Latest news with #BenjaminMills
CNN
12 hours ago
- Science
- CNN
The ‘Great Dying' wiped out 90% of life, then came 5 million years of lethal heat. New fossils explain why
Around 252 million years ago, life on Earth suffered its most catastrophic blow to date: a mass extinction event known as the 'Great Dying' that wiped out around 90% of life. What followed has long puzzled scientists. The planet became lethally hot and remained so for 5 million years. A team of international researchers say they have now figured out why using a vast trove of fossils — and it all revolves around tropical forests. Their findings, published Wednesday in the journal Nature Communications, may help solve a mystery, but they also spell out a dire warning for the future as humans continue to heat up the planet by burning fossil fuels. The Great Dying was the worst of the five mass extinction events that have punctuated Earth's history, and it marked the end of the Permian geological period. It has been attributed to a period of volcanic activity in a region known as the Siberian Traps, which released huge amounts of carbon and other planet-heating gases into the atmosphere, causing intense global warming. Enormous numbers of marine and land-based plants and animals died, ecosystems collapsed and oceans acidified. What has been less clear, however, is why it got so hot and why 'super greenhouse' conditions persisted for so long, even after volcanic activity ceased. 'The level of warming is far beyond any other event,' said Zhen Xu, a study author and a research fellow at the School of Earth and Environment at the University of Leeds. Some theories revolve around the ocean and the idea that extreme heat wiped out carbon-absorbing plankton, or changed the ocean's chemical composition to make it less effective at storing carbon. But scientists from the University of Leeds in England and the China University of Geosciences thought the answer may lie in a climate tipping point: the collapse of tropical forests. The Great Dying extinction event is unique 'because it's the only one in which the plants all die off,' said Benjamin Mills, a study author and a professor of Earth system evolution at the University of Leeds. To test the theory, they used an archive of fossil data in China that has been put together over decades by three generations of Chinese geologists. They analyzed the fossils and rock formations to get clues about climate conditions in the past, allowing them to reconstruct maps of plants and trees living on each part of the planet before, during and after the extinction event. 'Nobody's ever done that before,' Mills told CNN. The results confirmed their hypothesis, showing that the loss of vegetation during the mass extinction event significantly reduced the planet's ability to store carbon, meaning very high levels remained in the atmosphere. Forests are a vital climate buffer as they suck up and store planet-heating carbon. They also play a crucial role in 'silicate weathering,' a chemical process involving rocks and rainwater — a key way of removing carbon from the atmosphere. Tree and plant roots help this process by breaking up rock and allowing fresh water and air to reach it. Once the forests die, 'you're changing the carbon cycle,' Mills said, referring to the way carbon moves around the Earth, between the atmosphere, land, oceans and living organisms. Michael Benton, a professor of paleontology at the University of Bristol, who was not involved in the study, said the research shows 'the absence of forests really impacts the regular oxygen-carbon cycles and suppresses carbon burial and so high levels of CO2 remain in the atmosphere over prolonged periods,' he told CNN. It highlights 'a threshold effect,' he added, where the loss of forests becomes 'irreversible on ecological time scales.' Global politics currently revolve around the idea that if carbon dioxide levels can be controlled, damage can be reversed. 'But at the threshold, it then becomes hard for life to recover,' Benton said. This is a key takeaway from the study, Mills said. It shows what might happen if rapid global warming causes the planet's rainforests to collapse in the future — a tipping point scientists are very concerned about. Even if humans stop pumping out planet-heating pollution altogether, the Earth may not cool. In fact, warming could accelerate, he said. There is a sliver of hope: The rainforests that currently carpet the tropics may be more resilient to high temperatures than those that existed before the Great Dying. This is the question the scientists are tackling next. This study is still a warning, Mills said. 'There is a tipping point there. If you warm tropical forests too much, then we have a very good record of what happens. And it's extremely bad.'
