̽��ֱ�� of Cambridge - Ian Willis

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.

̽��ֱ��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.

Yes

Seasonal change in Antarctic ice sheet movement observed for first time

sc604 — Thu, 06 Oct 2022 11:40:23 +0000

Some estimates of Antarctica’s total contribution to sea-level rise may be over- or underestimated, after researchers detected a previously unknown source of ice loss variability.

Lakes on Greenland Ice Sheet can drain huge amounts of water, even in winter

sc604 — Wed, 31 Mar 2021 23:19:20 +0000

̽��ֱ��researchers, from the ̽��ֱ�� of Cambridge, used radar data from a European Space Agency satellite to show that even when the heat from the Sun is absent, these lakes can discharge large amounts of water to the base of the ice sheet. These ‘drainage events’ are thought to play a significant role in accelerating the movement of the ice by lubricating it from below.

Previous studies of draining lakes have all been carried out during the summer months, through a combination of direct field observations and optical satellite data, which requires daylight.

̽��ֱ��approach developed by the Cambridge researchers uses the radar ‘backscatter’ – the reflection of waves back to the satellite from where they were emitted – to detect changes in the lakes during the winter months, when Greenland is in near-total darkness.

̽��ֱ��results, reported in the journal ̽��ֱ��Cryosphere, imply that the ‘plumbing’ system beneath the Greenland Ice Sheet doesn’t just slowly leak water from the previous summer, but even in the depths of the Arctic winter, it can be ‘recharged’, as large amounts of surface lake water cascade to the base of the ice sheet.

Many previous studies have shown that the Greenland Ice Sheet is losing mass, and the rate of loss is accelerating, due to melting and runoff.

“One of the unknowns in terms of predicting the future of the ice sheet is how fast the glaciers move – whether they will speed up and if so, by how much,” said co-author Dr Ian Willis from Cambridge’s Scott Polar Research Institute (SPRI). “ ̽��ֱ��key control on how fast the glaciers move is the amount of meltwater getting to the bottom of the ice sheet, which is where our work comes in.”

Lakes form on the surface of the Greenland ice sheet each summer as the weather warms. They exist for weeks or months but can drain in a matter of hours due to hydrofracturing, transferring millions of cubic metres of water and heat to the base of the ice sheet. ̽��ֱ��affected areas include sensitive regions of the ice sheet interior where the impact on ice flow is potentially large.

“It’s always been thought that these lakes drained only in the summer, simply because it’s warmer and the sun causes the ice to melt,” said co-author Corinne Benedek, also from SPRI. “In the winter, it’s dark and the surfaces freeze. We thought that the filling of the lakes is what caused their eventual drainage, but it turns out that isn’t always the case.”

Benedek, who is currently a PhD candidate at SPRI, first became interested in what happens to surface lakes in the winter while she was a Master’s student studying satellite thermal data.

“ ̽��ֱ��thermal data showed me that liquid water can survive in the lakes throughout the winter,” she said. “Previous studies using airborne radar had also identified lakes buried a few metres beneath the surface of the ice sheet in the summer. Both of these things got me thinking about ways to observe lakes all year long. ̽��ֱ��optical satellite imagery we normally use to observe the lakes isn’t available in winter, or even when it’s cloudy.”

Benedek and Willis developed a method using data from the Sentinel-1 satellite, which uses a type of radar called synthetic aperture radar (SAR). SAR functions at a wavelength that makes it possible to see through clouds and in the dark. Ice and water read differently using SAR, and so they developed an algorithm that tracks when sudden changes in SAR backscatter occur.

Over three winters, they identified six lakes that appeared to drain over the winter months. These lakes were buried lakes or surface lakes that were frozen over. ̽��ֱ��algorithm was able to identify where the backscatter characteristics of the lake changed markedly between one image and the next one recorded 12 days later.

̽��ֱ��SAR data was backed up with additional optical data from the previous autumn and subsequent spring, which confirmed that lakes areas shrank considerably for the six drained lakes. For three of the lakes, the optical data, as well as data from other satellites, was used to show the snow- and ice-covered lakes collapsed, dropping by several metres, again confirming the water had drained.

