be thought of as both an asteroid and a comet, or more specifically, a main-belt asteroid that has just recently been recognized to also be a comet.”

“It fits the physical definitions of a comet, in that it is likely icy and is ejecting dust into space, even though it also has the orbit of an asteroid.”

“This duality and blurring of the boundary between what were previously thought to be two completely separate types of objects — asteroids and comets — is a key part of what makes these objects so interesting.”

2005 QN173 has a diameter of 3.6 km (2 miles). In July 2021, its tail was more than 720,000 km (450,000 miles) long and 1,400 km (900 miles) wide.

“This extremely narrow tail tells us that dust particles are barely floating off of the nucleus at extremely slow speeds and that the flow of gas escaping from the comet that normally lifts dust off into space from a comet is extremely weak,” Dr. Hsieh said.

“Such slow speeds would normally make it difficult for dust to escape from the gravity of the nucleus itself, so this suggests that something else might be helping the dust to escape.”

“For example, the nucleus might be spinning fast enough that it’s helping to fling dust off into space that has been partially lifted by escaping gas.”

“Further observations will be needed to confirm the rotation speed of the nucleus though.”

The team’s paper was published in the Astrophysical Journal Letters.

_____

Henry H. Hsieh et al. 2021. Physical Characterization of Main-Belt Comet (248370) 2005 QN173. ApJL, in press; arXiv: 109.14822

Weird Space Rock Confirmed as Super-Rare Hybrid of Comet And Asteroid

MICHELLE STARR

5 OCTOBER 2021

Comets and asteroids are both types of rocks that hang out in space, but their differences are pretty pronounced.

Comets typically hail from the outer Solar System and have long, elliptical orbits. They're filled with ices that start to sublimate when the comet gets close to the Sun, generating a dusty, misty atmosphere (called a coma) and the famous cometary tails.

Asteroids usually hang out in the main asteroid belt, between Mars and Jupiter, with orbits that are more like those of the planets. They're also thought to be pretty dry and rocky, so they don't tend to engage in the picturesque outgassing seen in their more exotic relatives.

A newly discovered space rock, however, seems to have characteristics of both. It's called (248370) 2005 QN173, and it hangs out in the main asteroid belt, like millions of other asteroids, going around the Sun in a nice, planet-style almost-circle.

But, like a comet, in July of this year, 248370 was spotted showing signs of outgassing at its closest approach to the Sun (perihelion), and a long, cometary tail. This would make it a rare hybrid of the two – a type of object we call an active asteroid, or main-belt comet.

It's one of just 20 or so of these rarely seen objects – among the over 500,000 known main-belt objects – that have been suspected of being main-belt comets, and just the eighth object of this type confirmed. Moreover, astronomers have discovered that the object has been active more than once.

"This behavior strongly indicates that its activity is due to the sublimation of icy material," said astronomer Henry Hsieh of the Planetary Science Institute.

"248370 can be thought of as both an asteroid and a comet, or more specifically, a main-belt asteroid that has just recently been recognized to also be a comet. It fits the physical definitions of a comet, in that it is likely icy and is ejecting dust into space, even though it also has the orbit of an asteroid.

"This duality and blurring of the boundary between what were previously thought to be two completely separate types of objects – asteroids and comets – is a key part of what makes these objects so interesting."

The behavior of 248370 was discovered  on 7 July 2021, in data from the robotic astronomical survey Asteroid Terrestrial-Impact Last Alert System (ATLAS). Confirmation observations taken by Lowell Discovery Telescope showed clear signs of a tail, and a perusal of the data from the Zwicky Transient Facility showed the tail appeared as early as 11 June.

Between 8 July and 14 August, new follow-up observations were taken using different telescopes, confirming earlier data. There, in the asteroid belt, 248370 was sporting an absolutely stylin' tail

Measurements taken by Hsieh and his team revealed that the cometary nucleus – that's the chunk of rock from which the tail extends – is around 3.2 kilometers (2 miles) across. In July, the tail was more than 720,000 kilometers (450,000 miles) long, but just 1,400 kilometers (900 miles) wide. That's crazy narrow in comparison to the tail's length.

"This extremely narrow tail tells us that dust particles are barely floating off of the nucleus at extremely slow speeds and that the flow of gas escaping from the comet that normally lifts dust off into space from a comet is extremely weak," Hsieh explained.

"Such slow speeds would normally make it difficult for dust to escape from the gravity of the nucleus itself, so this suggests that something else might be helping the dust to escape.

"For example, the nucleus might be spinning fast enough that it's helping to fling dust off into space that has been partially lifted by escaping gas. Further observations will be needed to confirm the rotation speed of the nucleus, though."

Further observations will help us better understand the object, too. Based on our understanding of the Solar System, 248370 and the other main-belt comets shouldn't exist. That's because the main asteroid belt is thought to have been there since the formation of the Solar System, around 4.6 billion years ago.