Forbes
2 days ago
- Science
- Forbes
NASA Study Finds Surprising Link Between Magnetic Field And Earth's Oxygen Levels
For 540 million years, Earth's magnetic field has correlated with fluctuations in atmospheric ... More oxygen, according to a newly released study. For 540 million years, the ebb and flow in the strength of Earth's magnetic field has correlated with fluctuations in atmospheric oxygen, according to a newly released analysis by NASA scientists. The research suggests that processes deep inside the Earth might influence habitability on the planet's surface. Earth's early atmosphere was mainly a toxic mix of carbon dioxide, nitrogen and water vapor. Then, between 2.4 billion and 400 million years ago, oxygen levels began to increase exponentially, maybe triggered by an intense phase of volcanic degassing or the emergence of the first photosynthetic microorganisms, able to split water into hydrogen and oxygen. Scientists can deduce historic oxygen levels by analyzing ancient rocks (like Banded Iron Formations) because their chemical composition depend on the amount of oxygen available when they were formed. "Tiger Iron" from the Ord Ranges near Port Hedland in Western Australia´s Pilbara region. Such ... More Banded Iron Formations formed when in the sea dissolved iron reacted with free oxygen, a byproduct of the metabolism of the first photosynthetic life-forms on Earth. The oldest evidence of Earth's magnetic field comes from 3.7-billion-year-old rocks preserved in Greenland. The history of the Earth's magnetic field is recorded in magnetized minerals. When minerals that rise with magma at gaps between spreading tectonic plates cool down, they freeze into place, preserving the direction and strength of the surrounding magnetic field. The origin of Earth's magnetic field is not yet fully understood. However, it is widely believed that circulating currents within the molten iron-nickel alloy of the Earth's outer core generate and sustain the field through a process known as geodynamo. Because the flow is not perfectly stable, the magnetic field fluctuates over time. For the first time, comparing the two separate datasets, a research team at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and University of Leeds, U.K., found that Earth's magnetic field has followed similar rising and falling patterns as oxygen in the atmosphere for nearly a half billion years. Correlating curves of Earth's magnetic field strength (in red) and atmospheric oxygen levels (in ... More blue) over the past 500 million years. The solid lines are the mean values, and the banded regions are the data uncertainties. 'This correlation raises the possibility that both the magnetic field strength and the atmospheric oxygen level are responding to a single underlying process, ' explains study coauthor Benjamin Mills, a biogeochemist at the University of Leeds. As for the specific causes linking Earth's geodynamo to atmospheric oxygen levels the scientists can only speculate. For example, the growth and fragmentation of continents during a magnetic fluctuation can influence global weathering rates, a process that removes oxygen from the atmosphere. The researchers hope to examine longer datasets to see if the correlation extends farther back in time. They also plan to investigate the historic abundance of other chemicals essential for life as we know it, such as nitrogen, to determine whether they also support these patterns. The study,"Strong link between Earth's oxygen level and geomagnetic dipole revealed since the last 540 million years," was published in the journal Science Advances. Additional material and interviews provided by NASA.
