Latest news with #icecores
Yahoo
3 days ago
- Science
- Yahoo
New start date for the Anthropocene proposed – when humans first changed global methane levels
Humans have been reshaping the environment for at least 10,000 years. But the Anthropocene is the name given to the specific period of Earth history during which humans have had a global effect on the planet's climate and ecosystems. Despite formal rejection as a geological epoch, it's widely understood within academic research as useful shorthand for the age of human interference in the Earth system. Various dates have been proposed for when the anthropocene effectively began, from the early 17th century to the mid-20th century, when the first atomic weapons were detonated. My new research into atmospheric methane concentration supports the idea of an early date, when European arrival in the Americas first had a notable impact on the atmosphere, but slightly before previous estimates. Ice cores – cylinders of ice drilled from glaciers and ice sheets – provide important evidence of historical changes in the global atmospheric composition. It is from these records that a date for the Anthropocene's pre-industrial beginnings was first proposed in 2015 by two Earth systems scientists at the University College London, Simon Lewis and Mark Maslin. They suggested that an unprecedented drop in the level of CO₂ in the atmosphere that was recorded in ice cores – known as the 'Orbis spike' – dates back to 1610. This unusually low level reflects additional atmospheric CO₂ absorption into trees from forest regrowth in the Americas following European arrival in the late 1400s. Get your news from actual experts, straight to your inbox. Sign up to our daily newsletter to receive all The Conversation UK's latest coverage of news and research, from politics and business to the arts and sciences. From European arrival in 1492 and colonisation in the 1500s, the introduction of disease, mostly smallpox, resulted in demographic collapse of around 50 million people across the Americas. Lewis and Maslin proposed that, as millions of hectares of farmland went untended, forests could regrow and this increased CO₂ removal from the atmosphere. This happened in sufficient quantities to be recorded in glacial ice. And that change became a global marker for the start of the so-called Anthropocene. Read more: My own research into changing methane concentrations indicates that the Anthropocene began slightly earlier than that, in 1592. Ice core records show a minimum atmospheric methane concentration exactly 100 years after explorer Christopher Columbus first set foot in the Americas. This, I believe, strengthens support for the hypothesis put forward by Lewis and Maslin a decade ago. In a paper published in Nature Reviews, Earth and Environment, I consider the effects of global fluctuations in how trees and forests exchange methane. Methane is a greenhouse gas that is around 80 times more powerful than carbon dioxide over a 20-year period. Crucially, methane has a short lifetime of just under ten years, so any ice core record will be far more responsive to changes to the methane cycle than that of longer-lived CO₂. Read more: So what's the link to trees? Trees and their woody bark surfaces, despite their biologically inert appearance when compared to leaves, are important interfaces of methane exchange. In swamps and forested floodplains like the Amazon, they are exit points of methane to the atmosphere from the saturated soils where the methane is formed by anaerobic soil microbes. However, last year, my team uncovered how the more extensive areas of forest growing on free-draining soils interact with atmospheric methane. The trees host microbes that directly remove methane from the atmosphere. This is one of two mechanisms that, together, might explain an unprecedented drop in atmospheric methane concentrations recorded in Antarctic ice cores in the first century following European arrival in the Americas. This would support Lewis and Maslin's idea that regrowing forests in that period had global effects. With more trees growing on abandoned farmland, there was more woody tree surface area in contact with the atmosphere. This meant more methane being taken up by the microbes they host. The second mechanism relates to how trees intercept incoming rainfall. Some rainfall is re-evaporated before reaching the soil. Any rain reaching the soil may then be taken up by tree roots and released back to the atmosphere. The rest moves into the soil or washes off into rivers and wetlands. It is possible that the spike in forest regrowth led to more evaporation and transpiration. So more water was released by the trees back to the atmosphere and less washed off over the soil surface. This limited water flowing into wetlands. Those wetlands are a major methane source. So a small shrinkage in