̽��ֱ�� of Cambridge - Antarctic

Thriving Antarctic ecosystems found following iceberg calving

Anonymous — Tue, 25 Mar 2025 10:22:45 +0000

An international team of scientists have uncovered a thriving underwater ecosystem off the coast of Antarctica that had never before been accessible to humans.

̽��ֱ��team, including researchers from the ̽��ֱ�� of Cambridge, were working in the Bellingshausen Sea off the coast of Antarctica when a massive iceberg broke away from the George VI Ice Shelf in January of this year.

̽��ֱ��team, on board Schmidt Ocean Institute’s R/V Falkor (too), changed their plans and reached the newly exposed seafloor 12 days later, becoming the first to investigate the area.

Their expedition was the first detailed study of the geology, physical oceanography, and biology beneath such a large area once covered by a floating ice shelf. ̽��ֱ��A-84 iceberg was approximately 510 square kilometres (209 square miles) in size, and revealed an equivalent area of seafloor when it broke away from the ice shelf.

"We seized upon the moment, changed our expedition plan, and went for it so we could look at what was happening in the depths below," said expedition co-chief scientist Dr Patricia Esquete from the ̽��ֱ�� of Aveiro, Portugal. "We didn't expect to find such a beautiful, thriving ecosystem. Based on the size of the animals, the communities we observed have been there for decades, maybe even hundreds of years.”

Using Schmidt Ocean Institute’s remotely operated vehicle, ROV SuBastian, the team observed the deep seafloor for eight days and found flourishing ecosystems at depths as great as 1300 meters.

Their observations include large corals and sponges supporting an array of animal life, including icefish, giant sea spiders, and octopus. ̽��ֱ��discovery offers new insights into how ecosystems function beneath floating sections of the Antarctic ice sheet.

Little is known about what lies beneath Antarctica’s floating ice shelves. In 2021, British Antarctic Survey researchers first reported signs of bottom-dwelling life beneath the Filchner-Ronne ice shelf in the Southern Weddell Sea. ̽��ֱ��current expedition was the first to use an ROV to explore this remote environment.

̽��ֱ��team was surprised by the significant biomass and biodiversity of the ecosystems and suspect they have discovered several new species.

Deep-sea ecosystems typically rely on nutrients from the surface slowly raining down to the seafloor. For centuries, the ecosystems under the ice shelf have been covered by ice almost 150 metres thick, completely cutting them off from surface nutrients. " ̽��ֱ��fact that we found long-living species suggests that the lateral transport, which mostly consists of glacial meltwater from the ice shelf, could be the source of the nutrients to sustain the life we found," said team member Dr Laura Cimoli, from Cambridge’s Department of Applied Mathematics and Theoretical Physics.

̽��ֱ��newly exposed Antarctic seafloor also allowed the team, with scientists from Portugal, the United Kingdom, Chile, Germany, Norway, New Zealand, and the United States, to gather critical data on the past behaviour of the larger Antarctic ice sheet. ̽��ֱ��ice sheet has been shrinking and losing mass over the last few decades due to climate change.

“ ̽��ֱ��ice loss from the Antarctic Ice Sheet is a major contributor to sea level rise worldwide,” said expedition co-chief scientist Sasha Montelli of ̽��ֱ�� College London (UCL). “Our work is critical for providing longer-term context of these recent changes, improving our ability to make projections of future change — projections that can inform actionable policies. We will undoubtedly make new discoveries as we continue to analyse this data.”

“We were thrilled by the opportunity to explore the newly exposed seafloor,” said team member Dr Svetlana Radionovskaya from Cambridge’s Department of Earth Sciences. “ ̽��ֱ��research will provide key insights into ice sheet dynamics, oceanography and sub-ice shelf ecosystems. At a time when the West Antarctic Ice Sheet is melting at an alarming rate, understanding these dynamics and their impacts is crucial.”

photo1_fkt250110-20250117-gliderdeploymentzodiac-ingle-2717.jpg

̽��ֱ��oceanography team, led by Cimoli in collaboration with the ̽��ֱ�� of East Anglia and the British Antarctic Survey, used autonomous underwater vehicles to characterise the ocean circulation of the region and study the impacts of glacial meltwater on the physical and chemical seawater properties. "Antarctica and the Southern Ocean are a nexus point for ocean circulation, so changes that happen around Antarctica can affect global ocean circulation and global climate," said Cimoli.

