Antarctic Science News - archive from 2011
(Most recent first)
The Southern Ocean's role in carbon exchange during the last deglaciation
21 December 2011
Changes in the upwelling and degassing of carbon from the Southern Ocean are one of the leading hypotheses for the cause of glacial-interglacial changes in atmospheric CO2. A new paper, written by Burke and Robinson, presents a 25,000-year-long Southern Ocean radiocarbon record reconstructed from deep-sea corals, which shows radiocarbon-depleted waters during the glacial period and through the early deglaciation. This depletion and associated deep stratification disappeared by ~ 14.6 ka (thousand years ago) consistent with the transfer of carbon from the deep ocean to the surface ocean and atmosphere via a Southern Ocean ventilation event. Given this evidence for carbon exchange in the Southern Ocean, the authors show that existing deep-ocean radiocarbon records from the glacial period are sufficiently depleted to explain the ~190‰ drop in atmospheric radiocarbon.
20 December 2011
Emperor penguins "time" their dives by the number of flaps they can manage with their wings. This is according to a new study published in the Journal of Experimental Biology. It aimed to show how the birds reached the "decision" that it was time to stop feeding and return to the surface to breathe.
Tracking the birds revealed that they flapped their wings, on average, 237 times on each dive. The study was led by Dr Kozue Shiomi, from the University of Tokyo, Japan. Dr Shiomi and his team think that the penguins' decision to end their foraging dive and return to the surface is constrained by how much power their muscles can produce after every pre-dive breath. This "flying" motion propels the birds forwards, allowing them to swim quickly through the water, gulping fish.
5 December 2011
Antarctica has been covered with ice for the past 34 million years. Falling concentrations of atmospheric CO2 have been the prime suspects in causing the cooling that produced the accumulation of ice, but reconstructions of atmospheric CO2 content have contradicted this notion. Pagani et al. present alkenone-based CO2 reconstructions, from both high- and low-latitude sites in the Atlantic and Southern oceans, which show that CO2 levels did in fact decline precipitously just prior to and during the onset of glaciations, confirming that CO2 played a dominant role in the inception of Antarctic glaciation.
The temperature histories of Antarctica and the Arctic during the last deglaciation are quite different. What about changes in the masses of the ice sheets? Weber et al. present marine sedimentary records from the Weddell Sea coast of the East Antarctic ice sheet which show that the ice sheet reached its maximum extent contemporaneously with that of Northern Hemispheric ice sheets.
Read the full articles on the Science website:
- The Role of Carbon Dioxide During the Onset of Antarctic Glaciation by Pagani, et al.
- Interhemispheric Ice-Sheet Synchronicity During the Last Glacial Maximum by Weber, et al.
21 November 2011
Scientists say they can now explain the existence of what are perhaps Earth's most extraordinary mountains. The Gamburtsevs are the size of the European Alps and yet they are totally buried beneath the Antarctic ice. Their discovery in the 1950s was a major surprise. Most people had assumed the rock bed deep within the continent would be flat and featureless. Survey data now suggests the range first formed over a billion years ago, researchers told the journal Nature.
The Gamburtsevs are important because they are thought to be the location where the ice sheet we know today initiated its march across Antarctica. Unravelling the mountains' history will therefore inform climate studies, helping scientists to understand not just past changes on Earth but possible future scenarios as well.
"Surveying these mountains was an incredible challenge, but we succeeded and it's produced a fascinating story," Dr Fausto Ferraccioli from the British Antarctic Survey (BAS) told BBC News.
3 November 2011
Flying over Antarctica's Pine Island Glacier in a DC-8 research plane, scientists participating in NASA's IceBridge mission made a startling discovery on October 14: a massive crack running about 29 kilometres (18 miles) across the glacier's floating tongue. The rift is 80 metres (260 feet) wide on average and 50 to 60 metres (165 to 195 feet) deep, and it marks the moment of creation for a new iceberg that will span about 880 square kilometres (340 square miles) once it breaks loose from the glacier.
View of the crack in the Pine Island Glacier taken directly from above
The crack viewed from the side (thin horizontal line across centre of image)
Birthing large icebergs is nothing new for the Pine Island Glacier. Among the fastest moving glaciers in Antarctica, Pine Island drains about 79 cubic kilometres (19 cubic miles) of ice per year from the West Antarctic Ice Sheet. The end of the glacier stretched about 48 kilometres (30 miles) past the edge of land, floating on the ocean. As more ice flows toward the water, the tongue grows longer. Eventually, a piece will break off, forming a large iceberg.
The last calving event occurred in late 2001 and resulted in an iceberg that measured 42 kilometres by 17 kilometres (26 by 11 miles). That event, too, was preceded by a large crack that was observed in satellite imagery in late 2000.
While satellites have tracked the formation of new icebergs, this is the first detailed airborne survey of such an event. "We are actually now witnessing how it happens," said IceBridge project scientist Michael Studinger. "It's part of a natural process but it's pretty exciting to be here and actually observe it while it happens."
Read the full article on the NASA Earth Observatory website
2 November 2011
|A century ago, Captain Scott and his team set out on a doomed race to be first to the South Pole. They failed in this quest - but that wasn't all they were doing in this mysterious ice-bound land.
It is an expedition best known for its failure. Not only did a Norwegian rival beat Captain Robert Scott to the South Pole, but his five-man team died on the return journey. Found in the tent alongside their frozen bodies were 16kg (35lb) of fossils, a meteorological log, scores of notes, and rolls of film taken by Scott himself. The dying explorers thought these too valuable to jettison, even though lightening their load could have played a part in the life and death struggle after weeks of travelling in temperatures below -37C (-35F).
Scott's expedition had a dual purpose - to reach the Pole for the British Empire, and to explore and document this great southern land. He first led an expedition to the region in 1901, and returned a decade later with a young and hungry team of experts (including, for the first time, a professional photographer) to collect a treasure trove of specimens, data and observations for analysis on their return.
Photograph of moraine under Mount Buckley, taken by Captain Scott not long
Just a handful of his 38-man team set off for the Pole on that final ill-fated journey. The remainder continued their research around base camp and beyond. Gathered to answer the pressing questions of their day, these findings continue to shed light on the pressing scientific questions of our day too.
