Over the last two decades, scientists have discovered unusual ridge networks on Mars using images from spacecraft orbiting the Red Planet. How and why the ridges formed and what clues they may provide about the history of Mars has remained unknown.
A team of scientists, led by Aditya Khuller of Arizona State University’s School of Earth and Space Exploration and Laura Kerber of NASA’s Jet Propulsion Laboratory, set out to learn more about these ridges by mapping a large area of Mars with the help of thousands of citizen scientists.
Their findings, which have been recently published in Icarus, show that the ridges on Mars may hold fossilized records of ancient groundwater flowing through them.
How the ridge networks were formed on Mars has remained a mystery ever since they were found from orbit. Scientists have determined that there are three stages that were involved to create the ridges, including polygonal fracture formation, fracture filling and finally erosion, which revealed the ridge networks.
To learn more about these ridges, the team combined data from the NASA Mars Odyssey orbiter’s THEMIS camera and the Mars Reconnaissance orbiter’s CTX and HiRISE instruments. Then, they deployed their citizen scientist project using the platform Zooniverse.
Map of polygonal ridge networks (black dots) identified in mapping area (dashed black outline), covering approximately a fifth of Mars’ total surface area. The Mars Perseverance rover landing site is shown in purple. Background: Mars Orbiter Laser Altimeter Elevation Map. Credit: NASA/JPL/GSFC.
Nearly 14,000 citizen scientists from around the world joined in the search for the ridge networks on Mars, focusing on an area around Jezero Crater, where NASA’s Perseverance rover landed last February. Ultimately, with the help of the citizen scientists, the team was able to map the distribution of 952 polygonal ridge networks in an area that measures about a fifth of Mars’ total surface area.
“Citizen scientists played an integral role in this research because these features are essentially patterns at the surface, so almost anyone with a computer and internet can help identify these patterns using images of Mars,” Khuller said.
Most of the ridge networks (91%, or 864 out of 952) that were analyzed are located in ancient, eroded terrain that is approximately 4 billion years old. During this time period, Mars is believed to have been warmer and wetter, which might be related to how these ridges form.
Previous research in this area has shown that those ridges which were not covered with layers of dust showed spectral signatures of clays. Since clays form from weathering in the presence of water, this suggested to the research team that the ridges may have been formed by groundwater. While the abundant surface dust in these regions makes it difficult to check whether the newly mapped ridge networks by Khuller and Kerber’s team also contain clays, their similarities in shape and dimension suggest that they might form from similar groundwater processes.
This discovery helps scientists “trace” the footprints of groundwater running through the ancient Martian surface and determine where it was suitable, during that time 4 billion years ago, for liquid water to be flowing near the surface.
“We hope to eventually map the entire planet with the help of citizen scientists,” Khuller said. “If we are lucky, the Mars 2020 Perseverance rover might be able to confirm these findings, but the nearest set of ridges is a few kilometers away, so they might only be visited on a potential extended mission.”
More information: Aditya R. Khuller et al, Irregular polygonal ridge networks in ancient Noachian terrain on Mars, Icarus (2021). DOI: 10.1016/j.icarus.2021.114833 Journal information: Icarus Provided by Arizona State University
Plant-foliage-derived gases drive a previously unknown atmospheric phenomenon over the Amazon rainforest, according to a recent study by researchers at Pacific Northwest National Laboratory (PNNL).
The findings have important applications for atmospheric science and for climate change modeling.
“The tropical Amazon rainforest constitutes the lungs of the Earth, and this study connects natural processes in the forest to aerosols, clouds, and the Earth’s radiative balance in ways that have not been previously recognized,” said Manish Shrivastava, Earth scientist at PNNL and principal investigator of the study.
The findings were recently published in ACS Earth and Space Chemistry.
Filling the missing data gap
Shrivastava and his team were studying fine particles in the upper atmosphere when they discovered a large disparity between their measurements and what would have been expected based on current understanding in atmospheric models. Through further study, the team found that there were key forest-atmosphere interactions missing from current atmospheric models that govern the amount of fine particles in the upper atmosphere.
The researchers discovered a previously unrecognized process involving semi-volatile gases that are emitted by plants throughout the Amazon rainforest and transported into the upper atmosphere by clouds. These gases are natural carbon-based chemical compounds that can easily condense to form fine particles in the upper atmosphere. This process, Shrivastava said, is very efficient at producing fine particles at high altitudes and cold temperatures. These fine particles cool the planet by reducing the amount of sunlight reaching Earth, and they also seed clouds that affect precipitation and the water cycle.
“Without a full understanding of the semi-volatile source of organic gases, we simply cannot explain the presence and role of key particle components at high altitudes,” Shrivastava said.
Crucial discovery in atmospheric processes
Shrivastava’s research project, funded through a Department of Energy (DOE) Early Career Research Award, involved investigating the formation of aerosol particles known as isoprene epoxydiol secondary organic aerosols (IEPOX-SOAs), which are measured by aircraft flying at different altitudes.
IEPOX-SOAs are essential building blocks for fine particles found at all altitudes of the troposphere—the region of the atmosphere extending from Earth’s surface to approximately 20 kilometers in altitude above tropical regions. However, atmospheric models did not sufficiently account for these particles and their influence on clouds high above Earth.