̽��ֱ��researchers are also investigating how the iceberg calving event has contributed to mix the upper ocean, not just in the recently exposed area, but also further downstream as the iceberg floats away. As the giant iceberg drifts, it can generate turbulence that mixes water properties and could potentially mix the deep nutrient-rich water with the surface waters, fuelling biological productivity.

̽��ֱ��expedition was part of Challenger 150, a global cooperative focused on deep-sea biological research and endorsed by the Intergovernmental Oceanographic Commission of UNESCO (IOC/UNESCO) as an Ocean Decade Action.

“ ̽��ֱ��science team was originally in this remote region to study the seafloor and ecosystem at the interface between ice and sea,” said Schmidt Ocean Institute Executive Director, Dr Jyotika Virmani. “Being right there when this iceberg calved from the ice shelf presented a rare scientific opportunity. Serendipitous moments are part of the excitement of research at sea – they offer the chance to be the first to witness the untouched beauty of our world.”

Svetlana Radionovskaya is a Junior Research Fellow at Queens’ College, Cambridge. Laura Cimoli is a Research Fellow at the Institute of Computing for Climate Science, Department of Applied Mathematics and Theoretical Physics at the ̽��ֱ�� of Cambridge.

Adapted from a media release by the Schmidt Ocean Institute.

Inset image: Dr Cimoli (right) and Dr Meyer (UEA, left) prepare an underwater glider for deployment. Credit: Alex Ingle/Schmidt Ocean Institute.

Scientists explore a seafloor area newly exposed by iceberg A-84; discover vibrant communities of ancient sponges and corals.

ROV SuBastian / Schmidt Ocean Institute

Deep-sea coral at a depth of 1200 metres

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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Historic fires trapped in Antarctic ice yield key information for climate models

cmm201 — Fri, 09 Aug 2024 15:25:07 +0000

Researchers from the ̽��ֱ�� of Cambridge and the British Antarctic Survey tracked fire activity over the past 150 years by measuring carbon monoxide trapped in Antarctic ice. This gas is released, along with smoke and particulates, by wildfires, cooking and communal fires.

̽��ֱ��findings, reported in the Proceedings of the National Academy of Sciences, reveal that biomass burning has been more variable since the 1800s than had been thought. ̽��ֱ��new data could help improve climate models, which rely on information about past atmospheric gases, such as carbon monoxide, to improve their forecasts.

“We’ve been missing key information from the period when humans started to dramatically alter Earth’s climate; information needed to test and develop climate models,” said Rachael Rhodes, senior author of the paper from Cambridge’s Department of Earth Sciences.

̽��ֱ��new carbon monoxide record fills that gap in time. ̽��ֱ��researchers charted the strength of biomass burning between 1821 and 1995 by measuring carbon monoxide in ice cores from Antarctica. ̽��ֱ��layers of ice inside these cores formed when snow was buried under subsequent years’ snowfall, encasing pockets of air that directly sample the atmosphere's composition at the time.

“It’s rare to find trace gases trapped in ice cores for the most recent decades,” said Ivo Strawson, lead author of the study who is jointly based at Cambridge Earth Sciences and the British Antarctic Survey. “We need information on the atmosphere's composition following the onset of industrialisation to reduce uncertainties in climate models, which rely on these records to test or drive their simulations.”

A major difficulty with taking gas measurements from very young ice is that pressurised air bubbles haven’t had time to form under the weight of more snow, said Strawson. To get around this problem, the researchers studied ice from locations where snow accumulates rapidly. These ice cores, held in BAS’ dedicated Ice Core Laboratory, were collected from the Antarctic Peninsula as part of previous international projects.

To measure carbon monoxide, the researchers developed a state-of-the-art analysis method, which melts ice continuously while simultaneously extracting the air. They collected tens of thousands of gas measurements for the past 150 years.

̽��ֱ��researchers found that the strength of biomass burning has dropped steadily since the 1920s. That decline, said Rhodes, coincides with the expansion and intensification of agriculture in southern Africa, South America, and Australia during the early 20th century. With wildlands converted into farmland, forest cover was restricted and in turn fire activity dropped. “This trend reflects how land conversion and human expansion have negatively impacted landscapes and ecosystems, causing a major shift in the natural fire regime and in turn altering our planet’s carbon cycle,” said Rhodes.