To learn of four of the key discoveries made by the expedition (besides the Pole), and one thing that found them, please read the full article on the BBC News Magazine website.
19 October 2011
A "criminal" stone-stealing Adelie penguin has been captured on camera by a BBC film crew. The team, filming for the documentary Frozen Planet, spent four months with the penguin colony on Ross Island, Antarctica. The footage they captured shows a male penguin stealing stones from its neighbour's nest.
The birds build their stone nests to elevate and protect their eggs from run-off when the Antarctic ice melts. Males with the best nests are more likely to attract a mate, so, in a colony of half a million penguins, the best stones are highly prized.
Jeff Wilson, director of the shoot, explained that he and the cameraman, Mark Smith, knew that the birds occasionally stole stones from one another. But he said it was a challenge to capture the moment in the chaos of a busy penguin colony.
19 October 2011
NASA's Operation IceBridge mission comprises the largest airborne research campaign ever flown over Earth's polar region. The mission is designed to continue critical ice sheet measurements in a period between active satellite missions and help scientists understand how much the major ice sheets of Greenland and Antarctica could contribute to sea level rise.
12 October 2011
Remote observatories generating gigabytes of data on the weather from Antarctica's vast ice sheets, powered by nothing more than wind and sun. An array of buoys and gliders bobbing and cruising through the Southern Ocean. Satellites using ever more powerful sensors to peer through disintegrating ice shelves.
It's a possible vision from 20 years hence offered by a committee of scientists and experts tasked with identifying and summarizing future research priorities in the Antarctic.
The report recommends "establishing a new infrastructure for sustained observations capable of detecting and recording the full suite of environmental changes occurring over decades within the Antarctic system of atmosphere, oceans, land and ice; to further the understanding of the causes and mechanisms of change and develop the capability to predict the course of future changes; and to better manage the continent for future generations."
For further details, please see the full article in Space Ref News
12 October 2011
Scientists on the ice, three kilometres above Lake Ellsworth
Antarctic researchers are set to make first contact with long-lost lakes deep beneath the continent's ice – closely followed by second and third contact.
Three expeditions will attempt to enter the hidden lakes over the next two years, in search of unknown kinds of life that have evolved in isolation. The projects could also determine if or when the west Antarctic ice sheet will collapse – one of the worst-case scenarios in future climate change.
Over the next few months a team from the British Antarctic Survey, based in Cambridge, UK, and other institutions will set up drilling equipment on the ice above Lake Ellsworth. They will return late next year to drill into the lake. Ellsworth is buried under 3 kilometres of ice, in what was once a fjord. The team will break in by firing a jet of hot water into the ice. "We can get through those 3000 metres of ice in about three days," says lead scientist Martin Siegert of the University of Edinburgh, UK. The hot-water drill should also minimise contamination of the lake, as the melted pristine ice from the bottom of the borehole is cleaned and then used in the jet.
The Ellsworth team are not the first to seek life in an Antarctic lake. Last year a Russian expedition drilled to within 29 metres of the surface of Lake Vostok, which lies 3750 metres below the ice of east Antarctica. They were forced to stop when winter closed in, but will resume drilling in January. When they break into the lake early next year, its water should rise up the hole and refreeze. They will return late next year to get samples from this fresh ice – a sampling technique that is designed to minimise the human contamination.
The third project, WISSARD, will drill into west Antarctica's Lake Whillans. Unlike Vostok and Ellsworth, which have been isolated for tens of thousands of years, Lake Whillans is part of an extensive network of lakes and channels running under the ice, and is much more active. "We know it fills with water and discharges," says Ross Powell of Northern Illinois University in DeKalb. It is "part of the plumbing" that collects water from streams under the ice and releases it into the sea.
27 September 2011
The West Antarctic Peninsula (WAP) is a hotspot of recent rapid regional warming and ice loss. The WAP sea surface freezes each winter to form a 'fast-ice' skin that can reduce iceberg drift and collisions between their keels and the sea bed, in what is termed scouring. Scouring disturbance is thus inversely correlated with fast-ice duration.
In a new study, scientists have examined long-term records of fast ice, ice scour and mortality of benthos around Rothera research station (WAP) to determine whether there is a biological response from the sea bed coincident with fast-ice changes and show that the duration of fast ice at Rothera has significantly decreased over the last 25 years and that this is strongly correlated with increased ice scour and mortality of benthos in the shallows. The authors of the study found that survival of one of the most common shallow species, the bryozoan Fenestrulina rugula, is linked to ice-scour frequency and has markedly decreased over the past 12 years. The chance of colonies reaching two years old, the age at which they typically begin to sexually reproduce, has halved since 1997. These findings suggest that increased scouring of the sea bed has led to higher benthic mortality, with implications for the region's biodiversity.
15 September 2011
The Antarctic continent's immense mantle of ice is diminishing as warming ocean waters drive melt and accelerated glacier flow at the coasts. The importance of this process is widely recognized: A mere 5% reduction in the total mass of ice, for example, would place much of Miami, Amsterdam, and Bangkok below sea level. Predicting such changes in the centuries ahead requires understanding not only climate and its direct impact on ice loss but also the glacial flow that carries ice from the continent's interior out to its edges. Crudely, the ice sheet's flow resembles, at enormous scale, the spreading puddle formed by pouring pancake batter onto a skillet. Ice sheet flow, however, includes interesting features such as narrow, fast-moving zones called ice streams. Such irregularities largely govern how the ice sheet reacts to changes imposed at its edges. The spatial pattern of ice flow must therefore be known. In the journal Science (9 September 2011), Rignot et al. report the first nearly complete measurement and mapping of ice flow for the entire Antarctic continent, providing a new foundation for studies of ice sheet evolution.
7 September 2011
King crabs have been found on the edge of Antarctica, probably as a result of warming in the region, scientists say.
Writing in the journal Proceedings B, scientists report a large, reproductive population of crabs in the Palmer Deep, a basin cut in the continental shelf. They suggest the crabs were washed in during an upsurge of warmer water. The crabs are voracious crushers of sea floor animals and will probably change the ecosystem profoundly if and when they spread further, researchers warn. Related species have been found around islands off the Antarctic Peninsula and on the outer edge of the continental shelf. But here the crabs (Neolithodes yaldwyni) are living and reproducing in abundance right on the edge of the continent itself.
