̽��ֱ�� of Cambridge - ̽��ֱ�� of Colorado

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.

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First Australians ate giant eggs of huge flightless birds

fpjl2 — Wed, 25 May 2022 15:09:43 +0000

Scientists settle debate surrounding 'Thunder bird' species, and whether its eggs were exploited by early Australian people around 50,000 years ago.

Cambridge launches new Leverhulme Centre for Life in the Universe

Anonymous — Mon, 10 Jan 2022 15:11:51 +0000

̽��ֱ��Leverhulme Centre for Life in the Universe will bring together an international team of scientists and philosophers, led by 2019 Nobel Laureate Professor Didier Queloz.

Thanks to simultaneous revolutions in exoplanet discoveries, prebiotic chemistry and solar system exploration, scientists can now investigate whether the Earth and the processes that made life possible are unique in the Universe.

̽��ֱ�� ̽��ֱ�� has recently launched the Initiative for Planetary Science and Life in the Universe (IPLU) to enable cross-disciplinary research on planetology and life in the Universe.

Building on IPLU’s activities, the new Leverhulme Centre for Life in the Universe will support fundamental cross-disciplinary research over the next 10 years to tackle one of the great interdisciplinary challenges of our time: to understand how life emerged on Earth, whether the Universe is full of life, and ask what the nature of life is.

̽��ֱ��Centre will include researchers from Cambridge’s Cavendish Laboratory, Department of Earth Sciences, Yusuf Hamied Department of Chemistry, Department of Applied Mathematics and Theoretical Physics, Institute of Astronomy, Department of Zoology, Department of History and Philosophy of Science, Faculty of Divinity, and the MRC Laboratory of Molecular Biology.

“ ̽��ֱ��Centre will act as a catalyst for the development of our vision to understanding life in the Universe through a long-term research programme that will be the driving force for international coordination of research and education,” said Queloz, Jacksonian Professor of Natural Philosophy at the Cavendish Laboratory and Director of the Centre.

Research within the Centre will focus on four themes: identifying the chemical pathways to the origins of life; characterising the environments on Earth and other planets that could act as the cradle of prebiotic chemistry and life; discovering and characterising habitable exoplanets and signatures of geological and biological evolution; and refining our understanding of life through philosophical and mathematical concepts.

̽��ֱ��Centre will collaborate with researchers at the ̽��ֱ�� of Colorado Boulder (USA), ̽��ֱ�� College London, ETH Zurich (Switzerland), Harvard ̽��ֱ�� (USA) and the Centre of Theological Inquiry in Princeton, New Jersey (USA).

“Understanding the reactions that predisposed the first cells to form on Earth is the greatest unsolved mystery in science,” said programme collaborator Matthew Powner from ̽��ֱ�� College London. “Critical challenges of increasing complexity must be addressed in this field, but these challenges represent one of the most exciting frontiers in science.”

Carol Cleland, Director of the Center for the Study of Origins and Professor of Philosophy at the ̽��ֱ�� of Colorado Boulder, also collaborator on the programme said: “ ̽��ֱ��new Centre is unique in the breadth of its interdisciplinarity, bringing together scientists and philosophers to address central questions about the nature and extent of life in the universe.

“Characteristics that scientists currently take as fundamental to life reflect our experience with a single example of life, familiar Earth life. These characteristics may represent little more than chemical and physical contingencies unique to the conditions under which life arose on Earth. If this is the case, our concepts for theorising about life will be misleading. Philosophers of science are especially well trained to help scientists 'think outside the box' by identifying and exploring the conceptual foundations of contemporary scientific theorising about life with an emphasis on developing strategies for searching for truly novel forms of life on other worlds.”

Didier Queloz is a Fellow of Trinity College, Cambridge.

With a £10 million grant awarded by the Leverhulme Trust, the ̽��ֱ�� of Cambridge is to establish a new research centre dedicated to exploring the nature and extent of life in the Universe.

̽��ֱ��Centre will act as a catalyst for the development of our vision to understanding life in the Universe through a long-term research programme that will be the driving force for international coordination of research and education

Didier Queloz

ESO/M Kornmesser

Artists’s impression of the rocky super-Earth HD 85512 b

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Emissions from melting permafrost could cost $43 trillion

sc604 — Mon, 21 Sep 2015 15:00:00 +0000

Increased greenhouse gas emissions from the release of carbon dioxide and methane contained in the Arctic permafrost could result in $43 trillion in additional economic damage by the end of the next century, according to researchers from the ̽��ֱ�� of Cambridge and the ̽��ֱ�� of Colorado.

In a letter published today (21 September) in the journal Nature Climate Change, the researchers have for the first time modelled the economic impact caused by melting permafrost in the Arctic to the end of the twenty-second century, on top of the damage already predicted by climate and economic models.

̽��ֱ��Arctic is warming at a rate which is twice the global average, due to anthropogenic, or human-caused, greenhouse gas emissions. If emissions continue to rise at their current rates, Arctic warming will lead to the widespread thawing of permafrost and the release of hundreds of billions of tonnes of methane and CO₂ – about 1,700 gigatonnes of carbon are held in permafrost soils in the form of frozen organic matter.

Rising emissions will result in both economic and non-economic impacts, as well as a higher chance of catastrophic events, such as the melting of the Greenland and West Antarctic ice sheets, increased flooding and extreme weather. Economic impacts directly affect a country’s gross domestic product (GDP), such as the loss of agricultural output and the additional cost of air conditioning, while non-economic impacts include effects on human health and ecosystems.

̽��ֱ��researchers’ models predict $43 trillion in economic damage could be caused by the release of these greenhouse gases, an amount equivalent to more than half the current annual output of the global economy. This brings the total predicted impact of climate change by 2200 to $369 trillion, up from $326 trillion – an increase of 13 percent.

“These results show just how much we need urgent action to slow the melting of the permafrost in order to minimise the scale of the release of greenhouse gases,” said co-author Dr Chris Hope from the Cambridge Judge Business School.

Hope’s calculations were conducted in collaboration with Kevin Schaefer of the National Snow and Ice Data Center at the ̽��ֱ�� of Colorado.

Hope and Schaefer used the PAGE09 (Policy Analysis of the Greenhouse Effect) integrated assessment model to measure the economic impact of permafrost thawing on top of previous calculations of the climate change costs of business-as-usual greenhouse gas emissions from the Intergovernmental Panel on Climate Change (IPCC).

“We want to use these models to help us make better decisions – linking scientific and economic models together is a way to help us do that,” said Hope. “We need to estimate how much it will cost if we do nothing, how much it will cost if we do something, and how much we need to spend to cut back greenhouse gases.”

̽��ֱ��researchers say that if an aggressive strategy to reduce emissions from thawing permafrost is adopted, it could reduce the impact by as much as $37 trillion.

Reference:
Hope, C. and Schaefer, K. ‘Economic impacts of carbon dioxide and methane released from thawing permafrost’. Nature Climate Change (2015). DOI: 10.1038/nclimate2807

New analysis of the effects of melting permafrost in the Arctic points to $43 trillion in extra economic damage by the end of the next century, on top of the more than the $300 trillion economic damage already predicted.

These results show just how much we need urgent action to slow the melting of the permafrost in order to minimise the scale of the release of greenhouse gases

Chris Hope

Steve Jurvetson

Not so Permafrost

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