A radar survey conducted between 2004 and 2008 by Japanese, Chinese, and British scientists reveals how the ice on Antarctica grew, and what the land looks like beneath the ice. At the center of the continent, a nearly two-mile-thick slab of ice has clung to Antarctica’s rocky surface for 14 million years; this is the first time scientists have gotten a virtual glimpse beneath the sheet’s surface.
The topography beneath the ice is mountainous, with peaks and valleys like the European Alps, according the study published Nature. Scientists say that 34 million years ago, small glaciers expanded from the mountaintops and shifted to carve out the terrain. To collect the data, scientists drove huge trains of caterpillar tractors in tight lines over Dome A, a plateau of ice at the heart of Antarctica. The tractors carried radars that pinged down through the ice and sent back profiles of the frozen rock landscape below [New Scientist]. Scientists knew the velocity of the radar’s radio waves, so they calculated the depth of the ice by timing how long it took the waves to hit the rock and come back to the surface.
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If global warming melts the West Antarctic ice sheet, the thick slab of ice that covers an area the size of Texas, the situation for coastal dwellers around the world may not be as dire as previously estimated. A new study, which has sparked some debate, suggests that the water released by West Antarctica‘s melting glaciers would raise sea levels by about 10 feet, not the 15 to 20 feet that had previously been predicted.
While the results sound like good news, Antarctic experts and the study’s lead author, Jonathan L. Bamber of the Bristol Glaciology Center in England, agreed that the odds of a disruptive rise in seas over the next century or so from the buildup of greenhouse gases remained serious enough to warrant the world’s attention [The New York Times]. They also note that some regions would also experience a larger surge in sea levels than others. “Sea level rise is not uniform across the world’s oceans, partly as a result of disruptions to the Earth’s gravity field,” explained Professor Bamber. “It turns out that the maximum increase in sea level rise is centred at a latitude of about 40 degrees along the Atlantic and Pacific seaboards of North America.” This would include cities such as San Francisco and New York [BBC News].
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At the bottom of the world, fluctuations in sea ice surrounding the frozen continent of Antarctica have posed a puzzle. In West Antarctica, the vast Wilkins Ice Shelf off the Antarctic peninsula appears to be headed towards a collapse. But in East Antarctica, sea ice has been expanding since the 1970s. Researchers from the British Antarctic Survey and NASA set out to determine what was going on, and quickly ruled out one possible answer: Global warming is not an illusion, they say, and Antarctica as a whole is gradually warming up, as is the world at large.
The answer to the riddle, they say, lies in a different (and almost forgotten) environmental problem: the hole in the ozone layer, which has altered weather patterns around Antarctica. These changes have drawn in warm air over the Antarctic Peninsula in West Antarctica and cooled the air above East Antarctica [New Scientist].
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Life sure turns up in the darnedest places. The latest discovery comes from Blood Falls, a rusty red discolouration on the face of the Taylor Glacier in Antarctica [that] occasionally gushes forth a transparent, briny, iron-rich liquid that quickly oxidizes and turns red, staining the ice below [Nature News].
The source of that water is an intensely salty lake trapped beneath 1,300 feet of ice, and a new study has now found that microbes have carved out a niche for themselves in that inhospitable environment, living on sulfur and iron compounds. The bacteria colony has been isolated there for about 1.5 million years, researchers say, ever since the glacier rolled over the lake and created a cold, dark, oxygen-poor ecosystem.
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Tourism to Antarctica is likely to soon be regulated, following a joint session last week of the Antarctic Treaty Consultative Meeting and the Arctic Council. At the meeting, U.S. Secretary of State Hillary Clinton called for tighter controls on cruise ships and tourists to preserve the continent’s pristine beauty and endangered wildlife.
Citing concerns about the recent Antarctic ice bridge collapse, Clinton spoke about the fragile environment of the region and the damage that global warming has already caused. She pointed both to the impact of cruise ships on the environment and to safety issues for visitors. Incidents last year in which two ships ran aground and another hit an iceberg have raised concerns about fuel spills and other environmental hazards, as well as passenger safety. Said Clinton: “We have submitted a resolution that would place limits on landings from ships carrying large numbers of tourists.” Ms. Clinton also called for “greater international cooperation” to avoid further degradation of “the environment around Antarctica” [The New York Times].
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An ice bridge between two Antarctic islands that pinned the vast Wilkins Ice Shelf in place has splintered, and researchers say the change will probably accelerate the disintegration of the ice shelf, which is currently the size of Connecticut. Temperatures on the Antarctic Peninsula, which reaches up towards the bottom tip of South America, have risen by five degrees Fahrenheit over the past 50 years; researchers believe the continent is being reshaped by global warming.
