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Life found in the sediments of an Antarctic subglacial lake
16 September 2013
Evidence of diverse life forms dating back nearly a hundred thousand years has been found in subglacial lake sediments.
The possibility that extreme life forms might exist in the cold and dark lakes hidden kilometres beneath the Antarctic ice sheet has fascinated scientists for decades. However, direct sampling of these lakes in the interior of Antarctica continues to present major technological challenges. Recognising this, scientists from the British Antarctic Survey (BAS), and the Universities of Northumbria and Edinburgh in the UK, have been searching around the retreating margins of the ice sheet for subglacial lakes that are becoming exposed for the first time since they were buried more than 100,000 years ago. This is because parts of the ice sheet are melting and retreating at unprecedented rates as the temperature rises at the poles.
The group targeted Lake Hodgson on the Antarctic Peninsula, which was covered by more than 400 metres of ice at the end of the last Ice Age, but is now considered to be an emerging subglacial lake, with a thin covering of just 3–4 metres of ice. Drilling through the ice, they used clean coring techniques to delve into the sediments at the bottom of the lake.
The lake was thought to be a harsh environment for any form of life but the layers of mud at the bottom of the lake represent a time capsule storing the DNA of the microbes which have lived there throughout the millennia. The top few centimetres of the core contained current and recent organisms which inhabit the lake but, once the core reached 3.2 m deep, the microbes found most likely date back nearly 100,000 years.
Some of the life discovered was in the form of Fossil DNA showing that many different types of bacteria live there, including a range of extremophiles which are species adapted to the most extreme environments. These use a variety of chemical methods to sustain life both with and without oxygen. One DNA sequence was related to the most ancient organisms known on Earth and parts of the DNA in twenty three percent has not been previously described. Many of the species are likely to be new to science, making clean exploration of the remote lakes isolated under the deeper parts of the ice sheet even more pressing. Scientists believe organisms living in subglacial lakes could hold clues for how life might survive on other planets.
The paper, "Preliminary Analysis of Life within a Former Subglacial Lake Sediment in Antarctica" has been published online in the Journal 'Diversity' as part of a special issue on Microbial Ecology and Diversity.
For more information, please see the item on the British Antarctic Survey website.
West Antarctic Ice Sheet 20 million years older than previously thought
12 September 2013
The results of research conducted by Wilson et al. in Geophysical Research Letters mark the beginning of a new paradigm for our understanding of the history of Earth's great global ice sheets. The research shows that an ice sheet on West Antarctica existed 20 million years earlier than previously thought.
The findings indicate that ice sheets first grew on the West Antarctic subcontinent at the start of a global transition from warm greenhouse conditions to a cool icehouse climate 34 million years ago. Previous computer simulations were unable to produce the amount of ice that geological records suggest existed at that time because neighbouring East Antarctica alone could not support it.
For more details, see the original paper in Geophysical Research Letters.
Douglas S. Wilson, David Pollard, Robert M. DeConto, Stewart S.R. Jamieson, Bruce P. Luyendyk. Initiation of the West Antarctic Ice Sheet and estimates of total Antarctic ice volume in the earliest Oligocene. Geophysical Research Letters, 2013; DOI: 10.1002/grl.50797
Moss growth in Antarctica linked to climate change
5 September 2013
Increases in temperature on the Antarctic Peninsula during the latter part of the 20th century were accompanied by an acceleration in moss growth, scientists have learned. Writing in the journal Current Biology, they describe the activity as unprecedented in the last 150 years.
The Peninsula sustains moss banks, some of which are more than 5000 years old. A team from the British Antarctic Survey (BAS), the University of Cambridge and the University of Exeter sampled the most southerly known moss bank, at Lazarev Bay on Alexander Island, in 2008. The researchers extracted a short peat core from the bank and, using radiocarbon dating techniques, ascertained the start of peat accumulation to have been around the year 1860. Microscopic tests established it was formed from a single species (Polytrichum strictum).
The Antarctic Peninsula is known to have witnessed significant warming since the 1950s, when official records started. Records from the BAS Rothera research station show the Peninsula warmed by between 1 and 1.4°C per decade during the 1980s and '90s. Along with one of the fastest rates of warming anywhere on the planet, the Peninsula has also seen significant increases in precipitation. The length of the melt season has been steadily increasing since 1948, with earlier thawing and later freezing extending the growing season.
The sampled moss bank accumulated at around 1.25 mm a year throughout the late 19th and early 20th centuries, then increased its growth rate from the mid-1950s to reach 5mm a year by the late 1970s. It is now estimated to be 3.5mm a year.
Lead author, Jessica Royles, from BAS and the University of Cambridge, said: "This moss bank provided a unique archive of growing conditions on the Antarctic Peninsula over the past one hundred and fifty years. By combining multiple analyses we have clearly demonstrated a substantial increase in plant growth since the 1960s, coincident with changes to the local climate."
The biological records in this region stretch back further than the meteorological records do, so this latest research will help scientists improve their understanding of the interaction between diversity and climate.
For more information, see the news item on the BAS website or read the original article in Current Biology.
East Antarctic ice sheet 'vulnerable' to temperature changes
5 September 2013
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Spatial and temporal variations in EAIS glacier terminus position from all measure- |
The world's thickest ice sheet may be at greater risk from variations in the climate than previously believed.
Scientists found that glaciers on the East Antarctic Ice Sheet (EAIS) advance and retreat in synch with changes in temperature. Researchers at Durham University looked at declassified spy satellite imagery dating from 1963 to 2012. They used the pictures to detect changes in 175 glaciers as they flow into the sea along the 5,400km of coastline. They found a strong pattern of ebb and flow. In the 1970s and 80s, when temperatures were rising they found that 63% of glaciers were retreating. During the 1990s, when temperatures decreased, 72% of the glaciers advanced. |
For more information, see the original Nature - Letter article.
