Latest news with #SnowballEarth
Forbes
30-03-2025
- Science
- Forbes
The ‘Boring Billion' Was A Geological Power Move — And It Changed Life Forever
Scientists once called it an uneventful stretch of history. In reality, it was quietly shaping the ... More future of life itself. Here's why the world's most 'boring' billion years were also its most important. For nearly a billion years, Earth seemed to fall into an evolutionary slumber. Between 1,800 and 800 million years ago — a stretch of time now infamously known as the boring billion — oxygen levels stagnated, tectonic movements slowed and life appeared stuck in a state of suspended animation. But this era was hardly the dull hiatus it's made out to be. Recent research suggests that the boring billion was less of an evolutionary dead zone and more of an incubator, steadily setting the stage for the explosion of complex life that followed. The term was coined by paleontologist Martin Brasier to describe what seemed like a geological and biological lull. Unlike the dramatic upheavals of the Snowball Earth events or the Cambrian explosion, this period was marked by tectonic stability, climatic stasis and a seeming lack of evolutionary progress. During this time, supercontinents like Columbia and Rodinia formed and remained relatively unchanged, while Earth's atmosphere lingered at oxygen levels far below today's breathable air. The planet was locked in a stable, low-energy state. Scientists once thought that nothing of significance transpired. However, this stability did not equate to stagnation — it contributed to a period of hidden transformation. It was during this time that some of life's most crucial evolutionary advancements took root: In fact, the relatively moderate changes that occurred during this period may have been a necessary prelude to complexity, according to a March 2018 study published in Scientific Reports. This would suggest that the billion years were 'boring' enough to stabilize Earth's biosphere before the planet was ready to support more advanced life forms. One of the most baffling aspects of the boring billion is the oxygen paradox. The Great Oxygenation Event around 2.4 billion years ago saw a dramatic rise in atmospheric oxygen. But instead of continuing to increase, oxygen levels plateaued for nearly a billion years. This was likely caused by a feedback loop in which cyanobacteria, the early oxygen producers, inadvertently slowed their own progress. This suggests that the enzyme nitrogenase, crucial for nitrogen fixation, was destroyed by oxygen. As oxygen levels crept up, it became harder for life to maintain the nitrogen cycle needed to sustain itself. Another major culprit may have been sulfur-loving microbes, which dominated the oceans and locked Earth into a cycle of low oxygen and high sulfide conditions. A September 2009 study published in Proceedings of the National Academy of Sciences suggests that these microbes thrived in the sulfur-rich oceans, keeping the planet in an anoxic stranglehold. The prolonged 'stability' afforded by the boring billion allowed Earth's systems to fine-tune key biochemical and geochemical processes, laying the groundwork for future complexity. When the long-standing oxygen plateau finally gave way to a surge in atmospheric and oceanic oxygen levels, this increase was fueled by a shift in microbial and algal activity, which ramped up photosynthesis and altered the carbon cycle. This new oxygen influx would become a crucial tipping point for complex life. The fracturing of Rodinia only tipped the scales further. While it had remained intact throughout the boring billion, limiting ocean circulation and nutrient upwelling, the end of this period saw the supercontinent begin to fracture. As it happened, ocean currents intensified, redistributing oxygen and nutrients across previously stagnant waters. This tectonic upheaval may have accelerated evolutionary change, setting the stage for biological diversification. With higher oxygen levels, increased nutrient cycling and shifting ocean currents, Earth's long dormancy ended in dramatic fashion. By 540 million years ago, the Cambrian explosion was underway — a rapid diversification of life that saw the emergence of complex multicellular organisms, predatory behavior and the foundations of modern ecosystems. Stories like the boring billion spotlight the endless potential of our natural world and the curious ways in which life adapts. How do you feel about nature's ability to adapt against the odds? Find out now with a 2-minute quiz to see where you stand on the Connectedness To Nature Scale.