The ice bridge between the islands Charcot and Latady shattered suddenly, says glaciologist David Vaughan: “It’s amazing how the ice has ruptured. Two days ago it was intact.” … The break left a jumble of huge flat-topped icebergs in the sea. The loss of the ice bridge, which was almost [60 miles] wide in 1950 and had been in place for hundreds of years at least, could allow ocean currents to wash away more of the Wilkins. “My feeling is that we will lose more of the ice, but there will be a remnant to the south,” Vaughan said [Reuters].
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A massive chunk of the Antarctic ice sheet seems destined to melt away due to global warming, raising sea levels dramatically. But the good news is, the process will take thousands of years. Those are the conclusions reached by two studies of the West Antarctic ice sheet, which can be considered the planet’s Achilles’ heel. It holds a vast amount of water, locked up as ice, and it’s sitting below sea level, so it’s inherently unstable [NPR].
By studying sediment samples from millions of years ago, researchers determined that the ice shelf has collapsed many times in the past, when warmer climate phases boosted ocean temperatures. With that historical data, another set of researchers simulated past and future changes to the West Antarctic ice sheet, and found that it could indeed begin to collapse sometime in the next century or so if nearby ocean temperatures increase roughly 5°C–a possibility if current warming trends continue. If that warming occurs, the sheet could totally collapse in a few thousand years but contribute to sea-level rise much sooner [ScienceNOW Daily News].
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By the year 2100, ocean levels may have risen twice as much as was predicted just two years ago, researchers announced at the International Scientific Congress on Climate Change in Copenhagen. This means that the lives of some 600 million people living on low-lying islands, as well as those living in Southeast Asia’s populous delta areas, will be put at serious risk if climate change is not quickly and radically mitigated [The New York Times]. Meanwhile, a separate study has cataloged the damage that rising seas would do to the California coastline.
Previous estimates of sea level rise from the Intergovernmental Panel on Climate Change didn’t take full account of the rapid melting of mountain glaciers and Greenland and Antarctic ice sheets, researchers in Copenhagen said. Antarctica, in particular, was thought to be little affected by global warming until recent research proved definitively that the southern continent is heating up. Taking into account the new findings, the upper range in the rise of sea levels could be approximately 1 meter (3.28 feet), “possibly more,” by 2100. At the lower end of the spectrum, it appears increasingly unlikely, say the study’s authors, that sea level rise will be much less than a half-meter by 2100…. “Two or three years ago, those making this type of statement were seen as extremists” [The New York Times], says study coauthor Eric Rignot.
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Antarctic researchers have succeeded in mapping a mountain range that is as tall and impressive as the Alps and yet invisible to the naked eye, since the entire range is hidden beneath miles of ice. The international expedition (which 80beats covered when it set off in October) used radar, gravity sensors, and other instruments mounted on airplanes to chart the contours of the mighty Gamburtsev mountains, but say the results mostly revealed new mysteries. For example, researchers expected to see a plateau formation, indicating that the peaks had been worn down over millennia. Instead, says researcher Robin Bell: “They are incredibly rough mountains — they look like alligators’ teeth” [Nature News].
“The surprising thing was that not only is this mountain range the size of the Alps, but it looks quite similar to the (European) Alps, with high peaks and valleys,” said Fausto Ferraccioli, a geophysicist at the British Antarctic Survey…. He told Reuters that the mountains would probably have been ground down almost flat if the ice sheet had formed slowly. But the presence of jagged peaks might mean the ice formed quickly, burying a landscape under up to 4 km (2.5 miles) of ice [Reuters]. Researchers say that understanding the behavior of polar ice sheets is crucial to scientists trying to predict the impacts of global warming.
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The collapse of an ice sheet in West Antarctica would not only threaten coastal areas of North America and nations in the southern Indian Ocean, but would also cause a shift in the earth’s rotation axis, researchers report in Science.
If the entire West Antarctic Ice Sheet (WAIS) collapses and melts, as some scientists feel is likely due to global warming, the earth’s rotation would shift an approximate 500 meters from its current position. Rather than cause a uniform rise in sea level, this would result in a 30 percent greater increase in certain areas—about 21 feet for Washington, D.C., for example, compared with the uniform 16 to 17 feet already predicted. The researchers say the melting would change the balance of the globe in much the same way that tsunamis move huge amounts of water from one area to another [ABC News].
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The predicted loss of sea ice around Antarctica over the next century may doom one of the celebrities of the animal world to extinction. Emperor penguins, the species of these aquatic flightless birds featured in the Oscar-winning 2005 documentary “March of the Penguins,” breed on Antarctic sea ice and dive from the sea ice to feed on krill, fish and squid [Reuters]. In a new study, researchers examined the Intergovernmental Panel on Climate Change’s (IPCC) projections on how global warming will alter sea ice coverage around Antarctica, and say the models don’t auger well for the emperor penguins.
