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Studying impact craters to uncover the secrets of the solar system

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While for humans the constants might be death and taxes, for planets the constants are gravity and collisions.

Brandon Johnson studies the latter, using information about impacts to understand the history and the composition of planets, moons, asteroids and meteorites throughout the solar system.

“Impact cratering is the most ubiquitous surface process shaping planetary bodies,” Johnson said. “Craters are found on almost every solid body we’ve ever seen. They are a major driver of change in planetary bodies. They drive the evolution of planetary crusts. All the planets and asteroids were built from a series of impacts. Studying impacts can help us determine the composition and structure of planets.”

As an associate professor in the Department of Earth, Atmospheric, and Planetary Sciences in Purdue University’s College of Science, Johnson has studied almost every major planetary body in the solar system. And the time scale of his research ranges from relatively recent impacts to nearly the beginning of the solar system itself.

Collecting clues about collisions helps Johnson reconstruct the environment in which the collisions took place, offering deep insights into how and when bodies formed. His research is helping humans explore the planetary bodies in the solar system with only physics, math and a computer. Space missions and laboratory analyses provide a constant supply of new data and questions to work on.

“Most meteorites contain chondrules—small, previously molten, particles,” Johnson said. “Essentially, by studying the formation of chondrules by impacts, we can better understand what was going on in the nascent solar system. For example, based on one impact, we were able to determine that Jupiter had already formed right around 5 million years after the first solar system solids, changing the timeline of our understanding of the solar system.”

Johnson and his lab staff incorporate known factors about the composition and physics of planetary bodies into complex computer models, running the models through a range of conditions and comparing the results with observed phenomena. Analyzing movements and collisions can offer insights into the composition of asteroids and meteorites, helping scientists understand how elements like water and metal are distributed through a solar system. By studying impact craters and basins on places like Pluto, Venus and icy moons, and the mechanics of other processes occurring on Europa and asteroids like Psyche, his team can understand more about their interiors; whether they have molten cores and plate tectonics, for example, or whether they have liquid oceans.

His work doesn’t just span the solar system. He studies impacts closer to home, too, including on Earth’s own moon and terrestrial impacts that may have affected the way Earth’s crust, atmosphere and biosphere evolved.

An online impact calculator tool developed by the late Jay Melosh, Johnson’s mentor and former Distinguished Professor of Earth, Atmospheric and Planetary Sciences, allows anyone to study the impacts of various rocks into the Earth. Johnson and his team are rebuilding the tool for a new generation of planetary students.

The research was published in Icarus.

More information: J.R. Elliott et al, The role of target strength on the ejection of martian meteorites, Icarus (2021). DOI: 10.1016/j.icarus.2021.114869

Gareth S. Collins et al, Earth Impact Effects Program: A Web-based computer program for calculating the regional environmental consequences of a meteoroid impact on Earth, Meteoritics & Planetary Science (2010). DOI: 10.1111/j.1945-5100.2005.tb00157.x

Journal information: IcarusProvided by Purdue University

Solar energy explains fast yearly retreat of Antarctica’s sea ice

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Solar energy explains fast yearly retreat of Antarctica’s sea ice

In the Southern Hemisphere, the ice cover around Antarctica gradually expands from March to October each year. During this time the total ice area increases by 6 times to become larger than Russia. The sea ice then retreats at a faster pace, most dramatically around December, when Antarctica experiences constant daylight.

New research led by the University of Washington explains why the ice retreats so quickly: Unlike other aspects of its behavior, Antarctic sea ice is just following simple rules of physics.

The study was published March 28 in Nature Geoscience.

“In spite of the puzzling longer-term trends and the large year-to-year variations in Antarctic sea ice, the seasonal cycle is really consistent, always showing this fast retreat relative to slow growth,” said lead author Lettie Roach, who conducted the study as a postdoctoral researcher at the UW and is now research scientist at NASA and Columbia University. “Given how complex our climate system is, I was surprised that the rapid seasonal retreat of Antarctic sea ice could be explained with such a simple mechanism.”

