Latest news with #mass extinction
Yahoo
04-07-2025
- Science
- Yahoo
'The Great Dying' mass extinction was a warning from the trees, study says
It happened before, and could happen again…. That's the message in a new study about the catastrophic collapse of Earth's tropical forests due to natural volcanic causes 252 million years ago. The collapse of tropical forests was the primary cause of the prolonged global warming that followed, according to a new study published July 2 in the British journal Nature Communications. This coincided with a mass extinction, likely the worst in Earth's history. 'There is a warning here about the importance of Earth's present-day tropical forests," study co-author and University of Leeds professor Benjamin Mills said, in a statement: "If rapid warming causes them to collapse in a similar manner, then we should not expect our climate to cool to preindustrial levels, even if we stop emitting CO2. 'Indeed, warming could continue to accelerate in this case even if we reach zero human emissions. We will have fundamentally changed the carbon cycle in a way that can take geological timescales to recover, which has happened in Earth's past.' The huge climate changes back then occurred during the Permian–Triassic Mass Extinction – sometimes referred to as the "Great Dying," which happened around 252 million years ago, leading to the massive loss of marine species and significant declines in terrestrial plants and animals. The event has been attributed to intense global warming triggered by a period of volcanic activity in Siberia, known as the Siberian Traps, the study says. This rapid increase in carbon dioxide in Earth's atmosphere and the resulting temperature increase is thought to be the primary kill mechanism for much of life at the time, according to the Conversation. However, scientists had been unable to pinpoint why super-greenhouse conditions persisted for around five million years afterwards. Now, in the new study, researchers have gathered data that supports the theory that the demise of tropical forests, and their slow recovery, limited carbon sequestration – a process where carbon dioxide is removed from the atmosphere and held in plants, soils or minerals. Our current understanding is that it was high temperatures which resulted from huge volcanic carbon dioxide emissions over thousands of years, Mills said in an e-mail to USA TODAY. "This volcanic event is called the Siberian Traps and may be the biggest to ever have occurred." "Yes," Mills said, adding that the climate had already warmed, which initially caused the tropical forests to die back, but the removal of forests took away one of the planet's most important carbon removal processes – photosynthesis. The lack of this "carbon sink" caused CO2 levels to build up even further, which drove excess warming. "While the climate is currently warming (and is doing so faster than during the event 252 million years ago), we are not yet at the temperature where tropical forests are expected to reach a tipping point and transition into a carbon source rather than sink," Mills told USA TODAY. "So it is not happening now, but we may not be that far away." We have warmed the planet by about 1 degree C since the Industrial Revolution, and estimates for Amazon rainforest tipping points range from 2 to 6 degrees C. It is hard to estimate this accurately. The Triassic super-greenhouse took thousands of years to establish, but because we are emitting carbon dioxide much more quickly than in the deep past, we might expect effects to begin to occur "over hundreds of years," Mills said. "To see 'super greenhouse' conditions we would need to remove almost all of the tropical forested area. It is debatable whether this could occur in the present day where the plants are different, and the shape of the continents is different than in the past. But personally I do not want us to run this experiment!" Speaking about the new study, co-author Jianxin Yu of the China University of Geosciences added: 'Let's make sure our work transcends academia: it is a responsibility to all life on Earth, today and beyond." "Earth's story is still being written, and we all have a role in shaping its next chapter," Yu said. This article originally appeared on USA TODAY: Forest loss fueled 'Great Dying' mass extinction, study says
The Independent
03-07-2025
- Science
- The Independent
Fossils reveal why earth was extremely hot for millions of years
