INFORMATION:
The study was funded by the Natural Environment Research Council and the Swedish Research Council.
The paper, published in the journal Nature Geoscience, is entitled: "Hydrological impact of Middle Miocene Antarctic ice-free areas coupled to deep ocean temperatures."
Antarctic ice sheet retreat could trigger chain reaction
2021-05-13
(Press-News.org) The Antarctic ice sheet was even more unstable in the past than previously thought, and at times possibly came close to collapse, new research suggests.
The findings raise concerns that, in a warmer climate, exposing the land underneath the ice sheet as it retreats will increase rainfall on Antarctica, and this could trigger processes that accelerate further ice loss.
The research is based on climate modelling and data comparisons for the Middle Miocene (13-17 million years ago) when atmospheric carbon dioxide and global temperatures reached levels similar to those expected by the end of this century.
The study was carried out by the Met Office, the universities of Exeter, Bristol, Cardiff and Stockholm, NORCE and the Bjerknes Centre for Climate Research.
"When an ice sheet melts, the newly exposed ground beneath is less reflective, and local temperatures become warmer," said lead author Dr Catherine Bradshaw, of the Met Office and the Global Systems Institute at the University of Exeter.
"This can dramatically change weather patterns.
"With a big ice sheet on the continent like we have today, Antarctic winds usually blow from the continent out to the sea.
"However, if the continent warms this could be reversed, with the winds blowing from the cooler sea to the warmer land - just as we see with monsoons around the world.
"That would bring extra rainfall to the Antarctic continent, causing more freshwater to run into the sea.
"Freshwater is less dense than saltwater and so it can sit on the sea surface, rather than sinking and circulating as saltwater does.
"This effectively breaks the connection between the deep ocean and the surface ocean, causing warmer water to accumulate at depth."
The study suggests that the processes triggered by increasing rainfall would reduce the ability of the climate system to maintain a large Antarctic ice sheet.
"Essentially, if more land is exposed in Antarctica, it becomes harder for a large ice sheet to reform, and without favourable orbital positions in the Middle Miocene playing a role, perhaps the ice sheet would have collapsed at that time," Dr Bradshaw said.
During the warm Middle Miocene period, unusually large swings back and forth in deep-sea temperatures were recorded.
The study shows that fluctuations in the area covered by the ice sheet were a major factor in causing deep-sea temperatures to change so dramatically. Fluctuations in the volume of ice were found to be of much less importance.
Variations in the positioning of the Earth relative to the Sun caused the ice sheet to advance and retreat, and this altered weather patterns - triggering processes that can accelerate ice loss or gain.
Rain falling on the ice sheet can cause fracturing, surface melt and extra freshwater running off the continent, which, in turn, can cause deep-sea temperatures to rise - potentially influencing Antarctic ice from beneath.
The findings of the new study suggest that the Antarctic ice sheet retreated significantly during the Middle Miocene, then stabilised when the warm period ended.
Co-author Associate Professor Agatha De Boer, from the University of Stockholm, said: "When the Middle Miocene climate cooled, the link we have found between the area of the ice sheet and the deep-sea temperatures via the hydrological cycle came to an end.
"Once Antarctica was fully covered by the ice sheet, the winds would always go from the land to the sea and as a result rainfall would have reduced to the low levels falling as snow over the continent we see today."
Dr Petra Langebroek, a Senior Researcher from NORCE and the Bjerknes Centre for Climate Research, another co-author, added: "These findings imply a shift in ocean sensitivity to ice sheet changes occurs when ice sheet retreat exposes previously ice-covered land."
Professor Carrie Lear, from Cardiff University, who first devised the project, concluded: "This study suggests that during a warm period about 15 million years ago, the Miocene Antarctic ice sheet was capable of major advance and retreat across the continent.
"This is concerning, but further research is needed to determine exactly what this means for the long-term future of the modern Antarctic ice sheet."
Dr Bradshaw stressed that conditions now are not identical to those in the Middle Miocene, and the model used in the study does not include the impact of feedbacks from the carbon cycle or the ice sheet itself.
[Attachments] See images for this press release:
ELSE PRESS RELEASES FROM THIS DATE:
New evidence for electron's dual nature found in a quantum spin liquid
2021-05-13
A new discovery led by Princeton University could upend our understanding of how electrons behave under extreme conditions in quantum materials. The finding provides experimental evidence that this familiar building block of matter behaves as if it is made of two particles: one particle that gives the electron its negative charge and another that supplies its magnet-like property, known as spin.
"We think this is the first hard evidence of spin-charge separation," said Nai Phuan Ong, Princeton's Eugene Higgins Professor of Physics and senior author on the paper published this week in the journal Nature Physics.
The experimental results fulfill a prediction made decades ago to explain one of the most mind-bending states ...
Ingredient in common weed killer impairs insect immune systems, study suggests
2021-05-13
The chemical compound glyphosate, the world's most widely used herbicide, can weaken the immune systems of insects, suggests a study from researchers at the Johns Hopkins Bloomberg School of Public Health. Glyphosate is the active ingredient in Round Up™, a popular U.S. brand of weed killer products.