Previous studies explored whether wind patterns or warm ocean waters might be responsible for the asymmetry in Antarctica’s seasonal sea ice cycle. But the new study shows that, just like a hot summer day reaches its maximum sizzling conditions in late afternoon, an Antarctic summer hits peak melting power in midsummer, accelerating warming and sea ice loss, with slower changes in temperature and sea ice when solar input is low during the rest of the year.

The researchers investigated global climate models and found they reproduced the quicker retreat of Antarctic sea ice. They then built a simple physics-based model to show that the reason is the seasonal pattern of incoming solar radiation.

At the North Pole, Arctic ice cover has gradually decreased since the 1970s with global warming. Antarctic ice cover, however, has seesawed over recent decades. Researchers are still working to understand sea ice around the South Pole and better represent it in climate models.

“I think because we usually expect Antarctic sea ice to be puzzling, previous studies assumed that the rapid seasonal retreat of Antarctic sea ice was also unexpected—in contrast to the Arctic, where the seasons of ice advance and retreat are more similar,” Roach said. “Our results show that the seasonal cycle in Antarctic sea ice can be explained using very simple physics. In terms of the seasonal cycle, Antarctic sea ice is behaving as we should expect, and it is the Arctic seasonal cycle that is more mysterious.”

The researchers are now exploring why Arctic sea ice doesn’t follow this pattern, instead each year growing slightly faster over the Arctic Ocean than it retreats. Because Antarctica’s geography is simple, with a polar continent surrounded by ocean, this aspect of its sea ice may be more straightforward, Roach said.

“We know the Southern Ocean plays an important role in Earth’s climate. Being able to explain this key feature of Antarctic sea ice that standard textbooks have had wrong, and showing that the models are reproducing it correctly, is a step toward understanding this system and predicting future changes,” said co-author Cecilia Bitz, a UW professor of atmospheric sciences.

Other co-authors are; Edward Blanchard-Wrigglesworth, a UW research assistant professor in atmospheric sciences; Ian Eisenman at Scripps Institution of Oceanography; and Till Wagner at the University of Wisconsin-Madison.

More information: Asymmetry in the seasonal cycle of Antarctic sea ice driven by insolation, Nature Geoscience (2022). DOI: 10.1038/s41561-022-00913-6

Journal information: Nature Geoscience

Provided by University of Washington

Where does all Earth’s gold come from?

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Where does all Earth’s gold come from?

Ultra high precision analyses of some of the oldest rock samples on Earth by researchers at the University of Bristol provides clear evidence that the planet’s accessible reserves of precious metals are the result of a bombardment of meteorites more than 200 million years
The research is published in Nature.

During the formation of Earth, molten iron sank to its centre to make the core. This took with it the vast majority of the planet’s precious metals — such as gold and platinum. In fact, there are enough precious metals in the core to cover the entire surface of Earth with a four-metre thick layer.

The removal of gold to the core should leave the outer portion of Earth bereft of bling. However, precious metals are tens to thousands of times more abundant in Earth’s silicate mantle than anticipated. It has previously been argued that this serendipitous over-abundance results from a cataclysmic meteorite shower that hit Earth after the core formed. The full load of meteorite gold was thus added to the mantle alone and not lost to the deep interior.

To test this theory, Dr Matthias Willbold and Professor Tim Elliott of the Bristol Isotope Group in the School of Earth Sciences analysed rocks from Greenland that are nearly four billion years old, collected by Professor Stephen Moorbath of the University of Oxford. These ancient rocks provide a unique window into the composition of our planet shortly after the formation of the core but before the proposed meteorite bombardment.

The researchers determined the tungsten isotopic composition of these rocks. Tungsten (W) is a very rare element (one gram of rock contains only about one ten-millionth of a gram of tungsten) and, like gold and other precious elements, it should have entered the core when it formed. Like most elements, tungsten is composed of several isotopes, atoms with the same chemical characteristics but slightly different masses. Isotopes provide robust fingerprints of the origin of material and the addition of meteorites to Earth would leave a diagnostic mark on its W isotope composition.

Dr Willbold observed a 15 parts per million decrease in the relative abundance of the isotope 182W between the Greenland and modern day rocks. This small but significant change is in excellent agreement with that required to explain the excess of accessible gold on Earth as the fortunate by-product of meteorite bombardment.