“As models wouldn’t predict the observed IEPOX-SOA loadings at 10-to-14-kilometer altitudes in the Amazon, we were getting what I believed to be either model failures or a lack of understanding of the measurements,” Shrivastava said. “I could explain it at the surface but couldn’t explain it at higher altitudes.”
Shrivastava and his team scoured data collected by the Grumman Gulfstream-159 (G-1) aircraft, a DOE flying laboratory operated by the Atmospheric Radiation Measurement (ARM) Aerial Facility, which was flown up to 5 kilometers in altitude. The team also compared data collected by a German aircraft known as the High Altitude and Long Range Research Aircraft, or HALO, which is flown at altitudes reaching 14 kilometers. Based on the modeled projections, their loadings of IEPOX-SOAs should have been at least an order of magnitude lower than what was measured, Shrivastava said. Neither he nor his colleagues outside of PNNL could explain the disparity in measurements and what the models projected.
Before the team’s research, it was believed that IEPOX-SOAs were formed primarily by multiphase atmospheric chemistry pathways involving reactions of isoprene in the gas phase and particles containing liquid water. However, the atmospheric chemistry pathways required to create IEPOX-SOAs do not occur in the upper troposphere because of its extremely cold temperatures and dry conditions. At that altitude, the particles and clouds are frozen and lack liquid water. Researchers therefore could not explain their formation observed at 10 to 14 kilometers in altitude using available models.
To unravel the mystery, the researchers combined specialized high-altitude aircraft measurements and detailed regional model simulations conducted using supercomputing resources at the Environmental Molecular Sciences Laboratory at PNNL. Their study revealed the undiscovered component of atmospheric processes. A semi-volatile gas known as 2-methyltetrol is transported by cloud updrafts into the cold upper troposphere. The gas then condenses to form particles that are detected as IEPOX-SOAs by the aircraft.
“This is certainly an important discovery because it aids in our understanding of how these fine particles are formed, and therefore shines a new light on how natural processes in the forest cool the planet and contribute to clouds and precipitation,” Shrivastava said. “Along with a changing global climate and rapid deforestation in many parts of the Amazon, humans are perturbing the key natural processes that make fine particles in the atmosphere and modulate global warming.”
Opening doors to further atmospheric research
The team’s finding only scratches the surface, Shrivastava said, in learning about this newfound atmospheric process and how it affects the formation of fine particles in the atmosphere. He said the newly identified process from plants could explain a broad array of atmospheric particle phenomena over other forested locations across the world.
“In the grand scheme, this is just the beginning of what we know and will open new frontiers of research in land-atmosphere-aerosol-cloud interactions,” he said. “Understanding how the forest produces these particles could help us understand how deforestation and changing climate will affect global warming and the water cycle.”
More information: Manish Shrivastava et al, Tight Coupling of Surface and In-Plant Biochemistry and Convection Governs Key Fine Particulate Components over the Amazon Rainforest, ACS Earth and Space Chemistry (2022). DOI: 10.1021/acsearthspacechem.1c00356 Provided by Pacific Northwest National Laboratory
On November 8, 2020, NASA’s Juno spacecraft flew through an intense beam of electrons traveling from Ganymede, Jupiter’s largest moon, to its auroral footprint on the gas giant. Southwest Research Institute scientists used data from Juno’s payload to study the particle population traveling along the magnetic field line connecting Ganymede to Jupiter while, at the same time, remotely sensing the associated auroral emissions to unveil the mysterious processes creating the shimmering lights.
“Jupiter’s most massive moons each create their own auroras on Jupiter’s north and south poles,” said Dr. Vincent Hue, lead author of a paper outlining the results of this research. “Each auroral footprint, as we call them, is magnetically connected to their respective moon, kind of like a magnetic leash connected to the moon glowing on Jupiter itself.”
Like the Earth, Jupiter experiences auroral light around the polar regions as particles from its massive magnetosphere interact with molecules in the Jovian atmosphere. However, Jupiter’s auroras are significantly more intense than Earth’s, and unlike Earth, Jupiter’s largest moons also create auroral spots. The Juno mission, led by SwRI’s Dr. Scott Bolton, is circling Jupiter in a polar orbit and flew through the electron “thread” connecting Ganymede with its associated auroral footprint.
“Prior to Juno, we knew that these emissions can be quite complex, ranging from a single auroral spot to multiple spots, which sometimes trail an auroral curtain that we called the footprint tail,” said Dr. Jamey Szalay, a co-author from Princeton University. “Juno, flying extremely close to Jupiter, revealed these auroral spots to be even more complex than previously thought.”
Ganymede is the only moon in our solar system that has its own magnetic field. Its mini-magnetosphere interacts with Jupiter’s massive magnetosphere, creating waves that accelerate electrons along the gas giant’s magnetic field lines, which can be directly measured by Juno.
Two SwRI-led instruments on Juno, the Jovian Auroral Distributions Experiment (JADE) and the Ultraviolet Spectrometer (UVS) provided key data for this study, which was also supported by Juno’s magnetic field sensor built at NASA’s Goddard Space Flight Center.
“JADE measured the electrons traveling along the magnetic field lines, while UVS imaged the related auroral footprint spot,” said SwRI’s Dr. Thomas Greathouse, a co-author on this study.