One assumption made by many climate models, including those used by the IPCC, is that fire activity has increased in tandem with population growth. But, said Rhodes, “our work adds to a growing mass of evidence that this assumption is wrong, and the inventories of historic fire activity need to be corrected so that models can accurately replicate the variability we see in our record.”

Rachael Rhodes is a Fellow of Wolfson College, Cambridge.

Reference:
Ivo Strawson et al. "Preindustrial Southern Hemisphere biomass burning variability inferred from ice core carbon monoxide records." Proceedings of the National Academy of Sciences(2024). DOI: https://doi.org/10.1073/pnas.2402868121

Pollutants preserved in Antarctic ice document historic fires in the Southern Hemisphere, offering a glimpse at how humans have impacted the landscape and providing data that could help scientists understand future climate change.

̽��ֱ�� of Cambridge

Rachael Rhodes

Yes

Antarctic ice shelves hold twice as much meltwater as previously thought

sc604 — Thu, 27 Jun 2024 08:56:09 +0000

Slush – water-soaked snow – makes up more than half of all meltwater on the Antarctic ice shelves during the height of summer, yet is poorly accounted for in regional climate models.

Ice shelves fracture under weight of meltwater lakes

sc604 — Fri, 03 May 2024 14:31:26 +0000

When air temperatures in Antarctica rise and glacier ice melts, water can pool on the surface of floating ice shelves, weighing them down and causing the ice to bend. Now, for the first time in the field, researchers have shown that ice shelves don’t just buckle under the weight of meltwater lakes — they fracture.

As the climate warms and melt rates in Antarctica increase, this fracturing could cause vulnerable ice shelves to collapse, allowing inland glacier ice to spill into the ocean and contribute to sea level rise.

Ice shelves are important for the Antarctic Ice Sheet’s overall health as they act to buttress or hold back the glacier ice on land. Scientists have predicted and modelled that surface meltwater loading could cause ice shelves to fracture, but no one had observed the process in the field, until now.

̽��ֱ��new study, published in the Journal of Glaciology, may help explain how the Larsen B Ice Shelf abruptly collapsed in 2002. In the months before its catastrophic breakup, thousands of meltwater lakes littered the ice shelf’s surface, which then drained over just a few weeks.

To investigate the impacts of surface meltwater on ice shelf stability, a research team led by the ̽��ֱ�� of Colorado Boulder, and including researchers from the ̽��ֱ�� of Cambridge, travelled to the George VI Ice Shelf on the Antarctic Peninsula in November 2019.

First, the team identified a depression or ‘doline’ in the ice surface that had formed by a previous lake drainage event where they thought meltwater was likely to pool again on the ice. Then, they ventured out on snowmobiles, pulling all their science equipment and safety gear behind on sleds.

Around the doline, the team installed high-precision GPS stations to measure small changes in elevation at the ice’s surface, water-pressure sensors to measure lake depth, and a timelapse camera system to capture images of the ice surface and meltwater lakes every 30 minutes.

In 2020, the COVID-19 pandemic brought their fieldwork to a screeching halt. When the team finally made it back to their field site in November 2021, only two GPS sensors and one timelapse camera remained; two other GPS and all water pressure sensors had been flooded and buried in solid ice. Fortunately, the surviving instruments captured the vertical and horizontal movement of the ice’s surface and images of the meltwater lake that formed and drained during the record-high 2019/2020 melt season.

GPS data indicated that the ice in the centre of the lake basin flexed downward about a foot in response to the increased weight from meltwater. That finding builds upon previous work that produced the first direct field measurements of ice shelf buckling caused by meltwater ponding and drainage.

̽��ֱ��team also found that the horizontal distance between the edge and centre of the meltwater lake basin increased by over a foot. This was most likely due to the formation and/or widening of circular fractures around the meltwater lake, which the timelapse imagery captured. Their results provide the first field-based evidence of ice shelf fracturing in response to a surface meltwater lake weighing down the ice.

“This is an exciting discovery,” said lead author Alison Banwell, from the Cooperative Institute for Research in Environmental Sciences (CIRES) at the ̽��ֱ�� of Colorado Boulder. “We believe these types of circular fractures were key in the chain reaction style lake drainage process that helped to break up the Larsen B Ice Shelf.”

“While these measurements were made over a small area, they demonstrate that bending and breaking of floating ice due to surface water may be more widespread than previously thought,” said co-author Dr Rebecca Dell from Cambridge’s Scott Polar Research Institute. “As melting increases in response to predicted warming, ice shelves may become more prone to break up and collapse than they are currently.”

