Scientists may have solved a key riddle about Antarctica — and you’re not going to like the answer


Sirius Group exposures near Mount Fleming, Antarctica, circa 1986. The snow pattern behind rocks shows prevailing winds across the East Antarctic Ice Sheet.
This story has been updated.

It’s one of the great — and unresolved — debates of Antarctic science.

In 1984, a team of Ohio State University researchers reported a surprising fossil find: More than a mile above sea level, in Antarctica’s freezing Transantarctic mountain range, fossilized deposits of tiny marine organisms called diatoms were found in rock layers dated to the Pliocene era, some 2 million to 5 million years ago. But how did they get all the way up there? Diatoms, ubiquitous marine microorganisms whose tiny shells coat the ocean floor when they die, wouldn’t show up in high, inland mountain rocks unless something rather dramatic happened, long ago, to transport them.

So began a storied debate over this rock formation, dubbed the “Sirius Group” after Mount Sirius, one of the range’s many peaks. It was between the “dynamicists,” on the one hand, and the “stabilists” on the other. The dynamicists argued that the enormous ice sheet of East Antarctica had dramatically collapsed in the Pliocene, bringing the ocean far closer in to the Transantarctic range, and that subsequent upthrusts of the Earth and re-advances of glaciers had then transported the diatoms from the seafloor to great heights. No way, countered the stabilists: The ice sheet had stayed intact, but powerful winds had swept the diatoms all the way from the distant sea surface and into the mountains.

“It became very much split into two camps,” remembers Reed Scherer, an Antarctic researcher at Northern Illinois University. “It got really nasty.” Some researchers even tried to resolve matters by suggesting that a meteorite, and subsequent cataclysms unleashed by it, could account for the odd fossil locations.

But the decades have given way to new research tools and new perspectives. And Scherer has now paired up with two researchers behind what is arguably the hottest (and most troubling) new computer simulation of how Antarctica’s ice behaves, using their model to revisit the tale of those pesky diatoms. Their solution, published Tuesday in Nature Communications, isn’t good news — for it suggests that large parts of East Antarctica can indeed collapse, and moreover, can do so in conditions not too dissimilar from those we’re creating today with all of our greenhouse gas emissions.

If we steer the Earth back to those Pliocene-type conditions — when sea levels are believed to have been radically higher around the globe — oddly located diatoms will be the least of our problems.


The new study is co-authored by Rob DeConto of the University of Massachusetts, Amherst, and David Pollard of Pennsylvania State University, who recently published a new ice sheet model of Antarctica that predicts the ice continent can melt and raise sea levels by nearly a meter, on its own, during this century. They reached this result by adding several new dynamic ice collapse processes to glacial models that, in the past, had been slow to melt East Antarctica even in quite warm conditions. These models had lent weight to the views of the stabilists in the debate over the Sirius fossils, while also seeming to suggest that we needn’t worry about truly radical sea-level rise from Antarctica.

The new study suggests otherwise. In the Pliocene — and especially the mid-Pliocene warm period, when atmospheric carbon dioxide was at about the level where it is now, 400 parts per million, but global temperatures were 1 or 2 degrees Celsius warmer than at present — the model not only collapses the entirety of West Antarctica (driving some 10 feet of global sea-level rise) but also shows the oceans eating substantially into key parts of East Antarctica. In particular, the multi-kilometer thick ice that currently fills the extremely deep Aurora and Wilkes basins of the eastern ice sheet retreats inland for hundreds of miles — which would have driven global seas to a much higher level than a West Antarctic collapse alone.
From Scherer et al, Nature Communications. The image depicts a computer simulation of what Antarctica may have looked like in the Pliocene era, with West Antarctica gone and major retreat of the ice in the Wilkes Basin (WB) and Aurora Basin (AB) of East Antarctica. The red spots indicate locations where diatoms have been found in Sirius Group rocks in the Transantarctic range. Brown areas depict previously below sea level regions that rebounded after ice retreat.
Not only is this the world we could be headed to if global warming continues. It’s also a world that can hurl diatoms up into the Transantarctic Mountains, the new study argues. Here’s how that would work.

At first, in the wake of ice retreats in the Aurora and Wilkes basins, what would be left behind are ocean bays filled with life — and many, many diatoms. But Scherer and his colleagues do not believe that winds simply scooped them out of the water and lifted them into the mountains — living, wet diatoms suspended in water would have been too heavy to travel so far, Scherer says.

So instead, the study postulates another development. After a few thousand years of seas filled with happy diatoms, dying and lining the ocean floor in front of the remnant glaciers of the Wilkes and Aurora basins, the once submerged Earth would slowly rebound in some spots (a process sometimes called “isostatic uplift” or “postglacial rebound”). This would create an archipelago of islands, new landmasses free to rise to the surface now that so much ice has sloughed off their backs.