“ ̽��ֱ��first lake I found was surprising,” said Benedek. “It took me a while to be sure that what I thought I was seeing was really what I was seeing. We used surface elevation data from before and after the events to confirm what we were thinking. We know now that drainage of lakes during the winter is something that can happen, but we don’t yet know how often it happens.”

“Glaciers slow down in the winter, but they’re still moving,” said Willis. “It must be this movement that causes fractures to develop in certain places allowing some lakes to drain. We don’t yet know how widespread this winter lake drainage phenomenon is, but it could have important implications for the Greenland Ice Sheet, as well as elsewhere in the Arctic and Antarctic.”

Reference:
Corinne L. Benedek and Ian C. Willis. ‘Winter drainage of surface lakes on the Greenland Ice Sheet from Sentinel-1 SAR imagery.’ ̽��ֱ��Cryosphere (2021). DOI: 10.5194/tc-15-1-2021

Using satellite data to ‘see in the dark’, researchers have shown for the first time that lakes on the Greenland Ice Sheet drain during winter, a finding with implications for the speed at which the world’s second-largest ice sheet flows to the ocean.

We don’t yet know how widespread this winter lake drainage phenomenon is, but it could have important implications for the Greenland Ice Sheet, as well as elsewhere in the Arctic and Antarctic

Ian Willis

Lake on the surface of the Greenland Ice Sheet

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 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

Surface lakes cause Antarctic ice shelves to ‘flex’

sc604 — Wed, 13 Feb 2019 10:00:00 +0000

A team of British and American researchers, co-led by the ̽��ֱ�� of Cambridge, has measured how much the McMurdo ice shelf in Antarctica flexes in response to the filling and draining of meltwater lakes on its surface. This type of flexing had been hypothesised before and simulated by computer models, but this is the first time the phenomenon has been measured in the field. ̽��ֱ��results are reported in the journal Nature Communications.

̽��ֱ��results demonstrate a link between surface melting and the weakening of Antarctic ice shelves and support the idea that recent ice shelf breakup around the Antarctic Peninsula may have been triggered, at least in part, by large amounts of surface meltwater produced in response to atmospheric warming.

As the climate continues to warm, more and more ice shelves may become susceptible to flex, fracture and break up over the coming century.

Most of the Antarctic continent is covered by the Antarctic Ice Sheet, which is up to four kilometres thick and contains enough ice to raise global sea levels by about 58 metres. Over most of the continent and for most of the year, air temperatures are well below zero and the ice surface remains frozen. But around 75% of the ice sheet is fringed by floating ice shelves, which are up to a kilometre thick, mostly below sea level, but with tens of metres of their total height protruding above the water. In the summer months, when air temperatures rise above freezing, the surfaces of these ice shelves are susceptible to melting.

“Surface water on ice shelves has been known about for a long time,” said co-author Dr Ian Willis from Cambridge’s Scott Polar Research Institute. “Over 100 years ago, members of both Shackleton’s Nimrod team and the Northern Party team of Scott’s British Antarctic Expedition mapped and recorded water on the Nansen Ice Shelf, around 300 kilometres from where we did our study on the McMurdo Ice Shelf. For the last few decades, it has also been possible to see widespread surface meltwater forming on many ice shelves each summer from satellite imagery.”

What is not fully known is the extent to which surface water might destabilise an ice shelf, especially in warmer summers when more meltwater is produced. If the slope of the ice shelf is sufficiently steep, the water may flow off the ice shelf to the ocean in large surface rivers, mitigating against any potential instability.

̽��ֱ��danger comes if water pools up in surface depressions on the ice shelf to form large lakes. ̽��ֱ��extra weight of the water will push down on the floating ice, causing it to sink a bit further into the sea. Around the edge of the lake, the ice will flex upwards to compensate. “If the lake then drains, the ice shelf will now flex back, rising up where the lake used to be, sinking down around the edge,” said lead author Dr Alison Banwell, also from SPRI. “It is this filling and draining of lakes that causes the ice shelf to flex, and if the stresses are large enough, fractures might also develop.”