Arabian Post
3 days ago
- Science
- Arabian Post
Earth's Inner Dynamo Emerges as Key to Oxygen Stability
Earth's magnetic field strength and atmospheric oxygen levels have oscillated in tandem for around 540 million years, according to a NASA-led study, pointing to a deep-Earth process that could knit our planet's life-supporting systems more tightly than previously understood. Mapping trends from the Cambrian explosion to modern times, scientists found that periods of peak geomagnetic force—often logged in minerals as they cool within erupting magma—align closely with elevated oxygen levels, inferred from charcoal deposits and geochemical signatures in ancient rocks. Lead author Weijia Kuang of NASA's Goddard Space Flight Center asserts this constitutes the first statistically robust link between the magnetic dipole and atmospheric oxygen across geological time. ADVERTISEMENT Rises in both parameters registered pronounced peaks during the span from around 330 to 220 million years ago—coinciding with both a supercontinent cycle and heightened wildfire evidence—suggesting an underlying mechanism shorter than the age of the planet but far-reaching in effect. The research, appearing in Science Advances on 13 June 2025, assigns a leading role to Earth's magnetic field in potentially preserving atmospheric oxygen. By deflecting solar and cosmic radiation, the magnetic shield may slow atmospheric erosion and guard oxygen-producing photosynthetic lifeforms from harmful radiation. Alternate hypotheses suggest plate tectonics as a grand orchestrator. As continental drift drives crustal recycling and alters the thermal and chemical gradient at the core–mantle boundary, it may influence both geomagnetic behaviour and oxygen cycling—mirroring the oxygen flux through time. 'The correlation raises the possibility that both the magnetic field strength and the atmospheric oxygen level are responding to a single underlying process, such as the movement of Earth's continents,' said co-author Benjamin Mills from the University of Leeds. Despite the strong correlation—approximately 0.72 across data spanning 540 million years—uncertainty lingers over cause and effect. The team points to a negligible lag between the datasets, but concedes that whether the magnetic field drove oxygen dynamics, vice versa, or if both were shaped by tectonic activity, remains unresolved. An intriguing outlier arose from nearly 591–565 million years ago, when a weaker geomagnetic field coincided with a dramatic oxygen spike and a surge in marine biodiversity, implying that at times other forces may dominate. Demonstrations from Mars reinforce the protective value of a magnetic field: as its field waned around four billion years ago, atmospheric loss ensued, drying the planet's surface and chilling its climate. If validated, this geophysical coupling could reshape the parameters scientists use in the search for life on other rocky worlds. As Ravi Kopparapu from NASA notes, understanding this interplay is vital—and yet still in preliminary stages. The team intends to probe further back in time, seeking whether earlier supercontinents beyond Pangaea exhibited the same synchronicity. They also aim to include other biologically relevant atmospheric constituents—such as nitrogen—to evaluate whether they too display linked fluctuations. Collaboration across geology, geochemistry and planetary science appears essential. As Kopparapu explains: 'One single mind cannot comprehend the whole system of the Earth. We're like kids playing with Legos… trying to fit all of it together and see what's the big picture'.
Yahoo
18-06-2025
- Science
- Yahoo
Mysterious Link between Earth's Magnetism and Oxygen Baffles Scientists
The strength of Earth's magnetic field seems to rise and fall hand-in-hand with the abundance of oxygen in its atmosphere, a study of geological records spanning the last half billion years has found. Explaining the link could help to reveal fundamental trends in the evolution of life on Earth — and could show astronomers the most promising places to look for signs of complex life on other planets. But it is so far unclear whether Earth's magnetism plays direct a role in keeping oxygen levels high — and sustaining animal life — or whether both are influenced by a third, unidentified mechanism. 'We don't really have a good explanation for it,' says Benjamin Mills, a biogeochemist at the University of Leeds, UK, and co-author of the study, published in Science Advances on 13 June. But the study suggests 'some potential causes that are exciting and potentially testable', says Aubrey Zerkle, a biogeochemist at the University of St Andrews, UK. [Sign up for Today in Science, a free daily newsletter] Knowing how Earth's deep interior could influence the evolution of the atmosphere is 'critical to understanding what makes our planet habitable', says Richard Bono, a geophysicist at Florida State University in Tallahassee who has helped to compile long-term records of geomagnetism. Oxygen is the main component of Earth's crust and mantle. But molecular oxygen only began to slowly accumulate in the atmosphere after organisms that produce oxygen through photosynthesis began to evolve, around 