“This has implications for sea level as the buttressing of inland ice is reduced or removed, allowing the glaciers and ice streams to flow more rapidly into the ocean,” said co-author Professor Ian Willis, also from SPRI.

̽��ֱ��work supports modelling results that show the immense weight of thousands of meltwater lakes and subsequent draining caused the Larsen B Ice Shelf to bend and break, contributing to its collapse.

“These observations are important because they can be used to improve models to better predict which Antarctic ice shelves are more vulnerable and most susceptible to collapse in the future,” Banwell said.

̽��ֱ��research was funded by the U.S. National Science Foundation (NSF) and the Natural Environment Research Council (NERC), part of UK Research and Innovation (UKRI). ̽��ֱ��team also included researchers from the ̽��ֱ�� of Oxford and the ̽��ֱ�� of Chicago. Rebecca Dell is a Fellow of Trinity Hall, Cambridge.

Reference:
Alison F Banwell et al. ‘Observed meltwater-induced flexure and fracture at a doline on George VI Ice Shelf, Antarctica.’ Journal of Glaciology (2024). DOI: 10.1017/jog.2024.31

Adapted from a CIRES press release.

Heavy pooling meltwater can fracture ice, potentially leading to ice shelf collapse

Ian Willis

Ali Banwell and Laura Stevens installing the time-lapse camera used in this study on the George VI Ice Shelf in Antarctica.

Yes

Ice cores provide first documentation of rapid Antarctic ice loss in the past

cmm201 — Thu, 08 Feb 2024 10:00:00 +0000

̽��ֱ��evidence, contained within an ice core, shows that in one location the ice sheet thinned by 450 metres — that’s more than the height of the Empire State Building — in just under 200 years.

This is the first evidence anywhere in Antarctica for such a fast loss of ice. Scientists are worried that today’s rising temperatures might destabilize parts of the West Antarctic Ice Sheet in the future, potentially passing a tipping point and inducing a runaway collapse. ̽��ֱ��study, published in Nature Geoscience, sheds light on how quickly Antarctic ice could melt if temperatures continue to soar.

“We now have direct evidence that this ice sheet suffered rapid ice loss in the past,” said Professor Eric Wolff, senior author of the new study from Cambridge’s Department of Earth Sciences. “This scenario isn’t something that exists only in our model predictions and it could happen again if parts of this ice sheet become unstable.”

From west to east, the Antarctic ice sheets contain enough freshwater to raise global sea levels by around 57 metres. ̽��ֱ��West Antarctic Ice Sheet is considered particularly vulnerable because much of it sits on bedrock below sea level.

Model predictions suggest that a large part of the West Antarctic Ice Sheet could disappear in the next few centuries, causing sea levels to rise. Exactly when and how quickly the ice could be lost is, however, uncertain.

One way to train ice sheet models to make better predictions is to feed them with data on ice loss from periods of warming in Earth’s history. At the peak of the Last Ice Age 20,000 years ago, Antarctic ice covered a larger area than today. As our planet thawed and temperatures slowly climbed, the West Antarctic Ice Sheet contracted to more or less its current extent.

“We wanted to know what happened to the West Antarctic Ice Sheet at the end of the Last Ice Age, when temperatures on Earth were rising, albeit at a slower rate than current anthropogenic warming,” said Dr Isobel Rowell, study co-author from the British Antarctic Survey. “Using ice cores we can go back to that time and estimate the ice sheet’s thickness and extent.”

Ice cores are made up of layers of ice that formed as snow fell and was then buried and compacted into ice crystals over thousands of years. Trapped within each ice layer are bubbles of ancient air and contaminants that mixed with each year’s snowfall — providing clues as to the changing climate and ice extent.

̽��ֱ��researchers drilled a 651-metre-long ice core from Skytrain Ice Rise in 2019. This mound of ice sits at the edge of the ice sheet, near the point where grounded ice flows into the floating Ronne Ice Shelf.

After transporting the ice cores to Cambridge at -20C, the researchers analysed them to reconstruct the ice thickness. First, they measured stable water isotopes, which indicate the temperature at the time the snow fell. Temperature decreases at higher altitudes (think of cold mountain air), so they could equate warmer temperatures with lower-lying, thinner ice.

