Antarctic ‘time bomb’ waiting to go off

 

Earth’s sea levels should be nine meters higher than they are — and dramatic melting in Antarctica may soon plug the gap, scientists warn.

They say global temperatures today are the same as they were 115,000 years ago, a time when modern humans were only just beginning to leave Africa.

Research shows during this time period, known as the Eemian, scorching ocean temperatures caused a catastrophic global ice melt. As a result, sea levels were six to nine meters higher than they are today.

But if modern ocean temperatures are the same as they were during the Eemian, that means our planet is “missing” a devastating sea rise.

If oceans were to rise by just 1.8 meters, large swathes of coastal cities would find themselves underwater, turning streets into canals and completely submerging some buildings.

Scientists think sea levels made this jump 115,000 years ago because of a sudden ice collapse in Antarctica.

The continent’s vulnerable West Antarctic ice sheet — which is already retreating again today — released a lot of sea level rise in a hurry.

“There’s no way to get tens of meters of sea level rise without getting tens of meters of sea level rise from Antarctica,” said Dr. Rob DeConto, an Antarctic expert at the University of Massachusetts in the U.S.

His team created state-of-the-art computer models that showed how Antarctic ice responded to warm ocean temperatures during the Eemian.

They showed two processes, called marine ice cliff collapse and marine ice sheet instability, rapidly melted the West Antarctic ice sheet.

They exposed thick glaciers that formed part of the ice sheet to the ocean, meaning the ice blocks floated out to sea more quickly. Here they quickly melted, adding thousands of tonnes of water to the world’s oceans.

Scientists warn if ice shelves in Antarctica undergo similar processes, it could spell disaster for Earth. Combined with melting in Greenland, we could see sea levels rise by almost two meters this century.

In the next century, ice loss would get even worse.

“What we pointed out was if the kind of calving that we see in Greenland today were to start turning on in analogous settings in Antarctica — Antarctica has way thicker ice, it’s a way bigger ice sheet — the consequences would be potentially really monumental for sea level rise,” Dr. DeConto said.

Last month, NASA warned Antarctica’s Thwaites glacier could collapse within decades and “sink cities” after the discovery of a 300-meter doomsday cavity lurking below the ice block.

If you fancy a fright, check out this sea level “doomsday” simulator if you’d like to know whether your home would be wiped out by rising oceans.

This story originally appeared in news.com.au.

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Antarctica is Losing Six Times More Ice Than It Was Four Decades Ago, Study Says

By Drew MacFarlane

2 days ago

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At a Glance

  • A new study found that Antarctica is losing six times more ice each year than it was 40 years ago.
  • Antarctic glaciers lost around 40 billion tons of ice melt each year from 1979 to 1989.
  • That amount jumped to 252 billion tons each year over the last decade.

An alarming new study found that Antarctica is losing six times more ice each year than it was 40 years ago. Researchers believe the accelerated melt could cause sea levels to rise at a quicker rate than predicted in coming years.

That’s just the tip of the iceberg, so to speak,” the study’s lead author, Eric Rignot, who serves as a research scientist for both NASA and the University of California — Irvine, said in a university press release. “As the Antarctic ice sheet continues to melt away, we expect multi-meter sea level rise from Antarctica in the coming centuries.”

From 1979 to 1989, Antarctic glaciers saw some 40 billion tons of ice melt each year. That amount jumped to 252 billion tons each year starting in 2009, the study published in the Proceedings of the National Academy of Sciences found after observing data from 176 drainage basins over 18 regions.

(MORE: Easter Island’s Statues Placed in ‘Ridiculously Predictable’ Locations)

Currently, the Antarctic ice sheet holds about 90 percent of the world’s ice, and if it were all to melt, sea level would rise some 240 feet, according to the U.S. Geological Survey. If the rest of the glacier ice on Earth were to melt — a measly 25 feet on top of Antarctica’s drastic total — every coastal city on the planet would flood.

Ice mass balance of Antarctica from 1979 to 1989 compared to 2009 to 2017.

(Proceedings of the National Academy of Sciences)

The fragility found in areas of East Antarctica — which holds the largest ice sheet on Earth — warrants more attention, Rignot warned.

“The places undergoing changes in Antarctica are not limited to just a couple places,” Rignot told the Washington Post. “They seem to be more extensive than what we thought. That, to me, seems to be reason for concern.”

Most of the ice lost is linked to circumpolar deep water (CDW), concentrations of warm water being driven under ice sheets by a shift in southern westerly winds, the British Antarctic Survey said.