In this way, Juno is both able to measure the electron “rain” and immediately observe the UV light it creates when it crashes into Jupiter. Previous Juno measurements showed that large magnetic perturbations accompanied the electron beams causing the auroral footprint. However, this time, Juno did not observe similar perturbations with the electron beam.
“If our interpretation is correct, this a confirmation of a decade-old theory that we put together to explain the morphology of the auroral footprints,” said Dr. Bertrand Bonfond, a co-author of the study from the Liège University in Belgium. The theory suggests that electrons accelerated in both directions create the multi-spot dance of auroral footprints.
“The Jupiter-Ganymede relationship will be further explored by Juno’s extended mission, as well as the forthcoming JUICE mission from the European Space Agency,” Hue said. “SwRI is building the next generation of UVS instrumentation for the mission.”
A paper describing this research was published in Geophysical Research Letters.
More information: V. Hue et al, A Comprehensive Set of Juno In Situ and Remote Sensing Observations of the Ganymede Auroral Footprint, Geophysical Research Letters (2022). DOI: 10.1029/2021GL096994 Journal information: Geophysical Research Letters Provided by Southwest Research Institute
In the 1930s, a Swiss astronomer named Fritz Zwicky noticed that galaxies in a distant cluster were orbiting one another much faster than they should have been given the amount of visible mass they had. He proposed than an unseen substance, which he called dark matter, might be tugging gravitationally on these galaxies.
Since then, researchers have confirmed that this mysterious material can be found throughout the cosmos, and that it is six times more abundant than the normal matter that makes up ordinary things like stars and people. Yet despite seeing dark matter throughout the universe, scientists are mostly still scratching their heads over it. Here are the 11 biggest unanswered questions about dark matter.
What is dark matter?
(Image credit: Shutterstock)
First and perhaps most perplexingly, researchers remain unsure about what exactly dark matter is. Originally, some scientists conjectured that the missing mass in the universe was made up of small faint stars and black holes, though detailed observations have not turned up nearly enough such objects to account for dark matter’s influence, as physicist Don Lincoln of the U.S. Department of Energy’s Fermilab previously wrote for Live Science. The current leading contender for dark matter’s mantle is a hypothetical particle called a Weakly Interacting Massive Particle, or WIMP, which would behave sort of like a neutron except would be between 10 and 100 times heavier than a proton, as Lincoln wrote. Yet, this conjecture has only led to more questions — for instance…
Can we detect dark matter?
(Image credit: Xinhua/Getty)
If dark matter is made from WIMPs, they should be all around us, invisible and barely detectable. So why haven’t we found any yet? While they wouldn’t interact with ordinary matter very much, there is always some slight chance that a dark-matter particle could hit a normal particle like a proton or electron as it travels through space. So, researchers have built experiment after experiment to study huge numbers of ordinary particles deep underground, where they are shielded from interfering radiation that could mimic a dark-matter-particle collision. The problem? After decades of searching, not one of these detectors has made a credible discovery. Earlier this year, the Chinese PandaX experiment reported the latest WIMP nondetection. It seems likely that dark-matter particles are much smaller than WIMPs, or lack the properties that would make them easy to study, physicist Hai-Bo Yu of the University of California, Riverside, told Live Science at the time.
Does dark matter consist of more than one particle?
(Image credit: Maria Starovoytova/Shutterstock)
Ordinary matter is made up of everyday particles like protons and electrons, as well as a whole zoo of more exotic particles like neutrinos, muons and pions. So, some researchers have wondered if dark matter, which makes up 85 percent of the matter in the universe, might also be just as complicated. “There is no good reason to assume that all the dark matter in the universe is built out of one type of particle,” physicist Andrey Katz of Harvard University said to Space.com, Live Science’s sister site. Dark protons could combine with dark electrons to form dark atoms, producing configurations as diverse and interesting as those found in the visible world, Katz said. While such proposals have increasingly been imagined in physics labs, figuring out a way to confirm or deny them has so far eluded scientists.
Do dark forces exist?
(Image credit: Shutterstock)
Along with additional particles of dark matter, there is the possibility that dark matter experiences forces analogous to those felt by regular matter. Some researchers have searched for “dark photons,” which would be like the photons exchanged between normal particles that give rise to the electromagnetic force, except they would be felt only by dark matter particles. Physicists in Italy are gearing up to smash a beam of electrons and their antiparticles, known as positrons, into a diamond, as Live Science previously reported. If dark photons do exist, the electron-positron pairs could annihilate and produce one of the strange force-carrying particles, potentially opening a brand-new sector of the universe.
Could dark matter be made of axions?
(Image credit: Marcel Clemens/Shutterstock)
As physicists increasingly fall out of love with WIMPs, other dark-matter particles are starting to gain favor. One of the leading replacements is a hypothetical particle known as an axion, which would be extremely light, perhaps as little as 10 raised to the 31st power less massive than a proton. Axions are now being searched for in a few experiments. Recent computer simulations have raised the possibility that these axions could form star-like objects, which might produce detectable radiation that would be quite similar to mysterious phenomena known as fast-radio bursts, as Live Science previously reported.
What are the properties of dark matter?