These islands rising from the sea, then, were the source of the diatoms, the study postulates.

The computer model “did show the ice retreated along the margins of East Antarctica, and isostatic uplift would then expose these areas that become new seaways, and with it would have been highly productive for plankton,” says Scherer. “So you would have been accumulating massive numbers of diatoms across this new basin, and with the loss of the ice, the land flexed upward, became exposed to winds, and the wind carried them to the mountains.”

Scherer notes that this new scenario doesn’t really proclaim either the dynamicists or the stabilists the victors. Rather, it merges their perspectives. His view is clearly reliant on a substantial amount of dynamics, but it also doesn’t suggest that the East Antarctica ice retreated nearly as far back as earlier proposals did. Nor does it use glacial processes to move the deposited diatoms. Rather, it borrows the stabilist idea of windblown transport, albeit only after ice has retreated and land has risen in its wake.

Commenting on this new compromise proposal Monday, one Antarctic researcher praised the work as representing an advance on old ways of thinking. “The paper is a great example of how much (paleo)climate modeling has improved in the last decade(s), particularly in the last few years,” said Simone Galeotti, an Antarctic researcher at the Università degli Studi di Urbino in Italy, by email.

The research also earned praise from David Harwood, one of the original dynamicists and now a professor at the University of Nebraska-Lincoln.
“This paper’s integration of climate, ice sheet, and atmospheric models provides interesting new perspective on potential source regions for the Antarctic, marine Pliocene diatoms present in glacial sediments of the Transantarctic Mountains, from interior basins of East Antarctica,” said Harwood in an emailed statement. “Their origin from deglaciated, exposed, rebounded marine basin floors in the Aurora and Wilkes basins is plausible, and the new model-derived wind patterns support their trajectory toward the [Transantarctic Mountains].”

Harwood therefore said that the study “comes close” to resolving the old debate between “dynamicists” and “stabilists” over the fossils.

“Bottom line, this paper suggests that marine diatoms in the Sirius Group do reflect dynamic ice behavior and Pliocene ice sheet retreat, just not of the scale suggested initially by Webb/Harwood,” he said, referring to the initial study that started off the debate. “Kind of like being right for the wrong reason.”

But beyond solving the riddle of the Sirius deposits in the Transantarctic Mountains, the new study also speaks strongly to the present moment. After all, the warm Pliocene, with its much higher seas, is one of the key past eras that scientists look to for an analogue for where we are currently driving the planet with our greenhouse gases.

Why researchers nearly doubled sea level rise estimates for the year 2100 Play Video1:13
[Why the Earth’s past has scientists so worried about sea level rise]

And thus, the new work suggests that if we keep pushing the system, we’ll not only have to worry about the loss of Greenland’s and West Antarctica’s ice, but also major losses from the biggest ice sheet of them all, East Antarctica.

Scherer, DeConto, and Pollard also have a fourth author on the study, the noted Penn State glaciologist Richard Alley, who has become more and more outspoken of late about his concerns that the world’s great ice sheets could be unstable. In a media statement accompanying the study’s release, Alley had this to say:

This is another piece of a jigsaw puzzle that the community is rapidly putting together, and which appears to show that the ice sheets are more sensitive to warming than we had hoped. If humans continue to warm the climate, we are likely to commit to large and perhaps rapid sea-level rise that could be very costly. No one piece of the puzzle shows this, but as they fit together, the picture is becoming clearer.

In other words, solving this key scientific problem from Antarctica’s past turns out to immediately raise major concerns about its future.
“We have now reached a point where atmospheric CO2 levels are as high as that during the Pliocene, 400 ppm, when geological evidence and new model results suggest substantial retreat of the EAIS [East Antarctic Ice Sheet] margin into interior basins. These perspectives bear fundamentally on predictions of future EAIS behavior,” said Harwood by email.

Granted, on a scientific and individual level, there’s also the satisfaction of finally being able to unify quite a lot of information into an explanation that fits the data and also matches our growing present day understanding of Antarctic vulnerability.
“Personally, I find the story rather cathartic, because it does explain the observations, I think, in a much better way than had been done before,” says Scherer.

Thousands of strange blue lakes are appearing in Antarctica, and it’s very bad news


Scientists have confirmed that thousands of pristine blue lakes have appeared on the ice sheets of East Antarctica, and it’s got them very worried.

The problem? They’ve seen this kind of thing happen before. Greenland’s ice sheet has been disintegrating rapidly, losing a whopping 1 trillion tonnes of icebetween 2011 and 2014, and research suggests it’s because of these lakes.

A team of UK researchers has analysed hundreds of satellite images and meteorological data taken of the Langhovde Glacier in East Antarctica, and found for the first time that between 2000 and 2013, nearly 8,000 of these lakes had formed.

Some of these formations, known as supraglacial – or meltwater – lakes, appear to be draining into the floating ice below, which could have serious consequences for the stability of the entire ice shelf.