Read the article on the BBC News - Science and Environment website, or read the full paper in the Royal Society's journal of Biological Sciences, Proceedings B.
South Africa's Antarctic Legacy Project takes shape
2 September 2011
The considerable role South African researchers have played in scientific, biological and meteorological discoveries in the sub-Antarctic Ocean over the past six decades lacks full recognition. But memories that lay scattered in national archives, personal diaries and mementos will now be accessible through a project to identify, digitise and archive this historical heritage online.
More than 100,000 pages of records - including an estimated 30,000 maps, drawings, photographs, slides and oral history interviews - will become accessible in the global public domain when the Antarctic Legacy Project becomes fully operational by the end of 2012.
The Antarctic Legacy Project milestones were revealed last month during the first-ever gathering in Africa of historians and archaeologists from around the world who focus on the Antarctic region. The 7th International Scientific Committee for Antarctic Research (SCAR) history workshop, held at Stellenbosch University, was attended by researchers from some 10 countries.
For more information, read the full article on the University World News website.
22 August 2011
Scientists have produced what they say is the first complete map of how the ice moves across Antarctica. Built from images acquired by radar satellites, the visualisation details all the great glaciers and the smaller ice streams that feed them. The map has been published online by Science magazine. It should aid the understanding of how the White Continent might evolve in the warmer world being forecast by climatologists. "This is like seeing a map of all the oceans' currents for the first time. It's a game changer for glaciology," said lead author Dr Eric Rignot. "We are seeing amazing flows from the heart of the continent that had never been described before," added the US space agency (Nasa) and University of California (UC), Irvine, researcher.
11 August 2011
The tsunami, caused by the Tohoku earthquake in Japan on 11 March this year, crossed the Pacific and broke off large chunks of ice from Antarctica, a study has shown.Satellite photos show huge icebergs were created when the tsunami hit West Antarctica's Sulzerberger Ice Shelf. This caused 125 sq km of ice to break off - or calve - from a shelf front that has remained stable for the past 46 years.
The waves generated by the 9.0 magnitude earthquake travelled about 13,000 km across the Pacific Ocean before reaching the Sulzerberger Ice Shelf, causing ice to break off and float into the sea. The largest of the icebergs measured 6.5 km by 9.5 km, (almost the size of Manhattan) and 80 m in thickness.
The swell was estimated to have been just 30cm high when it reached the Sulzerberger shelf. But the researchers say that over a period of hours to days, the dispersed waves caused repeated flexing of the ice, "fatiguing" the shelf and causing it to fracture.
Ice breaking away from the Sulzerberger Ice Shelf
Kelly Brunt from NASA's Goddard Space Flight Center in Maryland, USA, and colleagues studied a series of images from the European Space Agency's Envisat satellite taken between 11 and 13 March. This allowed the team to constrain the calving event to a period consistent with the arrival of the tsunami. Their study is published in the Journal of Glaciology, Vol. 57, No. 205 2011.
10 August 2011
Ice sheets are expected to shrink in size as the world warms, which in turn will raise sea level. The West Antarctic ice sheet is of particular concern, because it was probably much smaller at times during the past million years when temperatures were comparable to levels that might be reached or exceeded within the next few centuries. Much of the grounded ice in West Antarctica lies on a bed that deepens inland and extends well below sea level. Oceanic and atmospheric warming threaten to reduce or eliminate the floating ice shelves that buttress the ice sheet at present. Loss of the ice shelves would accelerate the flow of non-floating ice near the coast. Because of the slope of the sea bed, the consequent thinning could ultimately float much of the ice sheet's interior. In this scenario, global sea level would rise by more than three metres, at an unknown rate. Simplified analyses suggest that much of the ice sheet will survive beyond this century. We do not know how likely or inevitable eventual collapse of the West Antarctic ice sheet is at this stage, but the possibility cannot be discarded. For confident projections of the fate of the ice sheet and the rate of any collapse, further work including the development of well-validated physical models will be required.
For further details, read the full article in Nature Geoscience.
25 July 2011
A new reanalysis by two NASA scientists of the three standard ice-monitoring techniques slashes the estimated loss from East Antarctica, challenging the large, headline-grabbing losses reported lately for the continent as a whole. Although not the final word, the new study shows that researchers still have a lot to learn about the vast East Antarctic Ice Sheet. Understanding the role of East Antarctica is one key to figuring out what the ice sheets, and thus sea level, will be doing by century's end. For more information, read the full Science article.
SCAR has an Expert Group on Antarctic Ice Sheet Mass Balance and Sea Level which aims to help address this issue. ISMASS is currently co-sponsored by IASC (the International Arctic Science Committee).
25 July 2011
Newly discovered volcanoes. The peak in the foreground is thought to
A string of a dozen volcanoes, at least several of them active, has been found beneath the frigid seas near Antarctica, the first such discovery in that region. Some of the peaks tower nearly 10,000 feet above the ocean floor - nearly tall enough to break the water's surface. "That's a big volcano. That's a very big volcano. If that was on land it would be quite remarkable," said Philip Leat, a volcanologist with the British Antarctic Survey who led a seafloor mapping expedition to the region in 2007 and 2010.
The group of 12 underwater mountains lies south of the South Sandwich Islands — desolate, ice-covered volcanoes that rise above the southern Atlantic Ocean about halfway between South America and South Africa and erupted as recently as 2008. It's the first time such a large number of undersea volcanoes has been found together in the Antarctic region.
Read the full story on the MSNBC website.
14 July 2011
Penguins can't fly. But they can get airborne.
In fact, taking to the air, for even a brief instant, is actually a vital strategy penguins employ to avoid being eating by predators such as leopard seals or orcas. Now scientists have worked out the secret technique that penguins use to get airborne. It involves wrapping their bodies in a cloak of air bubbles – and it turns out to be the same technique that engineers use to speed the movement of ships and torpedoes through water.
Another interesting aspect of the discovery is that it was made by scientists examining in minute detail footage shot for the programme Blue Planet, a landmark natural history series filmed by the BBC's own Natural History Unit.