wetland area, combined with more trees absorbing atmospheric methane, could have reduced the atmospheric methane concentration and explain the minimum methane levels observed in 1592. When exactly the Anthropocene began may be an argument that has been overtaken by the decision to not label it a new epoch. Indeed, it's possible that forest clearance for early agriculture by humans around 5,000-8,000 years ago in the mid-Holocene, (a period of relative climate stability in the Neolithic period) contributed to the atmospheric methane increase observed in Antarctic ice from that time. As well as an ancient trace of human influence over our forests, the ice core methane records provide a chance to evaluate newly discovered processes operating in the world's forests. This is something I'm now investigating with my colleague Peter Hopcroft, a palaeoclimate modeller at the University of Birmingham. Whether through forest clearances for early agriculture or through the effects on forests of massive depopulation of Indigenous peoples following European contact, these traces of our past influence point to something significant: that there has always been an intimate and evolving connection between humanity and the natural world. A connection so fundamental that, for the vast span of our existence as a species, we have been inseparable from nature itself. Get a weekly roundup in your inbox instead. Every Wednesday, The Conversation's environment editor writes Imagine, a short email that goes a little deeper into just one climate issue. Join the 45,000+ readers who've subscribed so far. This article is republished from The Conversation under a Creative Commons license. Read the original article. Vincent Gauci receives funding from or has received funding from the Natural Environment Research Council, The Royal Society, Spark Climate Solutions, AXA Research Fund, Defra and the JABBS Foundation.
Yahoo
31-05-2025
- Politics
- Yahoo
‘Like touching climate change': glaciers reveal records of the way the world was
Howling wind relentlessly shakes the white tent, pitched among mounds of snow at a height of 4,100m (13,450ft) on the Corbassière, an Alpine glacier situated on the northern slopes of Switzerland's Grand Combin massif. Inside are scientists from Venice's Ca' Foscari University and the institute of polar science at Italy's national research council (CNR). They are camping here for 12 days, braving harsh conditions in freezing temperatures as low as -20C (-4F) as they work day and night to operate machinery that is drilling deep into the rapidly melting glacier. Their mission is to salvage the Corbassière's remaining ice and unlock the precious trove of knowledge it holds about past climates before global heating completely wipes the glacier out. The scientists do this by drilling a borehole and extracting long, cylinder-shaped ice cores. These are essentially centuries-old libraries containing records of preindustrial greenhouse gases, pollutants, pollen and bacteria that provide information about historic temperatures and the impact humans have had on the changing environment. The deeper they manage to drill, the greater the potential for older ice and its rich archive to emerge. An expedition on the Grenz glacier on Monte Rosa in 2021 yielded ice cores containing climate information dating back over the last 10,000 years, including pollutants from the Roman era. 'A glacier is like a book made up of many pages,' said Jacopo Gabrieli, a glaciologist at CNR. 'The pages are layers of ice, with the first few already unreadable because of the melt. It's like throwing a glass of water on an old manuscript and watching the ink quickly disappear. We know the deepest layers are still readable because it is cold enough. But it is an absolute race against time.' The Corbassière drilling expedition is the first of three planned by Follow the Ice, a scientific and educational project supported by Sea Beyond, an initiative led by the Prada Group. A week into the expedition, the team of 13, which includes mountain guides, a videographer and a nurse who doubles as a cook, welcomed a small group of journalists who were brought to base-camp by helicopter. The team extracted two ice cores from the glacier, although they won't know the secrets they hold until analysis is done. Along with greenhouse gases, previous glacier drills have enabled scientists to study cores for the DNA of ancient viruses that could resurface amid global heating, along with frozen insects and plants that could give insight into the history of forests and their ecosystems. The mission on the Corbassière, backed by the Ice Memory, a nonprofit organisation aimed at preserving and analysing ice cores from the world's most at-risk glaciers, is incredibly daring. For the first few days, the squad had to adapt to the altitude, many struggling to breathe or suffering headaches and nausea. Sleep has been scant, with hours spent clearing snow out of tents and away from pathways. Unexpected changes in weather have stalled progress, as did the sudden breakage of a cable powering the drill. Victor Zagorodnov, a scientist who, at 75, is the oldest on the team, said: 'Constant signs of danger play with your mind, but you have to resist.' Related: Almost 40% of world's glaciers already doomed due to climate crisis – study Zagorodnov has been leading drilling expeditions on glaciers around the world since the 1980s. 