Ice shelves are thick, floating slabs of ice that form where a glacier or masses of ice flow down a coastline, whereas an ice sheet is a massive chunk of glacier ice covering an area of land greater than 50,000 square kilometres (20,000 square miles).

What’s strange about this news is the fact that researchers had assumed that East Antarctica was fairly impervious to rising climate and ocean temperatures, and have instead been focussing their efforts on investigating the Antarctic Peninsula.

The Antarctic Peninsula is the northernmost part of the mainland of Antarctica, and has shown signs of rapid atmospheric and ocean warming in recent years.

The disintegration of the East Antarctic ice sheet, on the other hand, has been more subtle, and now researchers are concerned that our lack of knowledge on how supraglacial lakes are affecting it will impact our ability to predict the consequences.

“[East Antarctic is] the part of the continent where people have for quite a long time assumed that it’s relatively stable,” one of the team, glaciologist Stewart Jamieson from Durham University, told Chris Mooney at The Washington Post.

“There’s not a huge amount of change, it’s very, very cold, and so, it’s only very recently that the first supraglacial lakes, on top of the ice, were identified.”

As Mooney explains, as the air temperatures rise during the summer months, these supraglacial lakes form on the surface of the ice sheets, and on the slender glaciers that stretch out into the ocean.

These lakes don’t last long – they either disappear through refreezing (the best option), drain vertically through the floating ice, or overflow into rivers on the surface that drain into the ice below.

These last two options have been shown in Greenland’s case to eat away at and weaken the structure of the ice sheets and ice shelves, hastening their own disintegration.

“Sometimes, researchers have even been able to document fresh water flowing outward directly into the sea from the base of a glacier,” Mooney says.

“That injection of cold fresh water into salty water can then create tornado-like underwater flow patterns at the submerged glacier front that cause further ice loss.”

So why did thousands of these things suddenly appear in East Antarctica over the course of just three years? You guessed it – climate change.

The team found that over the 13-year period they studied, the warmest (Southern Hemisphere) summer was between 2012 and 2013, with a total of 37 “positive degree days”, and a mean daily surface air temperature of 0.8 degrees Celsius in January.

For comparison, the 2007/2008 summer had just five positive degree days and a mean daily surface air temperature of -1.8 degrees Celsius in January.

During this 2012/2013 summer, Langhovde’s glacier surface experienced 36 percent more new lakes and surface channels overspilling than ever before.

“What we find is that the appearance of these lakes, unsurprisingly, is correlated directly with the air temperature in the region, and so the maximum number of lakes, and the total area of the lakes, as well as the depth of the lakes, all of these things peak when the air temperatures peak,” Jamieson told The Washington Post.

The researchers aren’t ready to call this the beginning of the end of the East Antarctic ice sheet just yet, saying that if things stayed as they are, we wouldn’t have much to worry about.

But with July 2016 being confirmed as the world’s hottest month since records began, and the 10th consecutive month of record-breaking heat across the globe, historic levels of rising temperatures are something we’re going to have to get used to, and that could mean more and more supraglacial lakes.

“The size of the lakes … are probably not big enough to do much at present, but if climate warming continues in the future, we can only expect the size and number of these lakes to increase. So that’s what we’re looking at,” Jamieson says.

A subglacial lake has been found beneath Antarctica.


The Antarctic ice conceals a smorgasbord of secrets.

Once a warm forested part of the world during the age of the dinosaurs, many fossils of which are just waiting to be excavated, it also features the world’s largest canyon system and a treasure trove of meteorites that were forged in the fiery furnace at the beginning of the Solar System.

antarctica ice cave hole noaa

There are also liquid freshwater lakes beneath the surface of the icy realm.

Lake Vostok is probably the most well-known: After being left undisturbed for around 25 million years, scientists were overcome with curiosity and it was carefully breached.

Now it appears that researchers have another subterranean lake to add to their increasingly diverse collection of hidden geological gems. As revealed by the research team at the annual gathering of the European Geophysical Union (EGU) in Vienna this month, it is second only in size to the enormous Lake Vostok. The findings were reported by Motherboard.

Lake Vostok Antarctica

Ice at the surface is shaped by what type of rock it’s resting on, so by looking at unusual geographic features using ground-penetrating radar, scientists are able to make good guesses as to what may be concealed beneath. This time around, a collection of grooves at the surface revealed to the international team – who were in fact responsible for the canyon discovery last year using the same method – that a subglacial lake, complete with its own channels, still exists beneath the ice.

The lake itself is around 100 kilometers (62 miles) long, 10 kilometers (6.2 miles) wide, and isribbon-shaped. It also appears connected to the canyon, and channels leading away from it may be transporting water towards the West Ice Shelf and into the ocean.

