Environment

Large Hole Opens in Antarctica Ice

A mysterious hole as big as the state of Maine has been spotted in Antarctica’s winter sea ice cover. The hole was discovered by researchers about a month ago.

Known as a polynya, this year’s hole was about 30,000 square miles at its largest, making it the biggest polynya observed in Antarctica’s Weddell Sea since the 1970s.

The harsh winter in Antarctica makes it hard to find holes like this one, so it can be difficult to study them. This is the second year that a polynya formed, though last year’s hole was not as big.

The deep water in that part of the Southern Ocean is warmer and saltier than the surface water. Ocean currents bring the warmer water upwards, where it melts the blankets of ice that had formed on the ocean’s surface. That melting created the polynya.

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The blue curves represent the ice edge, and the polynya is the dark region of open water within the ice pack.

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Global Warming

Sea Ice Hits Record Lows at Both Poles

    

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Arctic temperatures have finally started to cool off after yet another winter heat wave stunted sea ice growth over the weekend. The repeated bouts of warm weather this season have stunned even seasoned polar researchers, and could push the Arctic to a record low winter peak for the third year in a row.

Meanwhile, Antarctic sea ice set an all-time record low on Monday in a dramatic reversal from the record highs of recent years.

Sea ice at both poles has been expected to decline as the planet heats up from the buildup of greenhouse gases in the atmosphere. That trend is clear in the Arctic, where summer sea ice now covers half the area it did in the early 1970s. Sea ice levels in Antarctica are much more variable, though, and scientists are still unraveling the processes that affect it from year to year.

The large decline in Arctic sea ice allows the polar ocean to absorb more of the sun’s incoming rays, exacerbating warming in the region. The loss of sea ice also means more of the Arctic coast is battered by storm waves, increasing erosion and driving some native communities to move. The opening of the Arctic has also led to more shipping and commercial activity in an already fragile region.

Sea ice area isn’t the only way to measure the health of Arctic sea ice; the thickness of the sea ice has also suffered during the repeated incursions of warmth.

Antarctic sea ice is an altogether different beast. Instead of an ice-filled ocean surrounded by land, it is a continent surrounded by ocean that sees much more variability in sea ice levels from year to year for reasons that aren’t fully understood.

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For several of the past few years, the sea ice that fringed Antarctic reached record highs. That growth of sea ice could have potentially been caused by the influx of freshwater as glaciers on land melted, or from changes in the winds that whip around the continent (changes that could be linked to warming or the loss of ozone high in the atmosphere).

But this year, a big spring meltdown in October and November suddenly reversed that trend and has led to continued record low sea ice levels as the summer melt season progressed. On Monday, Antarctic sea ice dropped to an all-time record low, beating out 1997.

Sea ice has been particularly low in the Amundsen Sea region of Western Antarctica, thanks to unusually high temperatures there. But it’s not clear what is ultimately driving this dramatic reversal in Antarctic sea ice, or whether it will be temporary or marks a longer-term shift.

Humans accelerating global warming by 170 times: study

Humans are driving the warming of the Earth 170 times faster than natural forces, according to a new mathematical formula.

Scientists in Australia and Sweden have developed the equation, which assesses the impact of human activity on the climate and compares it to events such as volcanic eruptions and changes to the planet’s orbit.

Professor Will Steffen, a climate scientist from the Australian National University (ANU), said no natural events came close to the impact humans have made.

“Over the last century or so, we can see that the impact of humans – through fossil fuels, through forest clearing, through all sorts of changes to the biosphere – have become more important than these other forces,” he said.

Professor Steffen, who is also on the Climate Council, and his fellow researchers have labelled the formula the Anthropocene Equation.

Officially, the Earth is in the Holocene period, but scientists such as Professor Steffen are pushing for the modern era to be reclassified to reflect the massive impact humans have had. The scientists behind the formula found the biggest change in the climate has come since 1970.

“Since 1970, temperature has been rising at a rate of about 1.7 degrees per century,” Professor Steffen said.

“When you compare those two, since the 1970s, the climate has been changing at a rate 170 times faster than that long-term background rate.”