It sounds implausible that penguins might get airborne. These short, squat birds, which tend to live in the colder parts of the southern hemisphere, are renowned for their waddling walks and flapping flippers – which are famously great for swimming, but useless for flying. But many species of penguin do take to the air.
Due to their body shape, and poor climbing ability, it is difficult for penguins to haul themselves ashore, especially onto rocky shorelines. And it can be almost impossible for a penguin to haul itself out from the ocean onto sea ice. So penguins leap ashore: they swim at speed to the surface, burst through and briefly get airborne to clear the rocks or ice shelf, and land on their breast.
6 July 2011
Captain Scott and members of the Terra Nova expedition team outside their huts
A century ago, on the evening of June 22, 1911, Captain Robert Falcon Scott and his companions celebrated the winter solstice in their hut on Ross Island, off the coast of Antarctica. The promise of lengthening days came as blessed relief, and the first Midwinter Dinner – a feast still celebrated on the Continent today – was a lavish, jolly affair. The hut was festooned with flags, and there was a plentiful supply of champagne.
Everyone knows what happened next: Scott, beaten to the South Pole by Roald Amundsen, died a lonely death on the ice. But what few people realise is that Scott and his men were scientists. When the search party found the tent containing his body, and those of his two companions, on November 12, 1912, they also found rolls of photographs; a meteorological log which had been kept until March 13, scarcely two weeks before the probable date of their deaths; 16 kilograms of fossils gathered on the way back from the Pole; as well as Scott's diary, various letters to supporters, friends and the wives of his colleagues, and the famous Message To The Public. In a letter to his wife Kathleen, he wrote, of their two-year-old son Peter: "Make the boy interested in natural history if you can; it is better than games."
One of the most telling botanical items from the expedition was the fossilised Glossopteris, a fernlike plant known to grow in what was then called the Southern Continent (Australia, New Zealand, Africa, India). Along with the other samples of fossilised wood and leaves that were found in Scott and Wilson's tent, it proved that the climate in the Permian period, 250 million years ago, had been mild enough to support trees. But the discovery of the Glossopteris raised another question: had the Southern Continent and Antarctica once been one? In 1912, the German scientist Alfred Wegener had proposed his theory of continental drift, but few believed it. Only in the late Fifties was the movement of tectonic plates understood.
29 June 2011
Antarctic birds should hunt at night, but they don't.
Like daily commuters, Adélie and emperor penguins are up at dawn, catching krill and fish in Antarctic waters, and back home to shore at dusk. Yet the food they prefer to dine on is easiest to catch after dark. Most researchers assumed that penguins had poor night-time vision, which was why they stayed out of the water after dusk.
But in a new study, two marine ecologists argue that the penguins actually have no trouble seeing in the dark. Instead, they say, penguins head for shore at night because they cannot gauge the risk of being eaten by leopard seals or killer whales.
For further details, read the full Science news item.
7 June 2011
Survey data taken across a great swathe of the east of the white continent has allowed scientists to map the shape of the bedrock buried deep under the ice. It reveals in new detail a huge trough hundreds of kilometres long that is cut by fjord-like features.
Researchers tell Nature magazine that this hidden landscape was probably moulded by the action of glaciers more than 14 million years ago. This was a time when Antarctica was only part way through acquiring the extensive ice covering we know today. The team behind the survey work believes its data will improve not only our understanding of Antarctica's past but also its future, as the continent contends with a potentially much warmer world.
"This type of study is important to understand how ice flows in Antarctica and how it will flow in the future," said Professor Martin Siegert, from the University of Edinburgh, UK. "The only way you can do that is with models, and models need topography on which to grow and flow the ice. If our topography doesn't resemble the reality then the outputs from the models won't either," he told BBC News.
7 June 2011
Remote, windswept Macquarie Island in the Southern Ocean is being purged of its rabbits in a massive eradication program designed to reverse more than a hundred years of environmental destruction. Lying between Australia and Antarctica, the island has been over-run by the rabbits which were introduced by sealers in the 1870s as a source of food. Rob Muir reports in a Reuters video news item.
7 June 2011
Global cooling and the development of continental-scale Antarctic glaciation occurred in the late middle Eocene to early Oligocene (~38 to 28 million years ago), accompanied by deep-ocean reorganisation attributed to gradual Antarctic Circumpolar Current (ACC) development. Katz et al in Science (27 May 2011) use benthic foraminiferal stable isotope comparisons to show that a large δ13C offset developed between mid-depth (~600 metres) and deep (>1000 metres) western North Atlantic waters in the early Oligocene, indicating the development of intermediate-depth δ13C and O2 minima closely linked in the modern ocean to northward incursion of Antarctic Intermediate Water. At the same time, the ocean's coldest waters became restricted to south of the ACC, probably forming a bottom-ocean layer, as in the modern ocean. They show that the modern four-layer ocean structure (surface, intermediate, deep, and bottom waters) developed during the early Oligocene as a consequence of the ACC.
For further details, please read the full article in Science
6 June 2011
Why removing some man-made coastal flood defences might not be such a harebrained idea, what it's like studying gas exchange in the wilds of the Southern Ocean, and – in what could be the first case of 'natural' geoengineering – how forests could be whitening the clouds right above them.
David Tupman from the University of Leeds is on a research ship in the wilds of the Southern Ocean to attempt to measure how fast rough seas take up carbon dioxide compared with calm seas. It's not all plain sailing though – as we find out.
6 June 2011
For more than 100 years, researchers have understood that stratosphere ozone, the atmospheric layer between 10 and 50 km above Earth's surface, plays an important role in absorbing ultraviolet radiation and protecting life on Earth. In 1985, scientists and the public became alarmed when it was reported that, during the Antarctic spring, stratospheric ozone concentrations over the continent were declining by as much as 50%, indicating the presence of a polar "ozone hole." Implementation of the 1987 Montreal protocol, an international agreement that phased out the use of some chlorofluorocarbons and other compounds that destroy stratospheric ozone, has led to the first stage of recovery. Researchers, however, had not widely recognized the ozone hole's impact on the climate of the troposphere (the lowest 10 km of the atmosphere) until recent observational and state-of-the-art climate modelling studies. These studies showed that ozone depletion has a large influence during the Antarctic summer, when it drives a major air current called the mid-latitude westerly jet to a higher latitude, closer to Antarctica; this reduces sea level pressure over the continent, cooling much of the continental interior, coinciding with a warming of the Antarctic Peninsula. Kang et al. expand our understanding of ozone depletion's impact on climate. Using a series of carefully designed climate model experiments, they show that ozone-induced climate change is not confined just to the vicinity of Antarctica but extends over much of the Southern Hemisphere, even reaching the tropics, where it appears to have resulted in increased summer precipitation in the subtropics.