Yahoo
26-02-2025
- Science
- Yahoo
Ancient glacier finding reveals clues to how complex life on Earth evolved, scientists say
Sign up for CNN's Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more. More than half a billion years ago on a frigid, ice-covered Earth, glaciers stirred up ingredients for complex life by bulldozing land minerals and then depositing them in the ocean, according to a new study. Inch by inch, as massive glaciers crept over frozen land toward an ice-covered sea, they scoured the ground beneath them, gouging and scraping rocks from Earth's crust. When the glaciers eventually melted, they released a torrent of terrestrial chemicals into the ocean, researchers recently reported. Minerals swept up on land by this 'glacial broom' altered marine chemistry and infused oceans with nutrients that they say may have shaped how complex life evolved. This ancient period of deep freeze, known as the Neoproterozoic Era, or 'Snowball Earth,' lasted from about 1 billion to 543 million years ago. During that time, landmasses consolidated into a supercontinent called Rodinia and then broke apart again. Earth's earliest forms of life, such as microbes, cyanobacteria, sponges and seafloor-dwelling organisms, populated the oceans. After the end of the Neoproterozoic came the rise of more complex life, with the first appearance of marine creatures sporting armor, shells and spikes. Scientists have attributed this evolutionary boom to increased oxygen levels in Earth's atmosphere and in shallow ocean waters. And now, research published Tuesday in the journal Geology suggests the flowing of ancient glaciers may have directly shaped chemical changes in the ocean that were critical for the evolution of complex organisms. Studying Snowball Earth offers a window into our planet's past, but it also presents valuable insights into modern climate change, lead study author Dr. Chris Kirkland said. 'Our deep time geological record indicates how changing one part of Earth affects another,' he said. Right now, the dramatic warming of the planet that marks the human-fueled climate crisis is happening at breakneck speed compared with these ancient processes that took millions of years. 'This rapid pace limits Earth's ability to naturally regulate itself, underscoring the urgency of addressing anthropogenic climate change.' Glacier movement, or glaciation, is known to scrape up and ferry terrestrial sediments into oceans, lakes and rivers, forming the basis of aquatic food webs. However, researchers who study ancient Earth were previously uncertain whether Neoproterozoic glaciers moved at all, let alone enough to erode the ground beneath them and transfer minerals into the sea. 'It had been hypothesized that widespread glacial erosion of continental interiors could be caused by the Snowball Earth ice,' said Kirkland, a professor in the School of Earth and Planetary Sciences at Curtin University in Perth, Australia. 'However, aspects of this idea were not clear because that ice may not have moved or moved only slightly or indeed even flowed.' Kirkland and his colleagues found answers in Scotland and Northern Ireland, where they studied sediments from rock formations dating to the Neoproterozoic. The team looked at zircons — crystallized minerals that are exceptionally durable and can weather extreme geological events. Zircons also contain uranium; by measuring the stages of uranium's decay in zircons, geologists use the minerals as chronometers for studying Earth's past. The researchers examined sediments dating to the time when Earth was covered with ice, and from the 'hothouse Earth' period millions of years later when the ice was gone, and found the mineral composition of Snowball Earth sediments differed dramatically from that of later sediments. 'We recovered distinctive patterns in the populations of these mineral grains,' Kirkland told CNN in an email. 'In essence the 'DNA' fingerprint of these sedimentary rocks changed.' The findings appear to bolster the notion of active glaciation 'somewhat,' said Dr. Graham Shields, a professor of geology at University College London. Shields was not involved in the new research. However, the study did not include data from a significant glacial interval called the Marinoan, which marked the end of Snowball Earth, he told CNN in an email. Shields was also cautious about directly linking glacial erosion to the evolution of complex life. 