The asteroid belt lies between around 2.2 and 3.2 astronomical units from the Sun. The Solar System's frost line – the point beyond which it is cold enough for ice to form in a vacuum – is at around 5 astronomical units. So it's unclear why these main-belt comets have retained enough ice to produce cometary sublimation activity.

In addition, they could help us understand a little bit about Earth, too. In the early days of the Solar System, impacts from asteroids bearing water could have been one of the ways water was delivered to Earth. If main-belt comets have water, we might be able to explore this idea a little further.

"In the long term, 248370 will be well-placed for monitoring during the approach to its next perihelion passage on UT 2026 September 3," the researchers write in their paper.

"Monitoring during this time will be extremely valuable for further confirming the recurrent nature of 248370's activity, constraining the orbital range over which activity occurs (with implications for constraining ice depth on the object, as well as its active lifetime), measuring initial dust production rates, and comparing the object's activity levels from one orbit to another as well as to other main-belt comets."

The research was presented at the 53rd Annual Meeting of the AAS Division for Planetary Sciences, and has been accepted into The Astrophysical Journal Letters. It's currently available on preprint site arXiv.

THUMBNAIL PHOTO (248370) 2005 QN173, with long, thin tail. (Henry H. Hsieh/PSI, Jana Pittichová/NASA/JPL-Caltech)

DEEP BLUE SEA

The fishy business of artificial reefs

by University of New South Wales

Yellowtail scad are an example of the baitfish found in abundance around the artificial reefs surveyed by UNSW researchers. Credit: John Turnbull

UNSW scientists have uncovered why artificial reefs attract more small foraging fish, or baitfish, than natural reefs.

It's an important finding which could lead to more effective manmade reefs being built to help recreational fishers.

Using a high-tech fish finder called a multibeam echosounder, the School of Biological, Earth and Environmental Sciences researchers gained a 3D picture of five natural and three artificial reefs off Sydney during the day and at night and under different conditions.

They found that the tall vertical habitats provided by the 9-meter-high artificial reef allowed baitfish such as yellowtail scad and mado to spread out and feed much higher above the seafloor while still remaining close to the safety afforded by physical structures.

Because they had a higher structure to protect them, these bottom-of-the-food chain fish also had more access to food—drifting plankton—than they would receive on a low-lying natural reef.

And thanks to the 'meal delivery service'—the East Australian Current—consistently delivering a conveyor belt of plankton as their food, these baitfish are eating more, with subsequent benefits for their predators, including the bluespotted flathead, one of NSW's most iconic commercial and recreational fish.

Their study, which has been published in Marine Ecology Progress Series, has implications for the eight artificial reefs in New South Wales.

"Zooplankton and these small fish support around half of the fish biomass," one of the study authors, Professor Iain Suthers from the School of Biological, Earth and Environmental Sciences says.

"The schools of these small fish are sometimes referred to as a 'wall of mouths' as they persist over a reef and peck the zooplankton from the tidal flow.

"They connect plankton to the fishery and underpin the sustainability of bluespotted flathead and this has implications for the sustainability of coastal fishing near heavily urbanized areas because the flathead ambush these small baitfish."

The study describes the so-called "pinch point" of the coastal food web and helps explain why reefs around Sydney can be such productive habitat for forage fish, despite a 50 percent decline in kelp, which itself supports coastal food webs and subsequently fish off the NSW coast.

Lead author Matthew Holland, who conducted the research when he was a Ph.D. candidate at UNSW Science and is now a Research Fellow at University of Plymouth in the UK, says artificial reefs allow the fish to use space differently than they do in nearby natural habitats.

"Across temperate and subtropical coastal areas, like the coast of Sydney, much of the seafloor is relatively flat and featureless," Dr. Holland says.

"But rocky reefs or any form of hard structure on the seafloor is rare overall and fish tend to congregate on structures such as artificial reefs.

"By building artificial reefs as 'skyscrapers' rather than 'single-story buildings," we can provide more usable space for the fish, which can travel up and down in the water column while remaining close to these structures for protection from predators."

Dr. Holland says they were surprised by the huge quantity of plankton actually drifting over the natural and artificial Sydney reefs.

"We collected zooplankton samples by towing nets behind the boat during our surveys," he says.

"Based on the speed of the current, we worked out that 43 grams of zooplankton was delivered to each square meter of reef every hour during the day.

"Based on the energy requirements of the fish we studied, each square meter of reef could potentially support up to 25 kilograms of fish feeding only on these tiny organisms."

The eight artificial reefs in New South Wales are installed at South Head in Sydney, Port Hacking in South Sydney, Shoalhaven, Port Macquarie, Merimbula, Newcastle, Wollongong and Tweed Heads.

Like artificial reefs, oil rigs off California have been found to be some of the most productive reef habitats.

Prof. Suthers says the study justifies the decommissioning of old oil and gas pipelines or platforms in the Bass Strait and the North-West Shelf for use as artificial reefs.

But Dr. Holland says that while the scientists demonstrated why artificial reefs can be more productive than natural ones, they aren't necessarily a replacement for natural reefs.