Banwell and co-author Professor Doug MacAyeal from the ̽��ֱ�� of Chicago had previously suggested that the filling and draining of hundreds of lakes might have led to the catastrophic breakup of the Larsen B Ice Shelf 2002 when 3,250 square kilometres of ice was lost in just a few days.

“We had been able to model the rapid disintegration of that ice shelf via our meltwater loading-induced fracture mechanism,” said Banwell. “However, the problem was that no one had actually measured ice shelf flex and fracture in the field, and so we were unable to fully constrain the parameters in our model. That’s partly why we set out to try to measure the process on the McMurdo ice shelf.”

Using helicopters, snow machines and their own two feet, the researchers set up a series of pressure sensors to monitor the rise and fall of water levels in depressions which filled to become lakes, and GPS receivers to measure small vertical movements of the ice shelf.

“It was a lot of work to obtain the data, but they reveal a fascinating story,” said MacAyeal. “Most of the GPS signal is due to the ocean tides, which move the floating ice shelf up and down by several metres twice a day. But when we removed this tidal signal we found some GPS receivers moved down, then up by around one metre over a few weeks whereas others, just a few hundred metres away, hardly moved at all. ̽��ֱ��ones that moved down then up the most were situated where lakes were filling and draining, and there was relatively little movement away from the lakes. It is this differential vertical motion that shows the ice shelf is flexing. We’d anticipated this result, but it was very nice when we found it.”

̽��ֱ��team hope that their work will inspire others to look for evidence of flex and fracture on other ice shelves around Antarctica. Their work will also help in developing ice sheet scale models that could be used to predict the stability of ice shelves in the future and to understand the controls on ice shelf size since they act as buffers against fast-moving ice from the continent. As ice shelves shrink, glaciers and ice streams behind them flow more rapidly to the ocean, contributing to global sea level rise.

̽��ֱ��work was funded by the US National Science Foundation, the Leverhulme Trust, NASA, and CIRES, ̽��ֱ�� of Colorado, Boulder.

Reference:
Alison F. Banwell et al. ‘Direct Measurements of Ice-Shelf Flexure caused by Surface Meltwater Ponding and Drainage.’ Nature Communications (2019). DOI: 10.1038/s41467-019-08522-5

A bold response to the world’s greatest challenge
̽��ֱ�� ̽��ֱ�� of Cambridge is building on its existing research and launching an ambitious new environment and climate change initiative. Cambridge Zero is not just about developing greener technologies. It will harness the full power of the ̽��ֱ��’s research and policy expertise, developing solutions that work for our lives, our society and our biosphere.

̽��ֱ��filling and draining of meltwater lakes has been found to cause a floating Antarctic ice shelf to flex, potentially threatening its stability.

Filling and draining of lakes causes the ice shelf to flex, and if the stresses are large enough, fractures might also develop

Alison Banwell

Surface lakes on the McMurdo Ice Shelf

Yes

Perspectives on the Nepal earthquake

jeh98 — Tue, 28 Apr 2015 14:50:40 +0000

As many agencies are now reporting, the death toll associated with the 7.9 magnitude earthquake that hit Nepal on Saturday is likely to rise considerably over the coming days and weeks. On Tuesday it stands at over 4,000 but the Nepalese Prime Minister, Sushil Koirala, announced that it might reach 10,000. ̽��ֱ��UN declared that 8 million people have been affected, with 1.4 million people urgently needing aid.

̽��ֱ��full scale of the damage will become clear as contact is made with remote settlements away from the capital, which are now largely cut off from communication and supply. In Kathmandu and other urban centres, the greatest cause of injury and death was collapsing buildings.

But in more isolated, mountainous regions, further problems arose from the shaking ground triggering a range of natural hazards. One such region is the Langtang Valley, 60km north of Kathmandu, where we have been doing research for the last two years.

A recent analysis shows the entire valley would have been particularly susceptible to landslides following the earthquake due to its proximity to the epicentre and the topography of the mountain slopes there.