In the last ten years, the study found West Antarctica was responsible for 63 percent of the total loss, East Antarctica contributed 20 percent and 17 percent of the total loss was from the Antarctic Peninsula.

“As ice-shelf melt increases, the glaciers will feel less resistance to flow, accelerate, and contribute to sea level rise,” the study states.

“In the decades to come, it is likely that sea level rise from Antarctica will originate from the same general areas,” researchers noted, resulting in feet of sea level rise if climate change isn’t combated.

Antarctic ice melts to January record low

https://www.usatoday.com/story/news/world/2019/01/04/antarctic-sea-ice-melts-record-low-january-scientists/2481706002/

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The amount of sea ice around Antarctica has melted to a record low for January, scientists announced this week.

As of January 1, there was 2.11 million square miles of sea ice around the continent, the smallest January area since records began in 1978, according to the National Snow and Ice Data Center.

Sea ice is frozen ocean water that melts each summer, then refreezes each winter. Antarctic sea ice is typically at its smallest in late February or early March, toward the end of summer in the Southern Hemisphere.

“Antarctic sea ice extent is astonishingly low this year, not just near the Ross Ice Shelf, but around most of the continent,” Cecilia Bitz, a polar scientist at the University of Washington, told Grist on Thursday.

Specifically, the area of sea ice around Antarctica on Jan. 1 was 11,600 square miles below the previous record low for that date, set in 2017. It was 726,000 square miles below average – an area roughly twice the size of the state of Texas.

With six to eight weeks remaining in the melt season, the ice center said it remains to be seen whether the Antarctic sea ice will set its all-time record-low minimum.

More: Ancient Antarctic ice sheet collapse could happen again, triggering a new global flood

More: Greenland’s ice sheet melt has ‘gone into overdrive’ and is now ‘off the charts’

Sea ice loss – especially in the Arctic and less so in the Antarctic – is one of the clearest signals of global warming, the National Climate Assessment reported last year.

In addition to human-caused warming of the Earth’s atmosphere and oceans, multiple factors – including the geography of Antarctica, the region’s winds, as well as air and ocean temperatures – affect the ice around Antarctica.

“Although it is too soon for us to isolate what caused the rapid December decline and recent record low extents, it is likely that unusual atmospheric conditions and high sea surface temperatures – important factors in the 2016-2017 record lows – are playing a role,” according to a statement from the National Snow and Ice Data Center.

The center added that even though sea ice occurs primarily in the polar regions, it influences our global climate and weather patterns around the world.

Ancient Antarctic ice sheet collapse could happen again, triggering a new global flood

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It’s happened before, and it could happen again.

Tens of thousands of years ago, a giant ice sheet in Antarctic melted, raising sea levels by up to 30 feet around the world. This inundated huge swaths of what had been dry land. Scientists think it could happen again as the world heats up because of man-made global warming, new research suggests.

Such a collapse would again cause seas to rise dramatically, which would lead to a global flood.

Researchers led by geologist Anders Carlson of Oregon State University said the ice sheet disappeared about 125,000 years ago under climate conditions that were similar to today’s.

If future research confirms this finding, “the West Antarctic ice sheet might not need a huge nudge to budge,” Jeremy Shakun, a paleoclimatologist at Boston College told Science magazine. That, in turn, means “the big uptick in mass loss observed there in the past decade or two is perhaps the start of that process rather than a short-term blip.”

And once the ancient ice sheet melt got started, things got out of hand rather quickly. Global ocean waters may have risen as fast as 8 feet per century, a blink of an eye in climatological terms.

To do their research, Carlson’s team examined several marine sediment cores taken offshore of Antarctica. The cores are long cylinders of mud and silt that give clues about past changes in Earth’s climate.

Obviously, climate change 125,000 years ago was natural, not human caused as it is today.

Scientists speculate that a slight change in Earth’s orbit and spin axis created warmer temperatures in the Northern Hemisphere, which caused climate changes around the world, Nathaelle Bouttes at the National Centre for Atmospheric Science in the U.K. told Smithsonian magazine.

The research was announced earlier in December at a meeting of the American Geophysical Union in Washington, D.C.

Some of the process is well underway: Global warming has caused over 3 trillion tons of ice to melt from Antarctica in the past quarter-century and tripled ice loss there in the past decade, a study released in June said.

That total is equivalent to more than 2 quadrillion gallons of water added to the world’s oceans, making Antarctica’s melting ice sheets one of the largest contributors to rising sea levels.  That amount of water is enough to fill more than a billion swimming pools or cover Texas to a depth of nearly 13 feet.