Some 252 million years ago, almost all life on Earth disappeared. Known as the Permian–Triassic mass extinction – or the Great Dying – this was the most catastrophic of the five mass extinction events recognised in the past 539 million years of our planet's history. Up to 94 per cent of marine species and 70 per cent of terrestrial vertebrate families were wiped out. Tropical forests – which served, as they do today, as important carbon sinks that helped regulate the planet's temperature – also experienced massive declines. Scientists have long agreed this event was triggered by a sudden surge in greenhouse gases which resulted in an intense and rapid warming of Earth. But what has remained a mystery is why these extremely hot conditions persisted for millions of years. Our new paper, published in Nature Communications, provides an answer. The decline of tropical forests locked Earth in a hothouse state, confirming scientists' suspicion that when our planet's climate crosses certain 'tipping points', truly catastrophic ecological collapse can follow. A massive eruption The trigger for the Permian–Triassic mass extinction event was the eruption of massive amounts of molten rock in modern day Siberia, named the Siberian Traps. This molten rock erupted in a sedimentary basin, rich in organic matter. The molten rock was hot enough to melt the surrounding rocks and release massive amounts of carbon dioxide into Earth's atmosphere over a period as short as 50,000 years but possibly as long as 500,000 years. This rapid increase in carbon dioxide in Earth's atmosphere and the resulting temperature increase is thought to be the primary kill mechanism for much of life at the time. On land it is thought surface temperatures increased by as much as 6°C to 10°C – too rapid for many life forms to evolve and adapt. In other similar eruptions, the climate system usually returns to its previous state within 100,000 to a million years. But these 'super greenhouse' conditions, which resulted in equatorial average surface temperatures upwards of 34°C (roughly 8°C warmer than the current equatorial average temperature) persisted for roughly five million years. In our study we sought to answer why. The forests die out We looked at the fossil record of a wide range of land plant biomes, such as arid, tropical, subtropical, temperate and scrub. We analysed how the biomes changed from just before the mass extinction event, until about eight million years after. We hypothesised that Earth warmed too rapidly, leading to the dying out of low- to mid-latitude vegetation, especially the rainforests. As a result the efficiency of the organic carbon cycle was greatly reduced immediately after the volcanic eruptions. Plants, because they are unable to simply get up and move, were very strongly affected by the changing conditions. Before the event, many peat bogs and tropical and subtropical forests existed around the equator and soaked up carbon. However, when we reconstructed plant fossils from fieldwork, records and databases around the event we saw that these biomes were completely wiped out from the tropical continents. This led to a multimillion year 'coal gap' in the geological record. These forests were replaced by tiny lycopods, only two to 20 centimetres in height. Enclaves of larger plants remained towards the poles, in coastal and in slightly mountainous regions where the temperature was slightly cooler. After about five million years they had mostly recolonised Earth. However these types of plants were also less efficient at fixing carbon in the organic carbon cycle. This is analogous in some ways to considering the impact of replacing all rainforests at present day with the mallee-scrub and spinifex flora that we might expect to see in the Australian outback. Finally, the forests return Using evidence from the present day, we estimated the rate at which plants take atmospheric carbon dioxide and store it as organic matter of each different biome (or its 'net primary productivity') that was suggested in the fossil record. We then used a recently developed carbon cycle model called SCION to test our hypothesis numerically. When we analysed our model results we found that the initial increase in temperature from the Siberian Traps was preserved for five to six million years after the event because of the reduction in net primary productivity. It was only as plants re-established themselves and the organic carbon cycle restarted that Earth slowly started to ease out of the super greenhouse conditions. Maintaining a climate equilibrium It's always difficult to draw analogies between past climate change in the geological record and what we're experiencing today. That's because the extent of past changes is usually measured over tens to hundreds of thousands of years while at present day we are experiencing change over decades to centuries. A key implication of our work, however, is that life on Earth, while resilient, is unable to respond to massive changes on short time scales without drastic rewirings of the biotic landscape. In the case of the Permian–Triassic mass extinction, plants were unable to respond on as rapid a time scale as 1,000 to 10,000 years. This resulted in a large extinction event. Overall, our results underline how important tropical and subtropical plant biomes and environments are to maintaining a climate equilibrium. In turn, they show how the loss of these biomes can contribute to additional climate warming – and serve as a devastating climate tipping point. Zhen Xu was the lead author of the study, which was part of her PhD work. Andrew Merdith is a DECRA Fellow at the School of Earth Sciences, University of Adelaide. Benjamin J. W. Mills is a Professor of Earth System Evolution at the University of Leeds. Zhen Xu is a Research Fellow at the School of Earth and Environment, University of Leeds.