"Natural reefs often have higher biodiversity because they contain a wider variety of habitats which can therefore support a wider variety of organisms," he says.

"It is important that we preserve natural reefs as well to maintain this biodiversity."

Now the scientists are keen to see their findings shape the design and location of future artificial reefs in the hope of enhancing coastal environments and improving opportunities for recreational fishers.Fish reef domes a boon for environment, recreational fishing

More information: MM Holland et al, Fine-scale spatial and diel dynamics of zooplanktivorous fish on temperate rocky and artificial reefs, Marine Ecology Progress Series (2021). DOI: 10.3354/meps13831

Journal information: Marine Ecology Progress Series 

Provided by University of New South Wales 

 

Region of “Super Corals” Discovered Thriving in Extremely High Levels of Carbon Dioxide

By UNIVERSITY OF TEXAS AT AUSTIN OCTOBER 4, 2021

Corals found in an area of the ocean with extremely high levels of Carbon Dioxide in the Verde Island Passage in the Philippines. Credit: University of Texas at Austin,

In 2019, a hydrology professor at The University of Texas at Austin set out on a research project to see if he could identify harmful nutrients flowing through groundwater into a delicate coral reef sanctuary in the Philippines. He achieved this goal, but following the long history of accidental scientific discoveries, he instead stumbled upon something completely unexpected: a region of possible “super corals” that are thriving despite high levels of carbon dioxide.

The findings based on the 2019 field work were published in August in the journal ACS ES&T Water.

For the first time, the UT Austin professor, Bayani Cardenas, and a team of international researchers were able to attribute the source of CO₂ and other gases and nutrients in seawater at this location to groundwater, a finding that the researchers believe shows how the undersea reef environment can be vulnerable to the way communities discharge wastewater, agricultural runoff and other byproducts into the sea.

“This is an unseen vulnerability,” said Cardenas, a professor in the Department of Geological Sciences at the UT Jackson School of Geosciences. “We’ve been able to show with this site that groundwater is part of these delicate coral reef environments. There is a connection, and that’s still not as accepted in science and in many parts of the world.”

Bayani Cardenas, a professor at the University of Texas Jackson School of Geosciences, prepares to dive during research to track the impact of harmful nutrients flowing through groundwater into a delicate coral reef sanctuary in the Philippines. Credit: University of Texas at Austin,

More than that, Cardenas said the research has led to new questions — and new research proposals — about the super corals they found that could be replicated elsewhere in the coming years as global CO₂ levels are expected to rise.

Coral reefs have long been suffering due to climate change, most notably during a global coral bleaching event from 2014 to 2017 that caused heat stress to 75% of the world’s reefs, according to the American Meteorological Society. Yet the coral-filled area Cardenas studied in the Verde Island Passage in the Philippines, a region so vibrant and diverse that he refers to it as the “Amazon of the ocean,” is thriving despite the vast amounts of CO₂ being pumped in from groundwater.

Lead author Rogger E. Correa, a researcher at Southern Cross University in Australia, estimated that groundwater is pumping about 989 grams of CO₂ per square meter per year into the area they studied, which is known as “Twin Rocks” and borders a chain of volcanoes. That’s the equivalent of parking two cars on the seabed and letting them emit carbon dioxide for a full year on every hectare of reef.

To distinguish groundwater from seawater, the scientists submerged devices that measure the levels of CO₂ and radon 222, a naturally occurring radioactive isotope that is found in local groundwater but not in open ocean water. The measurement technique was developed by co-author Isaac Santos, a professor at the University of Gothenburg in Sweden.

This work follows a 2020 study conducted by Cardenas where he discovered CO₂ bubbling up from the seafloor off an area of the Philippine coast so dramatically that he dubbed it “Soda Springs.”

The end result from the latest investigation is an entire region of coral reefs that must be studied more closely, said Cardenas, who is a geoscientist and not a coral researcher.

Adina Paytan, a research scientist at the Institute of Marine Sciences at the University of California, Santa Cruz, who was not associated with the study, warned that other human-made stressors, including sedimentation, overfishing and pollution, can still doom coral reefs. But she was heartened that Cardenas’ team showed corals can grow in high-carbon environments, a finding that “provides some hope for the future of corals.”

Reference: “Submarine Groundwater Discharge Releases CO₂ to a Coral Reef” by Rogger E. Correa, M. Bayani Cardenas, Raymond S. Rodolfo, Mark R. Lapus, Kay L. Davis, Anna B. Giles, Jose C. Fullon, Mithra-Christin Hajati, Nils Moosdorf, Christian J. Sanders and Isaac R. Santos, 4 August 2021, ACS ES&T Water.
DOI: 10.1021/acsestwater.1c00104

Study co-authors included researchers from the Leibniz Centre for Tropical Marine Research (ZMT) in Germany; the State Office for Mining, Energy and Geology in Germany; and the following institutions in the Philippines: Ateneo de Manila University, Agricultural Sustainability Initiatives for Nature Inc., and Planet Dive Resort.