Overall, scientists say the melting ice in Antarctica is responsible for about one-third of all sea-level rise around the world.

Earth’s Ice Loss “Is a Nuclear Explosion of Geologic Change”

Much of the frozen water portion of the Earth, otherwise known as the cryosphere, is melting.

This is not news: It’s been happening for decades. What is news is that the long-term melting trends in the Arctic, Antarctica, and with most land-based glaciers are accelerating, often at shocking rates, largely due to human-caused climate change.

Antarctica is melting three times as fast as it was just 10 years ago, alarming scientists. A study earlier this year showed 3 trillion tons of ice had disappeared since 1992. That is the equivalent of enough water to cover the entire state of Texas with 13 feet of water, and raise global sea levels a third of an inch.

“From 1992 to 2011, Antarctica lost nearly 84 billion tons of ice a year (76 billion metric tons),” read the AP story on the study. “From 2012 to 2017, the melt rate increased to more than 241 billion tons a year (219 billion metric tons).”

“I think we should be worried,” one of the study’s 88 co-authors, University of California, Irvine’s Isabella Velicogna, told AP. “Things are happening. They are happening faster than we expected.”

In fact, the polar ice caps have melted faster in the last 25 years than they have in the last 10,000 years.

In the Arctic, the Greenland Ice Sheet is losing an average of 270 billion tons of ice each year, and the strongest sea ice in the region broke up for the first time on record this summer.

For glaciers that exist outside of the Polar Regions, the situation is even worse.

“You can count on all alpine glaciers in the world to be gone by 2100,” Dan Fagre, US Geological Survey (USGS) research ecologist and director of the USGS Climate Change in Mountain Ecosystems Project, told Truthout.

Truthout spoke with experts like Fagre, as well as others with expertise in the Antarctic and Arctic, who shared an often-grim prognosis of what lies in store for the cryosphere.

Greenland

Ruth Mottram is a climate scientist at the Danish Meteorological Institute who has been studying Greenland for the last 11 years, and the Arctic for the last 15. Mottram is also one of the scientists behind the Polar Portal – a Danish web portal that gives near real-time data on the Arctic, including sea ice and Greenland ice sheet processes.

She explained to Truthout that melting in Greenland can vary significantly from year to year and is highly dependent upon weather conditions any given year.

“However, since the turn of the millennium there has been a series of summers where there have been increasingly large amounts of melt and runoff into the ocean,” Mottram explained.

She studies the surface mass budget, which is the balance between income — snowfall — and the outgoing melt and runoff. Mottram and her colleagues sum these up daily on the Polar Portal, as well as over the entire year, which in turn gives them an idea of the “health” of the ice sheet.

Her data is alarming.

“Of the top 10 lowest surface mass budget years,” Mottram said of this data, “only 2 occurred before the year 2000.”

She explained that on top of this, the ice sheet can also lose mass by calving (ice breaking off a glacier at its terminus) from glaciers and basal melting.

“Yet, both of these processes also have to be balanced by snowfall and what we see in the last two years is that the total budget, as opposed to the surface-only budget, has been roughly neutral – around 0,” she added.

However, Mottram also pointed out how the ice sheet has lost 200 – 300 gigatonnes (one gigatonne is about 1 cubic kilometer) of ice every year from 2003-2011. This means that the two aforementioned neutral and relatively lower melting years, as she put it, “do not nearly reverse the mass losses of the last decades.”

Greenland Ice Sheet meltwater is influencing the circulation of the Atlantic Meridional Overturning Circulation (AMOC), a massive oceanic conveyor belt current that moves huge amounts of warm water from the tropics northward, and from the Atlantic up toward the Arctic. The AMOC plays a critical role in creating the mild climate of the UK and other parts of Western Europe.

“There is also some evidence that Arctic climate change in general is influencing mid-latitude weather patterns – leading to the kind of persistent and extreme weather that leads to, for example, the heatwave we had in northern Europe this year,” Mottram explained. “The idea is that the warming of the Arctic – which has been more rapid than in other parts of the planet – has led to a smaller difference in temperature between pole and tropics, which then leads to a more wavy jet-stream.”

While Mottram believes longer observations are needed on this topic, some studies have pointed out how the wavier jet-stream is intensifying extreme weather events like hurricanes, as well as altering global climate patterns.

Meanwhile, the increasing melt of the Greenland Ice Sheet is directly linked to the increase in calving and iceberg production at outlet glaciers.