Dr Willbold said: “Extracting tungsten from the rock samples and analysing its isotopic composition to the precision required was extremely demanding given the small amount of tungsten available in rocks. In fact, we are the first laboratory world-wide that has successfully made such high-quality measurements.”

The impacting meteorites were stirred into Earth’s mantle by gigantic convection processes. A tantalising target for future work is to study how long this process took. Subsequently, geological processes formed the continents and concentrated the precious metals (and tungsten) in ore deposits which are mined today.

Dr Willbold continued: “Our work shows that most of the precious metals on which our economies and many key industrial processes are based have been added to our planet by lucky coincidence when the Earth was hit by about 20 billion billion tonnes of asteroidal material.”

This research was funded by the Natural Environment Research Council (NERC), the Science and Technology Facilities Council (STFC) and the Deutsche Forschungsgemeinschaft (DFG).

Reference: Matthias Willbold, Tim Elliott, Stephen Moorbath. The tungsten isotopic composition of the Earth’s mantle before the terminal bombardment. Nature, 2011; 477 (7363): 195 DOI: 10.1038/nature10399

Hidden weaknesses within volcanoes may cause volcano collapse

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Hidden weaknesses within volcanoes may cause volcano collapse

Lava domes form at the top of many volcanoes when viscous lava erupts. When they become unstable, they can collapse and cause a hazard. An international team of researchers has analysed summit dome instabilities at Merapi Volcano, Indonesia. The researchers hope that by understanding the inner processes, volcano collapses can be better forecasted.

Catastrophic volcano collapses and associated explosions, like the famous collapse of Mt St Helens in 1980, are widely considered as unpredictable. This is because the physical properties, stress conditions, and internal structure of volcanoes and the lava domes on top of many volcanoes are not well understood and can change rapidly from one day to another.

A new study jointly led by Gadja Mata University in Yogyakarta Indonesia, Uppsala University in Sweden, and the German Research Center GFZ at Potsdam is now able to explain summit dome instabilities and associated pyroclastic flows at Merapi volcano, Indonesia. The study combines novel drone-based photogrammetry surveillance over several years with mineralogical, geochemical, and mechanical rock strength measurements.

The research demonstrated that a horseshoe-shaped fracture zone in the volcanoes summit region that formed in 2012 and which guided intense gas emission in the past was subsequently buried by renewed lava outpourings in 2018. The new lava dome that has been forming since 2018 started to show signs of instability in 2019 and the researchers were able to show that the summit dome of the volcano is currently collapsing along this now-hidden fracture zone. The research team then considered the changes that must have occurred along this now buried fracture zone from long term gas flux by measuring the composition and physical properties along similar fracture zones in the volcano’s summit region, and concludes that weakened rocks of the hidden fracture zone are likely the main cause for the location of the ongoing summit instabilities at Merapi.

Reference: Herlan Darmawan, Valentin R. Troll, Thomas R. Walter, Frances M. Deegan, Harri Geiger, Michael J. Heap, Nadhirah Seraphine, Chris Harris, Hanik Humaida, Daniel Müller. Hidden mechanical weaknesses within lava domes provided by buried high-porosity hydrothermal alteration zones. Scientific Reports, 2022; 12 (1) DOI: 10.1038/s41598-022-06765-9

Warmer summers and meltwater lakes are threatening the fringes of the world’s largest ice sheet

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Warmer summers and meltwater lakes are threatening the fringes of the world’s largest ice sheet

A first-of-its-kind study looking at surface meltwater lakes around the East Antarctic Ice Sheet across a seven-year period has found that the area and volume of these lakes is highly variable year-to-year, and offers new insights into the potential impact of recent climatic change on the ‘Frozen Continent’.

The research, led by Durham University (UK), used over 2000 satellite images from around the edge of the East Antarctic Ice Sheet to determine the size and volume of lakes on the ice surface, also known as supraglacial lakes, across seven consecutive years between 2014 and 2020.