They also measured the pressure of air bubbles trapped in the ice. Like temperature, air pressure also varies systematically with elevation. Lower-lying, thinner ice contains higher-pressure air bubbles.

These measurements told them that ice thinned rapidly 8,000 years ago. “Once the ice thinned, it shrunk really fast,” said Wolff, “this was clearly a tipping point — a runaway process.”

They think this thinning was probably triggered by warm water getting underneath the edge of the West Antarctic Ice Sheet, which normally sits on bedrock. This likely untethered a section of the ice from bedrock, allowing it to float suddenly and forming what is now the Ronne Ice Shelf. This allowed neighbouring Skytrain Ice Rise, no longer restrained by grounded ice, to thin rapidly.

̽��ֱ��researchers also found that the sodium content of the ice (originating from salt in sea spray) increased about 300 years after the ice thinned. This told them that, after the ice thinned, the ice shelf shrunk back so that the sea was hundreds of kilometres nearer to their site.

“We already knew from models that the ice thinned around this time, but the date of this was uncertain,” said Rowell. Ice sheet models placed the retreat anywhere between 12,000 and 5,000 years ago and couldn’t say how quickly it happened. “We now have a very precisely dated observation of that retreat that can be built into improved models,” said Rowell.

Although the West Antarctic Ice Sheet retreated quickly 8,000 years ago, it stabilised when it reached roughly its current extent. “It’s now crucial to find out whether extra warmth could destabilise the ice and cause it to start retreating again,” said Wolff.

Reference

Grieman et al. (2024) Abrupt Holocene ice loss due to thinning and ungrounding in the Weddell Sea Embayment. Nature Geoscience. DOI: 10.1038/s41561-024-01375-8

Researchers from the ̽��ֱ�� of Cambridge and the British Antarctic Survey have uncovered the first direct evidence that the West Antarctic Ice Sheet shrunk suddenly and dramatically at the end of the Last Ice Age, around 8,000 years ago.

̽��ֱ�� of Cambridge / British Antarctic Survey

Tents at Skytrain Ice Rise

Yes

Why do climate models underestimate polar warming? ‘Invisible clouds’ could be the answer

sc604 — Wed, 08 Nov 2023 16:06:47 +0000

̽��ֱ��Earth’s average surface temperature has increased drastically since the start of the Industrial Revolution, but the warming effect seen at the poles is even more exaggerated. While existing climate models consider the increased heating in the Arctic and Antarctic poles, they often underestimate the warming in these regions. This is especially true for climates millions of years ago, when greenhouse gas concentrations were very high.

This is a problem because future climate projections are generated with these same models: if they do not produce enough warming for the past, we might underestimate polar warming – and therefore the associated risks, such as ice sheet or permafrost melting – for the future.

“During my PhD, I was drawn to the fact that the climate models we are using do not represent the magnitude of warming that happens in the Arctic,” said lead author Dr Deepashree Dutta from Cambridge’s Department of Geography, who carried out the work during her PhD at UNSW. “At the same time, we knew that the majority of these models do not represent the upper layers of the atmosphere very well. And we thought this might be a missing link.”

̽��ֱ��team turned their focus to a key atmospheric element that is missing in most models — polar stratospheric clouds — and found that they can explain a large part of the missing warming in models.

Their results, published in the journal Nature Geoscience, show that there is still much to learn about the climate of the past, present and future.

Climate models are computer simulations of our global climate system that are built using our theoretical understanding of how the climate works. They can be used to recreate past conditions or predict future climate scenarios.

Climate models incorporate many factors that influence the climate, but they cannot include all real-world processes. One consequence of this is that generally, climate models simulate polar climate change that is smaller than actual observations.

“ ̽��ֱ��more detail you include in the model, the more resources they require to run,” said co-author Dr Martin Jucker from UNSW. “It’s often a toss-up between increasing the horizontal or vertical resolution of the model. And as we live down here at the surface of the earth, the detail closer to the surface is often prioritised.”

In 1992, American paleoclimatologist Dr Lisa Sloan first suggested that the extreme warming at high latitudes during past warm periods may have been caused by polar stratospheric clouds.

Polar stratospheric clouds form at very high altitudes (15-25 km above the Earth's surface), and at very low temperatures (over the poles). They are also called nacreous or mother-of-pearl clouds because of their bright and sometimes luminous hues, although they are not normally visible to the naked eye.