Global Warming

Blue lakes are appearing in Antarctica – and that’s a bad thing

In a new study, scientists who study the largest ice mass on Earth – East Antarctica – have found that it is showing a surprising feature reminiscent of the fastest melting one: Greenland.

More specifically, the satellite-based study found that atop the coastal Langhovde Glacier in East Antarctica’s Dronning Maud Land, large numbers of “supraglacial” or meltwater lakes have been forming – nearly 8,000 of them during summer months between the year 2000 and 2013. Moreover, in some cases, just as in Greenland, these lakes appear to have then been draining down into the floating parts of the glacier, potentially weakening it and making it more likely to fracture and break apart.

This is the first time that such a drainage phenomenon has been observed in East Antarctica, the researchers say – though it was previously spotted on the warmer Antarctic Peninsula and was likely part of what drove spectacular events there like the shattering of the Larsen B ice shelf in 2002.

When it comes to East Antarctica, however, “that’s the part of the continent where people have for quite a long time assumed that it’s relatively stable, 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,” said Stewart Jamieson, a glaciologist at Durham University in the UK and one of the study’s authors.

The research raises concern, for the following reason: Mounting evidence suggests one reason that Greenland has been melting so fast lately is precisely these kinds of lakes. In the summer as air temperatures warm, lakes form on top of the ice sheet, and on its finger-like glaciers that extend outwards into deep ocean fjords.

These lakes can then suddenly disappear all at once, or flow into rivers that drain into the ice below, lubricating the ice and helping to increase the lurch forward of glaciers. Sometimes, researchers have even been able to document fresh water flowing outward directly into the sea from the base of a glacier. 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.

Global Warming

Scientists reconcile growth in Antarctic sea ice with global warming models

The small minority of climate change models accurately predicted the expansion of Antarctic sea ice, and now scientists think they know why.

Even as sea ice was disappearing globally at an average rate of 13,500 square miles, or about an area the size of Maryland, every year, Antarctic sea ice went on a record streak beginning in 2012, expanding annually until reaching a new record high extent of 7.78 million square miles in fall of 2014.

A new study, published Monday in Nature Geoscience, suggests that the explanation of the phenomenon lies not in the Southern Ocean itself, but in the Pacific.

Researchers with the National Centre for Atmospheric Research (NCAR) in Boulder, Colo., together with colleagues in Seattle and Australia, identified that the expansion in Antarctic ice began to accelerate around the turn of the 21st century. At approximately the same time, the Interdecadal Pacific Oscillation (IPO), a prolonged fluctuation in atmospheric pressure that affects sea temperatures, shifted into a negative phase, cooling the ocean surface in the tropical Pacific, with global ramifications.

The few climate change models that take the IPO into account accurately predict the growth in Antarctic sea ice – and the global warming slowdown in the early 2000s.

Looking forward, the scientists behind the study predict that the IPO has turned back, so the Antarctic ice won’t continue to expand. Notably, measurements of the extent of Antarctic sea ice in 2015 were only the 16th highest on record.

But scientists have suggested other possible drivers of Antarctic ice expansion, including the possibility that the Antarctic ozone hole changed the circulation of winds around the continent.

In the end of May, NASA and the NOAA set forward another explanation for the gains in Antarctic ice coverage. Geophysical characteristics, including local ocean depth and continental surface features, influence the region’s wind and ocean currents in such a way as to produce and protect sea ice. Winds push building ice out and around the continent in the summer months, when the ice is growing, creating a “Great Shield” zone that shelters young ice in the interior, allowing it to grow quickly.

Global Warming

Antarctic seas defy global warming

A persistent chill in the ocean off Antarctica that defies the global warming blamed for melting Arctic ice at the other end of the planet is caused by cold waters welling up from the depths after hundreds of years, scientists said on Monday.

The Southern Ocean off Antarctica may be among the last places on Earth to feel the impact of man-made climate change, with a lag of centuries to affect waters emerging from up to 5,000 meters (16,000 ft) deep, the U.S. study said.