(Image credit: NASA)
Astronomers discovered dark matter through its gravitational interactions with ordinary matter, suggesting that this is its main way of making its presence known in the universe. But when trying to understand the true nature of dark matter, researchers have remarkably little to go on. According to some theories, dark-matter particles should be their own antiparticles, meaning that two dark-matter particles would annihilate with one another when they meet. The Alpha Magnetic Spectrometer (AMS) experiment on the International Space Station has been searching for the telltale signs of this annihilation since 2011and has already detected hundreds of thousands of events. Scientists still aren’t sure if these are coming from dark matter, and the signal has yet to help them pin down exactly what dark matter is.
Does dark matter exist in every galaxy?
(Image credit: Shutterstock)
Because it so massively outweighs ordinary matter, dark matter is often said to be the controlling force that organizes large structures such as galaxies and galactic clusters. So, it was strange when, earlier this year, astronomers announced that they had found a galaxy named NGC 1052-DF2 that seemed to contain hardly any dark matter at all. “Dark matter is apparently not a requirement for forming a galaxy,” Pieter van Dokkum of Yale University told Space.com at the time. However, over the summer, a separate team posted an analysis suggesting that van Dokkum’s team had mismeasured the distance to the galaxy, meaning its visible matter was much dimmer and lighter than the first findings and that more of its mass was in dark matter than was previously suggested.
What’s up with the DAMA/LIBRA results?
(Image credit: Pigi Cipelli/Getty)
A long-standing mystery in particle physics are the puzzling results of a European experiment known as DAMA/LIBRA. This detector — located in an underground mine below the Gran Sasso mountain in Italy — has been searching for a periodic oscillation in dark matter particles. This oscillation should arise as the Earth moves in its orbit around the sun while flying through the galactic stream of dark matter surrounding our solar system, sometimes called the dark matter wind. Since 1997, DAMA/LIBRA has claimed to see exactly this signal, though no other experiment has seen anything like this.
Could dark matter have an electrical charge?
(Image credit: Shutterstock)
A signal from the beginning of time has led some physicists to suggest that dark matter might have an electrical charge. Radiation with a wavelength of 21 centimeters was emitted by stars in the universe’s infancy, just 180 million years after the Big Bang. It was then absorbed by cold hydrogen that was around at the same time. When this radiation was detected in February of this year, its signature suggested that the hydrogen was much colder than scientists had predicted. Astrophysicist Julian Muñoz of Harvard University hypothesized that dark matter with an electrical charge could have drawn heat away from the all-pervasive hydrogen, sort of like ice cubes floating in lemonade, as he told Live Science at the time. But the conjecture has yet to be confirmed.
Can ordinary particles decay into dark matter?
(Image credit: Shutterstock)
Neutrons are regular matter particles with a limited lifetime. After around 14.5 minutes, a lone neutron unmoored from an atom will decay into a proton, an electron and a neutrino. But two different experimental setups give slightly different lifetimes for this decay, with the discrepancy between them about 9 seconds, according to experiments cited in a July study in the journal Physical Review Letters. Earlier this year, physicists suggested that if 1 percent of the time, some neutrons were decaying into dark-matter particles, it could account for this anomaly. Christopher Morris from the Los Alamos National Laboratory, in New Mexico, and his team monitored neutrons for a signal that could be dark matter but were unable to detect anything. They suggested that other decay scenarios might still be possible, according to the study.
Does dark matter actually exist?
(Image credit: NASA)
Given the difficulties that scientists have faced trying to detect and explain dark matter, a reasonable questioner might wonder if they’re going about it all wrong. For many years, a vocal minority of physicists have pushed the idea that perhaps our theories of gravity are simply incorrect, and that the fundamental force works differently on large scales than we expect. Often known as “modified Newtonian dynamics,” or MOND models, these suggestions posit that there is no dark matter and the ultrafast speeds at which stars and galaxies are seen to rotate around one another is a consequence of gravity behaving in surprising ways. “Dark matter is still an unconfirmed model,” wrote physicist Don Lincoln in an explainer for Live Science. Yet the detractors have yet to convince the larger field of their ideas. And the latest evidence? It also suggests that dark matter is real.
When the rock now known as the Chicxulub impactor plummeted from outer space and slammed into the Earth 66 million years ago, cockroaches were there. The impact caused a massive earthquake, and scientists think it also triggered volcanic eruptions thousands of miles from the impact site. Three-quarters of plants and animals on Earth died, including all dinosaurs, except for some species that were ancestors of today’s birds.
How could roaches a couple of inches long survive when so many powerful animals went extinct? It turns out that they were nicely equipped to live through a meteoric catastrophe.
If you’ve ever seen a cockroach, you’ve probably noticed that their bodies are very flat. This is not an accident. Flatter insects can squeeze themselves into tighter places. This enables them to hide practically anywhere – and it may have helped them survive the Chicxulub impact.
When the meteor struck, temperatures on Earth’s surface skyrocketed. Many animals had nowhere to flee, but roaches could take shelter in tiny soil crevices, which provide excellent protection from heat.
The meteor’s impact triggered a cascade of effects. It kicked up so much dust that the sky darkened. As the sun dimmed, temperatures plunged and conditions became wintry around the globe. With little sunlight, surviving plants struggled to grow, and many other organisms that relied on those plants went hungry.