The Independent
03-07-2025
- Science
- The Independent
Fossils unlock 250-million-year-old mystery of the ‘Great Dying'
Some 252 million years ago, almost all life on Earth disappeared. Known as the Permian–Triassic mass extinction – or the Great Dying – this was the most catastrophic of the five mass extinction events recognised in the past 539 million years of our planet's history. Up to 94 per cent of marine species and 70 per cent of terrestrial vertebrate families were wiped out. Tropical forests – which served, as they do today, as important carbon sinks that helped regulate the planet's temperature – also experienced massive declines. Scientists have long agreed this event was triggered by a sudden surge in greenhouse gases which resulted in an intense and rapid warming of Earth. But what has remained a mystery is why these extremely hot conditions persisted for millions of years. Our new paper, published in Nature Communications, provides an answer. The decline of tropical forests locked Earth in a hothouse state, confirming scientists' suspicion that when our planet's climate crosses certain 'tipping points', truly catastrophic ecological collapse can follow. A massive eruption The trigger for the Permian–Triassic mass extinction event was the eruption of massive amounts of molten rock in modern day Siberia, named the Siberian Traps. This molten rock erupted in a sedimentary basin, rich in organic matter. The molten rock was hot enough to melt the surrounding rocks and release massive amounts of carbon dioxide into Earth's atmosphere over a period as short as 50,000 years but possibly as long as 500,000 years. This rapid increase in carbon dioxide in Earth's atmosphere and the resulting temperature increase is thought to be the primary kill mechanism for much of life at the time. On land it is thought surface temperatures increased by as much as 6°C to 10°C – too rapid for many life forms to evolve and adapt. In other similar eruptions, the climate system usually returns to its previous state within 100,000 to a million years. But these 'super greenhouse' conditions, which resulted in equatorial average surface temperatures upwards of 34°C (roughly 8°C warmer than the current equatorial average temperature) persisted for roughly five million years. In our study we sought to answer why. The forests die out We looked at the fossil record of a wide range of land plant biomes, such as arid, tropical, subtropical, temperate and scrub. We analysed how the biomes changed from just before the mass extinction event, until about eight million years after. We hypothesised that Earth warmed too rapidly, leading to the dying out of low- to mid-latitude vegetation, especially the rainforests. As a result the efficiency of the organic carbon cycle was greatly reduced immediately after the volcanic eruptions. Plants, because they are unable to simply get up and move, were very strongly affected by the changing conditions. Before the event, many peat bogs and tropical and subtropical forests existed around the equator and soaked up carbon. However, when we reconstructed plant fossils from fieldwork, records and databases around the event we saw that these biomes were completely wiped out from the tropical continents. This led to a multimillion year 'coal gap' in the geological record. These forests were replaced by tiny lycopods, only two to 20 centimetres in height. Enclaves of larger plants remained towards the poles, in coastal and in slightly mountainous regions where the temperature was slightly cooler. After about five million years they had mostly recolonised Earth. However these types of plants were also less efficient at fixing carbon in the organic carbon cycle. This is analogous in some ways to considering the impact of replacing all rainforests at present day with the mallee-scrub and spinifex flora that we might expect to see in the Australian outback. Finally, the forests return Using evidence from the present day, we estimated the rate at which plants take atmospheric carbon dioxide and store it as organic matter of each different biome (or its 'net primary productivity') that was suggested in the fossil record. We then used a recently developed carbon cycle model called SCION to test our hypothesis numerically. When we analysed our model results we found that the initial increase in temperature from the Siberian Traps was preserved for five to six million years after the event because of the reduction in net primary productivity. It was only as plants re-established themselves and the organic carbon cycle restarted that Earth slowly started to ease out of the super greenhouse conditions. Maintaining a climate equilibrium It's always difficult to draw analogies between past climate change in the geological record and what we're experiencing today. That's because the extent of past changes is usually measured over tens to hundreds of thousands of years while at present day we are experiencing change over decades to centuries. A key implication of our work, however, is that life on Earth, while resilient, is unable to respond to massive changes on short time scales without drastic rewirings of the biotic landscape. In the case of the Permian–Triassic mass extinction, plants were unable to respond on as rapid a time scale as 1,000 to 10,000 years. This resulted in a large extinction event. Overall, our results underline how important tropical and subtropical plant biomes and environments are to maintaining a climate equilibrium. In turn, they show how the loss of these biomes can contribute to additional climate warming – and serve as a devastating climate tipping point. Zhen Xu was the lead author of the study, which was part of her PhD work. Andrew Merdith is a DECRA Fellow at the School of Earth Sciences, University of Adelaide. Benjamin J. W. Mills is a Professor of Earth System Evolution at the University of Leeds. Zhen Xu is a Research Fellow at the School of Earth and Environment, University of Leeds.