The study, which involved Newcastle and Lancaster universities and the Georgia Institute of Technology, showed that lake volume varied year-to-year by as much as 200% on individual ice shelves (floating extensions of the main Antarctic ice sheet), and by around 72% overall.

Lakes were also found to be deeper and larger in warmer melt seasons and formed on some potentially vulnerable ice shelves.

This research, published today in Nature Communications, is the first time that meltwater lakes have been studied over consecutive melt seasons across the whole ice sheet, enabling the controls on their development to be explored. The study therefore provides vital insight into why and where lakes grow, and will help experts understand which ice shelves may be most at risk of breaking up as a consequence of surface melting.

Warmer summers and meltwater lakes are threatening the fringes of the world's largest ice sheet
Meltwater lake in East Antarctica observed from the Landsat 8 satellite. Credit: USGS Geological Survey

Lead researcher, Ph.D. student Jennifer Arthur, Department of Geography, Durham University, said; “We knew that supraglacial lakes were more extensive than previously thought around the East Antarctic Ice Sheet, but until now only had snapshots of these in some years.

“Our study reveals these lakes change in scale far more than we originally suspected. We were surprised at how much lakes can change year-to-year between ice shelves.

“We explored the potential reasons for this and found that warmer summer air temperatures in Antarctica correlated with more extensive lakes.

“Due to climate change, air temperatures in Antarctica will continue to rise and our study suggests that this will lead to an increase in the number and volume of supraglacial lakes, which will in turn put some East Antarctic ice shelves at risk of meltwater-driven collapse.”

Warmer summers and meltwater lakes are threatening the fringes of the world's largest ice sheet
Meltwater lake on the Sørsdal Glacier, East Antarctica. Credit: Sue Cook, UTAS

The East Antarctic Ice Sheet is the world’s largest ice mass and holds enough ice to raise global sea levels by around 52 meters.

The loss of ice shelves fringing an ice sheet allows ice further inland to flow faster into the ocean, contributing to global sea-level rise.

Until now, observations of supraglacial lakes on the East Antarctica Ice Sheet were relatively scarce and the year-to-year variability was largely unknown, making it difficult to assess whether some ice shelves are close to meltwater-driven break up under climate change.

Warmer summers and meltwater lakes are threatening the fringes of the world's largest ice sheet
Meltwater lake on the Sørsdal Glacier. Credit: Dave Lomas

This study will help experts understand supraglacial lake formation, climatic impacts on this and predict which ice shelves may be most at risk of collapse.

Understanding the climatic conditions controlling meltwater lake variability will also improve the accuracy of regional climate models used to replicate observations and predict future ice sheet change in Antarctica.

The study used images from the Landsat 8 satellite.

More information: Large interannual variability in supraglacial lakes around East Antarctica, Nature Communications (2022). DOI: 10.1038/s41467-022-29385-3

Journal information:Nature Communications

Provided by Durham University

Solid aerosols found in Arctic atmosphere could impact cloud formation and climate

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Solid aerosols found in Arctic atmosphere could impact cloud formation and climate

The Arctic is rapidly losing sea ice, and less ice means more open water, and more open water means more gas and aerosol emissions from the ocean into the air, warming the atmosphere and making it cloudier.

So when researchers from the lab of University of Michigan aerosol scientist Kerri Pratt collected aerosols from the Arctic atmosphere during summer 2015, Rachel Kirpes, then a doctoral student, discovered a curious thing: Aerosolized ammonium sulfate particles didn’t look like typical liquid aerosols.

Working with fellow aerosol scientist Andrew Ault, Kirpes discovered that ammonium sulfate particles, which should have been liquid, were actually solid. The team’s results are published in the Proceedings of the National Academy of Sciences.

Solid aerosols can change how clouds form in the Arctic. And, as the Arctic loses ice, researchers expect to see more of these unique particles formed from oceanic emissions combined with ammonia from birds, which will impact cloud formation and climate. Additionally, understanding the characteristics of aerosols in the atmosphere is critical for improving the ability of climate models to predict current and future climate in the Arctic and beyond.