How having a favourite food can kill you: An 83 million year chronicle of shark evolution

by University of New England

Lamniformes and Carcharhiniformes across the last 83 million years. Credit: José Vitor Silva

The availability of prey and the ability to adapt to changing environments played key roles in the evolution of sharks. A new study, where 3,000 shark teeth were analyzed, provides new insight into how modern shark communities were established. The results are published in the journal Current Biology.

The new research investigated the diversity of shark teeth from the final stages of the Mesozoic (approximately 80 million years ago) to today. In particular, it sought to understand why there are only 15 species of mackerel sharks living today (scientific name: Lamniformes), whereas there are more than 290 species of ground sharks (Carcharhiniformes).

"The modern-day imbalance in diversity between the mackerel ground sharks have, until now, lacked a deep-time ecological perspective. However, if we look to the past, we see the opposite pattern: lamniforms were more diverse than carcharhiniforms" says study leader Dr. Mohamad Bazzi, previously a researcher at Uppsala University but now at the University of Zurich.

The evolution of sharks is a story told by their teeth. This is because most of what remains behind for paleontologists to work on are shed teeth. As a result, researchers must seek innovative approaches to help us fill out the many gaps in knowledge that relates to their past.

"Tooth morphology is a more direct proxy for the living habits of sharks and our study is the first attempt to explore how diet impacted lamniform and carcharhiniform sharks over the past 83 million years. By measuring the association between tooth shapes and diets from living sharks, we built a foundation for interpreting changes in diet in the fossil record," says Dr. Bazzi.

Shark tooth shape and environmental shifts over the sampled time interval.

 Credit: Mohamad Bazzi

The research team compiled an extensive database of over 3000 shark teeth and then evaluated their shape. To attain a measure of shape diversity (or disparity as it's technically called) the study relied on a method known as geometric morphometrics, which is a type of mathematical shape analysis.

Likewise, to understand the role diet played in shaping the diversity of sharks, the team assembled previously published records of sharks diets attained from stomach contents.

Many Cretaceous Lamniformes had specialized diets for eating marine reptiles and, following their loss at the end of the age of dinosaurs, these Lamniformes went extinct. On the other hand, Lamniformes with more generalized diets and Carcharhiniformes survived the extinction event. Carcharhiniforms particularly benefited from the diversification of bony fish following the extinction event, and the spread of coral reefs about 56 million years ago.

As it turns out, the same extinction that killed off the non-bird dinosaurs, may have set the stage for the modern shark community.

A similar event may have occurred only 5 million years ago to the largest shark to have ever existed, the lamniform megalodon (scientific name: Otodus megalodon).

The Shortfin mako, Isurus oxyrinchus (ROM R7940). Scale bar = 100 mm. 

Credit: Mohamad Bazzi

Megalodon fossils are mostly from the Miocene (which spanned from approximately 23 to 5 million years ago). During this period, lamniform sharks had record-low tooth disparity. Megalodon likely specialized on eating the large whales of that time and so this low disparity again suggests that specialized diets among top predatory sharks may be placing them at a greater risk of extinction.

"Here, we have a good example of the important biological insights offered by studying fossils," says Dr. Nicolás Campione, co-author and member of the University of New England's Palaeoscience Research Centre.

"Our research demonstrates that living Lamniformes are the result of repeated extinction events, perhaps resulting from a tendency to specialize. Dietary specialization, on top of environmental changes, were likely major factors behind the previously mentioned imbalance between Lamniformes and Carcharhiniformes," says Dr. Campione.

"We now have evidence that the availability of prey and the ability of sharks to adapt to changing environments played an important role in their past evolution. These factors underpinned the modern diversity of sharks and, critically, will likely decide their survival into the future," says Dr. Bazzi.

Shark diversity unaffected when the dinosaurs were wiped out

More information: Bazzi M, Campione NE, Kear BP, Pimiento, C, Ahlberg, PE (2021). Feeding ecology drove shark evolution. Current Biology.

Journal information: Current Biology 

Provided by University of New England 

Warping of Planet’s Crust: Melting of Polar Ice Shifting Earth Itself, Not Just Sea Levels

By HARVARD UNIVERSITY OCTOBER 4, 2021

Research by new Ph.D. finds warping of planet’s crust, with far-reaching effects.

The melting of polar ice is not only shifting the levels of our oceans, it is changing the planet Earth itself. Newly minted Ph.D. Sophie Coulson and her colleagues explained in a recent paper in Geophysical Research Letters that, as glacial ice from Greenland, Antarctica, and the Arctic Islands melts, Earth’s crust beneath these land masses warps, an impact that can be measured hundreds and perhaps thousands of miles away.

“Scientists have done a lot of work directly beneath ice sheets and glaciers,” said Coulson, who did her work in the Harvard University, Department of Earth and Planetary Sciences and received her doctorate in May from the Harvard University, Graduate School of Arts and Sciences. “So they knew that it would define the region where the glaciers are, but they hadn’t realized that it was global in scale.”