We are exceptionally fortunate not to have been in the area when the earthquake struck. We were in Kathmandu for an International Glaciology Society Symposium in early March.

One of us (Ian Willis) stayed on to do glaciological fieldwork with two other scientists from Cambridge (Dr Hamish Pritchard and PhD student Mike McCarthy) towards the top of the Langtang Valley, returning very recently.

In fact Hamish Pritchard is still in Kathmandu, safe and now helping the UN effort.

̽��ֱ��other of us (Evan Miles) was due to fly to Nepal on Sunday and walk to the head of the Langtang Valley this week, but of course his trip was cancelled.

For the past two years, we have been working there with science colleagues from Switzerland, Netherlands and Nepal and aided by a professional Nepali team of guides, porters and cooks.

̽��ֱ��overall aim of the research project has been to better understand the climate of the region, and to investigate how the changing climate is affecting the glaciers and the discharge of water in the streams.

This is of huge societal importance, as the people of the valley rely on ground and stream water for their livelihoods – drinking, washing and irrigating crops.

In addition, a small hydro-electric plant was due to be built later this year at the uppermost village in the valley, Kyanjin Gompa, but this will presumably now be put on hold.

Our specific work focuses on improving knowledge about the glaciers of the region. And it is while undertaking our research that we have come to appreciate many of the natural hazards that occur in the area.

Many of the glaciers in Nepal and elsewhere across High Mountain Asia are covered by debris, which may inhibit the rate of ice melting underneath.

̽��ֱ��debris gets onto the glaciers through rockfalls, debris avalanches and mudflows. These are continuous processes, but would have been orders of magnitude more severe during the recent earthquake than anything we ever saw.

Many of the glaciers across the Himalaya and surrounding mountains are nourished by snow avalanches.

Again, these occur regularly (we have both been caught in snow avalanches sweeping down the glacier we work on) but the energy they contain is typically dissipated by the time they reach the valley bottoms.

As the recent footage from the Everest region shows, however, snow avalanches can be particularly large and devastating when triggered by an earthquake.

Video of a snow avalanche that swept down the Lirung Glacier on 20th March 2015. This one was harmless by the time it reached the village of Kyanjin Gompa. Bigger snow avalanches triggered by the earthquake would have been much more destructive. Video by Ian Willis.

Finally, many glaciers in the region are associated with lakes – these form on the glacier surface where they are dammed by ice, or in front of the glacier where they are blocked by moraines (large ridges of sediment ‘bulldozed’ by a formerly more extensive glacier).

̽��ֱ��rapid draining of such lakes provides another hazard, causing floods or mudflows to downstream regions. Again, the flooding and mudflows associated with lake dams rupturing is likely to have had a significant impact during the recent earthquake.

Our field research is on hold at present while we wait to hear the fate of the people of the Langtang Valley and other remote regions of Nepal. But initial reports from Langtang sound very bleak. Eye witness accounts state “From where we were, there was nothing you could see. All the villages were gone,” and “the whole valley has been destroyed”.

Helicopter-based photographs seem to confirm that Langtang village has been wiped out by a large landslide. We are busy scouring satellite data to identify zones of the worst impact, but Nepal has been shrouded in heavy clouds and rain since the earthquake inhibiting our efforts.

We are holding our breath awaiting a clear picture of Langtang Valley. We are hoping for the best but fearing the worst for the Nepali families that reside there.

DEC Nepal Earthquake Appeal

Inset images:

Looking downvalley to Langtang village in May 2014. Reports suggest that this entire village has been buried by a debris avalanche during the earthquake. Credit: Ian Willis.

Preliminary landslide susceptibility map created by Dr Tom Robinson ( ̽��ֱ�� of Canterbury). Susceptibility ranges from 0 to 1 with higher numbers indicating a greater chance of landslides occurring. Earthquake epicentre shown with a star. Langtang Valley is circled.

Evan Miles on the extremely debris-covered Lirung Glacier in 2014. Credit: Eduardo Soteras.