“The Arctic is warming faster than anywhere else in the world. As we have more emissions from open water in the atmosphere, these types of particles could become more important,” said Pratt, associate professor of chemistry, and earth and environmental sciences. “These types of observations are so critical because we have so few observations to even evaluate the accuracy of models of the Arctic atmosphere.

“With so few observations, sometimes you get surprises like this when you make measurements. These particles didn’t look like anything we had ever seen in the literature, in the Arctic, or anywhere else in the world.”

The aerosols observed in the study were up to 400 nanometers, or about 300 times smaller than the diameter of a human hair. Ault, associate professor of chemistry, says that aerosols in the Arctic are typically assumed to be liquid.

Once the relative humidity of the atmosphere reaches 80%—about the level of a humid day—the particle becomes liquid. When you dry the aerosol back out, it doesn’t turn into a solid until the relative humidity is about 35%-40%. Because the air over the Arctic Ocean—or any ocean—is humid, researchers expect to see liquid aerosols.

“But what we saw is a pretty new phenomenon where a small particle collides with our droplets when it’s below 80% humidity, but above 40% humidity. Essentially, this provides a surface for the aerosol to solidify and become a solid at a higher relative humidity than you would have expected,” Ault said.

“These particles were much more like a marble than a droplet. That’s really important, particularly in a region where there haven’t been a lot of measurements because those particles can eventually end up acting as the seeds of clouds or having reactions happen on them.”

Additionally, the researchers say, the size, composition and phase of atmospheric aerosols impact climate change through water uptake and cloud formation.

“It’s our job to keep helping modelers refine their models,” Ault said. “It’s not that the models are wrong, but they always need more new information as events on the ground change, and what we saw was something completely unexpected.”

Pratt’s team collected aerosols in August-September 2015 in Utqiaġvik, the northernmost point of Alaska. To do this, they used what’s called a multistage impactor, a device that has several stages that collect particles according to their size. Kirpes later analyzed these particles in Ault’s lab using microscopy and spectroscopy techniques that can examine the composition and phase of particles less than 100 nanometers in size.

“If we were to go back several decades when there was ice near the shore, even in August and September, we would not be observing these particles. We’re observing the consequences of this climate already changing,” Pratt said. “We need to have the reality captured in models that simulate clouds and the atmosphere, which are critical for understanding the energy budget of the Arctic atmosphere, for this place that is changing faster than anywhere else.”

More information: Rachel M. Kirpes et al, Solid organic-coated ammonium sulfate particles at high relative humidity in the summertime Arctic atmosphere, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2104496119

Journal information: Proceedings of the National Academy of Sciences

Provided by University of Michigan

Video: Astronomers reveal remarkable simulations of the early universe epoch of reionization

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Video: Astronomers reveal remarkable simulations of the early universe epoch of reionization

It looks like fireflies flickering in the darkness. Slowly, more and more amass, lighting up the screen in large chunks and clusters.

But this is not a video about insects. It’s a simulation of the early universe, a time after the Big Bang when the cosmos transformed from a place of utter darkness to a radiant, light-filled environment.

The stunning video is part of a large suite of simulations described in a series of three papers accepted to the Monthly Notices of the Royal Astronomical Society. Created by researchers at the Center for Astrophysics | Harvard & Smithsonian, the Massachusetts Institute of Technology and the Max Planck Institute for Astrophysics, the simulations represent a monumental advancement in simulating the formation of the first galaxies and reionization—the process by which neutral hydrogen atoms in space were transformed into positively charged, or ionized, hydrogen, allowing light to spread throughout the universe.

The simulated period, known as the epoch of reionization, took place some 13 billion years ago and was challenging to reconstruct, as it involves immensely complicated, chaotic interactions, including those between gravity, gas and radiation, or light.

“Most astronomers don’t have labs to conduct experiments in. The scales of space and time are too large, so the only way we can do experiments is on computers,” explains Rahul Kannan, an astrophysicist at the Center for Astrophysics and the lead author of the first paper in the series. “We are able to take basic physics equations and governing theoretical models to simulate what happened in the early universe.”

The team’s simulations—named Thesan after the Etruscan goddess of dawn—resolve interactions in the early universe with the highest detail and over the largest volume of any previous simulation. Physics in the early universe are captured down to scales that are a million times smaller than the simulated regions, providing unprecedented detail on properties of early galaxies and how light from these galaxies impacted gas.