By analyzing satellite data on melt from 2003 to 2018 and studying changes in Earth’s crust, Coulson and her colleagues were able to measure the shifting of the crust horizontally. Their research, which was highlighted in Nature, found that in some places the crust was moving more horizontally than it was lifting.  In addition to the surprising extent of its reach, the Nature brief pointed out, this research provides a potentially new way to monitor modern ice mass changes.

Sophie Coulson and colleagues analyzed satellite data on melting glaciers and its impact on the Earth’s crust. Credit: Courtesy of Sophie Coulson

To understand how the ice melt affects what is beneath it, Coulson suggested imagining the system on a small scale: “Think of a wooden board floating on top of a tub of water. When you push the board down, you would have the water beneath moving down. If you pick it up, you’ll see the water moving vertically to fill that space.”

These movements have an impact on the continued melting. “In some parts of Antarctica, for example, the rebounding of the crust is changing the slope of the bedrock under the ice sheet, and that can affect the ice dynamics,” said Coulson, who worked in the lab of Jerry Mitrovica, the Frank B. Baird, Jr. Professor of Science.

The current melting is only the most recent movement researchers are observing. “The Arctic is an interesting region because, as well as the modern-day ice sheets, we also have a lasting signal from the last ice age,” Coulson explained. An ice sheet once covered what is now Northern Europe and Scandinavia during the Pleistocene Epoch, the ice age that started about 2.6 million years ago and lasted until roughly 11,000 years ago. “The Earth is actually still rebounding from that ice melting.”

“On recent timescales, we think of the Earth as an elastic structure, like a rubber band, whereas on timescales of thousands of years, the Earth acts more like a very slow-moving fluid,” said Coulson, explaining how these newer repercussions come to be overlaid on the older reverberations. “Ice age processes take a really, really long time to play out, and therefore we can still see the results of them today.”

The implications of this movement are far-reaching. “Understanding all of the factors that cause movement of the crust is really important for a wide range of Earth science problems. For example, to accurately observe tectonic motions and earthquake activity, we need to be able to separate out this motion generated by modern-day ice-mass loss,” she said.

Coulson is continuing her research as a Director’s Postdoctoral Fellow at Los Alamos National Laboratory in New Mexico as part of a climate group that works on future projections of ice sheets and ocean dynamics.

Glenn Antony Milne, professor of Earth and Environmental Sciences at the University of Ottawa, explained that understanding the extent of this movement clarifies all studies of the planet’s crust. “Sophie’s work is important because it is the first to show that recent mass loss of ice sheets and glaciers causes 3D motion of the Earth’s [solid] surface that is greater in magnitude and spatial extent than previously identified,” he said. “Also, one could look for this signal in regional and larger-scale global navigation satellite system datasets to, in principle, produce improved constraints on the distribution of ice mass fluctuations and/or solid Earth structure.”

References:

“The Global Fingerprint of Modern Ice-Mass Loss on 3-D Crustal Motion” by Sophie Coulson, Mila Lubeck, Jerry X. Mitrovica, Evelyn Powell, James L. Davis and Mark J. Hoggard, 16 August 2021, Geophysical Research Letters.
DOI: 10.1029/2021GL095477

“So much ice is melting that Earth’s crust is moving,” Research Highlight, 24 August 2021, Nature.
DOI: 10.1038/d41586-021-02285-0

What is Driving the Changes in Arctic Ice Cover?

Image courtesy NASA

PUBLISHED OCT 4, 2021 2:30 AM BY THE CONVERSATION

 

[By Alek Petty and Linette Boisvert]

September marks the end of the summer sea ice melt season and the Arctic sea ice minimum, when sea ice over the Northern Hemisphere ocean reaches its lowest extent of the year.

For ship captains hoping to navigate across the Arctic, this is typically their best chance to do it, especially in more recent years. Sea ice cover there has dropped by roughly half since the 1980s as a direct result of increased carbon dioxide from human activities.

As NASA scientists, we analyze the causes and consequences of sea ice change. In 2021, the Arctic’s sea ice cover reached its minimum extent on Sept. 16. While it wasn’t a record low, a look back through the melt season offers some insight into the relentless decline of Arctic sea ice in the face of climate change.

The Arctic is heating up

In recent years, Arctic sea ice levels have been at their lowest since at least 1850 for the annual mean and in at least 1,000 years for late summer, according to the latest climate assessment from the U.N.’s Intergovernmental Panel on Climate Change. The IPCC concluded that “the Arctic is likely to be practically sea ice free in September at least once before 2050.”

Arctic sea ice decline (black line) and projections for the future under five scenarios. NSIDC, Ed Hawkins

As the Arctic’s bright ice is replaced by a darker open ocean surface, less of the sun’s radiation is reflected back to space, driving additional heating and ice loss. This albedo feedback loop is just one of several reasons why the Arctic is warming about three times faster than the planet as a whole.

What happened to the sea ice in 2021?