The researchers, from the UK, China and the US, are meeting this May to discuss the radar data that they have independently gathered, in order to try and absolutely confirm the existence of both the canyon system and the subglacial lake. Both would be of immense interest to biologists, who are keen to explore ecosystems that have remained untouched for tens of millions of years.

Antarctica

Whether or not these newly-discovered regions contain life is yet to be seen. However, this possibility isn’t a particularly unlikely one: The research team investigating Lake Vostok, for example, have found hints that simple microbes could still be thriving at these icy depths.

Possibly heated by hydrothermal activity – hot, mobile fluids associated with volcanic processes – Vostok was reported to have evidence of more than 3,500 different DNA sequences hiding within it, from bacteria and archaea to viruses and even fish. However, the study in question has been openly doubted by other researchers, so more data is required before this can be settled.

Life, however, has indeed been found in other lakes across the icy continent. A drill core from one, Lake Whillans, contained 130,000 cells per milliliter of subglacial lake water, which is a density of life similar to that found in the depths of the world’s oceans.

This microbial life has survived without sunlight for up to 1 million years, so it seems more than likely that it can also be found in more of Antarctica’s 350 buried lakes – including, of course, this new addition to the family.

SUDDEN ONSET OF ICE LOSS IN ANTARCTICA SO LARGE IT AFFECTS EARTH’S GRAVITY FIELD


A glacier system on Livingstone Island located near the Antarctic Peninsula, discharging ice into the ocean Credit: Dr Alba Martin-Español

A group of scientists, led by a team from the University of Bristol, UK has observed a sudden increase of ice loss in a previously stable region of Antarctica. The research is published today inScience.

Using measurements of the elevation of the Antarctic ice sheet made by a suite of satellites, the researchers found that the Southern Antarctic Peninsula showed no signs of change up to 2009. Around 2009, multiple glaciers along a vast coastal expanse, measuring some 750km in length, suddenly started to shed ice into the ocean at a nearly constant rate of 60 cubic km, or about 55 trillion litres of water, each year.

This makes the region the second largest contributor to sea level rise in Antarctica and the ice loss shows no sign of waning.

Dr Bert Wouters, a Marie Curie Fellow at the University of Bristol, who lead the study said: “To date, the glaciers added roughly 300 cubic km of water to the ocean. That’s the equivalent of the volume of nearly 350,000 Empire State Buildings combined.”

The changes were observed using the CryoSat-2 satellite, a mission of the European Space Agency dedicated to remote-sensing of ice. From an altitude of about 700km, the satellite sends a radar pulse to Earth, which is reflected by the ice and subsequently received back at the satellite. From the time the pulse takes to travel, the elevation of the ice surface can retrieved with incredible accuracy. By analysing roughly 5 years of the data, the researchers found that the ice surface of some of the glaciers is currently going down by as much as 4m each year.

The ice loss in the region is so large that it causes small changes in the gravity field of the Earth, which can be detected by another satellite mission, the Gravity Recovery and Climate Experiment (GRACE).

“The fact that so many glaciers in such a large region suddenly started to lose ice came as a surprise to us,” continued Dr Wouters. “It shows a very fast response of the ice sheet: in just a few years the dynamic regime completely shifted.”

Data from an Antarctic climate model shows that the sudden change cannot be explained by changes in snowfall or air temperature. Instead, the team attributes the rapid ice loss to warming oceans.

Many of the glaciers in the region feed into ice shelves that float on the surface of the ocean. They act as a buttress to the ice resting on bedrock inland, slowing down the flow of the glaciers into the ocean. The westerly winds that encircle Antarctica have become more vigorous in recent decades, in response to climate warming and ozone depletion. The stronger winds push warm waters from the Southern Ocean poleward, where they eat away at the glaciers and floating ice shelves from below.

Ice shelves in the region have lost almost one-fifth of their thickness in the last two decades, thereby reducing the resisting force on the glaciers. A key concern is that much of the ice of the Southern Antarctic Peninsula is grounded on bedrock below sea level, which gets deeper inland. This means that even if the glaciers retreat, the warm water will chase them inland and melt them even more.

Dr Wouters said: “It appears that sometime around 2009, the ice shelf thinning and the subsurface melting of the glaciers passed a critical threshold which triggered the sudden ice loss. However, compared to other regions in Antarctica, the Southern Peninsula is rather understudied, exactly because it did not show any changes in the past, ironically.

“To pinpoint the cause of the changes, more data need to be collected. A detailed knowledge of the geometry of the local ice shelves, the ocean floor topography, ice sheet thickness and glacier flow speeds are crucial to tell how much longer the thinning will continue.”

THIS ONCE-STABLE ANTARCTIC REGION HAS SUDDENLY STARTED MELTING


This once-stable Antarctic region has suddenly started melting

Antarctica’s glaciers have been making headlines during the past year, and not in a good way. Whether it’s a massive ice shelf facing imminent risk of collapse, glaciers in the West Antarctic past the point of no return, or new threats to East Antarctic ice, it’s all been rather gloomy.