'This connection has been proposed before but it is controversial because the linkage is assumed rather than explained,' Shields said. 'Dramatic landscape change causing the emergence of macroscopic animals is a neat idea, but the paper introduces a hypothesis about glacial erosion/weathering that can be tested, rather than settling the debate.' Rocks from the time of Snowball Earth contained older minerals, but also featured a range of mineral ages, hinting that the rocks were exposed and eroded over time by the scraping movement of glaciers. This evidence told the scientists that the glaciers of the Neoproterozoic were mobile. Younger rocks, from when Snowball Earth was thawing, had a narrower range of mineral ages, and more fragile grains were absent, suggesting flowing water had dissolved material that was previously ground down. At the waning of the Neoproterozoic, one of the known changes in ocean chemistry was a rise in uranium. Other research had previously explained this increase as resulting from the rise in atmospheric oxygen, 'however, our data imply that the delivery of chemical elements into the oceans also played a role in this,' Kirkland said. 'The 'lost' dissolved component in these rocks is seen 'popping back up' in changes in ocean chemistry at this time,' he added. By mapping these changes in terrestrial and marine environments, 'we are imaging the transfer of chemical elements through the Earth as a system.' The scientists reported that major glaciation events took place at least twice between 720 million and 635 million years ago. By the end of the Neoproterozoic, as Earth's icy cover began to thaw, major chemistry shifts were taking place in Earth's atmosphere and oceans. 'The end of these glaciations is marked by rapid increases in atmospheric and oceanic oxygen, possibly due to enhanced weathering of exposed rock surfaces and increased nutrient fluxes into the ocean,' Kirkland said. Such changes could have infused nutrient cycles and provided emerging life with the boost it needed to evolve into more complex forms. 'The idea that glacial debris from Neoproterozoic ice ages provided nutrients to support early animal evolution has been around for a while,' said Dr. Andrew Knoll, a professor emeritus of Earth and planetary sciences at Harvard University, who was not involved in the new research. However, questions remain about whether the minerals poured into the ocean by Neoproterozoic glaciation would have been enough to spur long-term environmental changes with biological consequences, Knoll told CNN in an email. Other research previously suggested that the impacts of glaciation events, such as the ones described in the new study, 'might well have only transient consequences — a bolus of nutrients raising primary production and perhaps increasing oxygen levels, before relaxing back to the earlier state of the environment,' Knoll said. The new findings are 'an interesting addition to the conversation,' he added. 'But the conversation continues.' From the Neoproterozoic to the present, similar processes shape climate change, including the role played by carbon dioxide (CO2) and the behavior of feedback loops, when a process feeds into an existing aspect of Earth's climate system and intensifies it. Ancient climate evidence also illuminates what happens during climate tipping points — when a threshold is crossed, triggering large-scale changes that are often irreversible. Today, Earth is heating up rapidly rather than cooling gradually over time. It took millions of years for glaciation to overtake the planet during Earth's snowball phase, while modern warming is accelerating over mere decades, 'much faster than past natural climate shifts,' Kirkland said. However, climate change's global progress is still mapped by studying the interplay of CO2 buildup, feedback loops and tipping points, he added. 'We can see how different parts of the planet are interrelated via chemical links,' he said. 'Change one part of the system, other parts also change.' Mindy Weisberger is a science writer and media producer whose work has appeared in Live Science, Scientific American and How It Works magazine.