Ozone hole could boost global warming
4 September 2013
The thinning of the atmosphere's ozone layer could be contributing to warming the planet, according to a study published this week in Geophysical Research Letters.
Kevin Grise, an atmospheric scientist at Columbia University in New York, and his team modelled the weather dynamics around the ozone hole above the Antarctic. They calculated the knock-on effects of ozone depletion on cloud cover, and ultimately on radiative forcing — the balance of solar and thermal radiation absorbed, reflected or emitted by the planet and its atmosphere.
The team's models predicted a shift in the southern-hemisphere jet stream — the high-altitude air currents flowing around Antarctica — as a result of ozone depletion. This produced a change in the cloud distribution, with clouds moving towards the South Pole, where they are less effective at reflecting solar radiation.
For more information, see the item on the Nature News Blog or read the full article in Geophysical Research Letters.
Bone-Eating Worms Found in Antarctic Waters
27 August 2013
When you drop a whale backbone into Antarctic waters and retrieve it a year later, you'll find it covered with a pelt of wriggling, rosy-hued worms. Drop a chunk of wood in the same spot, and you'll discover that it's hardly changed. That's the result of a simple experiment to find out if some of the world's weirdest worms also live in Antarctic waters. The discovery extends the range of bone-eating worms to the Southern Ocean and suggests that Antarctic shipwrecks may be remarkably intact.
For more details, see the article on the Science Now website or read the original paper in the Proceedings of the Royal Society B.
8th session of the CLIVAR/CliC/SCAR Southern Ocean Panel Report available
1 August 2013
The Report from the 8th Session of the CLIVAR/CliC/SCAR Southern Ocean Panel (SOP), held in Hobart, Australia from 21st to 22nd February 2013, is now available. The SOP meetings occur every 15 to 18 months, often scaffolded onto other relevant meetings the panel members would be attending. In this case, the meeting was held in conjunction with a workshop on sea level rise.
Attendees of the meeting included 9 members of the SOP and 13 other invited experts, including representatives from the modelling, palaeo-, and early-career scientist communities. Discussions focused on: the status of SOOS and the under ice observations workshop; the use of the C-SOBOM program (Center for Southern Ocean Biogeochemical Observations and Modeling); Antarctica 2K Working Group activities; and a joint session with the CLIVAR Working Group on Ocean Model Development (WGOMD).
ESA request for Antarctic satellite data users
1 August 2013
The ESA Climate Change Initiative (CCI) Program has asked for input from the community about which Antarctic satellite data products would be most valuable. They invite you, as a possible future user of these data products, to provide recommendations and feedback about what products you think it would be most useful for an Antarctic CCI project to focus on. To help them assess the user requirements for satellite based Antarctic ice sheet data products, please complete the short on-line survey, containing just 16 multiple choice questions which take only ten minutes to complete. The survey will remain open until 16 September 2013.
Go to the ESA Antarctic Climate Change Initiative (CCI) user survey.
Bringing up baby - in Antarctica
1 August 2013
Life with a young child can sometimes be challenging - but how would you feel if you were bringing up your son in Antarctica?
Fernando Font, an officer in the Chilean Air Force, made the tough decision to move his wife Carolina and young son, also called Fernando, to Antarctica for two years while he serves as head of air operations on King George Island. For Carolina, the move involved a huge amount of organisation - including buying nearly 2,500 nappies in advance and shipping them over. But both insist that living in Antarctica has only improved their family life.
BBC News travelled to King Edward Island to meet them. Watch the video on the BBC News Magazine website.
Sea level rise: new iceberg theory points to areas at risk of rapid disintegration
1 August 2013
In events that could exacerbate sea level rise over the coming decades, stretches of ice on the coasts of Antarctica and Greenland are at risk of rapidly cracking apart and falling into the ocean, according to new iceberg calving simulations from the University of Michigan.
For more information, see the item on the Science Daily website or read the full article in Nature Geoscience.
Progress of Chinese research in physical oceanography of the Southern Ocean
1 August 2013
A review article on the progress of Chinese research in the physical oceanography of the Southern Ocean over the past 30 years has recently been published in the journal Advances in Polar Science.
Oceanographic surveying has been one of the key missions of the Chinese National Antarctic Research Expedition since 1984. Using the field data obtained in these surveys and the results from remote sensing and numerical models, Chinese physical oceanographers have investigated the water masses, fronts and circulation patterns in the Southern Ocean. Most oceanographic observations have been conducted in Prydz Bay and the adjacent seas. Conductivity, temperature and depth data (CTD) have been applied to study several features of the water masses in this region, including the spatial variation of warm summer surface water, the northward extension of shelf water, the flow of ice shelf water from the cavity beneath the Amery Ice Shelf, the upwelling of the Circumpolar Deep Water, and the formation of the Antarctic Bottom Water.
For more details, please see the review in Advances in Polar Science.
Antarctic glass sponges live life in fast lane
22 July 2013
An explosion in glass sponge population has forced researchers to rethink how animals live in Antarctica.
Conventional wisdom holds that life in Antarctica moves at a glacial pace. Marine creatures called sponges, which live on the seafloor, have been known to go a decade without any measurable growth in the Antarctic. But that thinking has changed, in part because of a startling discovery off the eastern coast of the Antarctic Peninsula.
Researchers have found a "boomtown" of sponges. In a study published in the journal Current Biology, they report on the explosion of a community of glass sponges - organisms with skeletons made of silica, a mineral component of glass - on the seafloor below where an enormous ice shelf used to be.