Not cockroaches, though. Unlike some insects that prefer to eat one specific plant, cockroaches are omnivorous scavengers. This means they will eat most foods that come from animals or plants as well as cardboard, some kinds of clothing and even poop. Having appetites that aren’t picky has allowed cockroaches to survive lean times since the Chicxulub extinction and other natural disasters.
Another helpful trait is that cockroaches lay their eggs in little protective cases. These egg cartons look like dried beans and are called oothecae, which means “egg cases.” Like phone cases, oothecae are hard and protect their contents from physical damage and other threats, such as flooding and drought. Some cockroaches may have waited out part of the Chicxulub catastrophe from the comfort of their oothecae.
Modern cockroaches are little survivors that can live just about anywhere on land, from the heat of the tropics to some of the coldest parts of the globe. Scientists estimate that there over 4,000 cockroach species.
A handful of these species like to live with humans and quickly become pests. Once cockroaches become established in a building, it’s hard to rid every little crack of these insects and their oothecae. When large numbers of roaches are present in unsanitary places, they can spread diseases. The biggest threat they pose to human health is from allergens they produce that can trigger asthma attacks and allergic reactions in some people.
Cockroach pests are hard to manage because they can resist many chemical insecticides and because they have the same abilities that helped their ancestors outlive many dinosaurs. Still, cockroaches are much more than a pest to control. Researchers study cockroaches to understand how they move and how their bodies are designed to get ideas for building better robots.
As a scientist, I see all insects as beautiful, six-legged inspirations. Cockroaches have already overcome odds that were too great for dinosaurs. If another meteorite hit the Earth, I’d be more worried for humans than for cockroaches.
This article is republished from The Conversation under a Creative Commons license. Read the original article. The views expressed are those of the author and do not necessarily reflect the views of the publisher.
The director general of Russia’s Roscosmos space agency has threatened to end its Russia’sinvolvement with the ISS.
Russia could end its cooperation on the International Space Station in as little as two years, using the sanctions imposed on Russia over its invasion of Ukraine as an excuse, according to space experts.
Most commentators characterize the threats by the director general of Russia’s Roscosmos space agency to end its involvement with the orbital outpost as mere political bluster. But the threat to sever such relations could come to fruition, as some experts Live Science spoke to noted that Russia has only committed to the ISS project until 2024, rather than “after 2030” as had been proposed by NASA and other partners.
And Russia’s withdrawal from the project could mean it will be mainly up to NASA to keep the ISS physically in orbit for almost another 10 years — something that Russia has been responsible for up until now. Even further, the threats signal just how badly Russia’s actions in Ukraine have damaged ties in the scientific community between the country and the rest of the world, meaning that any science-related cooperation with Russia may be difficult, experts said.
Roscosmos chief Dmitry Rogozin stated in Russian on Twitter(opens in new tab) on Saturday (April 2) that “normal relations” between partners on the ISS could only be restored after “the complete and unconditional lifting of illegal sanctions.”
Rogozin is a political figure with close ties to Russian president Vladimir Putin and a history of making blustery statements.
Related: Russia’s Ukraine invasion could imperil international science
He tweeted on Feb. 24 — the day Russia invaded Ukraine — that any sanctions imposed as a result could “destroy” the partnership(opens in new tab) between Russia and the United States that keeps the ISS operating and aloft.
But activities on the space station have been relatively normal since then, with the arrival of three Russian cosmonauts(opens in new tab) in mid-March and the return to Earth of NASA astronaut Mark Vande Hei last week on board a Russian Soyuz spacecraft.
There may be more than political posturing, however, to Rogozin’s latest threats to end Russia’s cooperation on the ISS. In his tweets on Saturday, he shared what he said was a March 30 letter from NASA administrator Bill Nelson.
That letter stated the new sanctions were designed to allow continued cooperation between the U.S. and Russia, “to ensure continued safe operations of the ISS.”
A statement by Nelson dated Sunday (April 3) and given to Live Science by a NASA spokesperson made the same point, and stressed that the “professional relationship” between astronauts and cosmonauts on the ISS was continuing to keep everyone safe on board.
But Rogozin claimed on Twitter he doesn’t agree that the ISS project can continue to operate under the international sanctions imposed on Russia.
A new study provides the first evidence that rising greenhouse gases have a long-term warming effect on the Amundsen Sea in West Antarctica. Scientists from British Antarctic Survey (BAS) say that while others have proposed this link, no one has been able to demonstrate it.
Ice loss from the West Antarctic Ice Sheet in the Amundsen Sea is one of the fastest growing and most concerning contributions to global sea level rise. If the West Antarctic Ice Sheet were to melt, global sea levels could rise by up to three meters. The patterns of ice loss suggest that the ocean may have been warming in the Amundsen Sea over the past one hundred years, but scientific observations of the region only began in 1994.
In the study—published in the journal Geophysical Research Letters—oceanographers used advanced computer modeling to simulate the response of the ocean to a range of possible changes in the atmosphere between 1920 and 2013.
The simulations show the Amundsen Sea generally became warmer over the century. This warming corresponds with simulated trends in wind patterns in the region that increase temperatures by driving warm water currents towards and beneath the ice. Rising greenhouse gases are known to make these wind patterns more likely, and so the trend in winds is thought to be caused in part by human activity.