CNN
26-02-2025
- Science
- CNN
Ancient glaciers reshaped Earth's surface, fueling the rise of complex life on Earth, scientists say
More than half a billion years ago on a frigid, ice-covered Earth, glaciers stirred up ingredients for complex life by bulldozing land minerals and then depositing them in the ocean, according to a new study. Inch by inch, as massive glaciers crept over frozen land toward an ice-covered sea, they scoured the ground beneath them, gouging and scraping rocks from Earth's crust. When the glaciers eventually melted, they released a torrent of terrestrial chemicals into the ocean, researchers recently reported. Minerals swept up on land by this 'glacial broom' altered marine chemistry and infused oceans with nutrients that they say may have shaped how complex life evolved. This ancient period of deep freeze, known as the Neoproterozoic Era, or 'Snowball Earth,' lasted from about 1 billion to 543 million years ago. During that time, landmasses consolidated into a supercontinent called Rodinia and then broke apart again. Earth's earliest forms of life, such as microbes, cyanobacteria, sponges and seafloor-dwelling organisms, populated the oceans. After the end of the Neoproterozoic came the rise of more complex life, with the first appearance of marine creatures sporting armor, shells and spikes. Scientists have attributed this evolutionary boom to increased oxygen levels in Earth's atmosphere and in shallow ocean waters. And now, research published Tuesday in the journal Geology suggests the flowing of ancient glaciers may have directly shaped chemical changes in the ocean that were critical for the evolution of complex organisms. Studying Snowball Earth offers a window into our planet's past, but it also presents valuable insights into modern climate change, lead study author Dr. Chris Kirkland said. 'Our deep time geological record indicates how changing one part of Earth affects another,' he said. Right now, the dramatic warming of the planet that marks the human-fueled climate crisis is happening at breakneck speed compared with these ancient processes that took millions of years. 'This rapid pace limits Earth's ability to naturally regulate itself, underscoring the urgency of addressing anthropogenic climate change.' From snowball Earth to hothouse planet Glacier movement, or glaciation, is known to scrape up and ferry terrestrial sediments into oceans, lakes and rivers, forming the basis of aquatic food webs. However, researchers who study ancient Earth were previously uncertain whether Neoproterozoic glaciers moved at all, let alone enough to erode the ground beneath them and transfer minerals into the sea. 'It had been hypothesized that widespread glacial erosion of continental interiors could be caused by the Snowball Earth ice,' said Kirkland, a professor in the School of Earth and Planetary Sciences at Curtin University in Perth, Australia. 'However, aspects of this idea were not clear because that ice may not have moved or moved only slightly or indeed even flowed.' Kirkland and his colleagues found answers in Scotland and Northern Ireland, where they studied sediments from rock formations dating to the Neoproterozoic. The team looked at zircons — crystallized minerals that are exceptionally durable and can weather extreme geological events. Zircons also contain uranium; by measuring the stages of uranium's decay in zircons, geologists use the minerals as chronometers for studying Earth's past. The researchers examined sediments dating to the time when Earth was covered with ice, and from the 'hothouse Earth' period millions of years later when the ice was gone, and found the mineral composition of Snowball Earth sediments differed dramatically from that of later sediments. 'We recovered distinctive patterns in the populations of these mineral grains,' Kirkland told CNN in an email. 'In essence the 'DNA' fingerprint of these sedimentary rocks changed.' The findings appear to bolster the notion of active glaciation 'somewhat,' said Dr. Graham Shields, a professor of geology at University College London. Shields was not involved in the new research. However, the study did not include data from a significant glacial interval called the Marinoan, which marked the end of Snowball Earth, he told CNN in an email. Shields was also cautious about directly linking glacial erosion to the evolution of complex life. 'This connection has been proposed before but it is controversial because the linkage is assumed rather than explained,' Shields said. 'Dramatic landscape change causing the emergence of macroscopic animals is a neat idea, but the paper introduces a hypothesis about glacial erosion/weathering that can be tested, rather than settling the debate.' Mass glacier thaw transforms oceans Rocks from the time of Snowball Earth contained older minerals, but also featured a range of mineral ages, hinting that the rocks were exposed and eroded over time by the scraping movement of glaciers. This evidence told the scientists that the glaciers of the Neoproterozoic were mobile. Younger rocks, from when Snowball Earth was thawing, had a narrower range of mineral ages, and more fragile grains were absent, suggesting flowing water had dissolved material that was previously ground down. At the waning of the Neoproterozoic, one of the known changes in ocean chemistry was a rise in uranium. Other research had previously explained this increase as resulting from the rise in atmospheric oxygen, 'however, our data imply that the delivery of chemical elements into the oceans also played a role in this,' Kirkland said. 