These sponges - filter feeders not known for their rapid development - doubled in biomass and tripled in number over the course of two growing seasons.
For more details, see the item on the National Geographic website, view the press release on the Alfred Wegener Institute website or read the paper in Current Biology.
Antarctic's Pine Island glacier produces giant iceberg
22 July 2013
Pine Island Glacier (PIG), the longest and fastest flowing glacier in the Antarctic, has spawned a huge iceberg. The block measures about 720 sq km in area - roughly eight times the size of Manhattan Island in New York.
Scientists have been waiting for the PIG to calve since October 2011 when they first noticed a spectacular crack spreading across its surface. Confirmation that the fissure had extended the full width of the glacier was obtained on Monday when it was seen by the German TerraSAR-X satellite. This carries a radar instrument that can detect the surface of the ice stream even though the Antarctic is currently in the grip of winter darkness.
The glacier's behaviour means it is now under close scrutiny, not least because it drains something like 10% of all the ice flowing off the west of the continent.
"The PIG is the most rapidly shrinking glacier on the planet," explained Prof David Vaughan from the British Antarctic Survey (BAS). "It's losing more ice than any other glacier on the planet, and it's contributing to sea level rise faster than any other glacier on the planet. That makes it worthy of study."
For more information, please see the item on the BBC News - Science and Environment website.
Antarctic Lake Vostok buried under two miles of ice found to "teem with life"
22 July 2013
A giant lake buried more than two miles beneath the Antarctic ice has been found to contain a "surprising" variety of life.
Analysis of ice cores obtained from the basin of Lake Vostok, the subglacial lake that Russian scientists drilled down to in 2012, have revealed DNA from an estimated 3,507 organisms. While the majority were found to be bacteria, many of which were new to science, there were also other single celled organisms and multicellular organisms found, including from fungi. The diversity of life from the lake has surprised scientists as many had thought the lake would be sterile due to the extreme conditions.
For further details, see the item on The Telegraph website or read the original research article in PLOS One.
Antarctic crabs: invasion or endurance?
22 July 2013
Recent scientific interest, following the "discovery" of lithodid crabs around Antarctica, has centred on a hypothesis that these crabs might be poised to invade the Antarctic shelf if the recent warming trend continues, potentially decimating its native fauna. The authors, however, conclude there is no evidence for a modern-day "crab invasion" and recommend a repeated targeted lithodid sampling programme along the West Antarctic shelf to fully test the validity of the "invasion hypothesis".
For more information, please read the original research article in PLOS One.
Antarctic flood produces 'ice crater'
22 July 2013
Scientists have seen evidence for a colossal flood under Antarctica that drained six billion tonnes of water, quite possibly straight to the ocean.
The cause is thought to be a deeply buried lake that suddenly over-topped. Satellites were used to map the crater that developed as the 2.7km-thick overlying ice sheet slumped to fill the void left by the escaping water. The location of the flood was Cook Sub-Glacial Lake (SGL) in the east of the continent, and the event itself occurred over a period of about 18 months in 2007-2008. It was detected and described using a combination of data gathered by the now-retired US Icesat mission and Europe's new Cryosat platform.
At present, Antarctica is losing mass at a rate of 50-100 billion tonnes a year, helping to raise global sea level. This study suggests that a not insignificant fraction of this mass loss could be due to flood events like that seen at Cook SGL. "This one lake on its own represents 5-10% of [Antarctica's] annual mass imbalance," said Leeds co-author Prof Andy Shepherd.
For further details, see the item on the BBC News - Science and Environment website or read the original paper in Geophysical Research Letters.
'Hoff' yeti crab hitched ride on ocean super-highway
28 June 2013
A hairy crab named after David Hasselhoff hitched a ride on an ocean "super-highway" to cross from the Pacific to the Atlantic millions of years ago.
In a study published in the journal Proceedings of the Royal Society B, Dr Christopher Roterman and colleagues propose that the "Hoff crab" probably originated around the vents that populate mid-ocean ridges in the eastern Pacific Ocean. It then expanded into the Atlantic through the Drake Passage that separates South America and Antarctica, spreading along volcanic vent regions that are now extinct.
The crab appears to have exploited the ocean current known as the Antarctic Circumpolar Current (ACC), which flows in a clockwise direction, west to east around Antarctica, through the Drake Passage.
For more information, please see the item on the BBC News - Science and Environment website or read the full paper in the Proceedings of the Royal Society B.
Building block for life found in Mars meteorite
28 June 2013
Scientists have found a potential building block for life in a Martian meteorite recovered from Antarctica. Parts of the rock contain rich concentrations of boron, which biochemists suspect played a key role in the development of ribonucleic acid, or RNA.
Read more on the News Discovery website.
Oceans melt Antarctica's ice from below
28 June 2013
More than half of the melting of Antarctica's ice occurs at just ten small ice shelves.
Ice shelves are portions of the larger ice sheet that extend over the ocean, floating on seawater. Conventional wisdom once held that calving, the break off of large chunks of ice, was the main factor driving ice-shelf dynamics, but recent research has underscored the role of melting from below, or 'basal' melting. Capitalizing on newly available monitoring data as well as recent modelling, a team of scientists led by Eric Rignot at the University of California, Irvine, has for the first time quantified this effect for the entire continent.
The results, which appear in Science, suggest that warm ocean currents are melting ice shelves predominantly at certain locations around the continent, to an extent that accounts for 55% of the annual meltwater. The findings will help scientists to tackle larger questions about how the Antarctic ice sheet might change in future and its contribution to global sea-level rise.