The team accomplishes this by combining a realistic model of galaxy formation with a new algorithm that tracks how light interacts with gas, along with a model for cosmic dust.

With Thesan, researchers can simulate a piece of our universe spanning over 300 million light years across. The team can run the simulation forward in time to track and visualize the first appearance and evolution of hundreds of thousands of galaxies within this space, beginning around 400,000 years after the Big Bang, and through the first billion years.

The simulations reveal a gradual change in the universe from complete darkness to light.

“It’s a bit like water in ice cube trays; when you put it in the freezer, it does take time, but after a while it starts to freeze on the edges and then slowly creeps in,” says study co-author Aaron Smith, a NASA Einstein Fellow in MIT’s Kavli Institute for Astrophysics and Space Research. “This was the same situation in the early universe—it was a neutral, dark cosmos that became bright and ionized as light began to emerge from the first galaxies.”

The simulations were created to prepare for observations from the James Webb Space Telescope (JWST), which will be able to peer further back in time—approximately 13.5 billion years—than predecessors like the Hubble Space Telescope.

Scientists develop the largest, most detailed model of the early universe to date
Evolution of simulated properties in the main Thesan run. Time progresses from left to right. The dark matter (top panel) collapse in the cosmic web structure, composed of clumps (haloes) connected by filaments, and the gas (second panel from the top) follows, collapsing to create galaxies. These produce ionising photons that drive cosmic reionization (third panel from the top), heating up the gas in the process (bottom panel). Credit: Credits: THESAN Simulations

“A lot of telescopes coming online, like the JWST, are specifically designed to study this epoch,” Kannan says. “That’s where our simulations come in; they are going to help us interpret real observations of this period and understand what we’re seeing.”

Real telescope observations and data will soon be compared to Thesan simulations, the team explains.

“And thats the interesting part,” says study co-author Mark Vogelsberger, an associate professor of physics at MIT. “Either our Thesan simulations and model will agree with what JWST finds, which would confirm our picture of the universe, or there will be a significant disagreement showing that our understanding of the early universe is wrong.”

The team, however, won’t know how various aspects of their model fares until the first observations roll in, which will cover a wide range of topics, including galaxy properties and the absorption and escape of light in the early universe.

“We have developed simulations based on what we know,” Kannan says. “But while the scientific community has learned a lot in recent years, there is still quite a bit of uncertainty, especially in these early times when the universe was very young.”

The simulations were created using one of the world’s largest supercomputers, the SuperMUC-NG, over the course of 30 million CPU-hours. The same simulations would have required more than 3,500 years to complete on a normal computer.

More information: The THESAN project: Lyman-α emission and transmission during the Epoch of Reionization , Monthly Notices of the Royal Astronomical Society (2022). DOI: 10.1093/mnras/stac713 , academic.oup.com/mnras/advance … nras/stac713/6553849

Journal information: Monthly Notices of the Royal Astronomical Society

Provided by Harvard-Smithsonian Center for Astrophysics

Ancient helium leaking from core offers clues of Earth’s formation

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Ancient helium leaking from core offers clues of Earth’s formation

Helium-3, a rare isotope of helium gas, is leaking out of Earth’s core, a new study reports. Because almost all helium-3 is from the Big Bang, the gas leak adds evidence that Earth formed inside a solar nebula, which has long been debated.

Helium-3 has been measured at Earth’s surface in relatively small quantities. But scientists did not know how much was leaking from the Earth’s core, as opposed to its middle layers, called the mantle.

The new study pins down the core as a major source of helium-3 on the Earth. Some natural processes can generate helium-3, such as the radioactive decay of tritium, but helium-3 is made primarily in nebulae—massive, spinning clouds of gas and dust like the one that gave rise to our Solar System. Because helium is one of the earliest elements produced in the universe, most helium-3 can be traced back to the Big Bang.

As a planet grows, it accumulates material from its surroundings, so its composition reflects the environment in which it formed. To get high concentrations of helium-3 deep in the core, Earth would have had to form inside a thriving solar nebula, not on its fringes or during its waning phase.