'The 'lost' dissolved component in these rocks is seen 'popping back up' in changes in ocean chemistry at this time,' he added. By mapping these changes in terrestrial and marine environments, 'we are imaging the transfer of chemical elements through the Earth as a system.' The scientists reported that major glaciation events took place at least twice between 720 million and 635 million years ago. By the end of the Neoproterozoic, as Earth's icy cover began to thaw, major chemistry shifts were taking place in Earth's atmosphere and oceans. 'The end of these glaciations is marked by rapid increases in atmospheric and oceanic oxygen, possibly due to enhanced weathering of exposed rock surfaces and increased nutrient fluxes into the ocean,' Kirkland said. Such changes could have infused nutrient cycles and provided emerging life with the boost it needed to evolve into more complex forms. 'The idea that glacial debris from Neoproterozoic ice ages provided nutrients to support early animal evolution has been around for a while,' said Dr. Andrew Knoll, a professor emeritus of Earth and planetary sciences at Harvard University, who was not involved in the new research. However, questions remain about whether the minerals poured into the ocean by Neoproterozoic glaciation would have been enough to spur long-term environmental changes with biological consequences, Knoll told CNN in an email. Other research previously suggested that the impacts of glaciation events, such as the ones described in the new study, 'might well have only transient consequences — a bolus of nutrients raising primary production and perhaps increasing oxygen levels, before relaxing back to the earlier state of the environment,' Knoll said. The new findings are 'an interesting addition to the conversation,' he added. 'But the conversation continues.' Lessons for today's climate crisis From the Neoproterozoic to the present, similar processes shape climate change, including the role played by carbon dioxide (CO2) and the behavior of feedback loops, when a process feeds into an existing aspect of Earth's climate system and intensifies it. Ancient climate evidence also illuminates what happens during climate tipping points — when a threshold is crossed, triggering large-scale changes that are often irreversible. Today, Earth is heating up rapidly rather than cooling gradually over time. It took millions of years for glaciation to overtake the planet during Earth's snowball phase, while modern warming is accelerating over mere decades, 'much faster than past natural climate shifts,' Kirkland said. However, climate change's global progress is still mapped by studying the interplay of CO2 buildup, feedback loops and tipping points, he added. 'We can see how different parts of the planet are interrelated via chemical links,' he said. 'Change one part of the system, other parts also change.'
Yahoo
26-02-2025
- Science
- Yahoo
Glaciers ‘bulldozed' snowball Earth and changed ocean chemistry, paving the way for complex life, scientists say
Sign up for CNN's Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more. More than half a billion years ago on a frigid, ice-covered Earth, glaciers stirred up ingredients for complex life by bulldozing land minerals and then depositing them in the ocean, according to a new study. Inch by inch, as massive glaciers crept over frozen land toward an ice-covered sea, they scoured the ground beneath them, gouging and scraping rocks from Earth's crust. When the glaciers eventually melted, they released a torrent of terrestrial chemicals into the ocean, researchers recently reported. Minerals swept up on land by this 'glacial broom' altered marine chemistry and infused oceans with nutrients that they say may have shaped how complex life evolved. This ancient period of deep freeze, known as the Neoproterozoic Era, or 'Snowball Earth,' lasted from about 1 billion to 543 million years ago. During that time, landmasses consolidated into a supercontinent called Rodinia and then broke apart again. Earth's earliest forms of life, such as microbes, cyanobacteria, sponges and seafloor-dwelling organisms, populated the oceans. After the end of the Neoproterozoic came the rise of more complex life, with the first appearance of marine creatures sporting armor, shells and spikes. Scientists have attributed this evolutionary boom to increased oxygen levels in Earth's atmosphere and in shallow ocean waters. And now, research published Tuesday in the journal Geology suggests the flowing of ancient glaciers may have directly shaped chemical changes in the ocean that were critical for the evolution of complex organisms. Studying Snowball Earth offers a window into our planet's past, but it also presents valuable insights into modern climate change, lead study author Dr. Chris Kirkland said. 'Our deep time geological record indicates how changing one part of Earth affects another,' he said. Right now, the dramatic warming of the planet that marks the human-fueled climate crisis is happening at breakneck speed compared with these ancient processes that took millions of years. 'This rapid pace limits Earth's ability to naturally regulate itself, underscoring the urgency of addressing anthropogenic climate change.' Glacier movement, or glaciation, is known to scrape up and ferry terrestrial sediments into oceans, lakes and rivers, forming the basis of aquatic food webs. However, researchers who study ancient Earth were previously uncertain whether Neoproterozoic glaciers moved at all, let alone enough to erode the ground beneath them and transfer minerals into the sea. 'It had been hypothesized that widespread glacial erosion of continental interiors could be caused by the Snowball Earth ice,' said Kirkland, a professor in the School of Earth and Planetary Sciences at Curtin University in Perth, Australia. 