And now I’m afraid there’s more bad news: a new study published in the journalScience, led by a team of my colleagues and I from the University of Bristol, has observed a sudden increase of ice loss in a previously stable part of Antarctica.

The Antarctic Peninsula.

The region in question is the southernmost half of the Antarctic Peninsula, a section of the mainland which extends 1300km into the Southern Ocean. Its northern half is the continent’s mildest region and the climate effects there are clear. We already knew for instance that the glaciers of the Northern Antarctic Peninsula were in trouble following the disintegration of some of its ice shelves, most famously Larsen A and B.

Further to the west, the massive glaciers feeding into the Amundsen Sea have been shedding ice into the ocean at an alarming rate for decades. Out of the blue, the Southern Peninsula filled up the gap between these two regions and became Antarctica’s second largest contributor to sea level rise.

Using satellite elevation measurements, we found the Southern Antarctic Peninsula showed no signs of change up to 2009. Around that year, multiple glaciers along a vast 750km coastline suddenly started to shed ice into the ocean at a nearly constant rate of 60 cubic km, or about 55 trillion litres of water, each year – enough water to fill 350,000 Empire State Buildings over the past five years.

Some of the glaciers are currently thinning by as much as 4 metres each year. The ice loss in the region is so large that it causes small changes in the Earth’s gravity field, which can be detected by another satellite mission, the Gravity Recovery and Climate Experiment (GRACE).

So sudden even the supply ship seems to have been caught out.
J Bamber, Author provided

Is this an effect of global warming?

The answer is both yes and no. Data from an Antarctic climate model shows that the sudden change cannot be explained by changes in snowfall or air temperature. Instead, we attribute the rapid ice loss to warming oceans.

Many of the glaciers in the region feed into ice shelves that float on the surface of the ocean. They act as a buttress to the ice resting on bedrock inland, slowing down the flow of the glaciers into the ocean. The westerly winds that encircle Antarctica have become more vigorous in recent decades, in response to climate warming and ozone depletion. The stronger winds push warm waters from the Southern Ocean poleward, where they eat away at the glaciers and floating ice shelves from below.

Ice shelves in the region have lost almost one-fifth of their thickness in the last two decades, thereby reducing the resisting force on the glaciers. A key concern is that much of the ice of the Southern Antarctic Peninsula is grounded on bedrock below sea level, which gets deeper inland. This means that even if the glaciers retreat, the warm water will chase them inland and melt them even more.

Cause for concern?

The region’s melting glaciers are currently adding about 0.16 millimetres to global sea levels per year, which won’t immediately make you run for the hills. But it’s yet another source of sea level rise, about 5% of the global total increase. What might be a bigger source of concern is that the changes occurred so suddenly and in an area that was behaving quietly until now. The fact that so many glaciers in such a large region suddenly started to lose ice came as a surprise. It shows a very fast response of the ice sheet: in just a few years everything changed.

The Southern Antarctic Peninsula contains enough ice to add 35 cm to sea level, but that won’t happen any time soon. It’s too early to tell how much longer the ice loss will continue and how much it will contribute to future sea level rise. For this, a detailed knowledge of the geometry of the local ice shelves, the ocean floor topography, ice sheet thickness and glacier flow speeds are crucial.

But the ice on Antarctica is like a sleeping giant. Even if we would stop emitting greenhouse gases as of today, or the inflow of warm water would stop, this inert system would take a long time to find an equilibrium again.

Gravity data show that Antarctic ice sheet is melting increasingly faster


Researchers ‘weighed’ Antarctica’s ice sheet using gravitational satellite data and found that during the past decade, Antarctica’s massive ice sheet lost twice the amount of ice in its western portion compared with what it accumulated in the east. Their conclusion — the southern continent’s ice cap is melting ever faster.


Princeton University researchers “weighed” Antarctica’s ice sheet using gravitational satellite data and found that from 2003 to 2014, the ice sheet lost 92 billion tons of ice per year.
Credit: Image by Christopher Harig, Department of Geosciences

During the past decade, Antarctica’s massive ice sheet lost twice the amount of ice in its western portion compared with what it accumulated in the east, according to Princeton University researchers who came to one overall conclusion — the southern continent’s ice cap is melting ever faster.

The researchers “weighed” Antarctica’s ice sheet using gravitational satellite data and found that from 2003 to 2014, the ice sheet lost 92 billion tons of ice per year, the researchers report in the journal Earth and Planetary Science Letters. If stacked on the island of Manhattan, that amount of ice would be more than a mile high — more than five times the height of the Empire State Building.