“These can pose hazards to shipping and fisheries,” Mottram added. “But they also allow the ice sheet to contribute water to the ocean faster than just by melting.”

She and her colleagues also note the number of storms tracking up the east coast of Greenland of late, which have brought a lot of snow and rain to eastern Greenland and seem to be penetrating higher up into the Arctic – possibly due to the lower sea ice extent there.

“The winds associated with these storms can bring quite high temperatures to east and northeast Greenland, and this year we twice saw very unusual warm periods – associated with Foehn winds (similar to the Chinook in north America) – that also opened up the pack ice around the coast of Greenland,” Mottram explained. She also pointed out the role this could have played in the way in which the aforementioned “last ice area” of sea ice recently began to move away from the coast and break up.

This led to the north coast of Greenland briefly becoming navigable over the summer. The Polarstern and Oden – two research ships from Germany and Sweden respectively – were able to access areas of the Arctic to do research much more easily than had been expected.

The same is true of the Venta Maersk – the Danish “ice class” container ship that was the first to traverse the northern sea route this summer.

“It’s not to say it’s easy to sail in the Arctic right now, quite not,” Mottram said. “But the time is coming soon!”

Michael MacCracken, the chief scientist for climate change programs at the Climate Institute in Washington, DC, told Truthout that the loss of land ice, such as the loss of mass from the Greenland Ice Sheet, clearly raises sea level globally.

“This threatens low-lying coastal areas and island nations, and additionally, the rise in sea level can lift up glacial ice streams around Antarctica,” he said. “This then allows ocean waters better access to the ice streams, warming them and making calving more likely, ultimately contributing to further sea level rise.”

Antarctica

NASA emeritus scientist Robert Bindschadler, who worked for 35 years as a glaciologist at NASA Goddard Space Flight Center, previously told Truthout that the world may see three to four meters of sea level rise by the year 2200.

Bindschadler has led 18 field expeditions to Antarctica, published more than 130 scientific papers, and advised the US Congress and a former vice president on the stability of ice sheets and ice shelves. His current primary concern about what is happening in the Antarctic is linked to the fact that many of the glaciers there exist within deep valleys, as remote sensing has proven as of late.

“These deep valleys matter because they mean the glacier is sitting in a trough so deep that were you to remove the ice, it is below sea level,” Bindschadler told Truthout. “The damage the ocean can do only extends to the point where the glacier retreats onto the land. But the fact that these big outlet glaciers in Antarctica are sitting in a valley whose floor is below sea level means they can never escape the impact the oceans have on them.”

In other words, these land-based glaciers are now at risk of being melted from below by warming seawater that could flow into the valleys within which the glaciers are located.

He pointed out another worrisome fact about these valleys: Many of their depths may increase the further they get from the ocean.

“So, the ocean has greater impact on them the more they melt, which means the potential for fast and continual retreat of these outlet glaciers is probably more widespread than we appreciated four years ago,” Bindschadler added.

Bindschadler is concerned that these valleys – in which so many of the major glaciers exist – could be the next major factor in how glacial ice is rapidly released into the oceans, causing sea levels to rise further.

Alpine Glaciers

Fagre, who is the lead investigator in the USGS Benchmark Glacier Program and has been working in Glacier National Park since 1991, is concerned about how mountain snowpack has been shrinking in Glacier National Park, like in so many other places, over the last half century.

In Glacier National Park, the snow is on the ground an average of 30 days less than it used to be.

“Since the planet is warming up, more of the precipitation in Glacier is now falling as rain instead of snow,” Fagre told Truthout. Since they’re less likely to be covered in snow, glaciers are more directly exposed to the sun, which obviously hastens their melting.

In 1850, Glacier National Park, before it was designated a national park, contained 150 glaciers, covering around 100 square kilometers. Today, only between 14 and 15 square kilometers of ice coverage remain, an 85 percent loss. Instead of 150 glaciers, there are now only 26. Even this alarming tally of ice loss is a conservative estimate, as measuring area doesn’t account for thinning.

Fagre and his team started monitoring the mass balance of Glacier National Park’s Sperry Glacier in 2005.

“Our program mirrors what the others are seeing in Alaska and the Cascades,” he said. Aside from a couple of years where the glacier accumulated more ice, the glacier lost mass consistently, “as is true for almost every mountain glacier in the world for which we have mass balance information.”

“Our trajectory has well exceeded previous worst-case projections for many of our glaciers,” said Fagre, and added that the Blackfoot and Jackson Glaciers in the park had melted faster than the predictions by a full decade.