These polar stratospheric clouds have a similar effect on climate as greenhouse gases – they trap heat that would otherwise be lost to space and warm the surface of the Earth.

“These clouds form under complex conditions, which most climate models cannot reproduce. And we wondered if this inability to simulate these clouds may result in less surface warming at the poles than what we’ve observed in the real world,” said Dutta.

Thirty years after Sloan’s research, Dutta wanted to test this theory using one of the few atmospheric models that incorporates polar atmospheric clouds, to see if it might explain the disparities in warming between observational data and climate models.

“I wanted to test this theory by running an atmospheric model that includes all necessary processes with conditions that resembled a time period over 50 million years ago, known as the early Eocene. It was a period of Earth’s history when the planet was very hot and the Arctic was ice-free throughout the year,” said Dutta.

̽��ֱ��Eocene was also a period characterised by high methane content, and the position of continents and mountains was different to today.

“Climate models are far too cold in the polar regions, when simulating these past hot climates, and this has been an enigma for the past thirty years,” said Jucker. “ ̽��ֱ��early Eocene was a period in the Earth’s climate with extreme polar warming, so presented the perfect test for our climate models.”

̽��ֱ��team found that the elevated methane levels during the Eocene resulted in an increase in polar stratospheric cloud formation. They found that under certain conditions, the local surface warming due to stratospheric clouds was up to 7 degrees Celsius during the coldest winter months. This temperature difference significantly reduces the gap between climate models and temperature evidence from climate archives.

By comparing future simulations to simulations of the Eocene, the researchers also discovered that it isn’t just methane that was needed to produce polar stratospheric clouds. “This is another key finding of this work,” said Dutta. “It’s not just methane, but it's also the Earth’s continental arrangement, which plays an important role in forming these stratospheric clouds. Because if we input the same amount of methane for our future climate, we do not see the same increase in stratospheric clouds.”

̽��ֱ��research has provided some of the answers to questions about the climate of the deep past, but what does that mean for future projections?

“We found that stratospheric clouds account for the accelerated warming at the poles that is often left out of our climate models, and of course this could potentially mean that our future projections are also not warm enough,” said Jucker. “But the good news is that these clouds are more likely to form under the continental arrangement that was present tens of millions of years ago, and is not found on Earth now. Therefore, we don’t expect such large increases in stratospheric clouds in the future.”

This new research has not only helped to provide a piece of the puzzle as to why temperature recordings in the Arctic are always warmer than climate models – it has also provided new insights into the Earth’s past climate.

“Our study shows the value of increasing the detail of climate models, where we can,” said Dutta. “Although we already know a lot about these clouds theoretically, until we include them in our climate models, we won’t know the full scale of their impact.”

Reference:
Deepashree Dutta et al. ‘Early Eocene low orography and high methane enhance Arctic warming via polar stratospheric clouds.’ Nature Geoscience (2023). DOI: 10.1038/s41561-023-01298-w

Adapted from a UNSW press release.

Stratospheric clouds over the Arctic may explain the differences seen between the polar warming calculated by climate models and actual recordings, according to researchers from the ̽��ֱ�� of Cambridge and UNSW Sydney.

Our study shows the value of increasing the detail of climate models where we can

Deepashree Dutta

Cavan Images / Per-Andre Hoffmann via Getty Images

Mother of pearl clouds (nacreous clouds), Polar Stratospheric Clouds.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

Medieval monks accidentally recorded some of history’s biggest volcanic eruptions

sc604 — Wed, 05 Apr 2023 14:58:42 +0000

An international team, including researchers from the ̽��ֱ�� of Cambridge, drew on readings of medieval texts, along with ice core and tree ring data, to accurately date some of the biggest volcanic eruptions the world has ever seen. Their results, reported in the journal Nature, uncover new information about one of the most volcanically active periods in Earth’s history, which some think helped to trigger the Little Ice Age, a long interval of cooling that saw the advance of European glaciers.

It took the researchers, led by the ̽��ֱ�� of Geneva (UNIGE), almost five years to examine hundreds of annals and chronicles from across Europe and the Middle East, in search of references to total lunar eclipses and their colouration.

Total lunar eclipses occur when the moon passes into the Earth’s shadow. Typically, the moon remains visible as a reddish orb because it is still bathed in sunlight bent round the Earth by its atmosphere. But after a very large volcanic eruption, there can be so much dust in the stratosphere – the middle part of the atmosphere starting roughly where commercial aircraft fly – that the eclipsed moon almost disappears.