Lake on the surface of Lirung Glacier. ̽��ֱ��rapid drainage of such lakes may cause flooding downstream and may have contributed to devastating mudflows during the earthquake. Credit: Evan Miles.

Ian Willis with the owners of the Shangri-La Guest House, Langtang. L-R: Saylie, Tsering Dolma Lama, Karma, Ian, Nima, Samden Dindu. Photo taken May 2014. This family and many others are in our thoughts.

As the death toll continues to rise in Nepal, Senior Lecturer Dr Ian Willis, and PhD student Evan Miles, from the Scott Polar Research Institute contemplate the fate of people in a remote part of the country, where they have been doing research for the past two years.

We are holding our breath awaiting a clear picture of Langtang Valley. We are hoping for the best but fearing the worst for the Nepali families that reside there.

Ian Willis

Evan Miles. Homepage banner image credit: Bhuwan Maharjan

Lake on the surface of Lirung Glacier. ̽��ֱ��rapid drainage of such lakes may cause flooding downstream and may have contributed to devastating mudflows during the earthquake.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

'Extreme Sleepover #11’ - moulins and meltwater on the Greenland ice sheet

bjb42 — Sun, 01 Jan 2012 09:00:57 +0000

“What? No coffee?” We had been dropped off by helicopter onto the Greenland ice sheet where we were to live and work for three weeks. ̽��ֱ��sky was clear and the sun was out, but the air temperature hovered around 0^oC and a cutting katabatic wind blew from the top of the ice sheet in the east, through our ‘windproof’ jackets, and down the coast to our west. We had speedily put up our personal tents and three mess tents (the ‘kitchen’, the ‘workshop’ and the ‘office’). By late afternoon, we had set up the stove; dug through the snow to get water; the kettle was boiling; and now all we needed was the coffee. But someone had forgotten to pack it. “Three weeks without coffee?” Our heads throbbed, our hands shook and our moods sank into our felt-lined boots.

That early-June morning, we had flown to the ice sheet from the small coastal town of Ilulissat, Disko Bay, west central Greenland. Ilulissat, meaning ‘icebergs’ in the native language, has around 4,000 people and is remarkable for its brightly coloured wooden buildings. To the south is Ilulissat Fjord, which has at its head one of Greenland’s biggest and fastest moving outlet glaciers, Jakobshavn Isbræ. As it shudders forwards, thousands of icebergs calve off the front each year, some the size of aircraft carriers. For the last decade, local people and visiting scientists have witnessed one of the world’s most noticeable effects of climate change, as the floating front of the glacier has retreated by around 10 km. ̽��ֱ��glacier has also sped up; ten years ago it flowed at 7 km a year, but now that figure is closer to 15 km.

Our goal was to measure three key things on the ice sheet surface: melting, water flow through snow and along channels etched into the ice, and the filling (and hopefully drainage) of lakes. We radiated out from our camp each day, sometimes for 2–3 km, trussed up in harnesses jangling with ice screws and carabiners, roped together like beads on a string in case anyone disappeared into a crevasse or a hole under the snow. We advanced slowly as we probed for these hidden dangers, but also in an attempt to avoid large patches of slush that developed within the melting snow. We had 24 hours of daylight, of course, and quickly learnt to tell the time from the direction of the sun gyrating around us, higher to the south around midday and lower towards the north, reminding us to crawl into our sleeping bags at the end of each day.

For several days we had watched a nearby lake grow into what was now a thick sky blue ribbon, tapering at the edges, spread across the bright white of the ice sheet – about 800m across. But, as we watched, it suddenly began to shrink: the thick ribbon became a thin band, then a tiny thread, and then it was gone. During the final dying moments of the lake, ice blocks the size of truck containers swirled on the water like pieces of soap around an emptying plug hole. A volume equivalent to 600 Olympic-sized swimming pools (or 15 Royal Albert Halls) had drained in just 2.5 hours. On the floor of the former lake was a new fracture 600 m long that had been produced by the weight of the water. Six large holes or ‘moulins’ had formed along the fracture, the largest of which was around 10 m wide and still had water thundering into it when we reached it.