The vast majority of that loss was from West Antarctica, which is the smaller of the continent’s two main regions and abuts the Antarctic Peninsula that winds up toward South America. Since 2008, ice loss from West Antarctica’s unstable glaciers doubled from an average annual loss of 121 billion tons of ice to twice that by 2014, the researchers found. The ice sheet on East Antarctica, the continent’s much larger and overall more stable region, thickened during that same time, but only accumulated half the amount of ice lost from the west, the researchers reported.

“We have a solution that is very solid, very detailed and unambiguous,” said co-author Frederik Simons, a Princeton associate professor of geosciences. “A decade of gravity analysis alone cannot force you to take a position on this ice loss being due to anthropogenic global warming. All we have done is take the balance of the ice on Antarctica and found that it is melting — there is no doubt. But with the rapidly accelerating rates at which the ice is melting, and in the light of all the other, well-publicized lines of evidence, most scientists would be hard pressed to find mechanisms that do not include human-made climate change.”

Compared to other types of data, the Princeton study shows that ice is melting from West Antarctica at a far greater rate than was previously known and that the western ice sheet is much more unstable compared to other regions of the continent, said first author Christopher Harig, a Princeton postdoctoral research associate in geosciences. Overall, ice-loss rates from all of Antarctica increased by 6 billion tons per year each year during the 11-year period the researchers examined. The melting rate from West Antarctica, however, grew by 18 billion tons per year every year, Harig and Simons found. Accelerations in ice loss are measured in tons per year, per year, or tons per year squared.

Of most concern, Harig said, is that this massive and accelerating loss occurred along West Antarctica’s Amundsen Sea, particularly Pine Island and the Thwaites Glacier, where heavy losses had already been recorded. An iceberg more than 2,000 square miles in size broke off from the Thwaites Glacier in 2002.

In Antarctica, it’s the ocean currents rather than air temperatures that melt the ice, and melted land ice contributes to higher sea levels in a way that melting icebergs don’t, Harig said. As the ocean warms, floating ice shelves melt and can no longer hold back the land ice.

“The fact that West Antarctic ice-melt is still accelerating is a big deal because it’s increasing its contribution to sea-level rise,” Harig said. “It really has potential to be a runaway problem. It has come to the point that if we continue losing mass in those areas, the loss can generate a self-reinforcing feedback whereby we will be losing more and more ice, ultimately raising sea levels by tens of feet.”

The Princeton study differs from existing approaches to measuring Antarctic ice loss in that it derives from the only satellite data that measure the mass of ice rather than its volume, which is more typical, Simons explained. He and Harig included monthly data from GRACE, or the Gravity Recovery and Climate Experiment, a dual-satellite joint mission between NASA and the German Aerospace Center. GRACE measures gravity changes to determine the time-variable behavior of various components in the Earth’s mass system such as ocean currents, earthquake-induced changes and melting ice. Launched in 2002, the GRACE satellites are expected to be retired by 2016 with the first of two anticipated replacement missions scheduled for 2017.

While the volume of an ice sheet — or how much space it takes up — is also crucial information, it can change without affecting the amount of ice that is present, Simons explained. Snow and ice, for instance, compact under their own weight so that to the lasers that are bounced off the ice’s surface to determine volume, there appears to be a reduction in the amount of ice, Simons said. Mass or weight, on the other hand, changes when ice is actually redistributed and lost.

Simons equated the difference between measuring ice volume and mass to a person weighing himself by only looking in the mirror instead of standing on a scale.

“You shouldn’t only look at the ice volume — you should also weigh it to find the mass changes,” Simons said. “But there isn’t going to be a whole lot of research of this type coming up because the GRACE satellites are on their last legs. This could be the last statement of this kind on these kinds of data for a long time. There may be a significant data gap during which the only monitoring available will not be by ‘weighing’ but by ‘looking’ via laser or radar altimetry, photogrammetry or field studies.”

Harig and Simons developed a unique data-analysis method that allowed them to separate GRACE data by specific Antarctic regions. Because the ice sheet behaves differently in different areas, a continent-wide view would provide a general sense of how all of the ice mass, taken together, has changed, but exclude finer-scale geographical detail and temporal fluctuations. They recently published a paper about their computational methods in the magazine EOS, Transactions of the American Geophysical Union, and used a similar method for a 2012 paper published in the Proceedings of the National Academy of Sciences that revealed sharper-than-ever details about Greenland’s accelerating loss of its massive ice sheet.

Robert Kopp, a Rutgers University associate professor of earth and planetary sciences and associate director of the Rutgers Energy Institute, said the analysis method Harig and Simons developed allowed them to capture a view of regional Antarctic ice loss “more accurately than previous approaches.” Beyond the recent paper, Harig and Simons’ method could be important for testing models of Antarctic ice-sheet stability developed by other researchers, he said.

“The notable feature of this research is the power of their method to resolve regions geographically in gravity data,” Kopp said. “I expect that [their] technique will be an important part of monitoring future changes in the ice sheet and testing such models.”