23 May 2011
A team of scientists in the United Kingdom and the United States has warned that the native fauna and unique ecology of the Southern Ocean, the vast body of water that surrounds the Antarctic continent, is under threat from human activity. Their study is published this week in the peer-reviewed journal Annals of the New York Academy of Sciences.
"Although Antarctica is still the most pristine environment on Earth, its marine ecosystems are being degraded through the introduction of alien species, pollution, overfishing, and a mix of other human activities," said team member Dr Sven Thatje of the University of Southampton's School of Ocean and Earth Science (SOES), based at the UK's National Oceanography Centre.
Biodiversity can be conceptualised in terms of its information content: the greater the diversity of species and interactions between them, the more 'information' the ecosystem has. "By damaging the ecological fabric of Antarctica, we are effectively dumbing it down - decreasing its information content - and endangering its uniqueness and resilience," said lead author Professor Richard Aronson, a paleoecologist at the Florida Institute of Technology, USA.
Richard B. Aronson, Sven Thatje, James B. McClintock, Kevin A. Hughes. Anthropogenic impacts on marine ecosystems in Antarctica. Annals of the New York Academy of Sciences, 2011; 1223 (1): 82 DOI: 10.1111/j.1749-6632.2010.05926.x
23 May 2011
Diving under the Antarctic ice to get way too close to the much-feared leopard seal, photographer Paul Nicklen found an extraordinary new friend. Share his hilarious, passionate stories of the polar wonderlands, illustrated by glorious images of the animals who live on and under the ice.
Paul Nicklen photographs the creatures of the Arctic and Antarctic, generating global awareness about wildlife in these isolated and endangered environments.
9 May 2011
The brown rat has been a catastrophic introduction to South Georgia. Conservationists say they are pleased with early efforts to kill rats on the island, in what is the biggest rodent eradication campaign in history.
No-one really knows how many rats inhabit the island in the South Atlantic, but it could be millions. Introduced on the ships of sealers and whalers in the 19th and 20th Centuries, the rodents have had a devastating impact on local seabird populations.
But the laying of toxic bait in part of the island seems to have had success. Some 50 tonnes of rodenticide were spread by helicopters in March over a contained zone hemmed in by glaciers. Subsequent inspections on the ground found only dead rats.
Read the full story on the BBC News website.
9 May 2011
||The genome of one of the most successful species on Earth, Antarctic Krill, will be sequenced for the first time thanks to a new Australian Government $300,000 Antarctic Science Fellowship.
The inaugural R J L Hawke Post Doctoral Fellowship in Antarctic Environmental Science has been awarded to geneticist, Dr Bruce Deagle. The award honours former Prime Minister Bob Hawke's contribution to protecting the frozen continent.
Dr Deagle will use modern genetic technologies to sequence the crustacean's genome, as well as examine gene expression and how this relates to temperature and ocean acidification.
3 May 2011
In May 2009 in Wilhelmina Bay on the Western Antarctic Peninsula, researchers on the Lawrence M. Gould found a swarm of more than than two million tons of krill — the biggest, densest swarm documented in more than 20 years. And the next morning, the sun revealed another surprise: hundreds of humpback whales in the highest concentration ever recorded. The discovery of the krill and whale "super-aggregations" sheds light on an important but overlooked foraging ground for the endangered humpbacks — one that may be threatened by the region's rapidly changing climate.
The reigning wisdom has been that humpbacks feed in the Antarctic through the summer until krill move from offshore waters to take shelter from predators below the encroaching sea ice in the Austral fall. The whales then migrate to warmer breeding grounds, where the highest humpback densities had previously been observed. But during the six weeks the researchers spent on the Gould documenting the interaction between humpbacks and krill in Wilhelmina Bay and nearby waters, they counted 306 humpbacks parked on the huge krill swarm, and a total of 500 throughout the unusually ice-free bay at the record-setting density of 5.1 whales per square kilometer.
The researchers attribute their findings to the rapid warming in the Antarctic Peninsula, which now has up to 80 more ice-free days per year than it did a few decades ago. With such a rich banquet of krill, the humpbacks seem to be lingering longer into the winter — and the researchers suspect that some may even stay all year round. The team detected males singing, a behaviour usually restricted to breeding grounds.
That may be good news for the whales in the short term, but the long-term forecast is less rosy, researchers Nowacek and Friedlaender say. Krill require a cover of sea ice to spawn and hide from predators, and recent Antarctic krill declines have been linked to the retreating ice. Despite its size, the huge swarm in Wilhelmina Bay and others like it are probably vulnerable, too. In the long-run, the waning ice could hurt both the crustaceans and their numerous predators.
13 April 2011
A number of penguin species found in western Antarctica are declining as a result of a fall in the availability of krill, a study has suggested. Researchers, examining 30 years of data, said chinstrap and Adelie penguin numbers had been falling since 1986. Warming waters, less sea-ice cover and more whale and seal numbers was cited as reducing the abundance of krill, the main food source for the penguins. The findings appear in the Proceedings of the National Academy of Sciences.
Antarctic krill (Euphausia superba) is a shrimp-like creature that reach lengths of about 6cm (2in) and is considered to be one of the most abundant species on the planet, being found in densities of up to 30,000 creatures in a cubic-metre of seawater. It is also one of the key species in the ecosystems in and around Antarctica, as it is the dominant prey of nearly all vertebrates in the region, including chinstrap and Adelie penguins.
In their paper, a US team of scientists from the National Oceanic and Atmospheric Administration (NOAA) and the Scripps Institution of Oceanography said a number of factors were combining to change the shape of the area's environment. "The West Antarctic Peninsula (WAP) and adjacent Scotia Sea support abundant wildlife populations, many of which were nearly [wiped out] by humans," they wrote.