The stage for this year’s sea ice minimum was set last winter. The Arctic experienced an anomalous high pressure system and strong clockwise winds, driving the thickest, oldest sea ice of the Central Arctic into the Beaufort Sea, north of Alaska. Sea ice scientists were taking note.

Summer melt began in earnest in May, a month that also featured multiple cyclones entering the Arctic. This increased sea ice drift but also kept temperatures relatively low, limiting the amount of melt. The extent and pace of melting increased significantly in June, which featured a predominant low-pressure system and temperatures that were a few degrees higher than average.

By the beginning of July, conditions were tracking very close to the record low set in 2012, but the rate of decline slowed considerably during the second half of the month. Cyclones entering the Arctic from Siberia generated counterclockwise winds and ice drifts. This counterclockwise ice circulation pattern generally reduces the amount of sea ice moving out of the Arctic through the Fram Strait, east of Greenland. This likely contributed to the record low summer sea ice conditions observed in the Greenland Sea.

This ice circulation pattern also increased ice export out of the Laptev Sea, off Siberia, helping create a new record low for early summer ice area in that region. The low pressure system also increased cloudiness over the Arctic. Clouds generally block incoming solar radiation, reducing sea ice melt, but they can also trap heat lost from the surface, so their impact on sea ice melt can be a mixed bag.

In August, sea ice decline slowed considerably, with warm conditions prevailing along the Siberian coast, but cooler temperatures north of Alaska. The Northern Sea Route – which Russia has been promoting as a global shipping route as the planet warms – was actually blocked with ice for the first time since 2008, although ice breaker-supported transits were still very much possible.

At this stage of the melt season, the sea ice pack is at its weakest and is highly responsive to the weather conditions of a given day or week. Subtle shifts can have big impacts. Freak end-of-summer weather events have been linked to the record low sea ice years of 2007 and 2012. “The Great Arctic Cyclone of 2012” is an interesting example.

There’s ongoing debate over the effect they have. However, scientists are broadly in agreement that specific storms may not have actually played that big a role in driving the record lows in those years – things are never that straightforward when it comes to weather and sea ice.

Arctic sea ice reached its minimum extent on Sept. 16, 2021. NASA Earth Observatory/NSIDC

The Arctic sea ice reached its 2021 minimum extent on Sept. 16, coming in at 4.72 million square kilometers (1.82 million square miles), the 12th lowest on record.

So, the 2021 melt season was, despite all the stops and starts, pretty typical for our new Arctic, with the September minimum ending up slightly higher than what we would have expected from the long-term downward trend. But various new record lows were set in other months and regions of the Arctic.

As the hours of sunlight dwindle over the coming weeks and temperatures drop, Arctic sea ice will start to refreeze. The ice pack will thicken and expand as the surrounding ocean surface temperatures drop toward the freezing point, releasing a lot of the heat that had been absorbed and stored through summer.

This refreeze has started later in recent years, shifting into October and even November. The more heat the ocean gains during summer, the more heat needs to be lost before ice can begin to form again. Because of this, some of the biggest warming signals are actually observed in fall, despite all the attention given to summer ice losses.

There’s still a lot we don’t know

For people living and working in the high Arctic, understanding local ice conditions on a given day or week is what really matters. And predicting Arctic sea ice at these more local scales is even more challenging.

As 2021 demonstrated, sea ice is highly dynamic – it moves and melts in response to the weather patterns of the day. Think how hard it is for forecasters to predict the weather where you live, with good understanding of weather systems and many observations available, compared to the Arctic, where few direct observations exist.

Weather events can also trigger local feedback loops. A freak heat wave, for example, can trigger ice melt and further warming. Winds and ocean currents also break up and spread ice out across the ocean, where it can be more prone to melt.

Sea ice scientists are hard at work trying to understand these various processes and improve our predictive models. A key missing part of the puzzle for understanding sea ice loss is ice thickness.

Thickness times area equals volume. Like area, sea ice thickness is thought to have halved since the 1980s, meaning today’s Arctic ice pack is only about a quarter of the volume it was just a few decades ago. For those hoping to navigate the Arctic Ocean, knowing the thickness of any ice they may encounter is crucial. Sea ice thickness is much harder to measure consistently from space. However, new technologies, like ICESat-2, are providing key breakthroughs.

Despite all this uncertainty, it’s looking pretty likely that summer ice-free Arctic conditions are not too far away. The good news is that the path forward is still largely dependent on future emissions, and there is still no evidence the planet has passed a tipping point of sea ice loss, meaning humans are still very much in the driver’s seat.

Alek Petty is an Associate Research Scientist in polar sea ice variability at NASA.

Linette Boisvert is a Sea Ice Scientist and Deputy Project Scientist for NASA's Operation IceBridge.

This article appears courtesy of The Conversation and may be found in its original form here.