Antarctic Octopus’s ‘Blue Blood’ Helps It Survive in Frigid Waters


Octopuses in Antarctica survive subzero temperatures because of blue pigment in their blood, a new study finds.

The ice-cold temperatures in the Southern Ocean surrounding Antarctica range between 28.8 degrees Fahrenheit (minus 1.8 degrees Celsius) to 35.6 degrees F (2 degrees C). In such frigid conditions, animals have a harder time transporting oxygen throughout their bodies and therefore delivering it to tissues.

To cope, Antarctic octopuses use a copper-based protein called haemocyanin. It makes their blood run blue and is much more efficient at keeping their bodies properly oxygenated at freezing temperatures. [8 Crazy Facts About Octopuses]
“This is the first study providing clear evidence that the octopods’ blue blood pigment, haemocyanin, undergoes functional changes to improve the supply of oxygen to tissue at subzero temperature,” lead study author Michael Oellermann, a biologist at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research in Germany, said in a statement.

To find out what keeps an octopus’s body oxygenated, Oellermann and his colleagues compared haemocyanin levels in an Antarctic octopus species (Paraledone charcoti) and in two species that live in warmer climates (Octopus pallidus in southeast Australia and Eledone moschata in the Mediterranean).

The Antarctic octopus had the highest concentration of haemocyanin in its blood compared with other species. At 50 degrees F (10 degrees C), the Antarctic octopus could release far more oxygen (76.7 percent), than the two warm-water octopuses (at 33 percent for the Octopus pallidus and 29.8 percent for the Eledone moschata).

Although the Antarctic octopus is far more adept at producing oxygen in cold waters than its warm-water counterparts, these animals actually thrive when the water is a balmy 50 degrees F (10 degrees C), rather than at 32 degrees F (0 degrees C), which is typical in the Southern Ocean’s lowest latitudes.

“This is important because it highlights a very different response compared to Antarctic fish to the cold conditions in the Southern Ocean,” Oellermann said. “The results also imply that due to improved oxygen supply by haemocyanin at higher temperatures, this octopod may be physiologically better-equipped than Antarctic fishes to cope with global warming,” he said.

The Antarctic octopus’s ability to adjust its blood oxygen supply to suit variable temperatures could help it cope with warming temperatures as a result of climate change. But, this “blue blood” also helps explain why different species of octopuses live in such diverse environments, ranging from the freezing waters around Antarctica to the warm equatorial tropics.

Coldest spot on Earth identified by satellite


High Plateau
Antarctica‘s dry and clear conditions allow heat to be radiated very efficiently out into space

The coldest place on Earth has been measured by satellite to be a bitter minus 93.2 Celsius (-135.8F).

As one might expect, it is in the heart of Antarctica, and was recorded on 10 August, 2010.

Researchers say it is a preliminary figure, and as they refine data from various space-borne thermal sensors it is quite likely they will determine an even colder figure by a degree or so.

The previous record low of minus 89.2C was also measured in Antarctica.

This occurred at the Russian Vostok base on 21 July, 1983.

It should be stated this was an air temperature taken a couple of metres above the surface, and the satellite figure is the “skin” temperature of the ice surface itself. But the corresponding air temperature would almost certainly beat the Vostok mark.

“These very low temperatures are hard to imagine, I know,” said Ted Scambos from the US National Snow and Ice Data Center in Boulder, Colorado.

“The way I like to put it is that it’s almost as cold below freezing as boiling water is above freezing. The new low is a good 50 degrees colder than temperatures in Alaska or Siberia, and about 30 degrees colder than the summit of Greenland.

“It makes the cold snap being experienced in some places in North America right now seem very tame by comparison,” he told BBC News.

Dr Scambos was speaking here in San Francisco at the American Geophysical Union (AGU) Fall Meeting, the largest annual gathering of Earth scientists.

AntarcticThe 2010 cold spot (red) was just south of a ridge running between Dome A and Dome F

He and colleagues have been examining the data records from polar orbiting satellites stretching back some 30 years.

They find the coldest moments in Antarctica occur in the dark winter months at high elevations, where the extremely dry and clear air allows heat to be radiated very efficiently out into space.

It is evident that many super-cold spots are “strung out like pearls” along the ridges that link the high points, or domes, in the interior of the continent.

They are not quite at the ridge crests, but set slightly back down the slope.

“Air chilled near the surface flows downhill because it’s denser; and it flows into these very shallow topographic pockets,” explained Dr Scambos.

“If you were standing in one of these places, you’d hardly notice you were in a topographic low – it’s that gentle and that shallow. But it’s enough to trap this air.

“And once in those pockets, the air can cool still further and get down this extra three or four degrees below the previous record air temperature in Vostok.”