The new research adds further clues to the mystery surrounding Earth’s formation, lending additional evidence to the theory that our planet formed inside the solar nebula.

The study was published in the AGU journal Geochemistry, Geophysics, Geosystems, which publishes research on the chemistry, physics, geology and biology of Earth and planetary processes.

About 2,000 grams of helium-3 leak out of the Earth every year, “about enough to fill a balloon the size of your desk,” said lead study author Peter Olson, a geophysicist at the University of New Mexico. “It’s a wonder of nature, and a clue for the history of the Earth, that there’s still a significant amount of this isotope in the interior of the Earth.”

The researchers modeled helium during two key stages of Earth’s history: early formation, when the planet was accumulating helium, and following the formation of the Moon, after which helium was lost. Evidence suggests an object one-third the size of the Earth hit the planet early in its history, around 4 billion years ago and that impact would have re-melted the Earth’s crust, allowing much of the helium to escape. The gas continues escaping to this day.

Using the modern helium-3 leak rate along with models of helium isotope behavior, the researchers estimated there are between 10 teragrams (1013 grams) to a petagram (1015 grams) of helium-3 in the core—a vast quantity that Olson said points to Earth’s formation inside the solar nebula, where high concentrations of the gas would have allowed it to build up deep in the planet.

However, future work looking for other nebula-created gasses, such as hydrogen, leaking in similar rates and locations as helium-3 could be a “smoking gun” for the core as the source, Olson said. “There are many more mysteries than certainties.”

More information: Peter L. Olson et al, Primordial Helium‐3 Exchange Between Earth’s Core and Mantle, Geochemistry, Geophysics, Geosystems (2022). DOI: 10.1029/2021GC009985

Provided by American Geophysical Union624 

Mysterious, giant stone jars found in India

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Mysterious, giant stone jars found in India

Mysterious giant jars that may have been used for burial rituals have been unearthed across four new sites in Assam, India. The discovery comes from a major collaboration involving researchers at The Australian National University (ANU).  

The 65 newly discovered sandstone jars vary in shape and decoration, with some tall and cylindrical, and others partly or fully buried in the ground. Similar jars, some of which span up to three meters high and two meters wide, have previously been uncovered in Laos and Indonesia.  

“We still don’t know who made the giant jars or where they lived. It’s all a bit of a mystery,” ANU Ph.D. student Nicholas Skopal said.  

Another mystery is what the giant jars were used for. The researchers believe it is likely they were associated with mortuary practices.  

“There are stories from the Naga people, the current ethnic groups in north-east India, of finding the Assam jars filled with cremated remains, beads and other material artifacts,” Mr. Skopal said. This theory aligns with findings from the other jar sites in countries including Laos, which are also tied to burial rituals.  

Initially, the aim of the new research was to survey the existing sites in Assam. However, as the researchers moved about the landscape they realized there was more to be uncovered. ”At the start the team just went in to survey three large sites that hadn’t been formally surveyed. From there grids were set up to explore the surrounding densely forested regions,” Mr. Skopal said. ”This is when we first started finding new jar sites. The team only searched a very limited area so there are likely to be a lot more out there, we just don’t yet know where they are.”  

The surveying and reporting of these sites is of great importance in regards to heritage management in India.  

“It seems as though there aren’t any living ethnic groups in India associated with the jars, which means there is an importance to maintain the cultural heritage,” Mr. Skopal said. ”The longer we take to find them, the greater chance that they will be destroyed, as more crops are planted in these areas and the forests are cut down.”  

The researchers worked with local communities on the ground to uncover potential jar sites, often through areas of mountainous jungle that were difficult to navigate. 

“Once the sites have been recorded, it becomes easier for the government to work with the local communities to protect and maintain them so they are not being destroyed,” Mr. Skopal said. 

The research was led by Tilok Thakuria, from North Eastern Hill University and Uttam Bathari, from Gauhati University.  

The study’s findings are published in the Journal of Asian Archaeology.

Australia’s environment law doesn’t protect the environment

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Australia’s environment law doesn’t protect the environment

The Federal Court recently quashed a duty of care owed by the environment minister to Australian children, to protect them from the harms of climate change.