The researchers investigated the effects of glyphosate on two evolutionarily distant insects, Galleria mellonella, the greater wax moth, and Anopheles gambiae, a mosquito that is an important transmitter of malaria to humans in Africa. They found that ...
Study: Drivers with shift work sleep disorder 3x more likely to be in crash
2021-05-13
People who work nontraditional work hours, such as 11 p.m.-7 p.m., or the "graveyard" shift, are more likely than people with traditional daytime work schedules to develop a chronic medical condition -- shift work sleep disorder -- that disrupts their sleep. According to researchers at the University of Missouri, people who develop this condition are also three times more likely to be involved in a vehicle accident.
"This discovery has many major implications, including the need to identify engineering counter-measures to help prevent these crashes from happening," said Praveen Edara, department chair and professor of civil and environmental ...
Treating the COVID-19 'infodemic' as an epidemic
2021-05-13
Writing in the New England Journal of Medicine, a trio of science communication researchers proposes to treat the Covid-19 misinformation "infodemic" with the same methods used to halt epidemics.
"We believe the intertwining spreads of the virus and of misinformation and disinformation require an approach to counteracting deceptions and misconceptions that parallels epidemiologic models by focusing on three elements: real-time surveillance, accurate diagnosis, and rapid response," the authors write in a Perspective article.
"The word 'communicable' comes from the Latin communicare, ...
Many do not recognise animal agriculture's link to infectious diseases
2021-05-13
New research led by the University of Kent has found that people fail to recognise the role of factory farming in causing infectious diseases.
The study published by Appetite demonstrates that people blame wild animal trade or lack of government preparation for epidemic outbreaks as opposed to animal agriculture and global meat consumption.
Scientists forewarned about the imminence of global pandemics such as Covid-19, but humankind failed to circumvent its arrival. They had been warning for decades about the risks of intensive farming practices for public health. The scale of production and overcrowded conditions on factory farms make it easy for viruses to migrate and spread. Furthermore, ...
NK cells with bispecific antibody show activity against lymphoma cells
2021-05-13
HOUSTON - Cytokine-activated natural killer (NK) cells derived from donated umbilical cord blood, combined with an investigational bispecific antibody targeting CD16a and CD30 known as AFM13, displayed potent anti-tumor activity against CD30+ lymphoma cells, according to a new preclinical study from researchers at The University of Texas MD Anderson Cancer Center.
The findings were published today in Clinical Cancer Research, a journal of the American Association for Cancer Research. These results led to the launch of a Phase I clinical trial to evaluate the combination of cord blood-derived NK cells (cbNK cells) with AFM13 as an experimental cell-based immunotherapy in patients with CD30+ lymphoma.
"Developing novel NK cell therapies has been a priority for my ...
Researchers 3D print complex micro-optics with improved imaging performance
2021-05-13
WASHINGTON -- In a new study, researchers have shown that 3D printing can be used to make highly precise and complex miniature lenses with sizes of just a few microns. The microlenses can be used to correct color distortion during imaging, enabling small and lightweight cameras that can be designed for a variety of applications.
"The ability to 3D print complex micro-optics means that they can be fabricated directly onto many different surfaces such as the CCD or CMOS chips used in digital cameras," said Michael Schmid, a member of the research team from University of Stuttgart in Germany. "The micro-optics can ...
Species losses on isolated Panamanian island show importance of habitat connectivity
2021-05-13
CORVALLIS, Ore. - Free from human disturbance for a century, an inland island in Central America has nevertheless lost more than 25% of its native bird species since its creation as part of the Panama Canal's construction, and scientists say the losses continue.
The Barro Colorado Island extirpations show how forest fragmentation can reduce biodiversity when patches of remnant habitat lack connectivity, according to a study by researchers at Oregon State University.
Even when large remnants of forest are protected, some species still fail to survive because of subtle ...
Scientists identify source of weight gain from antipsychotics
2021-05-13
DALLAS - May 12, 2021 - Scientists with UT Southwestern's Peter O'Donnell Jr. Brain Institute have identified the molecular mechanism that can cause weight gain for those using a common antipsychotic medication. The findings, published in the Journal of Experimental Medicine, suggest new ways to counteract the weight gain, including a drug recently approved to treat genetic obesity, according to the study, which involved collaborations with scientists at UT Dallas and the Korea Advanced Institute of Science and Technology.
"If this effect can be shown in clinical trials, it could give us a way to effectively treat ...
Mixing massive stars
2021-05-13
Astronomers commonly refer to massive stars as the chemical factories of the Universe. They generally end their lives in spectacular supernovae, events that forge many of the elements on the periodic table. How elemental nuclei mix within these enormous stars has a major impact on our understanding of their evolution prior to their explosion. It also represents the largest uncertainty for scientists studying their structure and evolution.
A team of astronomers led by May Gade Pedersen, a postdoctoral scholar at UC Santa Barbara's Kavli Institute for Theoretical Physics, have now measured the internal mixing within an ensemble of these stars using observations ...