The cold pockets run in a line for hundreds of kilometres between Dome Argus [Dome A] and Dome Fuji [Dome F]. They all achieve more or less the same low temperature between minus 92C and minus 94C. The minus 93.2C figure is the temperature event in which the team has most confidence. It was recorded at a latitude of 81.8 degrees South and a longitude of 59.3 degrees East, at an elevation of about 3,900m.

Hottest place

One of the spacecraft instruments being used in the study is the Thermal Infrared Sensor on the recently launched Landsat-8.

It has very high resolution, but because it is so new the team says more time is needed to fully calibrate and understand its data.

“I’d caution Guinness not to take this result and put it in their world record book just yet, because I think the numbers will probably adjust over the coming year,” Dr Scambos told BBC News. “However, I’m now confident we know where the coldest places on Earth are, and why they are there.”

By way of comparison, the hottest recorded spot on Earth – again by satellite sensor – is the Dasht-e Lut salt desert in southeast Iran, where it reached 70.7C in 2005.

The coldest place in the Solar System will likely be in some dark crater on a planetary body with no appreciable atmosphere. On Earth’s Moon, temperatures of minus 238C have been detected.

BBC Weather presenter Peter Gibbs explains how he found life living in Antarctica for two years

 

Ozone hole could boost global warming.


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.

 

Previous research by Piers Forster, an atmospheric scientist at the University of Leeds, UK, and his collaborators attributed a slight cooling effect to the ozone hole. But the latest study, which focused on the Antarctic summer between December and February, found that there may be a warming effect instead.

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.

The result was that the effects on the Earth’s net energy balance were opposite to what had been calculated before. “A negative radiative forcing is what you’d expect when the ozone is depleted, but our research shows that there is a positive net radiative effect during the Antarctic summer,” Grise says.

The extra net energy absorbed by the Earth would be 0.25 watts per square metre, or roughly a tenth of the greenhouse effect attributed to CO2, Grise says. The result could be a small but non-negligible contribution to global temperature rise.

“I think it’s an interesting piece of research. They are talking about a new mechanism in the world of ozone and climate change,” says Forster. “There’s quite a lot of work to be done to pin down the mechanism, but it does sound reasonable.”

Source: Nature

LAKE VOSTOK MYSTERIES: BIOLOGISTS FIND OVER 3,500 LIFE FORMS IN ISOLATED ANTARCTIC BASIN.


Scientists have discovered more than 3,500 unique gene sequences in Lake Vostok – the underground Antarctic water reservoir isolated from the outside world for 15 million years – revealing a complex ecosystem far beyond anything they could have expected.

lake_vostok_sat_photo_color.si-Kopia

“The bounds on what is habitable and what is not are changing,” said Scott Rogers, Bowling Green State University professor of biological sciences, who led a genetic study of the contents of half a liter of water brought back from the lake after it was drilled by Russian scientists last year.

“We found much more complexity than anyone thought,”
 Rogers said. “It really shows the tenacity of life, and how organisms can survive in places where a couple dozen years ago we thought nothing could survive.”

There are few places on Earth more hostile to life forms than Lake Vostok, the largest subglacial lake in the Antarctic, and initially Rogers believed that the water from it may have been completely sterile.

Water is located 4,000 meters below the ice, which completely blocks sunlight, and creates huge pressure on the liquid. It is also literally located in the coldest place on Earth: the world’s lowest temperature of -89.2C was recorded at Vostok Station above the reservoir.

But after using bleach to remove outer layers of the ice (the form in which the water was extracted from the lake) which could potentially have been contaminated during the drilling, and conducting RNA and DNA testing, thousands of microscopic life forms, predominantly bacteria, were detected.

l-1-Kopia_5

Many had expected that if any life forms were to be found in the frozen crypt, they would be uniquely adapted to the harsh environment, and perhaps entirely different as a result of being shielded from evolution of life elsewhere on the planet for millions of years.

Rogers, who has just published his findings in PLOS One magazine, says this has not turned out to be the case.

“Many of the species we sequenced are what we would expect to find in a lake. Most of the organisms appear to be aquatic (freshwater), and many are species that usually live in ocean or lake sediments.”

Rogers’ team believes the relative ordinariness of the organisms discovered may be due to the fact that they are left there as a legacy of when Antarctica had a temperate climate 35 million years ago, rather than as a result of evolution inside the lake.

Some of the organisms found in Lake Vostok commonly exist in ocean environments (in the digestive systems of fish and crustaceans) suggesting that the reservoir was once connected to a bigger body of saltwater.

But Rogers believes “two huge drops of temperature” cut it off and conserved it in its present state.

Yet the study is not excluding the possibility of startling discoveries.

“It’s a very challenging project and the more you study, the more you want to know. Every day you are discovering something new and that leads to more questions to be answered,” said Yury Shtarkman, who conducted many of the analyses, and believes it could take a lifetime to untangle the secrets of the lake.

 

Source: http://myscienceacademy.org