2.5 billion years ago. And only in the current aeon, covering the last 540 million years or so, has it reached concentrations that are breathable by most animals. There is no direct way to measure the composition of the atmosphere in the deep past, but geochemists can use indirect clues to reconstruct oxygen levels starting in the Cambrian period, which began around 540 million years ago. For example, oxygen concentration 'has a strong relationship with how easy it is to start and maintain wildfires,' says Mills, and the frequency of large wildfires can be worked out by looking at ancient charcoal deposits, among other factors. Geophysicists can also reconstruct how the strength and direction of the geomagnetic field has varied across even longer stretches of Earth's history, by studying rocks produced by ancient volcanic eruptions. That's because magnetic crystals that form in the solidifying lava align themselves with the field, acting like tiny compasses frozen in time. To put these two long records side-by-side and compare them, Mills teamed up with geophysicists Weijia Kuang and Ravi Kopparapu, both at NASA Goddard Space Flight Center, Greenbelt, Maryland, and with exobiologist Joshua Krissansen-Totton at the University of Washington in Seattle. The authors found a strong correlation — both oxygen levels and geomagnetic intensity have increased over the past million years, and some of the major spikes or drops in both measures occur in the same geological eras (see 'Long-term trends'). The paper discusses some possible reasons for the correlation. Earth's magnetic field is known to have a protective effect on the upper atmosphere because it deflects solar wind, a stream of charged particles from the Sun that would otherwise cause oxygen and other gases to slowly escape into space. But the team calculated that the loss of oxygen caused by a drastic weakening of the field would still be small compared to the amounts generated by photosynthesis — or to those consumed by other organisms and by geological cycles in which elements are exchanged between the atmosphere, crust and the mantle. 'We don't necessarily think that the magnetic field impacts cycling directly, but it may be a result of the same processes,' says Mills. Over hundreds of millions of years, tectonic motions have repeatedly formed supercontinents, and have subsequently broken them up — releasing vast amounts of nutrients that in turn spurred massive blooms of oxygen-producing algae in Earth's oceans. Tectonics are driven by the slow churn of Earth's mantle, the region between crust and core. This churning could also have impacted the liquid outer core, where the geomagnetic field is produced, says Kuang. 'If things like the spreading rate [of the oceanic crust] influence the magnetic field, the tectonic cycle could be driving oxygenation — but also the magnetic field,' Mills says. Sanja Panovska, a geophysicist at the Helmholtz Centre for Geoscience in Potsdam, Germany, says that the study is convincing, but it introduces more questions than it answers. 'The authors mention a lot of hypotheses, but they are not put to the test in this paper.' Nevertheless, the discovery could feed into a long-standing debate on whether a strong magnetic field is essential for complex life to evolve on a planet. 'It's very expensive to observe exoplanets, and you need to choose which ones to observe,' says Mills. 'What this kind of work would inform is the kind of places you'd look.' This article is reproduced with permission and was first published on June 13, 2025.
Yahoo
16-06-2025
- Science
- Yahoo
As Earth's Magnetic Field Grows Stronger, Oxygen Levels Rise
When the magnetic field around the Earth grows stronger, oxygen levels rise. That is the surprising finding of a new study looking at more than half a billion years of planetary history. Researchers can track the rise and fall in oxygen levels by studying charcoal left over from ancient wildfires. The more oxygen, the larger the fires. And they can gauge changes in the geomagnetic field by studying rocks formed by ancient volcanic eruptions. Magnetic crystals found in cooling lava align with the geomagnetic field, offering some indication of its strength. The new study combined these data, revealing a powerful link between oxygen levels and the strength of the geomagnetic field. Over the last 540 million years, the strength of the magnetic field has trended up, and so has the level of oxygen, making the planet more hospitable to life. The findings were published in Science Advances. 'We don't really have a good explanation for it,' coauthor Benjamin Mills, of the University of Leeds, told Nature, though he offered a few ideas. As the tectonic plates have shifted, over hundreds of millions of years, their movements have, at times, unleashed essential nutrients, such as zinc and phosphorus, into the ocean, fueling massive algal blooms. Those blooms produced huge volumes of oxygen. It may be the case, scientists propose, that the same currents driving the movement of the tectonic plates may also be affecting the Earth's iron core, the source of its magnetic field. Can Toxic Mining Waste Help Remove CO2 from the Atmosphere?