They added that analysis of data gathered during 30 years of field studies, and recent penguin surveys, challenged a leading scientific idea, known as the "sea-ice hypothesis", about how the region's ecosystems was changing. "(It) proposes that reductions in winter sea-ice have led directly to declines in 'ice-loving' species by decreasing their winter habitat, while populations of 'ice-avoiding' species have increased," they explained.
However, they said that their findings showed that since the mid 1980s there had been a decline in both ice-loving Adelies (Pygoscelis adeliae) and ice-avoiding chinstraps (Pygoscelis antarctica), with both populations falling by up to 50%. As a result, the researchers favoured a "more robust" hypothesis that penguin population numbers were linked to changes in the abundance of their main food source, krill.
11 April 2011
Although ozone-destroying chemicals have been in decline for a decade now, scientists have long projected that they will not glimpse the first signs that the Antarctic ozone hole is healing until well past 2020. But for the first time, a group of researchers, in a paper now in press in Geophysical Research Letters (GRL), claim there is evidence that the ozone hole is already recovering.
For further details, read the article in Science.
11 April 2011
Chilean Antarctic survey finds dramatic variety of organisms adapted to unusual conditions
You might not expect bacteria living in Antarctic ice to be well suited to life in a boiling kettle, but that is what Chilean scientists discovered during an expedition last year. The researchers have turned up more than 200 new species of microorganisms adapted to living in extreme environments.
"We have discovered over 300 microorganisms, of which 70% correspond to new species," says Jenny Blamey, a biochemist and director of the Biosciences Foundation in Santiago, a leading organisation in Antarctic Bioresources, a public–private initiative begun in 2008 to identify biological resources with potential biotechnological uses in this largely unexplored territory. She and her colleagues were part of Antarctic Scientific Expedition 47 (ECA-47), which was organized by the Chilean Antarctic Institute in Puntas Arenas and involved multiple research projects over the southern summer of 2010–11.
As might be expected, the group discovered many psychrophiles — organisms that thrive in conditions cooler than 15 ºC — as well as halophiles, which survive in high concentrations of salt, and acidophiles and alkaliphiles, which can tolerate extremes of pH. But the researchers also found a surprising number of thermophiles and hyperthermophiles, which prefer temperatures above 50 ºC, including one microbe that could survive at 95 ºC despite spending its life encased in the ice. Such an organism, they say, must have evolved when the Antarctic environment was very different to how it is today.
11 April 2011
First of the parasitic parasites to be discovered in a natural environment points to hidden diversity
A genomic survey of the microbial life in an Antarctic lake has revealed a new virophage — a virus that attacks viruses. The discovery suggests that these life forms are more common, and have a larger role in the environment, than was once thought.
An Australian research team found the virophage while surveying the extremely salty Organic Lake in eastern Antarctica. While sequencing the collective genome of microbes living in the surface waters, they discovered the virus, which they dubbed the Organic Lake Virophage (OLV). The OLV genome was identified nestling within the sequences of phycodnaviruses — a group of giant viruses that attack algae. Evidence of gene exchange, and possible co-evolution, between the two suggests that OLV preys on the phycodnavirus. Although OLV is the dominant virophage in the lake, the work suggests others might be present.
By killing phycodnaviruses, the OLV might allow algae to thrive. Ricardo Cavicchioli, a microbiologist at the University of New South Wales in Sydney, Australia, and his colleagues found that mathematical models of the Organic Lake system that took account of the virophage's toll on its host showed lower algal mortality and more blooms during the lake's two ice-free summer months.
"Our work reveals not only an amazing diversity in microbial life in this lake, but also how little we understand about the complexity of the biological functions at work," says Cavicchioli. The findings are published in the Proceedings of the National Academies of Science1.
Another virophage described this month has similar ecological effects. The marine Mavirus attacks the giant Cafeteria roenbergensis virus, which preys on Cafeteria roenbergensis, one of the world's most widespread species of zooplankton2.
"The Mavirus is able to rescue the infected zooplankton — which, in a way, confers immunity from infection," says Curtis Suttle, a marine microbiologist at the University of British Columbia in Vancouver, Canada, and leader of the team that discovered the Mavirus. "We unknowingly had Mavirus in culture with our Cafeteria system since the early 1990s," says Suttle. But the virophage was not identified until the Cafeteria genome was sequenced.
The Mavirus genome is similar to DNA sequences called eukaryotic transposons, which insert themselves within the genomes of multicellular organisms such as plants and animals. These 'jumping genes' may be descended from a virophage, says Suttle. "One can imagine evolutionary pressure for hosts to somehow cultivate virophages to protect themselves from infection by giant viruses," he says.
6 April 2011
The last volume of the expedition newspaper, South Polar Times, written by the men waiting for news of Captain Scott's return from the South Pole in the Antarctic winter of 1912, has just been published in a limited edition by the Scott Polar Research Institute.
The journal was written and produced during Scott's 1910-13 Terra Nova expedition to Antarctica, during the winter of 1912, when those remaining at the base camp at Cape Evans knew that Scott and his Pole party must have perished somewhere south.
The contributors to the original volume would have been aware that Scott and his companions stood no chance of survival. Although there are attempts at humour and the text is enlivened with quirky illustrations, the loss of Scott and the other four members of the Polar Party overshadows this issue, put together to maintain morale during the long Polar night.
In 1959, former Director of the Scott Polar Research Institute, Frank Debenham, who had been the expedition's geologist, said: "It is noticeable that there is no reference whatever to the fate or the personnel of the Pole Party or even of the Northern Party though the preparations for the search next sledging season was the main pre-occupation of all hands."
The volume is filled with humorous tales, verses on food and man-hauling, records of the weather and an article entitled Universitas Antarctica on the men's scientific interests. This new volume includes a full colour facsimile of the illustrated typescript of South Polar Times, volume IV, dated Midwinter Day 1912. It was originally edited by Apsley Cherry-Garrard, famous as the author of The Worst Journey in the World.
For more information, read the full article on the University of Cambridge website.