'However, aspects of this idea were not clear because that ice may not have moved or moved only slightly or indeed even flowed.' Kirkland and his colleagues found answers in Scotland and Northern Ireland, where they studied sediments from rock formations dating to the Neoproterozoic. The team looked at zircons — crystallized minerals that are exceptionally durable and can weather extreme geological events. Zircons also contain uranium; by measuring the stages of uranium's decay in zircons, geologists use the minerals as chronometers for studying Earth's past. The researchers examined sediments dating to the time when Earth was covered with ice, and from the 'hothouse Earth' period millions of years later when the ice was gone, and found the mineral composition of Snowball Earth sediments differed dramatically from that of later sediments. 'We recovered distinctive patterns in the populations of these mineral grains,' Kirkland told CNN in an email. 'In essence the 'DNA' fingerprint of these sedimentary rocks changed.' The findings appear to bolster the notion of active glaciation 'somewhat,' said Dr. Graham Shields, a professor of geology at University College London. Shields was not involved in the new research. However, the study did not include data from a significant glacial interval called the Marinoan, which marked the end of Snowball Earth, he told CNN in an email. Shields was also cautious about directly linking glacial erosion to the evolution of complex life. 'This connection has been proposed before but it is controversial because the linkage is assumed rather than explained,' Shields said. 'Dramatic landscape change causing the emergence of macroscopic animals is a neat idea, but the paper introduces a hypothesis about glacial erosion/weathering that can be tested, rather than settling the debate.' Rocks from the time of Snowball Earth contained older minerals, but also featured a range of mineral ages, hinting that the rocks were exposed and eroded over time by the scraping movement of glaciers. This evidence told the scientists that the glaciers of the Neoproterozoic were mobile. Younger rocks, from when Snowball Earth was thawing, had a narrower range of mineral ages, and more fragile grains were absent, suggesting flowing water had dissolved material that was previously ground down. At the waning of the Neoproterozoic, one of the known changes in ocean chemistry was a rise in uranium. Other research had previously explained this increase as resulting from the rise in atmospheric oxygen, 'however, our data imply that the delivery of chemical elements into the oceans also played a role in this,' Kirkland said. 'The 'lost' dissolved component in these rocks is seen 'popping back up' in changes in ocean chemistry at this time,' he added. By mapping these changes in terrestrial and marine environments, 'we are imaging the transfer of chemical elements through the Earth as a system.' The scientists reported that major glaciation events took place at least twice between 720 million and 635 million years ago. By the end of the Neoproterozoic, as Earth's icy cover began to thaw, major chemistry shifts were taking place in Earth's atmosphere and oceans. 'The end of these glaciations is marked by rapid increases in atmospheric and oceanic oxygen, possibly due to enhanced weathering of exposed rock surfaces and increased nutrient fluxes into the ocean,' Kirkland said. Such changes could have infused nutrient cycles and provided emerging life with the boost it needed to evolve into more complex forms. 'The idea that glacial debris from Neoproterozoic ice ages provided nutrients to support early animal evolution has been around for a while,' said Dr. Andrew Knoll, a professor emeritus of Earth and planetary sciences at Harvard University, who was not involved in the new research. However, questions remain about whether the minerals poured into the ocean by Neoproterozoic glaciation would have been enough to spur long-term environmental changes with biological consequences, Knoll told CNN in an email. Other research previously suggested that the impacts of glaciation events, such as the ones described in the new study, 'might well have only transient consequences — a bolus of nutrients raising primary production and perhaps increasing oxygen levels, before relaxing back to the earlier state of the environment,' Knoll said. The new findings are 'an interesting addition to the conversation,' he added. 'But the conversation continues.' From the Neoproterozoic to the present, similar processes shape climate change, including the role played by carbon dioxide (CO2) and the behavior of feedback loops, when a process feeds into an existing aspect of Earth's climate system and intensifies it. Ancient climate evidence also illuminates what happens during climate tipping points — when a threshold is crossed, triggering large-scale changes that are often irreversible. Today, Earth is heating up rapidly rather than cooling gradually over time. It took millions of years for glaciation to overtake the planet during Earth's snowball phase, while modern warming is accelerating over mere decades, 'much faster than past natural climate shifts,' Kirkland said. However, climate change's global progress is still mapped by studying the interplay of CO2 buildup, feedback loops and tipping points, he added. 'We can see how different parts of the planet are interrelated via chemical links,' he said. 'Change one part of the system, other parts also change.' Mindy Weisberger is a science writer and media producer whose work has appeared in Live Science, Scientific American and How It Works magazine.