The duty was attached to Australia’s federal environment law, the Environment Protection and Biodiversity Conservation (EPBC) Act. In reversing the decision that had established the duty, the new judgment shone a spotlight on the EPBC Act’s limitations. Or at least, it should have.

Much of the commentary around the judgment focused on lamenting the hands-off position the court took in its unwillingness to delve into so-called political territory.

Less attention was paid to a key take-home message: the EPBC Act gives the minister power to approve coal projects, even if they’ll have adverse effects.

It doesn’t, in a general sense, protect the environment from these effects. It doesn’t protect the public from consequent harm, even if deadly. And it doesn’t, actually, tackle climate change at all.

Alarmed? You should be.

Why the duty was quashed

The appeal was heard by three judges, each with a different opinion on why there shouldn’t be a duty.

One key problem was that the class of victims won’t just include the children represented in the case. Currently unborn children will be affected too. The judges also found issues with the minister’s relationship with the children given the intervening steps that will lead to climate change, extreme weather events, and future harm.

To help resolve novel disputes, courts look to previous cases. One case that featured prominently was about protecting the public from contaminated oysters. In that case, a council wasn’t liable for failing to prevent water pollution that caused hepatitis infection. In another case, where there was no way of identifying the source of asbestos fibers that caused mesothelioma, it was found that whoever materially increased the risk of harm could be liable for it.

The fact these were considered the most relevant cases just goes to show how unprecedented the problem of climate change is. There was no case directly on point, which could help with the complex and cumulative cause-and-effects.

The problem of ‘incoherence’

Another important problem for two of the three judges was that the duty wasn’t coherent—meaning consistent or compatible—with the EPBC Act. That’s because the EPBC Act doesn’t squarely address climate change or human safety, and yet the duty concerns precisely those two things.

For decades, it’s been recognized that humans depend on the environment for survival, and that a stable climate system is necessary for life as we know it.

The third judge thought the minister’s obligations, embedded in an environment protection framework, could therefore sit side by side with a duty of care. Our environment, he said, “is not just there to admire and objectify.”

But the other two were dissuaded by their view that the EPBC Act doesn’t in fact protect the environment in a general sense. Nor does it explicitly aim to mitigate climate change. It operates in a piecemeal way, rather than concerning ecosystems as a whole, or our dependency on them.

Can this really be how the EPBC Act operates in practice? Well, yes.

We heard this same message just recently via the ten-yearly, independent review of the legislation. It concluded that the EPBC Act is outdated, and not fit for the purpose of environment protection.

What does the EPBC Act do, then?

For the most part, the EPBC Act is an impact assessment law. It’s triggered when specific environmental matters, like individual threatened species, are likely to be harmed by a proposed project (such as a coal mine). When it’s triggered, it sets in motion a procedural process that requires the minister to consider whether to approve the project given its impacts.

Year after year, nearly every single project that is put forward is approved. In fact, the coal mine that was the subject of the case was approved even before the appeal went to court. This explains why so many, including the independent review, feel the EPBC Act doesn’t really do enough to adequately safeguard against environmental loss.

The review recommended the introduction of science-backed environmental standards. If this happened, it may be easier for courts to judge ministerial decisions, with a legal reference point for what’s considered politically acceptable. It also recommended decision-making incorporate climate scenarios.

A call to action

Back in 2020, I wrote that whether the children win or lose, their case would make a difference.

Although not over yet (they have two more weeks to lodge an application to appeal to the High Court), it already has. It’s drawn attention to the fact that Australia doesn’t have a climate law to protect its children. That it has no law to protect against harmful floods and fire that have already manifest since the case began. And it’s forced the Federal Court to acknowledge the uncontested risks of climate change.

Let’s look at this case as a call to action. The Federal Court has essentially said it can’t act. Reading the judgment closely, there are hints to suggest the High Court might be able to, and that eventually, the law will have to evolve to manage complex causation.

But the decision certainly doesn’t mean the government can’t act. In fact, that’s exactly who the judges indicated must.

Provided by The Conversation.

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