This study supports theories that ocean temperatures in the Amundsen Sea have been rising since before records began. It also provides the missing link between ocean warming and wind trends that are known to be partly driven by greenhouse gases. Ocean temperatures around the West Antarctic Ice Sheet will probably continue to rise if greenhouse gas emissions increase, with consequences for ice melt and global sea levels. These findings suggest, however, that this trend could be curbed if emissions are sufficiently reduced and wind patterns in the region are stabilized.
Dr. Kaitlin Naughten, ocean-ice modeler at BAS and lead author of this study, says, “Our simulations show how the Amundsen Sea responds to long-term trends in the atmosphere, specifically the Southern Hemisphere westerly winds. This raises concerns for the future because we know these winds are affected by greenhouse gases. However, it should also give us hope, because it shows that sea level rise is not out of our control.”
Professor Paul Holland, ocean and ice scientist at BAS and a co-author of the study, says, “Changes in the Southern Hemisphere westerly winds are a well-established climate response to the effect of greenhouse gases. However, the Amundsen Sea is also subject to very strong natural climate variability. The simulations suggest that both natural and anthropogenic changes are responsible for the ocean-driven ice loss from the West Antarctic Ice Sheet.”
More information: Kaitlin A. Naughten et al, Simulated Twentieth‐Century Ocean Warming in the Amundsen Sea, West Antarctica, Geophysical Research Letters (2022). DOI: 10.1029/2021GL094566
Ground-breaking research into the hot structures deep in the Earth suggest they could be much more fluid than once supposed.
An article published this week by the prestigious journal, Nature, shows that the deep structure beneath Africa could be just 60 million years old—a fraction of the age previously supposed.
It was shown about 15 years ago that the largest volcanoes erupted over the last 300 million years coincide with the present-day location of these basal structures.
But the work by researchers at the School of Earth and Environmental Studies at the University of Wollongong (UOW) shows an alternative reality.
“Our work shows that the history of volcanism is compatible with both fixed and mobile structures at the base of the mantle, so that the hypothesis of stationary structures at the base of the mantle is no longer required,” lead author Dr. Nicolas Flament said.
“Understanding how the deeper, solid Earth works is important for understanding how life has evolved in the past, and then forecasting what may happen in the future. To some extent, the past is the key to the future.”
An Australian Research Council (ARC) Discovery Early Career Researcher Award fellow, Dr. Flament’s research and teaching focuses on how the dynamics of the interior of the Earth drive sea level change, shape surface landscape and control climate.
He has worked with resource companies to predict the location of both oil and diamonds more accurately.
“Our work has set the deep Earth free,” Dr. Flament said.
“It shows that hot structures deep in the Earth come together in a way that is reminiscent of the formation of supercontinents at the surface.
Credit: University of Wollongong
“We show that the structure beneath Africa could have assembled in the last 60 million years, which is geologically recent, and in sharp contrast of the view that the African structure had been in place for at least 300 million years.”
Dr. Flament’s research used models to suggest the structures deep in the Earth shift similar to the continents on the surface.
The research reconstructs mantle flow over the past one billion years ago to show that volcanic activity on the planet’s surface is as consistent with deep structures that shift, as well as with the idea that they are fixed.
The models also predict the presence of continental material beneath Africa consistent with existing geo-chemical data.
More information: Nicolas Flament et al, Assembly of the basal mantle structure beneath Africa, Nature (2022). DOI: 10.1038/s41586-022-04538-y
If the world acts now, we can avoid the worst outcomes of climate change without any significant effect on standards of living. That’s a key message from the new report from the Intergovernmental Panel on Climate Change (IPCC).
The key phrase here is “acts now”. Jim Skea, co-chair of the IPCC working group behind the report, said it’s “now or never” to keep global warming to 1.5℃. Action means cutting emissions from fossil fuel use rapidly and hard. Global emissions must peak within three years to have any chance of keeping warming below 1.5℃.
Unfortunately, Australia is not behaving as if the largest issue facing us is urgent—in fact, we’re doubling down on fossil fuels.
In recent years, Australia overtook Qatar to become the world’s largest exporter of liquefied natural gas (LNG). We’re still the second-largest exporter of thermal coal, and the largest for metallurgical coal.
Time’s up, Australia. We have to talk about weaning ourselves off fossil fuels and exporting our wealth of clean alternatives.
Why can’t Australia keep selling fossil fuels during the transition?
You might think: “Sure, Australia needs to transition. But it will take decades for the world to rid itself of fossil fuels. Why can’t we keep selling gas and coal in the meantime?”
Because we’re out of time. As the report states, “if existing fossil fuel infrastructure … continue to be operated as historically, they would entail CO₂ emissions exceeding the carbon budget for 1.5°℃”.
And US climatologist Michael Mann recently pointed out, if you were going to pick the worst continent to live on as the climate changes, it would be Australia. We are “a poster child for what the rest of the world will be dealing with,” he said.
Urgent action is needed to avoid the devastation and vast expense of unchecked climate change, recently estimated at close to 40% of global GDP by 2100.