'The first time was in Bolivia,' he said. 'The mind is telling you it's dangerous, and to leave. It causes nightmares. But you persevere.' Zagorodnov, who is also a glacier-drilling technology specialist, compared the experience to 'learning to ride a bike'. 'You get used to it,' he said. 'Plus, when I first started the equipment was basic, today it is much more advanced.' Gabrieli is more than used to witnessing the evidence of the climate crisis on glaciers. In 2020, during test drilling on the Corbassière, water was found at a 30m (98ft) depth. 'We put our hands in the water,' he said. 'It was like touching climate change.' Another thing that dismayed him during that visit was rain. 'I didn't think it was possible to have precipitation at this altitude,' he added. 'It was only a small amount of rain but it was really depressing.' The experience made the team realise even more that they needed to act quickly, and so returned to finish the work. This time, the team came equipped with the more advanced electro-thermal drill, a device that penetrates glacier ice through melting. The thermal drill had reached about seven metres deep when a burning stench overwhelmed the scientists. 'We thought something was wrong with the drill but then realised it had hit a plastic bag,' said Carlo Barbante, a professor at Ca' Foscari who co-founded the Ice Memory Foundation. 'It must have been left there by climbers years ago, and really proved the impact of human activity on the climate. Plastic is everywhere, pollution is everywhere. It is very disappointing.' After six days, the drill successfully reached a depth of 55m (180ft). But then the power cable breakage forced the team to revert to using an electromechanical drill. Still, the device helped them to finish the job, and by day nine they were euphoric after making a major breakthrough: the drill hit 'bedrock' – the solid rock lying beneath the glacier – at a depth of 99.5m (326ft). The first of the two ice cores was extracted and transported down the mountain, and the second followed a week later. The ice cores will be dated and the plan is for one to be analysed in Italy, while the other will be shipped to Antarctica, where a cave is being excavated to store ice extracted through glacier drills, providing a library of information for future climate scientists. Apart from Europe, the Ice Memory foundation has so far drilled on glaciers in Bolivia and Russia. The missions are costly and intense, but crucial, said Barbante. 'Glaciers, especially in non-polar regions, are very much at the forefront of global warming,' said Barbante. 'They are water reservoirs for millions of people, so if the ice completely disappears there will be huge problems. We are are witnessing what is happening and it must be documented so we can leave something for future scientists. This is our duty.'
The Guardian
31-05-2025
- Politics
- The Guardian
‘Like touching climate change': glaciers reveal records of the way the world was
Howling wind relentlessly shakes the white tent, pitched among mounds of snow at a height of 4,100m (13,450ft) on the Corbassière, an Alpine glacier situated on the northern slopes of Switzerland's Grand Combin massif. Inside are scientists from Venice's Ca' Foscari University and the institute of polar science at Italy's national research council (CNR). They are camping here for 12 days, braving harsh conditions in freezing temperatures as low as -20C (-4F) as they work day and night to operate machinery that is drilling deep into the rapidly melting glacier. Their mission is to salvage the Corbassière's remaining ice and unlock the precious trove of knowledge it holds about past climates before global heating completely wipes the glacier out. The scientists do this by drilling a borehole and extracting long, cylinder-shaped ice cores. These are essentially centuries-old libraries containing records of preindustrial greenhouse gases, pollutants, pollen and bacteria that provide information about historic temperatures and the impact humans have had on the changing environment. The deeper they manage to drill, the greater the potential for older ice and its rich archive to emerge. An expedition on the Grenz glacier on Monte Rosa in 2021 yielded ice cores containing climate information dating back over the last 10,000 years, including pollutants from the Roman era. 