The researchers combined ten different climate projections with a “population dynamics” model describing the mating patterns and breeding success of emperor penguins. The model has been honed using 43 years’ worth of observations of an emperor colony in Antarctica’s Terre Adelie…. They then ran 1,000 simulations of penguin population growth or decline under each of those 10 climate scenarios [BBC News]. The results predicted that the 6,000 breeding pairs in Terre Adelie could be reduced to 400 pairs by 2100. Researchers say this 95 percent decline qualifies as a “quasi-extinction,” as the colony’s tiny remaining population would be vulnerable to diseases and genetic defects. They also say that the possible demise of the Terre Adelie colony could indicate the fate of the entire species (about 200,000 breeding pairs currently live in 40 colonies around Antarctica).
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Researchers say they have an answer to a question that’s been befuddling climate scientists for years: Was it possible that Antarctica, alone among the earth’s seven continents, wasn’t feeling the effects of global warming? As recently as 2007, the Intergovernmental Panel on Climate Change declared that the jury was still out on the question, but now, finally, researchers say they have conclusive proof that the icy southern continent is also heating up. In October, a separate group of researchers came to much the same conclusion using computer models, but the new study bolsters previous research with empirical evidence.
The confusion over conditions in Antarctica arose mostly from strange weather patterns created by ozone depletion in the Southern Hemisphere, and allowed “climate skeptics” who deny the existence of global warming to use the continent as a talking point. Scientists had long thought that while some isolated parts of Antarctica had been warming, much of the continent had been cooling over the past 50 years. But the new analysis found that since 1957, when measured as a whole, the continent’s temperature has risen about 1 degree Fahrenheit. “The thing you hear all the time is that Antarctica is cooling — and that’s not the case,” says study lead author Eric Steig [USA Today].
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The cats ate the birds until the humans killed the cats, but now the rabbits are out of control.
That’s the sad state of affairs on Macquarie Island, an island near Antarctica that was declared a world heritage site in 1997 due to its status as the sole breeding ground for the royal penguin. For decades researchers have attempted to get rid of the invasive species that have altered the island’s ecological balance, but a new study notes that the latest effort, an all-out push to eradicate feral cats, has had the unintended consequence of allowing a boom in the rabbit population. Those rabbits have quickly denuded the landscape of its vegetation, researchers say.
Things began to go wrong on Macquarie Island … soon after it was discovered in 1810. The island’s fur seals, elephant seals and penguins were killed for fur and blubber, but it was the rats and mice that jumped from the sealing ships that started the problem. Cats were quickly introduced to keep the rodents from precious food stores. Rabbits followed some 60 years later, as part of a tradition to leave the animals on islands to give shipwrecked sailors something to eat [The Guardian]. The invasive species all thrived to the detriment of local species, and by the 1970s biologists were concerned enough to introduce a rabbit-killing disease called myxomatosis, which thinned the rabbit herds considerably. However, that left the cats with less available prey and caused them to begin hunting the island’s native burrowing birds.
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An enormous helium balloon floating about 24 miles above Antarctica has detected a mix of high-energy electrons so exotic that researchers say the particles must have been created by some fascinating process: They may have been formed when dark matter particles collided and annihilated each other, or else a surprisingly close astronomical object like a pulsar could be spitting the electrons at Earth.
Researchers can’t yet determine which answer is correct, but say the dark matter explanation is more exciting. Dark matter is one of astrophysics’ greatest enigmas. It is thought to be five times more common than visible matter, but there is no proof of what it is made of. The existence of dark matter has largely been inferred from its gravitational effects, such as the fact that most galaxies have enough mass to remain as well-defined objects despite having too little visible matter to account for the necessary gravity [National Geographic News]. If the research balloon did detect the signature of dark matter through the particles left over from collisions, it would be the closest researchers have ever gotten to seeing the mysterious stuff.
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Deep beneath the Antarctic ice sheet, floods of water from buried lakes can hurry glaciers along on their slow slide towards the sea, according to a new study that tracked recent floods beneath the Byrd Glacier. “It’s like putting in a squirt of oil,” says Andy Smith of the British Antarctic Survey, who was not involved in this latest study. “The water lubricates the base of the glacier” [New Scientist]. The findings will help researchers understand the movement of glaciers around the world, a matter of great interest to climate scientists who are investigating how rapidly ice sheets may melt into the ocean due to global warming.
Researchers discovered only recently that inaccessible subglacial lakes in Antarctica periodically shed huge quantities of water. Data collected by a satellite launched in 2003 … revealed a complex network of subglacial plumbing in which water periodically cascades from one hidden reservoir to another [AFP]. The water in the lakes remains liquid, despite being buried beneath a mile of ice in some places, due to warmth from the underlying rock. Now, researchers have shown that these hidden floods affect the thick mountains of ice above.
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