For more information, please read the Nature News item or read the full paper:
Rignot, E., Jacobs, S., Mouginot, J. & Scheuchl, B. Science DOI: 10.1126/science.1235798
Ice-sheet mass balance and climate change
6 June 2013
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A recent key paper has been published in the journal Nature, following from the ISMASS workshop held at the XXXII SCAR Open Science Conference and Meetings, in Portland, Oregon in July 2012. Since the 2007 Intergovernmental Panel on Climate Change Fourth Assessment Report, new observations of ice-sheet mass balance and improved computer simulations of ice-sheet response to continuing climate change have been published. Whereas Greenland is losing ice mass at an increasing pace, current Antarctic ice loss is likely to be less than some recently published estimates. It remains unclear whether East Antarctica has been gaining or losing ice mass over the past 20 years, and uncertainties in ice-mass change for West Antarctica and the Antarctic Peninsula remain large. The review discusses the past six years of progress and examines the key problems that remain. |
(a) Warm modified Circumpolar Deep Water (mCDW) leads to melting at the grounding line, |
For more information, see the full review article in Nature.
Further breakup of Wilkins Ice Shelf
4 June 2013
An ice shelf is a thick plate of ice attached to a coastline on one side and floating over the ocean on the other side. Many ice shelves fringe Antarctica, including the Wilkins Ice Shelf on the Antarctic Peninsula, which underwent a series of breakup events in 1998, 2008, and 2009.
Just as earthquakes can sometimes leave landscapes more prone to future quakes, the breakups on the Wilkins Ice Shelf left it vulnerable to further disintegration. In addition, the sea ice that had long pressed the shelf up against the coastline moved out, putting the remnants of the shelf in direct contact with open water. Ocean waves went to work on the ice, and in early 2013 the fracturing continued.
For further details, see the article on the NASA Earth Observatory website.
Organisms in 33.6 million year old ice pack evolved to survive
31 May 2013
Researchers publishing a paper in the latest issue of the journal Science have found, through Antarctic planktonic ice core examinations, that the continental ice cap formed more than 33 million years ago.
The ice cap was formed during the Oligocene (33.6 million years ago), according to carbon dating of the research data. Prior to the Oligocene, the southern continent had a warm tropical climate, teeming with life. However, when the cold came, most life forms died. Those that were able to adapt to the change, survived throughout time to the present age.
The paleoclimatic information was obtained through the work of the Integrated Ocean Drilling Program (IODP) expedition, which bore down into the sediment strata of the Antarctic depths to the preserved fossils. Carlota Escutia, co-chief officer of the new SCAR SRP Past Antarctic Ice Sheet Dynamics (PAIS), said the "fossil record of dinoflagellate cyst communities reflects the substantial reduction and specialization of these species that took place when the ice cap became established and, with it, marked seasonal ice-pack formation and melting began."
Dinoflagellates evolved into more simplified organisms enabling them to survive the formation of the Antarctic ice cap as well as thrive in the continual melting and freezing of the ice sheet during the seasonal changes. Over the course of millions of years, the dinoflagellates continued to evolve to assume their present-day form.
As the ice-pack melts during the approaching summer, an increase in productivity of endemic plankton communities occurs. The ice melt frees the nutrients it has accumulated throughout the previous year and releases it for consumption by plankton. "This phenomenon influences the dynamics of global primary productivity," said Dr. Escutia in a statement.
The dinoflagellate communities have continued to evolve throughout history of the ice pack. However, Escutia thinks: "the great change came when the species simplified their form and found they were forced to adapt to the new climatic conditions."
For more information, read the item on the Red Orbit website or read the original paper in Science.
Puzzle of why penguin cannot fly 'solved'
24 May 2013
The puzzle of why the penguin is unable to fly may have finally been solved. Researchers believe that the bird's underwater prowess may have cost it its ability to fly.
A study published in the Proceedings of the National Academy of Sciences, looked at seabirds closely related to the penguin. The study's authors confirmed that a wing that is good for flying cannot also be good for diving and swimming.
Professor John Speakman, from the University of Aberdeen and the Chinese Academy of Sciences, said: "Like many people, I've always been interested in penguins, and seeing them do these phenomenal marches across the ice, I've often thought: 'Why don't they just fly?'"
For more information, see the item on the BBC News - Science and Environment website or read the full article on the PNAS website.
Antarctic Neutrino Observatory detects unexplained high-energy particles
24 May 2013
Hot on the heels of detecting the two highest-energy neutrinos ever observed, scientists working with a mammoth particle detector buried in ice near the South Pole unveiled preliminary data showing that they also registered the signal of 26 additional high-energy neutrinos. The newfound neutrinos are somewhat less energetic than the two record-setters but nonetheless appear to carry more energy than would be expected if created by cosmic rays hitting the atmosphere — a prodigious source of neutrinos raining down on Earth. The particles thus may point to unknown energetic astrophysical processes deeper in the cosmos.
For more information, see the item on the Scientific American website.
Big brains may help baby seals survive under ice
15 May 2013
Weddell seals (Leptonychotes weddellii) are the only mammal that dares to swim long distances under sea ice, travelling up to 20 kilometres in hour-long bursts as they scan for air holes and an eventual exit somewhere in the midst of vast Antarctic sheets. There, mothers give birth so that their pups will be safe from leopard seals and killer whales. But how do those pups learn to navigate the risky underwater terrain so quickly? They're born with big brains, according to a study published online and in an forthcoming issue of Marine Mammal Science.