Medieval chroniclers recorded and described all kinds of historical events, including the deeds of kings and popes, important battles, and natural disasters and famines. Just as noteworthy were the celestial phenomena that, to the chroniclers, might foretell such calamities. Mindful of the Book of Revelation, a vision of the end times that speaks of a blood-red moon, the monks were especially careful to take note of the moon’s colouration.

Of the 64 total lunar eclipses that occurred in Europe between 1100 and 1300, the chroniclers had faithfully documented 51. In five of these cases, they also reported that the moon was exceptionally dark.

Asked what made him connect the monks’ records of the brightness and colour of the eclipsed moon with volcanic gloom, the lead author of the work, UNIGE’s Sébastien Guillet said: “I was listening to Pink Floyd's Dark Side of the Moon album when I realised that the darkest lunar eclipses all occurred within a year or so of major volcanic eruptions. Since we know the exact days of the eclipses, it opened the possibility of using the sightings to narrow down when the eruptions must have happened.”

̽��ֱ��researchers found that scribes in Japan took equal note of lunar eclipses. One of the best known, Fujiwara no Teika, wrote of an unprecedented dark eclipse observed on 2 December 1229: ‘the old folk had never seen it like this time, with the location of the disk of the Moon not visible, just as if it had disappeared during the eclipse... It was truly something to fear.’

̽��ֱ��stratospheric dust from large volcanic eruptions was not only responsible for the vanishing moon. It also cooled summer temperatures by limiting the sunlight reaching the Earth’s surface. This in turn could bring ruin to agricultural crops.

“We know from previous work that strong tropical eruptions can induce global cooling on the order of roughly 1°C over a few years,” said Markus Stoffel from the ̽��ֱ�� of Geneva, a specialist in converting measurements of tree rings into climate data, who co-designed the study. “They can also lead to rainfall anomalies with droughts in one place and floods in another.”

Despite these effects, people at the time could not have imagined that the poor harvests or the unusual lunar eclipses had anything to do with volcanoes – the eruptions themselves were all but one undocumented.

“We only knew about these eruptions because they left traces in the ice of Antarctica and Greenland,” said co-author Professor Clive Oppenheimer from Cambridge’s Department of Geography. “By putting together the information from ice cores and the descriptions from medieval texts we can now make better estimates of when and where some of the biggest eruptions of this period occurred.”

To make the most of this integration, Guillet worked with climate modellers to compute the most likely timing of the eruptions. “Knowing the season when the volcanoes erupted is essential, as it influences the spread of the volcanic dust and the cooling and other climate anomalies associated with these eruptions,” he said.

As well as helping to narrow down the timing and intensity of these events, what makes the findings significant is that the interval from 1100 to 1300 is known from ice core evidence to be one of the most volcanically active periods in history. Of the 15 eruptions considered in the new study, one in the mid-13th century rivals the famous 1815 eruption of Tambora that brought on ‘the year without a summer’ of 1816. ̽��ֱ��collective effect of the medieval eruptions on Earth’s climate may have led to the Little Ice Age, when winter ice fairs were held on the frozen rivers of Europe.

“Improving our knowledge of these otherwise mysterious eruptions, is crucial to understanding whether and how past volcanism affected not only climate but also society during the Middle Ages,” said Guillet.

̽��ֱ��research was supported in part by the Swiss National Science Foundation.

Reference:
Sébastien Guillet et al. ‘Lunar eclipses illuminate timing and climate impact of medieval volcanism.’ Nature (2023). DOI: 10.1038/s41586-023-05751-z

By observing the night sky, medieval monks unwittingly recorded some of history’s largest volcanic eruptions, according to a new analysis of 12th and 13th century European and Middle Eastern chronicles.

Recueil de poésies françaises. Consolation de Boèce, Ms. 822, fol. 61v, Bibliothèque Municipale de Toulouse /Gallica, BnF

An illuminated manuscript from the late 14th to the early 15th century, depicting two individuals observing a lunar eclipse

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

Runaway West Antarctic ice retreat can be slowed by climate-driven changes in ocean temperature

sc604 — Mon, 16 Jan 2023 09:45:30 +0000

New research finds that ice-sheet-wide collapse in West Antarctica isn’t inevitable: the pace of ice loss varies according to regional differences in atmosphere and ocean circulation.