Yahoo
25-06-2025
- Science
- Yahoo
Tiny night lizards survived dinosaur-killing asteroid strike, despite being close enough to see it happen
When you buy through links on our articles, Future and its syndication partners may earn a commission. Mysterious night lizards survived the giant asteroid strike that ended the reign of the dinosaurs 66 million years ago, and they still live there today, a new study finds. Thanks to a new evolutionary analysis, researchers discovered that the little lizards, in the family Xantusiidae, were living around the Gulf of Mexico before and after the asteroid struck what is now Mexico's Yucatán Peninsula. This makes night lizards the only group of land vertebrates known to have survived close to the impact location, and still have members living in the region today. The dinosaurs' doomsday asteroid was around 7.5 miles (12 kilometers) wide and caused widespread devastation when it hit at the end of the Cretaceous period (145 million to 66 million years ago). The impact was catastrophic for much of Earth's wildlife, triggering the Cretaceous-Paleogene (K-Pg) mass extinction event, in which around 75% of all species died out. However, two lineages of night lizard managed to persist through the disaster, despite likely being close enough to see the impact. "They would have been all around the margin of the asteroid impact," study lead author Chase Brownstein, a doctoral candidate in the Department of Ecology and Evolutionary Biology at Yale University, told Live Science. How did night lizards survive amid all the devastation? Researchers aren't sure, but Brownstein noted that they have slow metabolisms, so they wouldn't have needed to eat very often. The researchers published their findings Wednesday (June 25) in the journal Biology Letters. Related: Iguanas sailed one-fifth of the way around the world on rafts 34 million years ago Night lizards grow to only a few inches in length. Often very secretive, the lizards live in specialized microhabitats, like inside rock crevices and dense vegetation, or beneath bark and logs. Some previous studies suggested that night lizards' "crown" group — the group containing the last common ancestor of all living night lizards — evolved during the age of dinosaurs, which would have meant the animals persisted through the K-Pg devastation. The new study put that hypothesis to the test. Brownstein and his colleagues reconstructed the ancestry of the three living night lizard genera (Lepidophyma, Xantusia and Cricosaura). They used molecular clock dating to estimate when the night lizards evolved, based on their mutations and the rate at which mutations occur in DNA over time. The researchers found that the most recent common ancestor of living night lizards emerged during the Cretaceous around 90 million years ago and that night lizards have been living in North America and Central America since around that time, well before the asteroid struck 66 million years ago, according to the study. The new findings suggest that two night lizard lineages survived the asteroid strike. One of these lineages then gave rise to Xantusia, which ranges from the southwestern U.S. into Mexico, and Lepidophyma, which ranges across parts of North America and Central America. The second lineage then gave rise to Cricosaura and its only species, Cuban night lizards (Cricosaura typica), in Cuba. RELATED STORIES —Newly discovered Cretaceous sea monster named after world-ending Norse serpent —Surprise discovery of snake-like lizard feared extinct leaves scientists amazed —Watch chameleon erupt in color 'as if uttering her last words' in her final moments before death Night lizards weren't the only animals to survive the K-Pg mass extinction event. We wouldn't be here today if some of the mammal family tree hadn't lived through the asteroid impact. Avian dinosaurs (birds), fish and plenty of other animals survived, too. However, night lizards are the only known surviving group of terrestrial vertebrates that have remained endemic to — living only in — North America and Central America since the asteroid hit. Brownstein noted that some lineages of turtles and other lizards in the region probably survived the asteroid in a similar way as night lizards (scientifically named xantusiids) did. However, these other lineages have since disappeared. "The problem is that they just aren't there anymore," Brownstein said. "So, what's interesting is that xantusiids have persisted and have remained endemic to the region."
Yahoo
16-06-2025
- Science
- Yahoo
'Statistically, that shouldn't have happened': Something very weird occurred in the ocean after the dinosaur-killing asteroid hit
When you buy through links on our articles, Future and its syndication partners may earn a commission. About 66 million years ago — perhaps on a downright unlucky day in May — an asteroid smashed into our planet. The fallout was immediate and severe. Evidence shows that about 70% of species went extinct in a geological instant, and not just those famous dinosaurs that once stalked the land. Masters of the Mesozoic oceans were also wiped out, from mosasaurs — a group of aquatic reptiles topping the food chain — to exquisitely shelled squid relatives known as ammonites. Even groups that weathered the catastrophe, such as mammals, fishes and flowering plants, suffered severe population declines and species loss. Invertebrate life in the oceans didn't fare much better. But bubbling away on the seafloor was a stolid group of animals that has left a fantastic fossil record and continues to thrive today: bivalves — clams, cockles, mussels, oysters and more. What happened to these creatures during the extinction event and how they rebounded tells an important story, both about the past and the future of biodiversity. Marine bivalves lost around three-quarters of their species during this mass extinction, which marked the end of the Cretaceous Period. My colleagues and I — each of us paleobiologists studying biodiversity — expected that losing so many species would have severely cut down the variety of roles that bivalves play within their environments, what we call their "modes of