Researchers measured 12 carcasses and found that the brains of newborn pups are 70% the size of adult brains — the largest percentage of any mammal. In comparison, the brains of human babies are only 25% the size of adults. Good thing our trekking doesn't start until much later in life.
For more details, see the Science Shot or read the full article in Marine Mammal Science.
New Deep-Sea Fish Species Found in Antarctica
13 May 2013
| To catch Antarctic toothfish, you must bait your hook with Peruvian squid and cast it into the depths of the Ross Sea. This is what a team of Ukrainians did on a fishing trip near Antarctica. But sometimes, Mother Nature trips you up. Sometimes, you catch a hopbeard plunderfish.
In 2009-10, Ukrainian mariners happened to pull up three fish that looked unfamiliar. Further analysis found that they were a previously undiscovered species, dubbed the hopbeard plunderfish and described in a study published online on 29 April in the journal ZooKeys. The fish bear the scientific name Pogonophryne neyelovi. The strange-looking denizens of the deep have brownish-splotched bodies and are shaped somewhat like tadpoles, especially when young, according to the study. They have sharp dorsal fins that extend along the top of their bodies and strange "barbels," which resemble dirty Q-tips, that extend from their chins. |
The Hopbeard Plunderfish (Pogonophryne neyelovi). |
The longest of the three specimens measured 14 inches (35.5 centimetres). And they really like to live in the deep — they were pulled from depths of up to 4,560 feet (1,390 metres).
Currently, next to nothing is known about their behaviour, diet or what they do down there in the depths.
For more details, please read the article on the Live Science website or read the full paper in ZooKeys.
IceCube neutrinos came from outer space
24 April 2013
Two ultra-high-energy neutrinos captured by the IceCube experiment probably came from outside the Galaxy, according to an analysis posted by the collaboration today.
IceCube consists of 86 strings of detectors sunk in a cubic kilometre of ice near the South Pole, which pick up the light emitted when neutrinos and other particles pass through.
For more information, see the item on the Nature News Blog or visit the IceCube Neutrino Observatory website.
Reorganization of Southern Ocean plankton ecosystem at onset of Antarctic glaciation
22 April 2013
Antarctica has been mostly covered by ice since the inception of large-scale continental glaciation during the Oligocene, which profoundly altered the isotopic and mineralogical records of the sediments surrounding the continent. Houben et al. found records of the corresponding living systems in the fossil marine dinoflagellate cysts, which revealed that a microplankton ecosystem, similar to the one that exists today, appeared simultaneously with the first major Antarctic glaciation approximately 34 million years ago.
For more information, see the full article in Science.
Antarctic Peninsula melting season is getting longer
10 April 2013
The summer melting season in the Antarctic Peninsula has lengthened over the last 60 years, new research shows. This is contributing to sea-level rise, and may be linked to the rapid break-up of ice shelves in the area.
The Antarctic Peninsula, a mountainous finger of land pointing northwards towards South America, is warming much faster than the rest of Antarctica. Temperatures have risen by almost 3°C since the 1950s – three times faster than the global average. Scientists think this is because local westerly winds are getting stronger, pushing warmer air from the sea up and over the peninsula. Unusually for Antarctica, summer temperatures in the warmest few months are often high enough for snow to melt.
Melted snow running into the sea causes sea-levels to rise, but the longer melting season can have other important effects. Meltwater gathers in cracks in floating ice shelves, where the sheer weight of water can enlarge the cracks and shatter the ice, leading to retreat or collapse of the ice shelf.
With the physical barrier of the ice shelf removed, glaciers can flow into the sea faster, with a further impact on sea level. Also, melting and refreezing causes snow layers to become thinner and denser, affecting the height of the snow surface above sea level. Scientists need to know this so they can interpret satellite data correctly.
For more information, see the item on the NERC Planet Earth Online website or read the full article in the Journal of Geophysical Research: Earth Surface.
Rapid Climate Change and the Role of the Southern Ocean
10 April 2013
Research published this month, in the journal Nature Geoscience, concludes that oceanographic reorganisations and biological processes are linked to the supply of airborne dust in the Southern Ocean and this connection played a key role in past rapid fluctuations of atmospheric carbon dioxide levels, an important component in the climate system.
The scientists studied a marine sediment core from the Southern Ocean and reconstructed chemical signatures at different water depths using stable isotope ratios in the shells of foraminifera, single-celled marine organisms. They found that the chemical difference between intermediate level and deep waters over the last 300,000 years closely resembled the changes in atmospheric carbon dioxide levels and the input of windblown dust.
For further details, see the item on the Science Daily website or read the full article in Nature Geoscience.
Important role for ocean warming in Antarctic sea-ice expansion
2 April 2013
Global warming is expanding the extent of sea ice around Antarctica in winter in a paradoxical shift caused by cold plumes of summer melt water that re-freeze fast when temperatures drop, a recent study has shown. An increasing summer thaw of ice on the edges of Antarctica, twinned with less than expected snowfall on the frozen continent, is also adding slightly to sea level rise in a threat to low-lying areas around the world, the study said.
Scientists have been struggling to explain why sea ice around Antarctica has been growing, reaching a record extent in the winter of 2010, when ice on the Arctic Ocean at the other end of the planet shrank to a record low in 2012.
"Sea ice around Antarctica is increasing despite the warming global climate," said Richard Bintanja, lead author of the study at the Royal Netherlands Meteorological Institute. "This is caused by melting of the ice sheets from below," he said of the findings in the journal Nature Geoscience.
Ice is made of fresh water and, when ice shelves on the fringes of Antarctica thaw in summer because of upwellings of warming sea water, the meltwater forms a cool layer that floats on the denser, warmer salty sea water below, the study said. In winter, the melt water readily turns to ice because it freezes at zero degrees Celsius, above sea water at -2C (28.4F).