Many people who doubt mainstream scientific findings that human use of fossil fuels is warming the planet often point to the paradox of expanding winter sea ice off Antarctica in recent decades and a rapid shrinking of ice in the Arctic.

The upwelling of cold water helped to explain the persistence of sea ice but not its expansion, a trend other studies have linked to shifts in winds off the vast frozen continent.

Monday’s report found that warm waters in the Gulf Stream cool as they flow north into the North Atlantic, then sink and loop south towards Antarctica as part of an aquatic conveyor belt that takes centuries to complete.

Eventually, gale force winds in the Southern Ocean around Antarctica blow surface waters northwards and draw the chill, ancient waters from the depths.

That upwelling helps explain why the surface of the Southern Ocean have warmed by just 0.02 degree Celsius (0.036 Fahrenheit) per decade since 1950, a fraction of the global average of 0.08 degree (0.144F), the study said.

It was unclear if the cold waters could delay a melt of ice locked up on land in Antarctica, the biggest worry about the continent that could sharply raise global sea levels.

Global Warming

Antarctic’s massive Totten Glacier nearing ‘tipping point’

Global warming is threatening to trigger the catastrophic collapse of East Antarctica’s massive Totten Glacier and in turn raise sea levels to dangerous new heights, a new study warns.

East Antarctica is the world’s largest area of ice. Until recently, it was considered to be far more stable than the smaller, West Antarctic ice sheet, where scientists had originally focused fears and warnings.

Now, troubling research reveals that melting Totten would make global warming reach a “tipping point” and likely collapse with just a few degrees increase in warming, warned scientist Alan Aitken of the University of Western Australia, who heads a team of researchers from the US, UK, New Zealand and Australia.

Totten’s huge floating shelf of ice is 90 miles (145km) by 22 miles (35km) in area. It functions as a kind of giant plug holding back a far larger a mass of Antarctic ice. The entire region, or what scientists call a catchment – which could someday flow into the sea in the surrounding area if Totten collapses – represents an area bigger than California, notes the Washington Post. In some areas the ice is also 2.5 miles (4.0km) thick. The melted ice could then raise the world’s sea level by more than 11 feet (3.5m).

The Totten Glacier catchment (blue outline) is a collection basin for ice and snow that flows through the glacier. It’s estimated to contain enough material to raise sea levels by at least 11 feet.

Melting totten glacier

Global Warming

How Much Ice Can Antarctica Afford to Lose?

Over the past 20 years, ice shelves in Antarctica that normally support the rest of the continent’s glaciers have been shrinking, and some have disappeared entirely. How much more ice can disintegrate before Antarctic glaciers start freely tumbling into the ocean?

A recent study led by researchers at the Friedrich-Alexander-Universität, in Germany, has mapped out which Antarctic ice shelves are buttressing the most ice and which are more “passive” and thus can stand to lose a large area without any immediate effect on the rest of the ice shelf.

Ice shelves are slabs of ice several hundred meters thick that extend from the edges of the mainland and float on the surface of the sea. They are firmly linked to glaciers and ice streams in mainland Antarctica, which slowly push the floating ice farther seaward, according to the researchers. When the seaward fronts of these ice shelves break off, they form new icebergs and the loss of ice is naturally replenished by the glacier ice from the mainland flowing in.

Some of the ice shelves, however, also push back on the glaciers, providing resistance and reducing the speed at which the glaciers flow into the ocean, said lead study author Johannes Fürst, a research assistant at the Institute of Geography at the Friedrich-Alexander-Universität.

“Ice shelves restrain the outflow from upstream like a plug in a bathtub,” Fürst told Live Science. “If you take the plug out, the water runs out, except this is frozen water and if you take out the ice shelves its flow will accelerate out into the ocean and eventually raise sea levels.”

In 1995, Antarctica’s Larsen A ice shelf collapsed, removing ice cover from an area equivalent to the size of Berlin, according to Fürst. Seven years later, the much larger Larsen B ice shelf also broke apart. While the disintegration of the two shelves did not have an immediate effect on sea levels, the ice loss resulted in upstream glaciers accelerating by up to eight times their normal flow, according to the researchers.