We need to accelerate the shift, with much faster greening of electricity supply, electrification of transport, improvement of industrial processes and management of land use and food production. Luckily, the technologies needed to achieve this goal have already been developed and are mostly already competitive with carbon-emitting alternatives.
The economic costs of the transition would be marginal. The required investment in clean energy would be around 2.5% of GDP. That’s far less than the costs of allowing global heating to continue, with costs further offset by clean energy’s zero fuel costs and lower operating costs.
What are Australia’s prospects for weaning off the fossil fuel teat?
Are we seeing signs of the urgency of the situation? If you look at the election platforms of Australia’s major political parties, we are still falling far short.
After nine years in office, the Liberal government has reluctantly set a goal of net zero emissions by 2050, but has offered little more than wishful thinking as a policy response.
Last week’s budget projected funding cuts of as much as 35% for Australia’s clean energy finance and renewable energy initiatives.
By far the biggest shortcoming is the failure to plan for the transition. Despite calls for coal and gas workers to be given an honest assessment of their position, both Liberal and Labor sustain the illusion that coal and gas have a long-term future.
Labor has put forward worthwhile initiatives such as the Rewiring the Nation program aimed at supporting private investment to modernise the grid and make it ready for high levels of renewable energy.
But the opposition’s main concern has been to avoid any policy that leaves it open to attack from the Coalition and the Murdoch press. You can see this in Labor leader Anthony Albanese’s repeated declaration that “the climate wars are over”.
That means, in 2022, we are facing an election campaign in which neither major party has put up serious ideas to cut emissions. There’s no mention of a price on carbon or an emissions trading scheme, no real action on land clearing, and no expansion of the government’s safeguard mechanism, meant to provide incentives for large industries to cut emissions relative to a baseline.
Lagging on transport
The plunging cost of renewable energy is one of the bright spots in the fight against climate change. Cost alone is driving out coal and gas from the power sector.
The pace of transition is much slower in areas such as transport, which the IPCC report notes had excellent prospects of cutting emissions.
“Electric vehicles powered by low-emissions electricity offer the largest decarbonisation potential for land-based transport,” the report says.
In Australia, our failures on transport are palpable. To reach net zero by 2050, we have to move to an all-electric vehicle fleet. Given cars last 20 years on average, almost all new vehicles must be electric by 2030.
By contrast to almost all developed countries, Australia doesn’t have a fuel efficiency target, or plans to end new sales of petrol vehicles. The government has no proposal to address this, while Labor offers a minor tax concession on electric vehicles and a fuel efficiency information website.
Bizarrely, these baby steps sit in stark contrast to the bipartisan rush to shield petrol users from rising prices in the wake of the invasion of Ukraine.
We’ve stalled long enough
We’ve run out of time to deal with the problem of global heating. We cannot afford another three years of inaction.
What would it look like if Australia’s next government realises the urgency? It would begin by ending all new investment in fossil fuel production and electricity generation, as well as fossil-fuel reliant industrial plants such as blast furnaces for steel mills. It would accelerate investment in carbon-free replacements, and create pathways for fossil fuel workers to work in the green economy.
And our leaders would talk openly and clearly about the huge threat climate change poses to all of us here, and the benefits we stand to gain by quitting fossil fuels. We would go from laggards to leaders. Imagine that.
Usually when a geologist walks up to a sedimentary rock outcrop and starts scanning the layers of sand, mud and silt now turned to rock, they’re looking through millions of years of deep time to deduce what happened in that place in the world over many thousands of years to create that particular rock.
But when United States Geological Survey scientist Scott Hynek walked up to an outcrop of sediment in Calf Canyon, near Utah’s Lake Powell, he saw a thick layer of sand and thought “Crikey! That’s 1983!”
As drought forces Lake Powell to recede, the sediment that built up over the lake’s six-decade history is being revealed. Researchers are taking advantage of the relatively short, well-documented history of the sedimentary formations to learn more about how they came to be and how they might impact the future of the shrinking lake. Their study is published in The Sedimentary Record and was a collaborative effort between the USGS, University of Utah and Utah State University. This field-focused collaboration was made possible with the logistical support of the Returning Rapids Project, the University of Utah Global Change and Sustainability Center, American Rivers and the Glen Canyon Institute.
“We know that continued drawdown is going to expose a significant amount of sediment, and that sediment will be subject to remobilization,” says Cari Johnson, professor of geology and geophysics at the University of Utah, of the fine-grained, easily wind-blown sediments. “It’s likely going to want to redistribute itself. Where is it actually gonna go?”
The story of Lake Powell
Lake Powell came into existence with the completion of the Glen Canyon Dam in 1963. At its peak in 1983, the lake held nearly 26 million acre-feet of water (an acre-foot of water covers a football field to a depth of one foot).
But the reservoir, on the Colorado River, interrupts the natural flow of water and sediments downstream. Although U.S. Bureau of Reclamation Commissioner Floyd Dominy once declared that Lake Powell would not fill up with sediment, the decline of the lake level in recent decades has shown just how much sediment has accumulated in what was once the lake floor.
In Calf Canyon, where the researchers conducted their study of sedimentary formations, the sediments are 60 feet (18 m) tall. As a side canyon near the top of the lake’s elevation, Calf Canyon is only submerged when the lake is high and was among the first areas to dry out. A long-term decline in lake level that began in the year 2000 continues today, in the midst of a megadrought impacting the western United States.