'MAYBE' TECH CCS

Magnesium Can Make Carbon Capture Technology Faster; Could Bury Molecules Under the Sea for Hundreds of Years

Ron Jefferson 

SCIENCE TIMES

Oct 04, 2021 

The carbon capture approach is among the most promising methods to reduce the warming of water bodies on the planet, and ultimately hold off the threat of global climate change. A new study conducted by the University of Texas and ExxonMobil has found a way to develop a technology that uses carbon capture through crystalized hydrates. With the materials, experts have found that massive carbon dioxide content from the seafloor could be stored for more than hundreds of years. Moreover, adding magnesium to the system could speed up the reaction process of the crystalized hydrates up to 3,000 times faster than their standard capability.

Carbon Capture Technology vs Climate Change

(Photo : Emiliano Arano from Pexels)

The solutions to end the constant climate change on our planet have offered possibilities, but only a few were credible enough to take the burden. Among the best methods is to reduce the harmful gas content that hovers on Earth's atmospheric regions. Reducing greenhouse gases is theorized to significantly slow down the increasing risks of climate change. One of the applicable methods that experts are interested in is the carbon capture and sequestration approach. This procedure has the ability to suck up the carbon content from the skies and keep it for a very long time. Carbon capture has been tested and found to be effective, but only a small portion of CO2 content has been processed through the technique.

The University of Texas and Exxonmobil have conducted collaborative research to increase and speed up the carbon capture process. According to the study, the most effective way to quickly absorb the carbon dioxide and store it for more than centuries under the ocean floor is through synthesizing magnesium with the standard carbon-capturing model.

Magnesium-Induced Carbon Capture

Cockrell School of Engineering's Walker Department of Mechanical Engineering expert and lead author of the study Vaibhav Bahadur said in a SciTechDaily report that they view the carbon capture method as insurance for Earth's climate condition. The expert added that if carbon neutral is impossible to decrease the threat of climate change, they will take part to achieve a carbon-neutral environment. In this way, the damage inflicted is theorized to be healed.

Hydrates are the material that is expected to help experts absorb and trap CO2 underwater. Hydrates are formed whenever carbon dioxide is fused with a composition including water in an extremely high pressure but with a low temperature, respectively. The chemical reaction that goes through this method allows the water molecules to transition into another material that is capable of trapping and burying the carbon dioxide molecules.

Magnesium can speed up the carbon capture process by 3,000 times the standard reaction. Measured to be faster than the most effective carbon-capture method, the warming of the planet could be significantly lowered in just a shorter span of time. The study was published in the journal ACS Sustainable Chemistry Engineering, titled "Magnesium-Promoted Rapid Nucleation of Carbon Dioxide Hydrates."

Metals Supercharge Method To Bury Billions of Tons of Harmful Carbon Dioxide Under the Sea for Centuries

By UNIVERSITY OF TEXAS AT AUSTIN OCTOBER 3, 2021

• Capturing and burying carbon is one of the most promising ways to blunt the pace of climate change
• University of Texas and ExxonMobil researchers found a way to speed up the formation of crystal structures called hydrates that can store billions of tons of carbon for centuries
• Adding magnesium to the reaction led to a 3,000x increase in hydrate formation wait time — from hours or even days down to a few minutes

There’s a global race to reduce the amount of harmful gases in our atmosphere to slow down the pace of climate change, and one way to do that is through carbon capture and sequestration — sucking carbon out of the air and burying it. At this point, however, we’re capturing only a fraction of the carbon needed to make any kind of dent in climate change.

Researchers from The University of Texas at Austin, in partnership with ExxonMobil, have made a new discovery that may go a long way in changing that. They have found a way to supercharge the formation of carbon dioxide-based crystal structures that could someday store billions of tons of carbon under the ocean floor for centuries, if not forever.

“I consider carbon capture as insurance for the planet,” said Vaibhav Bahadur (VB), an associate professor in the Cockrell School of Engineering’s Walker Department of Mechanical Engineering and the lead author of a new paper on the research in ACS Sustainable Chemistry & Engineering. “It’s not enough anymore to be carbon neutral, we need to be carbon negative to undo damage that has been done to the environment over the past several decades.”

These structures, known as hydrates, form when carbon dioxide is mixed with water at high pressure and low temperature. The water molecules re-orient themselves and act as cages that trap CO2 molecules.

But the process initiates very slowly – it can take hours or even days to get the reaction started. The research team found that by adding magnesium to the reaction, hydrates formed 3,000 times faster than the quickest method in use today, as rapidly as one minute. This is the fastest hydrate formation pace ever documented.

“The state-of-the-art method today is to use chemicals to promote the reaction,” Bahadur said. “It works, but it’s slower, and these chemicals are expensive and not environmentally friendly.”

The hydrates form in reactors. In practice, these reactors could be deployed to the ocean floor. Using existing carbon capture technology, CO2 would be plucked from the air and taken to the underwater reactors where the hydrates would grow. The stability of these hydrates reduces the threat of leaks present in other methods of carbon storage, such as injecting it as a gas into abandoned gas wells.

Figuring out how to reduce carbon in the atmosphere is about as big of a problem as there is in the world right now. And yet, Bahadur says, there are only a few research groups in the world looking at CO2 hydrates as a potential carbon storage option.