Overall, the researchers found that 13 percent of the continent’s ice shelf area can be classified as passive — an area about twice the size of Spain. This includes the Larsen C ice shelf in the Weddell Sea, which the researchers found is almost entirely a passive ice shelf.

Ice shelves in the Amundsen and Bellingshausen seas, however, are the most susceptible to further ice loss, according to the research findings. They are made up of 7 percent and 5 percent passive ice, respectively, the researchers found.

Global Warming

Antarctic icebergs have surprise role in slowing warming

The biggest icebergs breaking off Antarctica unexpectedly help to slow global warming as they melt away into the chill Southern Ocean, scientists said on Monday.

The rare Manhattan-sized icebergs, which may become more frequent in coming decades because of climate change, release a vast trail of iron and other nutrients that act as fertilisers for algae and other tiny plant-like organisms in the ocean.

These extract carbon dioxide from the atmosphere as they grow, a natural ally for human efforts to limit the pace of climate change blamed on man-made greenhouse gas emissions.

Ocean blooms in the wake of giant icebergs off Antarctica absorbed 10 to 40 million tonnes of carbon a year, the study estimated, roughly equivalent to annual man-made greenhouse gas emissions of countries such as Sweden or New Zealand.

The scientists studied satellite images of 17 giant icebergs off Antarctica from 2003-2013 and found that algae could turn the water greener for hundreds of kms (miles) around the icebergs, with nutrients spread by winds and currents.

There are typically 30 giant icebergs floating off Antarctica at any one time – they can linger for years. The study said the giant icebergs had an outsized impact in promoting ocean fertilization when compared with small icebergs.

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Global Warming

Climate change and Antarctica

A world-renowned climate scientist visiting New Zealand will this week present new evidence suggesting a behemoth “sleeping giant” ice sheet is more sensitive to climate change than we ever thought.

To climate scientists, the vast East Antarctic Ice Sheet represents something of the elephant in the room in terms of what it could contribute to global sea level rise.

If all of it melted, the ice sheet, which forms most of Antarctica, would contribute an equivalent of around 50 metres of sea level rise – the vast majority of the total 58 metres that could come from the frozen continent.

The part of the ice sheet that rests on bedrock below sea level is most vulnerable and holds an equivalent of 19 metres of sea level rise.

In the face of climate change, which has brought warmer ocean water to the edges of Antarctica, the vast ice sheet has been long regarded by scientists to be much more stable when compared with the smaller, 25 million square kilometre West Antarctic Ice Sheet, which satellite measurements estimated was losing more than 150 cubic kilometres of ice each year.

But an Australian expedition that managed to reach the typically inaccessible Totten Glacier in East Antarctica in January revealed some of the first direct evidence that warmer waters were having a significant impact there as well.

This means the wider ice sheet’s contribution to future sea level rise could be much greater than realised.

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Buryatia: where thawing permafrost is turning to steppe

Buryatia has been hit in summer 2015 by the massive destruction of its pristine forests in a series of fast-spreading fires. Most shocking have been the scenes showing uncontrolled burning around Lake Baikal, the oldest and deepest lake in the world, containing 20% of the globe’s unfrozen freshwater.

Local scientists have accumulated startling evidence of the changes in temperature which are turning the region’s permafrost – established over many millennia – into steppe. Average annual temperatures in a rising number of areas are exceeding zero degrees Celsius.

Warming caused the upper layer of permafrost to become deeper – and where it is thin, to disappear altogether. The average annual precipitation isn’t changing, but it evaporates more easily which causes the climate to get drier. This results in changes in flora. It becomes more monotonous, dominated by drought-resistant plants.

As the climate becomes drier, the territory covered in forests and meadows reduces, while the dry steppe – arid grass plains with few trees – increases. Apart from that, there are changes in terms of the radial growth of trees. In dry lands, including Selenginskyi and Kyakhtinskyi districts, growth slows down.

Currently, some 55,000 hectares remain ablaze in Buryatia. In other regions, the figures are 46,000 hectares in Krasnoyarsk and 11,000 in Irkutsk.