life." But, as we explain in a study published in the journal Sciences Advances, that wasn't the case. In assessing the fossils of thousands of bivalve species, we found that at least one species from nearly all their modes of life, no matter how rare or specialized, squeaked through the extinction event. Statistically, that shouldn't have happened. Kill 70% of bivalve species, even at random, and some modes of life should disappear. Related: The 5 mass extinction events that shaped the history of Earth — and the 6th that's happening now Most bivalves happily burrow into the sand and mud, feeding on phytoplankton they strain from the water. But others have adopted chemosymbionts and photosymbionts — bacteria and algae that produce nutrients for the bivalves from chemicals or sunlight in exchange for housing. A few have even become carnivorous. Some groups, including the oysters, can lay down a tough cement that hardens underwater, and mussels hold onto rocks by spinning silken threads. We thought surely these more specialized modes of life would have been snuffed out by the effects of the asteroid's impact, including dust and debris likely blocking sunlight and disrupting a huge part of the bivalves' food chain: photosynthetic algae and bacteria. Instead, most persisted, although biodiversity was forever scrambled as a new ecological landscape emerged. Species that were once dominant struggled, while evolutionary newcomers rose in their place. The reasons some species survived and others didn't leave many questions to explore. Those that filtered phytoplankton from the water column suffered some of the highest species losses, but so did species that fed on organic scraps and didn't rely as much on the Sun's energy. Narrow geographic distributions and different metabolisms may have contributed to these extinction patterns. Life rebounded from each of the Big Five mass extinctions throughout Earth's history, eventually punching through past diversity highs. The rich fossil record and spectacular ecological diversity of bivalves gives us a terrific opportunity to study these rebounds to understand how ecosystems and global biodiversity rebuild in the wake of extinctions. The extinction caused by the asteroid strike knocked down some thriving modes of life and opened the door for others to dominate the new landscape. While many people lament the loss of the dinosaurs, we malacologists miss the rudists. These bizarrely shaped bivalves resembled giant ice cream cones, sometimes reaching more than 3 feet (1 meter) in size, and they dominated the shallow, tropical Mesozoic seas as massive aggregations of contorted individuals, similar to today's coral reefs. At least a few harbored photosymbiotic algae, which provided them with nutrients and spurred their growth, much like modern corals. Today, giant clams (Tridacna) and their relatives fill parts of these unique photosymbiotic lifestyles once occupied by the rudists, but they lack the rudists' astonishing species diversity. Mass extinctions clearly upend the status quo. Now, our ocean floors are dominated by clams burrowed into sand and mud, the quahogs, cockles and their relatives — a scene far different from that of the seafloor 66 million years ago. Ecological traits alone didn't fully predict extinction patterns, nor do they entirely explain the rebound. We also see that simply surviving a mass extinction didn't necessarily provide a leg up as species diversified within their old and sometimes new modes of life — and few of those new modes dominate the ecological landscape today. Like the rudists, trigoniid bivalves had lots of different species prior to the extinction event. These highly ornamented clams built parts of their shells with a super strong biomaterial called nacre — think iridescent pearls — and had fractally interlocking hinges holding their two valves together. But despite surviving the extinction, which should have placed them in a prime position to accumulate species again, their diversification sputtered. Other types of bivalves that made a living in the same way proliferated instead, relegating this once mighty and global group to a handful of species now found only off the coast of Australia. These unexpected patterns of extinction and survival may offer lessons for the future. The fossil record shows us that biodiversity has definite breaking points, usually during a perfect storm of climatic and environmental upheaval. It's not just that species are lost, but the ecological landscape is overturned. Many scientists believe the current biodiversity crisis may cascade into a sixth mass extinction, this one driven by human activities that are changing ecosystems and the global climate. Corals, whose reefs are home to nearly a quarter of known marine species, have faced mass bleaching events as warming ocean water puts their future at risk. Acidification as the oceans absorb more carbon dioxide can also weaken the shells of organisms crucial to the ocean food web. Findings like ours suggest that, in the future, the rebound from extinction events will likely result in very different mixes of species and their modes of life in the oceans. And the result may not align with human needs if species providing the bulk of ecosystem services are driven genetically or functionally extinct. RELATED STORIES —Are we in a 6th mass extinction? —After the 'Great Dying,' life on Earth took millions of years to recover. Now, scientists know why. —Refuge from the worst mass extinction in Earth's history discovered fossilized in China The global oceans and their inhabitants are complex, and, as our team's latest research shows, it is difficult to predict the trajectory of biodiversity as it rebounds — even when extinction pressures are reduced. Billions of people depend on the ocean for food. As the history recorded by the world's bivalves shows, the upending of the pecking order — the number of species in each mode of life — won't necessarily settle into an arrangement that can feed as many people the next time around. This edited article is republished from The Conversation under a Creative Commons license. Read the original article.