For more information, see the item on the Reuters website or read the original article in Nature Geoscience.
Russian Press Statement on Lake Vostok
28 March 2013
A joint Press Release has been issued by the Russian Arctic and Antarctic Research Institute and the St. Petersburg Institute of Nuclear Physics on a possible new type of bacteria discovered in water samples from subglacial Lake Vostok, lifted by the drill after entering the lake on the 5th Febuary 2012.
Warming world caused Southern Ocean to exhale
25 March 2013
The waters of the Southern Ocean now take up about 50% of the atmospheric carbon dioxide emitted by human activities, thanks in large part to the so-called "biological pump." Phytoplankton, tiny photosynthesizing organisms that bloom in the nutrient-rich waters of the Southern Ocean, suck up carbon dioxide from the atmosphere. When the creatures die, they sink to the ocean floor, effectively sequestering that carbon for hundreds or even thousands of years. It also helps that carbon dioxide is more soluble in colder waters, and that the churning winds mix the waters at the surface, allowing the gases to penetrate the waters more easily.
There are signs, however, that the ocean's capacity to sequester atmospheric carbon dioxide has been decreasing over the past few decades. Previous ocean sediment records suggest that, as the world slipped into the last glacial period, less carbon overall reached the sediments of the Southern Ocean, coinciding with declining atmospheric carbon dioxide. During cold periods, increased sea-ice cover can keep gases trapped in the ocean and the drier, dustier conditions bring much-needed iron to phytoplankton in the sub-Antarctic portion of the Southern Ocean, feeding blooms that gobble down carbon dioxide from the atmosphere.
What happens when the world moves into a warm, interglacial period isn't certain, but in 2009, a paper published in Science by researchers found that upwelling in the Southern Ocean increased as the last ice age waned, correlated to a rapid rise in atmospheric carbon dioxide. Now, using two deep cores collected at two Ocean Drilling Program sites in the Southern Ocean, Jaccard and colleagues have reconstructed ocean records of productivity and vertical overturning reaching back a million years, through multiple glacial-interglacial cycles. This rapid increase in carbon dioxide as the world transitions from glacial to interglacial seems to be a pretty regular thing, they've found.
For more information, read the full Science Now article.
Antarctica's first whale skeleton found with 9 new deep-sea species
25 March 2013
Marine biologists have, for the first time, found a whale skeleton on the ocean floor near Antarctica, giving new insights into life in the sea depths. The discovery was made almost a mile below the surface in an undersea crater and includes the find of at least nine new species of deep-sea organisms thriving on the bones.
"The planet's largest animals are also a part of the ecology of the very deep ocean, providing a rich habitat of food and shelter for deep sea animals for many years after their death," says Diva Amon, lead author of the paper based at University of Southampton Ocean and Earth Science (which is based at the UK's National Oceanography Centre) and the Natural History Museum. "Examining the remains of this southern Minke whale gives insight into how nutrients are recycled in the ocean, which may be a globally important process in our oceans."
Worldwide, only six natural whale skeletons have ever been found on the seafloor. Scientists have previously studied whale carcasses, known as a 'whale fall', by sinking bones and whole carcasses. Despite large populations of whales in the Antarctic, whale falls have not been studied in this region until now.
When a whale dies and sinks to the ocean floor, scavengers quickly strip its flesh. Over time, other organisms then colonise the skeleton and gradually use up its remaining nutrients. Bacteria break down the fats stored in whale bones, for example, and in turn provide food for other marine life. Other animals commonly known as zombie worms can also digest whale bone.
"One of the great remaining mysteries of deep ocean biology is how these tiny invertebrates can spread between the isolated habitats these whale carcasses provide on the seafloor," says co-author Dr Adrian Glover at the Natural History Museum. 'Our discovery fills important gaps in this knowledge.'
For more information, read the full article in Deep-Sea Research II: Topical Studies in Oceanography.
Telescopes in Antarctica and Chile discover starbursts in the early universe
25 March 2013
Distant, dust-filled galaxies were bursting with newborn stars much earlier in cosmic history than previously thought, according to newly published research. So-called "starburst galaxies" produce stars at the equivalent of a thousand new suns per year. Now, astronomers have found starbursts that were churning out stars when the universe was just a billion years old.
"I find that pretty amazing," said Joaquin Vieira, a postdoctoral scholar at the California Institute of Technology and leader of the study. "These aren't normal galaxies. These galaxies [reveal star formation] at an extraordinary rate, when the universe was very young. I don't think anyone expected us to find galaxies like this so early in the history of the universe."
An international team of astronomers, whose work is reported in the March 14 issue of the journal Nature, found dozens of these galaxies with the National Science Foundation (NSF)-funded South Pole Telescope (SPT). SPT is a 10-metre dish in Antarctica that surveys the sky in millimeter-wavelength light, whose waves fall between radio waves and infrared on the electromagnetic spectrum.
The team then took a more detailed look using the new Atacama Large Millimeter Array (ALMA) in Chile's Atacama Desert, which is funded in part by NSF. ALMA is an international facility and is a partnership between North America, Europe and East Asia in cooperation with the Republic of Chile.
"The new observations represent some of ALMA's most significant scientific results yet," Vieira said. "We couldn't have done this without the combination of SPT and ALMA. ALMA is so sensitive, it is going to change our view of the universe in many different ways."
For further details, see the press release on the NSF website or read the full article in Nature Letters.