Environment

Antarctic sea ice set to smash record

According to a recent report from the National Snow & Ice Data Center (NSIDC), Antarctic sea ice is set to smash a record this year, as it’s currently at 7.6 million square miles and continuing to increase.

The Arctic, on the other hand, continues to lose ice. In fact, the NSIDC says that the minimum extent will be somewhat lower than last year’s, making it the sixth lowest extent in the satellite record.

According to the NSIDC, Arctic sea ice extent for September 15 was 1.96 million square miles, which is 11,600 square miles below the same date in 2013. However, Arctic sea ice extent remains low when examined in contrast with the long-term 1981 to 2010 average.

Global Warming

Antarctic Riddle: How Much Will the South Pole Melt?

The melting of the Antarctic ice sheet has long been a relatively minor factor in the steady ascent of high-water marks, responsible for about an eighth of the 3 millimeters of annual sea-level rise. But when it comes to climate change, Antarctica is the elephantine ice sculpture in the boiler room. The ice sheet is so massive that its decline is, according to the recent Intergovernmental Panel on Climate Change assessment, “the largest potential source” of future sea level rise. Accurately forecasting how much of it will be unleashed as seawater, and when that will happen, could help coastal communities plan for surging flood risks.

A study published Aug. 14 in Earth System Dynamics — one that took more than 2 years and 50,000 computer simulations to complete, combining information from 26 atmospheric, oceanic, and ice sheet models from four polar regions — has helped scientists hone their forecasts for this century’s Antarctic thaw. And the results of the global research effort were more sobering than the findings of most of the more limited studies that came before it.

The world’s seas could rise anywhere from less than half an inch up to more than a foot by the end of this century solely because of the effects of balmier waters fanning Antarctica’s underside, causing ice to melt, icebergs to calve, and ice and snowpack to slough into the sea, the scientists calculated. The upper limit of that projection is more than double earlier estimates, with scientists attributing the change to advances in models.

Those figures do not include additional sea level rise caused by melting glaciers, by the melting of the Greenland ice sheet, by the expansion of warming water, or from the effects of groundwater pumping, which shifts water from aquifers to the seas. If the most recent IPCC projections for those sources of rising seas were combined with the new Antarctic figures, the U.N. group’s upper limit for overall sea level rise by century’s end would increase to 119 cm, or nearly 4 feet. That’s up by more than a fifth compared with the figure included in last year’s assessment.

Antarctic ice

Global Warming

Global Warming Slows Down Antarctica’s Coldest Currents

A shift from briny to fresh in Antarctica’s ocean waters in recent decades could explain the shutdown of the Southern Ocean’s coldest, deepest currents, a new study finds.

The cold currents, called the Antarctic Bottom Water, are chilly, salty rivers that flow from the underwater edge of the Antarctic continent north toward the equator, keeping to the bottom of the seafloor. The currents carry oxygen, carbon and nutrients down to the deepest parts of the ocean. Previous studies have found this deep, dense water is disappearing, though researchers aren’t sure if the shrinkage is part of a long-term trend linked to global warming, or a natural cycle.

The new study suggests that Antarctica’s changing climate is to blame for the shrinking Antarctica Bottom Water. In the past 60 years, the ocean surface offshore Antarctica became less salty as a result of melting glaciers and more precipitation (both rain and snow), researchers reported Sunday (March 2) in the journal Nature Climate Change. This growing freshwater layer is the key link in a chain that prevents the cold-water currents from forming, the study finds.

“Deep ocean waters only mix directly to the surface in a few small regions of the global ocean, so this has effectively shut one of the main conduits for deep-ocean heat to escape,” said Casimir de Lavergne, an oceanographer at McGill University in Montreal.

Holey ice

The linchpins linking freshwater and cold currents are polynyas, or natural holes within sea ice. These persistent regions of open water form when upwellings of warm ocean water keep water temperatures above freezing, or when winds drive sea ice away from the coast.