“We are only capturing about half of a percent of the amount of carbon that we’ll need to by 2050,” Bahadur said. “This tells me there is plenty of room for more options in the bucket of technologies to capture and store carbon.”

Bahadur has been working on hydrate research since he arrived at UT Austin in 2013. This project is part of a research partnership between ExxonMobil and the Energy Institute at UT Austin.

The researchers and ExxonMobil have filed a patent application to commercialize their discovery. Up next, they plan to tackle issues of efficiency — increasing the amount of CO2 that is converted into hydrates during the reaction — and establishing continuous production of hydrates.

Reference: “Magnesium-Promoted Rapid Nucleation of Carbon Dioxide Hydrates” by Aritra Kar, Palash Vadiraj Acharya, Awan Bhati, Ashish Mhadeshwar, Pradeep Venkataraman, Timothy A. Barckholtz, Hugo Celio, Filippo Mangolini and Vaibhav Bahadur, 11 August 2021, ACS Sustainable Chemistry & Engineering.
DOI: 10.1021/acssuschemeng.1c03041

The research was funded by ExxonMobil and a grant from the National Science Foundation. Bahadur led the team, which also includes Filippo Mangolini, an assistant professor in the Walker Department of Mechanical Engineering. Other team members include: from the Walker Department of Mechanical Engineering Aritra Kar, Palash Vadiraj Acharya and Awan Bhati; from Texas Materials Institute at UT Austin Hugo Celio and researchers from ExxonMobil.

'MAYBE' TECH

This startup is using sunlight and captured CO2 to make jet fuel

In the future, your flights could be powered by recycled carbon emissions.



In a field in the desert next to a freeway in Tucson, Arizona, the sun beams down on a large mirror in a research park, powering a small reactor nearby. Inside that reactor, captured carbon dioxide is being transformed into synthetic jet fuel.

“We remove the need for any sort of fossil fuel inputs,” says Jason Salfi, cofounder and CEO of Dimensional Energy, the startup running the small pilot installation. By early next year, the tiny facility will be producing only around half a barrel of fuel a day. But the company plans to use the same process—with a large field of heliostats, which are mirrors that concentrate solar power—at a sizable scale. In 2022, it hopes to get its sustainable aviation fuel certified for use and begin flight tests with a partner airline. The company is one of a handful of startups developing alternative jet fuels (LanzaTech, which turns steel-factory emissions into ethanol, is another).

[Photo: courtesy Dimensional Energy]For the airline industry, which emitted 918 million tons of CO2 in 2019 before the pandemic temporarily slowed travel, the technology could be part of a larger transformation. Electric planes are in development, but are only likely to be feasible for short flights and small aircraft in the near future. “Right now, the energy density of the batteries are several times less than the energy density of the hydrocarbon fuels,” says Salfi, “so you just simply can’t store enough energy to fly long distances and to fly large amounts of passengers.” The company’s process could also be used to make fuel for long-distance trucking or shipping.

[Photo: courtesy Dimensional Energy]The technology, which grew out of research at Cornell University, uses electrolysis to split water and produce hydrogen, and then mixes the hydrogen and CO2 in its reactor to make syngas, or synthetic gas—which can be converted into liquid fuel and then refined into jet fuel. “The magic of our technology is where we integrate everything into one single stream,” he says. The tech makes it possible to make carbon monoxide, one component of the process, at a low cost, and makes the resulting fuel cost competitive. At scale, the company projects that the fuel could eventually cost less than $1 per gallon.

[Photo: courtesy Dimensional Energy]“Our financial models show being able to have cost parity with fossil fuel-based jet fuel in the next decade,” says Salfi. It’s critical to get there if airlines are going to buy it. “It’s going to be a struggle to get them to pay a premium for any meaningful amount of sustainable aviation fuel,” he says. “Even if they are paying a premium today, sustainable aviation fuel only makes up something like less than a tenth of a percent of the overall market. . . . [T]hey just won’t respond unless it’s in their pricing model. Companies like ours just have to get the prices down.”

[Photo: courtesy Dimensional Energy]Dimensional Energy plans to begin its process with CO2 captured from industry—for example, cement plants, which produce carbon dioxide as part of the chemical process even if they’re able to run on renewable energy. Eventually, as direct air capture technology scales up to pull CO2 from the atmosphere, it could also be a source for the fuel, making it essentially carbon neutral. (Direct air capture also produces water, which could be used to make hydrogen in the process.) Other sources are also possible. New technology that captures CO2 from trucks as they drive, for example, could theoretically be the source for new fuel for those trucks.

At the moment, regulations limit the amount of synthetic fuel that planes can use, allowing a mix of up to 50%. That would still dramatically lower the carbon footprint of flights, but it’s possible that 100% sustainable aviation fuel may soon be allowed. The fuel could also eventually be used on hybrid aircraft that use fuel for energy-intensive takeoff, but then run on electric power in the sky.