Leads and lags at the end of the last Ice Age
4 March 2013
In an article in Science, Ed Brook discusses how, over the course of Earth history, it is generally believed that atmospheric carbon dioxide (CO2) and climate are closely coupled. The most direct evidence comes from polar ice cores. Snow falling in Antarctica and Greenland gradually compacts to form solid ice and trap air. Polar ice also records past temperatures in the ratio of heavy to light isotopes in the water molecule. Ice core analyses have shown that Antarctic temperature and atmospheric CO2 concentrations are highly correlated over the large-scale climate cycles of the past 800,000 years.
But which came first? Does CO2 drive climate cycles or is it a feedback in the system that contributes to warming? In another article in Science, Parrenin et al address this question in a study of CO2 concentrations and Antarctic temperatures during the last deglaciation. They conclude that temperature and CO2 changed synchronously.
For more information, read the articles on the Science website:
- Edward J Brook - Leads and Lags at the End of the Last Ice Age
- Parrenin et al - Synchronous Change of Atmospheric CO2 and Antarctic Temperature During the Last Deglacial Warming
Researchers find odd, cold volcanic vent in Antarctic waters
25 February 2013
| A group of researchers from the National Oceanography Center in Southampton has discovered a strange new deep-sea volcanic vent at Hook Ridge near the South Shetland Islands, Antarctica.
Hydrothermal vents are like hot springs, spewing jets of water from the seafloor out into the ocean. The expelled water, if hot enough, is rich in dissolved metals and other chemicals that can nourish a host of strange-looking life, via a process called 'chemosynthesis.' The hot water, being more buoyant than the surrounding cold seawater, rises up like a fountain or 'plume,' spreading the chemical signature up and out from the source. The newly discovered vent, named the Hook Ridge vent, however, was found to lack the high temperatures and alien-like creatures that scientists associate with hot hydrothermal vents. Instead there was a low-lying plume of shimmering water, caused by differences relative to the surrounding seawater in certain properties, such as salinity. "Geochemical measurements of the water column provided evidence of slightly reducing, localized plumes close to the seafloor at Hook Ridge," said Dr Alfred Aquilina, lead author of the study published in the journal PLOS ONE. |
Location map of the Bransfield Strait in the Southern |
"We therefore went in with sled-mounted cameras towed behind the Royal Research Ship James Cook and saw shimmering water above the seafloor, evidence of hydrothermal fluid seeping through the sediment."
So why were there no strange creatures around the vent? The team investigated this particular area of the deep-sea because prior measurements of the water column above Hook Ridge detected chemical changes consistent with a hydrothermal plume. On investigation, there was also a small relict 'chimney' of precipitated minerals on the seafloor, which suggests that the hydrothermal fluid flowing from the vent was once warmer.
The researchers therefore propose that hydrothermal activity at Hook Ridge is too irregular to provide the vital chemicals that support chemosynthetic life.
"This region was investigated because hydrothermal systems in this part of the Southern Ocean may potentially act as stepping stones for genetic material migrating between separate areas in the world ocean," Dr Aquilina said. "The more hydrothermal vents we can find and investigate, the more we can understand about the evolution and dispersal of the creatures that live off the chemicals expelled in these dark, deep environments."
For further information, see the item on the Sci-News webite or read the full research article on the PLOS ONE website.
Tagged seals help find missing piece in global climate puzzle
25 February 2013
By tracking the voyages of elephant seals off Antarctica, and with the help of satellite imaging and undersea sensors, researchers have discovered a long-elusive source for the deep-ocean streams of cold water that help to regulate the Earth's climate.
Three sources of Antarctic Bottom Water (AABW) were known until now. The first, in the Weddell Sea, was found in 1940; two others were found in the Ross Sea and along the Adélie Coast of East Antarctica in the 1960s and '70s. But for years, researchers have suggested that these were not the only ones. In particular, water samples from an area called the Weddell Gyre contain atmospheric pollutants known as chlorofluorocarbons (CFCs), indicating that the deep water came into contact with the air far too recently to have been carried there from one of the known AABW sinks.
Now, Kay Ohshima, a physical oceanographer at Hokkaido University in Sapporo, Japan, and his colleagues have traced that water to a fourth AABW source, in the Cape Darnley polynya. Their results are published in Nature Geoscience.
Dr Mike Meredith, a polar oceanographer at BAS and co-chair of the Southern Ocean Observing System (www.soos.aq), who wrote an accompanying commentary on the study, says that if the total rate of AABW formation declines, the resulting changes in cold-water circulation could have important effects on global climate, letting the ocean depths warm and thereby changing the rate of heat exchange between Antarctica and the tropics. Moreover, he says, sea levels could rise — owing to the fact that water expands as it warms — and temperature changes could affect deep-sea ecosystems
For further details, see the item on the Nature - News website, read Mike Meredith's article in Nature Geoscience - News and Views or read the full paper in Nature Geoscience.
Life found deep under Antarctic ice for first time?
7 February 2013
Last week, the US WISSARD team found and collected microbes in a lake hidden under more than a half-mile of ice.Among other things, the discovery may shed light on what lies under the icy moons of Jupiter and Saturn.
The newfound life-forms have little connection to life on the earth's surface and many apparently survive by "eating rocks," team member Brent Christner said in an interview from the U.S. McMurdo Station, after spending several weeks working at a remote field site at Lake Whillans. That may explain how life on other celestial objects — such as on the moons of Jupiter and Saturn — survive in the absence of available carbon.
"The conditions faced by organisms in Lake Whillans are quite parallel to what we think it would be like on those icy moons," Christner said. "What we found tells us a lot about extreme life on Earth," and how similar life beyond Earth might survive.
For further details, read the article on the National Geographic - Daily News website or visit the WISSARD Project website.