6 April 2011
The Royal Society for the Protection of Birds (RSBP), along with other local conservationists and volunteers, are working hard to save a colony of threatened penguins after a devastating oil spill in the Tristan da Cunha archipelago.
On the 16 March 2011, a cargo vessel the MS Oliva, crashed into Nightingale Island, which includes nearly half of the world population of the Northern Rockhopper penguin (Eudyptes moseleyi), one of the world's most threatened species of penguin. At least 1,500 oil-soaked Rockhoppers have now been put into 'rehab', but those assessing the disaster believe more than 10,000 birds could have been affected.
Katrine Herian, who works for the RSPB on the island, says: "The priority is to get food into the birds as they are very hungry. We are trying locally caught fish and some are starting to take small half inch squares of the food. We will do all we can to clean up as many penguins as possible after this disaster."
Sarah Sanders from the RSPB's International Division says: "We still can't believe this has happened and suspect that the full impacts of the oil spill will still be coming to light in weeks to come. Unlike previous spills of this size, it didn't happen way out to sea and gradually approach such a vital conservation area. It struck right at the heart of the penguin colony and it's devastating to them."
29 March 2011
In a finding that has global implications for climate research, scientists have discovered that when icebergs cool and dilute the seas through which they pass for days, they also raise chlorophyll levels in the water that may in turn increase carbon dioxide absorption in the Southern Ocean.
An interdisciplinary research team supported by the National Science Foundation (NSF) highlighted the research this month in the journal Nature Geoscience. The research indicates that "iceberg transport and melting have a role in the distribution of phytoplankton in the Weddell Sea," which was previously unsuspected, said John J. Helly, director of the Laboratory for Environmental and Earth Sciences with the San Diego Supercomputer Center at the University of California, San Diego and Scripps Institution of Oceanography.
Helly was the lead author of the paper, first published in the journal Deep-Sea Research Part II. The results indicate that icebergs are especially likely to influence phytoplankton dynamics in an area known as "Iceberg Alley," east of the Antarctic Peninsula, the portion of the continent that extends northwards toward Chile.
The latest findings add a new dimension to previous research by the same team that altered the perception of icebergs as large, familiar, but passive, elements of the Antarctic seascape. The team previously showed that icebergs act, in effect, as ocean "oases" of nutrients for aquatic life and sea birds. The teams's research indicates that ordinary icebergs are likely to become more prevalent in the Southern Ocean, particularly as the Antarctic Peninsula continues a well-documented warming trend and ice shelves disintegrate. Research also shows that these ordinary icebergs are important features of not only marine ecosystems, but even of global carbon cycling.
"These new findings confirm that icebergs contribute yet another, previously unsuspected, dimension of physical and biological complexity to polar ecosystems," said Roberta L. Marinelli, director of the NSF's Antarctic Organisms and Ecosystems Program.
The researchers studied the effects by sampling the area around a large iceberg more than 32 kilometres (20 miles) long; the same area was surveyed again ten days later, after the iceberg had drifted away. After ten days, the scientists observed increased concentrations of chlorophyll a and reduced concentrations of carbon dioxide, as compared to nearby areas without icebergs. These results are consistent with the growth of phytoplankton and the removal of carbon dioxide from the ocean. The new results demonstrate that icebergs provide a connection between the geophysical and biological domains that directly affects the carbon cycle in the Southern Ocean, Marinelli added.
17 March 2011
The major earthquake that hit Japan on Friday caused a massive ice stream in Antarctica to momentarily speed up.
As the surface seismic waves generated by the quake travelled around the world, they appear to have given the Whillans ice stream in West Antarctica a nudge, causing it to slide by about half a metre.
The movement was picked up by Jake Walter of the University of California, Santa Cruz, and his colleagues, who monitor the glacier remotely from California. They say the event is an "interesting insight", but are not suggesting it will destabilise the ice stream in any way.
The Whillans ice stream drains ice from the West Antarctic Ice Sheet into the Ross Ice Shelf. Since 2007, Walter and colleagues have been using GPS field stations on the ice sheet to monitor its movements. They have shown that the ice stream speeds up twice a day in slip events which last about 30 minutes.
15 March 2011
A small colony of emperor penguins on an island off the West Antarctic Peninsula is gone, and the most likely culprit is loss of sea ice caused by warming. Although it has been predicted that penguins could suffer greatly because of global warming, this is the first time the disappearance of a colony has been documented.
The researchers, however, caution that their study is hampered by a lack of long-term information on emperor penguins, both at this site and in general, and their environment.
Emperor penguins are regal, if bulky, birds that stand as high as 4 feet (1.2 meters) and can weigh as much as 84 pounds (38 kilograms). This colony, first spotted in 1948 on an island dubbed Emperor Island, was a small one that had approximately 150 breeding pairs.
Observations are spotty, but the populations appear to have been relatively stable until the 1970s. A report in 1978 showed a sharp drop in population, a trend that continued until an airplane survey found the island empty in 2009.
This raises the question: Did the penguins die off or just relocate? "That's one of the big unknowns," said Philip Trathan, the lead researcher and head of conservation biology at the British Antarctic Survey.
The cause of the disappearance is not clear-cut, but the evidence indicates a connection to climate change. It's possible that factors including disease or extreme weather may have caused this particular colony to disappear, but there is no data available to test these hypotheses, Trathan said.
"We need to look at more colonies so we can reduce the uncertainty," he said.
7 March 2011
|"Crazy green" pools teeming with life have been found among remote Antarctic sea ice, scientists say — and they may be a global warming boon.
Observed in the little-studied Amundsen Sea, the brilliant blooms owe their colours to chlorophyll, a pigment in various types of phytoplankton, or tiny algae. Algae-eating zooplankton, small crustaceans called krill, and fish and shrimp larvae also thrive in the area. A recent scientific expedition studied the blooms while plying the Amundsen Sea's polynya, a region of seasonally open water surrounded by sea ice.
Often hundreds of miles wide, polynyas are nutrient-rich "oases" that offer refuges for animals big and small, according to Patricia Yager, chief scientist for the Amundsen Sea Polynya International Research Expedition (ASPIRE), which is funded by the U.S. National Science Foundation and the Swedish Polar Research Secretariat. The open pockets occur for two reasons: because wind blows chunks of ice away from the coast, and because warm air or an upwelling of warmer water melts sections of ice away.