Fresh formations
For Johnson, USGS scientists Hynek and Casey Root, and Jack Schmidt of Utah State University, the exposed formations provide an incredible opportunity. Geoscientists are often using the textures and structures of sedimentary rocks to make inferences about what environments were like thousands or millions of years ago. Sandstone, for example, might suggest shallow water or a beach environment. Mudstones might suggest a deeper water environment. Layers of alternating sandstone and mudstone would suggest a shoreline that advanced and retreated rapidly and frequently.
“As geologists, we’re used to jumping into time machines when we look at rocks and stratigraphy,” Johnson says, “but our time machines are usually on the millions to maybe even billions of years range.”
So imagine the excitement of geologists who could study fresh sedimentary formations while almost within sight of the lake environment that created them.
“You can see the major forces that act on it, right there, in real-time,” Hynek says. “And you think to yourself, ‘Okay, all the ingredients are here. How did we make this pile of sediment?'”
“We know what the conditions were actually really well,” Johnson says. “So now we’re testing all of our conceptual models on how sedimentology and stratigraphy work, and we’re testing that against a known record. So I would classify it as both exciting and a little bit daunting because we don’t have as much wiggle as we normally do.”
That record, says Root, includes much more than just water level.
Closeup of a clay-rich lake deposit (on which the hammer head is laying), overlain by a ripple-marked sand bed formed by the Colorado River during flood stage. Credit: Cari Johnson
“It’s knowing what the rivers were doing with monitoring data, what the reservoir was doing with spatial data, satellite data and topographic data. You have a good idea how the rivers and landscape have changed over the lifespan of Lake Powell.”
Studies of sediments deposited by manmade reservoirs are rare. So this study, despite all of the “knowns,” is among the first of its kind.
What the sediments show
Apart from some gravel at the bottom and at the top of the formation, most of the lake sediments in Calf Canyon are alternating layers of sand and clay.
“We think of these as couplets that are linked by seasonal depositional processes,” Johnson says. “Because we know the reservoir history so well in our minds, we’re picturing the lake level coming up and lake level going back down. Rivers go into flood stage and that dominates sediment deposition for a while, then other processes take over.”
Because Calf Canyon was only submerged during times when the lake was high, Root says, the range of hydrological events that could have produced the sedimentary record is even narrower. “Looking for floods, you can start to match up deposits and cycles to actual events that were recorded,” he says.
One of those events is the extraordinarily wet year of 1983 that caused flooding in Salt Lake City and marked the high-water mark of the Great Salt Lake. In the Lake Powell sediments, Hynek says, the 1983 floods are represented by a “brightly colored, soft sandy layer that’s a meter and a half tall, maybe, clinging to the side of a mud cliff with all this interesting sedimentary structure in it.” Strong runoff that year, the researchers hypothesize, could have pushed a large amount of sand up into Calf Canyon.
With changes in lake level, the sediments have been exposed, at least partially, in earlier years. And with that exposure have come tamarisk trees, which grow abundantly on the banks of streams and rivers in the desert Southwest. In some places, the researchers only saw the effects of the tamarisk roots—churning up the sediment, leaving behind chemical changes in the rocks—but in other places they saw roots still in place. Hynek recalls finding a tamarisk that continued growing despite being partially buried in sand. Study co-author Jack Schmidt of Utah State University pointed out the tenacious tamarisk, and explained the story it told.
“So the sediment was piling in on top of these plants,” Hynek says, “and they just keep growing as sediment piles on top of them. So in some cases you could almost follow a dead tamarisk down and see that it germinated or originated on a certain horizon.”
“With good preservation of those root systems and plant systems,” Johnson says, “we can actually treat them a bit like tree rings and look at their growth history to further solidify our interpretations of what the reservoir level is doing.”
Looking to the future
Cataloging Lake Powell sediments is not only an academic exercise. It is a look into the reservoir’s past that can inform how it might change into the future. The lake’s surface area has shrunk to a third of its maximum extent, for example, returning around 100,000 formerly lakebed-acres to terrestrial habitat.
“Two-thirds of the land area that used to be a lake is now a terrestrial ecosystem full of tamarisk, Russian thistle, cheatgrass and fine-grained sediment that was never there before,” Hynek says. “It’s a completely new ecosystem emerging out of this area that used to be a lake.”
As the sediment is exposed, there’s a good chance it will move again, redistributing through wind and water. USGS scientists are trying to learn more about the nutrients and metals present in the sediments to understand the potential consequences of their redistribution.
Also, the plight of the shrinking Lake Powell, Root says, can be an indicator for the rest of the Upper Colorado River Basin. “There are a lot of reasons to keep Lake Powell high,” he says, citing water storage and hydroelectric power generation. “So if it’s low, then it is a good sign that water availability is limited. The sediment in Calf Canyon is an example of what we can expect as reservoir levels go lower and more of these sediments are exposed.”
More information: Cari Johnson et al, Sedimentary record of annual-decadal timescale reservoir dynamics: Anthropogenic stratigraphy of Lake Powell, Utah, U.S.A., The Sedimentary Record (2022). DOI: 10.2110/sedred.2022.1.3 Provided by University of Utah