The change of winds
6 February 2013
As the combined effects of Antarctic stratospheric ozone depletion and climate warming have forced the westerly surface winds in the Southern Hemisphere to shift toward the pole, mixing between the upper ocean and deeper waters has also changed.
Waugh et al. now show that water originating at the surface at subtropical latitudes is mixing into the deeper ocean at a higher rate than 20 years ago, while the reverse is true for those originating at higher latitudes. The summer westerly winds that blow in the Southern Hemisphere have shifted toward the South Pole over the past several decades, but why?
Lee and Feldstein show that greenhouse gas forcing and ozone depletion impart different signatures to wind patterns and conclude that ozone depletion has been responsible for more than half of the observed shift.
For further details on both studies, please see the Science website:
Waugh et al - Vol. 339 no. 6119 pp. 568-570; DOI: 10.1126/science.1225411
Lee & Feldstein - Vol. 339 no. 6119 pp. 563-567; DOI: 10.1126/science.1225154
WISSARD team successfully retrieve lake samples
30 January 2013
A US National Science Foundation (NSF)-funded research team has successfully drilled through 800 metres (2,600 feet) of Antarctic ice to reach a subglacial lake and retrieve water and sediment samples that have been isolated from direct contact with the atmosphere for many thousands of years.
Scientists and drillers with the interdisciplinary Whillans Ice Stream Subglacial Access Research Drilling project (WISSARD) announced on 28 January local time that they had used a customized clean hot-water drill to directly obtain samples from the waters and sediments of subglacial Lake Whillans.
For further details, visit the WISSARD Project website.
Cameras reveal penguins' efficient hunting techniques
22 January 2013
Details of Adelie penguin feeding behaviour have been filmed by Japanese scientists.
Using video cameras and accelerometers attached to free-swimming penguins, researchers have gained a unique insight into the birds' hunting techniques. Adelie penguins adopted different strategies depending on whether they were hunting fish or krill. The findings are published in the journal PNAS.
Lead scientist Dr Yuuki Watanabe from the National Institute of Polar Research in Tokyo, Japan, told BBC Nature: "Foraging is the most basic activity of animals, but details of foraging behaviour are poorly known, especially in marine animals."
For more details, please see the article on the BBC Nature News website.
An expert judgement assessment of future sea level rise from the ice sheets
17 January 2013
A major gap in predictive capability concerning the future evolution of the ice sheets was identified in the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change. As a consequence, it has been suggested that the AR4 estimates of future sea-level rise from this source may have been underestimated. A recent study used a formalized pooling of expert views on uncertainties in the future contributions of melting ice sheets to sea-level rise, with a structured elicitation approach. Expert opinion is shown to be both very uncertain and undecided on the key issue of whether recent ice-sheet behaviour is a long-term trend or due to natural variability.
For further information, please read the article in Nature Climate Change.
US Report on Future Science Opportunities in Antarctica and the Southern Ocean
8 January 2013
The report "Future Science Opportunities in Antarctica and the Southern Ocean" suggests actions for the United States to achieve success for the next generation of Antarctic and Southern Ocean science. The report highlights important areas of research by encapsulating each into a single, overarching question. The questions fall into two broad themes: (1) those related to global change, and (2) those related to fundamental discoveries. In addition, the report identifies key science questions that will drive research in Antarctica and the Southern Ocean in coming decades, and highlights opportunities to be leveraged to sustain and improve the US research efforts in the region.
The report is highly relevant to the planned SCAR Horizon Scanning Activity on Future Directions of Antarctica and Southern Ocean Science.
A PDF version of the full report can be retrieved from the National Academies Press website.
Study shows rapid warming on the West Antarctic Ice Sheet
3 January 2013
| In a discovery that raises further concerns about the future contribution of Antarctica to sea level rise, a new study finds that the western part of the ice sheet is experiencing nearly twice as much warming as previously thought.
The temperature record from Byrd Station, a scientific outpost in the center of the West Antarctic Ice Sheet (WAIS), demonstrates a marked increase of 4.3 degrees Fahrenheit (2.4 degrees Celsius) in average annual temperature since 1958 — that is, three times faster than the average temperature rise around the globe. This temperature increase is nearly double what previous research has suggested, and reveals — for the first time — warming trends during the summer months of the Southern Hemisphere (December through February), said David Bromwich, Professor of Geography at Ohio State University and senior research scientist at the Byrd Polar Research Center. For more information, please see the items on the BBC News - Science and Environment website or the EurekAlert website, or read the original article in Nature Geoscience. |
mean temperatures at Byrd and the annual mean temperatures at every other grid point in Antarctica. The correlations are computed using ERA-Interim 2-metre temperature time series from 1979 to 2011. The star symbol denotes the location of Byrd Station/AWS. The filled black circles denote the locations of permanent research stations with long-term temperature records (FV, Faraday/Vernadsky) |
Invasive insects changing Antarctic landscape
3 January 2013
An invasive species has the potential to drastically alter Antarctic ecosystems that have been isolated for millions of years, research suggests. A species of midge was able to release large volumes of nutrients into the soil, changing the way native species had lived and evolved, a UK team found. They added that the species was well-suited to thrive in the extreme conditions.
"In terms of function, their job is litter turnover - they help things decay in the soil - and the population density of this thing in the area where it has been introduced is responsible for more litter turnover than the community that was already there," explained co-presenter of the research Peter Convey, of the British Antarctic Survey and co-chief officer of SCAR's EBA programme. "So basically it is bringing a function into an ecosystem that is not very active already. In principle, it can be a fundamental change in the way that ecosystem works."
For further details, please see the news item on the BBC News - Science and Environment website.
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