CNN
26-02-2025
- Science
- CNN
Ancient glaciers reshaped Earth's surface, fueling the rise of complex life on Earth, scientists say
More than half a billion years ago on a frigid, ice-covered Earth, glaciers stirred up ingredients for complex life by bulldozing land minerals and then depositing them in the ocean, according to a new study. Inch by inch, as massive glaciers crept over frozen land toward an ice-covered sea, they scoured the ground beneath them, gouging and scraping rocks from Earth's crust. When the glaciers eventually melted, they released a torrent of terrestrial chemicals into the ocean, researchers recently reported. Minerals swept up on land by this 'glacial broom' altered marine chemistry and infused oceans with nutrients that they say may have shaped how complex life evolved. This ancient period of deep freeze, known as the Neoproterozoic Era, or 'Snowball Earth,' lasted from about 1 billion to 543 million years ago. During that time, landmasses consolidated into a supercontinent called Rodinia and then broke apart again. Earth's earliest forms of life, such as microbes, cyanobacteria, sponges and seafloor-dwelling organisms, populated the oceans. After the end of the Neoproterozoic came the rise of more complex life, with the first appearance of marine creatures sporting armor, shells and spikes. Scientists have attributed this evolutionary boom to increased oxygen levels in Earth's atmosphere and in shallow ocean waters. And now, research published Tuesday in the journal Geology suggests the flowing of ancient glaciers may have directly shaped chemical changes in the ocean that were critical for the evolution of complex organisms. Studying Snowball Earth offers a window into our planet's past, but it also presents valuable insights into modern climate change, lead study author Dr. Chris Kirkland said. 'Our deep time geological record indicates how changing one part of Earth affects another,' he said. Right now, the dramatic warming of the planet that marks the human-fueled climate crisis is happening at breakneck speed compared with these ancient processes that took millions of years. 'This rapid pace limits Earth's ability to naturally regulate itself, underscoring the urgency of addressing anthropogenic climate change.' From snowball Earth to hothouse planet Glacier movement, or glaciation, is known to scrape up and ferry terrestrial sediments into oceans, lakes and rivers, forming the basis of aquatic food webs. However, researchers who study ancient Earth were previously uncertain whether Neoproterozoic glaciers moved at all, let alone enough to erode the ground beneath them and transfer minerals into the sea. 'It had been hypothesized that widespread glacial erosion of continental interiors could be caused by the Snowball Earth ice,' said Kirkland, a professor in the School of Earth and Planetary Sciences at Curtin University in Perth, Australia. 'However, aspects of this idea were not clear because that ice may not have moved or moved only slightly or indeed even flowed.' Kirkland and his colleagues found answers in Scotland and Northern Ireland, where they studied sediments from rock formations dating to the Neoproterozoic. The team looked at zircons — crystallized minerals that are exceptionally durable and can weather extreme geological events. Zircons also contain uranium; by measuring the stages of uranium's decay in zircons, geologists use the minerals as chronometers for studying Earth's past. The researchers examined sediments dating to the time when Earth was covered with ice, and from the 'hothouse Earth' period millions of years later when the ice was gone, and found the mineral composition of Snowball Earth sediments differed dramatically from that of later sediments. 'We recovered distinctive patterns in the populations of these mineral grains,' Kirkland told CNN in an email. 'In essence the 'DNA' fingerprint of these sedimentary rocks changed.' The findings appear to bolster the notion of active glaciation 'somewhat,' said Dr. Graham Shields, a professor of geology at University College London. Shields was not involved in the new research. However, the study did not include data from a significant glacial interval called the Marinoan, which marked the end of Snowball Earth, he told CNN in an email. Shields was also cautious about directly linking glacial erosion to the evolution of complex life. 