After nearly three weeks on the ice sheet we were reluctantly ready to leave. It took a few days to bring our instruments back to camp, collapse our tents and pack our things into the boxes they had arrived in. ̽��ֱ��helicopter retrieved us and whisked us back to Ilulissat which felt warm, peculiarly dry underfoot, and was fused with colours and smells that we had been deprived of for three weeks. And at last there was coffee.

Dr Ian Willis and Alison Banwell

Ian is a Senior Lecturer and Alison is a PhD student at the Scott Polar Research Institute, and both are members of St Catharine’s College. Ian has over 20 years of extreme sleepover experience on top and in front of several of the World’s glaciers. In addition to his Greenland work, he currently has projects in Svalbard, Iceland and New Zealand. Alison has recently been awarded a Dow Sustainability Innovation Student Challenge Prize that will allow her to extend her Greenland work to the study of Himalayan glaciers. Ian and Alison’s work was supported by the Natural Environment Research Council, ̽��ֱ�� of Cambridge Travel Fund, BB Roberts Fund, Scandinavian Studies Fund and St Catharine's College.

A longer version of this article was originally published in the St Catharine’s College Society Magazine 2011.

In the eleventh of a series of reports contributed by Cambridge researchers, glaciologists Dr Ian Willis and Alison Banwell watch as a lake disappears before their eyes.

During the final dying moments of the lake, ice blocks the size of truck containers swirled on the water like pieces of soap around an emptying plug hole.

Dr Ian Willis

Ian Willis

Peering into a moulin

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Yes

Polar science: IPY and SPRI

bjb42 — Fri, 01 Jun 2007 09:00:38 +0000

As well as seeking to make major advances in polar knowledge, a key theme is to leave a lasting legacy of polar data that will be of scientific and educational value for the future. All polar years have provided snapshots of the state of the polar regions at that time, giving us a baseline for past, present and future changes to be monitored and predicted. Each of the 200-plus international projects beginning this year is also committed to demonstrating cutting-edge science in real-time to schools and communities around the world.

This element of outreach is viewed by Professor Julian Dowdeswell, Director of the Scott Polar Research Institute (SPRI) in Cambridge, as vitally important for public engagement with polar science: ‘ ̽��ֱ��international outreach component of each project is designed to present the polar regions in general and key IPY science issues in particular to people throughout the world.’

For SPRI, the impetus provided by IPY has strengthened and formalised links with other researchers in the UK and worldwide. Already internationally recognised for its work in geophysical, environmental and social sciences, SPRI has several activities that will take place during IPY.

SPRI projects are wide-ranging: from assessing the social, economic and cultural significance of Arctic reindeer and caribou hunting, to measuring and modelling changes to glaciers. Dr Ian Willis, studying the mass balance of glaciers in Svalbard and Iceland, stresses the importance of combining field-based, airborne and satellite remote sensing data to assess the current state of glaciers at the beginning of the 21st century. He adds, ‘Computer modelling can then link climate and the mass balance of glaciers in the past and be used to predict changes for the next 100 years – something that is of considerable significance to discussions of the effects of global warming on changes in sea-level.’

Professor Dowdeswell explains the importance of IPY: ‘ ̽��ֱ��IPY should be a time for everyone to learn and reflect on regions of our world which few have visited but which are essential to the future well-being of all of us.’

For further information, please go to the SPRI website www.spri.cam.ac.uk

̽��ֱ��largest coordinated programme of international polar activities in 50 years – International Polar Year (IPY) – kicked off globally on 1 March 2007. Building on a 125-year history of previous polar events in 1882–1883, 1932–1933 and 1957–1958, the aim of IPY is to promote even greater international scientific collaboration to address issues of global importance within the Arctic and Antarctic.

̽��ֱ��international outreach component of each project is designed to present the polar regions in general and key IPY science issues in particular to people throughout the world.

Julian Dowdeswell

Nasa Goddard Photo and Video

Mosaic of the Arctic

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Yes