Polynyas are one of the main sources of Antarctica Bottom Water. Polynyas act like natural refrigerators, letting frigid temperatures and cold winds chill seawater and send it sinking down to the ocean bottom. As the cold water sinks, warmer ocean water comes up to take its place, maintaining the polynya’s open water.

But as Antarctica’s ocean surface water has freshened, fewer polynyas have appeared, the researchers found. That’s because the fresher water is less dense. Even if the water is very cold, it doesn’t sink as readily as saltier water, de Lavergne explained. The freshwater acts like a lid, shutting down the ocean circulation that sends cold water to the seafloor, and brings up warm water into the polynyas.

“What we suggest is, the change in salinity of the surface water makes them so light that even very strong cooling is not sufficient to make them dense enough to sink,” de Lavergne told Live Science. “Mixing them gets harder and harder.”

Trapped heat

In addition to warming and shrinking the Antarctic Bottom Water currents, the reduction in polynyas could be trapping extra heat in the Southern Ocean, de Lavergne said.

“If the warm waters aren’t able to release their heat to the atmosphere, then the heat is waiting in the deep ocean instead,” he said. “This could have slowed the rate of warming in the Southern Hemisphere.”

De Lavergne cautioned that the heat-storage effect is localized and not related to the so-called global warming “hiatus” — the recent slowdown in the rise of global surface temperatures.

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Environment

Vast Antarctic iceberg ‘could threaten shipping’

UK researchers have been awarded an emergency grant to track a vast iceberg in Antarctica that could enter shipping lanes.

Latest images show several kilometres of water between the iceberg, estimated to be about 700 sq km (270 sq miles), and the glacier that spawned the block.

The icy giant broke away from the Pine Island Glacier (PIG) in July.

in the last couple of days, it has begun to break away and now a kilometre or two of clear water has developed between it and the glacier.

It often takes a while for bergs from this area to get out of Pine Island Bay but once they do that they can either go eastwards along the coast or they can circle out into the main part of the Southern Ocean.

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Global Warming

Antarctica Sea Ice Hitting Record Highs

Sea ice surrounding Antarctica hit a record high in August and is on track for another record-breaking month in September. Clocking in at a stunning 7.2 million square miles (18.7 million square kilometres), last month’s sea ice extent was 4.5 percent above the 1981 to 2010 average and the largest extent since record-keeping started in 1979, according to data released today from the National Oceanic and Atmospheric Administration in its monthly State of the Climate Report.

The record sea ice doesn’t contradict global warming. Because Antarctic sea ice encircles a frozen continent, the factors controlling its growth are complex, and include winds, warming air temperatures and even the ozone hole. Wind plays a greater role the size of the ice pack than air temperature or ocean currents, according to a study published in the Nov. 11, 2012, issue of the journal Nature Geoscience. The fierce circumpolar winds carry frigid air from the continent to the sea, freezing the ocean’s surface and pushing the ice around. The August ice surge was likely due to weather patterns that favoured more ice, the Antarctic Sun reported.

Antarctica

Global Warming

Warm Water Under Antarctic Glacier Spurs Rapid Melting

A two-month-long expedition to one of the most remote sites on the planet — the sprawling Pine Island Glacier in Antarctica — has revealed that currents of warm water beneath the glacier are melting the ice at a staggering rate of about 2.4 inches (6 centimetres) per day.

An international team of researchers journeyed to the southernmost continent to study the Pine Island Glacier, which is the longest and fastest-changing glacier on the West Antarctic Ice Sheet. This region, in the far reaches of Antarctica, has been of particular interest to scientists because it is among the most rapidly melting ice masses in the world, thinning as it flows to the Amundsen Sea at a rate of about 2.5 miles (4 kilometres) each year.

Since warm seawater flows beneath the ice shelf (the part of the glacier that floats on the ocean), scientists have known that the Pine Island Glacier was melting from below. Now, using sensors deployed across the 31-mile-long (50-km-long) glacier, the researchers have gauged the rate of glacial melt beneath the solid ice.

The results demonstrate the crucial need to better understand melting processes underneath massive glaciers, including how this undersea process will affect global sea-level rise in the future.

Pine island glacier mission