Photo of the emerald green waters of a polynya in Antarctic
When summer sea ice melts, it can release micronutrients into the ocean that supercharge algae blooms. Micronutrients are trace amounts of elements, such as iron, that are essential for plant growth. As glaciers and sea ice in western Antarctica begin to melt due to global warming, a greater influx of micronutrients may flow into the oceans and fuel bigger algae blooms, Yager said in an interview. Such an algae explosion may actually be a climate boon, since the plants gobble up more of the greenhouse gas carbon dioxide — but only to a point, she warned.
7 March 2011
The ice surface of Antarctica, looking toward the Gamburtsev
When it comes to ice, scientists are giving a whole new meaning to the phrase "bottoms up." Those massive ice sheets in Antarctica don't just grow on top when snow falls, they also grow from the bottom up, according to new research published on 3rd March.
The warmth of the planet causes ice melts at the bottom of ice sheets, and the water helps the sheets slide across the ground below. But the water can refreeze to the bottom of the sheets and push them up, the researchers report in the online edition of the journal Science.
The base of a massive ice plateau on the East Antarctic ice sheet called Dome A is about 24 percent refrozen water, according to the team headed by Robin Bell, a geophysicist at Columbia University's Lamont-Doherty Earth Observatory. According to the observations, massive ice blocks seem to form when liquid water — propelled by the pressure of the ice — moves up the steep walls of the Gamburtsev mountains. As the water rises, it encounters lower temperatures and less pressure from overlying ice, so it refreezes.
See also the related article in Science: 'Antarctica's Deep Frozen "Lakes" ' by Tulaczyk and Hossainzadeh.
22 February 2011
Samples of a marine creature collected during Captain Scott's Antarctic trips are yielding data that may prove valuable in projecting climate change.
The expeditions in the early 1900s brought back many finds including samples of life from the sea floor. Comparing these samples with modern ones, scientists have now shown that the growth of a bryozoan, a tiny animal, has increased in recent years. They say this means more carbon dioxide is being locked away on the ocean bed.
Read the full article on the BBC News Science and Environment section.
8 February 2011
A Russian drilling team hoping to reach the surface of Lake Vostok, a vast freshwater lake 3,750 metres under Antarctica's ice-sheet, appears to have run out of time as the region's summer drilling season draws to a close. On the 7 February 2011, Valery Lukin, director of the Russian Antarctic programme, confirmed that drilling at Lake Vostok stopped on 5 February at a depth of 3720.47 metres - 29.53 metres short. The drilling team left by aircraft on 6 February. Drilling will resume in December 2011.
8 February 2011
It may be hard to believe, but Antarctica was once covered in towering forests. One hundred million years ago, the Earth was in the grip of an extreme Greenhouse Effect. The polar ice caps had all but melted and rainforests inhabited by dinosaurs existed in their place. These Antarctic ecosystems were adapted to the long months of winter darkness that occur at the poles, and were truly bizarre. But if global warming continues unabated, could these ancient forests be a taste of things to come?
31 January 2011
Concern over human-driven climate change and the lack of success in constraining greenhouse gas emissions have increased scientific and policy interest in geoengineering − deliberate interventions in the Earth's climate system that might moderate global warming. Proposed approaches involve either removing carbon dioxide (CO2) from the atmosphere by biological or chemical means (to reduce the forcing of climate change), or reflecting part of the sun's energy back into space (to counteract the forcing, by altering Earth's radiation budget).
A recent report from UNESCO considers the practicalities, opportunities and threats associated with one of the earliest proposed carbon-removal techniques: large-scale ocean fertilization, achieved by adding iron or other nutrients to surface waters, directly or indirectly. The intention is to enhance microscopic marine plant growth, on a scale large enough not only to significantly increase the uptake of atmospheric carbon by the ocean, but also to remove it from the atmosphere for long enough to provide global climatic benefit. This suggestion grew out of scientific ideas developed in the late 1980s, based on analyses of natural, longterm climate changes (ice age cycles) and experiments that provided new insights into the natural factors that limit ocean productivity, and thereby control the cycling of carbon between sea and sky. Proposals for large-scale application of ocean fertilization have been controversial, attracting scientific and public criticism. Upholding the precautionary principle, the Convention on Biological Diversity (CBD) decided in 2008 that no further ocean fertilization activities for whatever purpose should be carried out in non-coastal waters until there was stronger scientific justification, assessed through a global regulatory mechanism.
Read the full Ocean Fertilization report from UNESCO.
13 January 2011
For decades, the standard practice for studying penguins — well established as bellwethers of climate change — has been to tag the birds with flipper bands. It is a controversial technique, however, with conflicting reports on whether the tags themselves can alter the birds' behaviour. Now, the results of a ten-year study of free-ranging king penguins provide convincing evidence that banding is harmful. Banded birds had a markedly lower survival rate, with every major life-history trait affected, and they were more affected by climate variation than birds without bands. As well as raising doubts over marine ecosystem data based on banding, this work has implications for the ethics of animal tagging.
10 January 2011
The deep Antarctic cold has created an ideal natural medium for detecting high-energy neutrinos. At a depth of 1.5 kilometres below the surface, the sheer weight of the overlying layers at the South Pole keeps the Antarctic ice sheet free of air bubbles and thus perfectly clear. Within its dark, transparent depths, even a faint flash of light can be spotted at some distance — including the kind of flash signalling that a fast-moving neutrino has hit an oxygen atom sitting in the ice and produced a muon.
The final Neutrino detector, a basketball-sized optical sensor, was the 5160th to be placed since construction began on IceCube in 2005. Since then, every Antarctic summer, researchers have used a jet of near-boiling water to drill holes in the ice. At every hole, a kilometre-long string of detectors was lowered down and the hole allowed to refreeze.
Now complete, at a cost of about US$271 million, IceCube monitors a cubic kilometre of ice — the size required for the experiment to have a realistic chance of spotting its rare and elusive quarry. But as the instrument has grown, so has its scope. Over the years, the team has realised that IceCube might also shed light on a broader range of questions, including an understanding of physics beyond the standard model.
For further details, read the full Nature article.