'This connection has been proposed before but it is controversial because the linkage is assumed rather than explained,' Shields said. 'Dramatic landscape change causing the emergence of macroscopic animals is a neat idea, but the paper introduces a hypothesis about glacial erosion/weathering that can be tested, rather than settling the debate.' Mass glacier thaw transforms oceans Rocks from the time of Snowball Earth contained older minerals, but also featured a range of mineral ages, hinting that the rocks were exposed and eroded over time by the scraping movement of glaciers. This evidence told the scientists that the glaciers of the Neoproterozoic were mobile. Younger rocks, from when Snowball Earth was thawing, had a narrower range of mineral ages, and more fragile grains were absent, suggesting flowing water had dissolved material that was previously ground down. At the waning of the Neoproterozoic, one of the known changes in ocean chemistry was a rise in uranium. Other research had previously explained this increase as resulting from the rise in atmospheric oxygen, 'however, our data imply that the delivery of chemical elements into the oceans also played a role in this,' Kirkland said. 'The 'lost' dissolved component in these rocks is seen 'popping back up' in changes in ocean chemistry at this time,' he added. By mapping these changes in terrestrial and marine environments, 'we are imaging the transfer of chemical elements through the Earth as a system.' The scientists reported that major glaciation events took place at least twice between 720 million and 635 million years ago. By the end of the Neoproterozoic, as Earth's icy cover began to thaw, major chemistry shifts were taking place in Earth's atmosphere and oceans. 'The end of these glaciations is marked by rapid increases in atmospheric and oceanic oxygen, possibly due to enhanced weathering of exposed rock surfaces and increased nutrient fluxes into the ocean,' Kirkland said. Such changes could have infused nutrient cycles and provided emerging life with the boost it needed to evolve into more complex forms. 'The idea that glacial debris from Neoproterozoic ice ages provided nutrients to support early animal evolution has been around for a while,' said Dr. Andrew Knoll, a professor emeritus of Earth and planetary sciences at Harvard University, who was not involved in the new research. However, questions remain about whether the minerals poured into the ocean by Neoproterozoic glaciation would have been enough to spur long-term environmental changes with biological consequences, Knoll told CNN in an email. Other research previously suggested that the impacts of glaciation events, such as the ones described in the new study, 'might well have only transient consequences — a bolus of nutrients raising primary production and perhaps increasing oxygen levels, before relaxing back to the earlier state of the environment,' Knoll said. The new findings are 'an interesting addition to the conversation,' he added. 'But the conversation continues.' Lessons for today's climate crisis From the Neoproterozoic to the present, similar processes shape climate change, including the role played by carbon dioxide (CO2) and the behavior of feedback loops, when a process feeds into an existing aspect of Earth's climate system and intensifies it. Ancient climate evidence also illuminates what happens during climate tipping points — when a threshold is crossed, triggering large-scale changes that are often irreversible. Today, Earth is heating up rapidly rather than cooling gradually over time. It took millions of years for glaciation to overtake the planet during Earth's snowball phase, while modern warming is accelerating over mere decades, 'much faster than past natural climate shifts,' Kirkland said. However, climate change's global progress is still mapped by studying the interplay of CO2 buildup, feedback loops and tipping points, he added. 'We can see how different parts of the planet are interrelated via chemical links,' he said. 'Change one part of the system, other parts also change.'