'A glacier is like a book made up of many pages,' said Jacopo Gabrieli, a glaciologist at CNR. 'The pages are layers of ice, with the first few already unreadable because of the melt. It's like throwing a glass of water on an old manuscript and watching the ink quickly disappear. We know the deepest layers are still readable because it is cold enough. But it is an absolute race against time.' The Corbassière drilling expedition is the first of three planned by Follow the Ice, a scientific and educational project supported by Sea Beyond, an initiative led by the Prada Group. A week into the expedition, the team of 13, which includes mountain guides, a videographer and a nurse who doubles as a cook, welcomed a small group of journalists who were brought to base-camp by helicopter. The team extracted two ice cores from the glacier, although they won't know the secrets they hold until analysis is done. Along with greenhouse gases, previous glacier drills have enabled scientists to study cores for the DNA of ancient viruses that could resurface amid global heating, along with frozen insects and plants that could give insight into the history of forests and their ecosystems. The mission on the Corbassière, backed by the Ice Memory, a nonprofit organisation aimed at preserving and analysing ice cores from the world's most at-risk glaciers, is incredibly daring. For the first few days, the squad had to adapt to the altitude, many struggling to breathe or suffering headaches and nausea. Sleep has been scant, with hours spent clearing snow out of tents and away from pathways. Unexpected changes in weather have stalled progress, as did the sudden breakage of a cable powering the drill. Victor Zagorodnov, a scientist who, at 75, is the oldest on the team, said: 'Constant signs of danger play with your mind, but you have to resist.' Zagorodnov has been leading drilling expeditions on glaciers around the world since the 1980s. 'The first time was in Bolivia,' he said. 'The mind is telling you it's dangerous, and to leave. It causes nightmares. But you persevere.' Zagorodnov, who is also a glacier-drilling technology specialist, compared the experience to 'learning to ride a bike'. 'You get used to it,' he said. 'Plus, when I first started the equipment was basic, today it is much more advanced.' Gabrieli is more than used to witnessing the evidence of the climate crisis on glaciers. In 2020, during test drilling on the Corbassière, water was found at a 30m (98ft) depth. 'We put our hands in the water,' he said. 'It was like touching climate change.' Another thing that dismayed him during that visit was rain. 'I didn't think it was possible to have precipitation at this altitude,' he added. 'It was only a small amount of rain but it was really depressing.' The experience made the team realise even more that they needed to act quickly, and so returned to finish the work. This time, the team came equipped with the more advanced electro-thermal drill, a device that penetrates glacier ice through melting. The thermal drill had reached about seven metres deep when a burning stench overwhelmed the scientists. 'We thought something was wrong with the drill but then realised it had hit a plastic bag,' said Carlo Barbante, a professor at Ca' Foscari who co-founded the Ice Memory Foundation. 'It must have been left there by climbers years ago, and really proved the impact of human activity on the climate. Plastic is everywhere, pollution is everywhere. It is very disappointing.' After six days, the drill successfully reached a depth of 55m (180ft). But then the power cable breakage forced the team to revert to using an electromechanical drill. Still, the device helped them to finish the job, and by day nine they were euphoric after making a major breakthrough: the drill hit 'bedrock' – the solid rock lying beneath the glacier – at a depth of 99.5m (326ft). The first of the two ice cores was extracted and transported down the mountain, and the second followed a week later. The ice cores will be dated and the plan is for one to be analysed in Italy, while the other will be shipped to Antarctica, where a cave is being excavated to store ice extracted through glacier drills, providing a library of information for future climate scientists. Apart from Europe, the Ice Memory foundation has so far drilled on glaciers in Bolivia, Russia and on Tanzania's Mount Kilimanjaro. The missions are costly and intense, but crucial, said Brabante. 'Glaciers, especially in non-polar regions, are very much at the forefront of global warming,' said Brabante. 'They are water reservoirs for millions of people, so if the ice completely disappears there will be huge problems. We are are witnessing what is happening and it must be documented so we can leave something for future scientists. This is our duty.'