“What we’ve found since then is that they continue to go, and at unsustainable rates,” he said.

“This is an explosion, a nuclear explosion of geologic change,” Fagre said of the global impacts from climate change, particularly in the cryosphere. “This is unusual. It is incredibly rapid and exceeds the ability for normal adaptation. We’ve shoved it into overdrive and taken our hands off the wheel.”

Conclusion

Kevin Lister, an associate with the Climate Institute in Washington, DC, co-authored a paper with MacCracken for the UN that addressed the crisis in the Arctic, among other climate change-related issues.

Lister and MacCracken’s paper showed that the natural rate of carbon sequestration is so slow as to not be measurable. This doesn’t bode well for the possibility of halting climate change: The researchers say that carbon sequestration will be incapable of bringing atmospheric CO2 down to safe levels even in the hypothetical circumstance of a zero-carbon economy emerging.

Their paper also shows that while carbon sequestration and mitigation measures must continue to be pursued, “the likelihood is that that they will be unable to bring [atmospheric] CO2 down fast enough.”

Lister believes that climate change “is fundamentally irreversible as there is strong evidence that the heating effects of the amplifying mechanisms are greater than that of increases in [atmospheric] CO2.”

Lister told Truthout that he and MacCracken have argued that dramatic solutions to the climate crisis “must be pursued with all urgency.”

“Should we fail to make a start, then the scale of intervention that we need and the risks associated with it will increase exponentially with any delay,” Lister said.

Temperatures Possible This Century Could Melt Parts of East Antarctic Ice Sheet, Raise Sea Levels 10+ Feet

A glacier flows towards East Antarctica. NASA Goddard Space Flight Center / CC BY 2.0

A section of the East Antarctic Ice Sheet that contains three to four meters (approximately 10 to 13 feet) of potential sea level rise could melt if temperatures rise to just two degrees above pre-industrial levels, a study published in Nature Wednesday found.

Researchers at Imperial College London, the University of Queensland, and other institutions in New Zealand, Japan and Spain looked at marine sediments to assess the behavior of the Wilkes Subglacial Basin during warmer periods of the Pleistocene and found evidence of melting when temperatures in Antarctica were at least two degrees Celsius above pre-industrial levels for periods of 2,500 years or more.

“With current global temperatures already one degree higher than during pre-industrial times, future ice loss seems inevitable if we fail to reduce carbon emissions,” Imperial College researcher Dr. David Wilson said in a University of Queensland press release published by ScienceDaily.

The East Antarctic Ice Sheet has been considered less susceptible to melting than the West Antarctic Ice Sheet because its basin is largely above sea level, but the Wilkes Subglacial Basin is below sea level and therefore more vulnerable, University of Queensland researcher Dr. Kevin Welsh said in press release.

“The evidence we have suggests that with the predicted two degrees Celsius warming in Antarctica—if sustained over a couple of millennia—the sheet would start melting in these locations,” Welsh said.

Wilson told The Washington Post that the earth could see temperatures this century that would be warm enough to start the melting process eventually, but the study did not indicate how fast or slow that process would be.

“What we definitely can say is that during the [geological] stages where temperatures were warm for a couple of degrees for a couple of millennia, this is where we see a distinct signature in our records,” Wilson told The Washington Post. “We can’t necessarily say things didn’t happen quick, but we can’t resolve that in our data.”

During one of the periods studied, around 125,000 years ago, sea levels were 20 to 30 feet higher than they are now, The Washington Post reported.

University of California at Irvine glaciologist Isabella Velicogna, who was not involved in the study, told The Washington Post that it “contributes to the mounting pile of evidence that East Antarctica is not as stable as we thought.”

The Paris agreement seeks to limit warming to “well below” two degrees above pre-industrial levels, but current efforts are not sufficient to meet this goal, according to an International Energy Agency report released in March.

Another study released this week offers a back-up plan: underwater walls of rock and sand to stop glaciers from sliding and collapsing and to protect them from the warmer ocean water that accelerates melting.

The study, published in the Cryosphere Thursday, used modeling to assess the impact of various geoengineering projects on halting the collapse of West Antarctica’s Thwaites Glacier, projected to be the greatest individual source of potential sea level rise.

“We are imagining very simple structures, simply piles of gravel or sand on the ocean floor,” study author and Princeton University Department of Geosciences researcher Michael Wolovick told The Guardian.

Wolovick said the designs were “within the order of magnitude of plausible human achievements.”

They calculated that the smallest design, constructing a series of columns or mounds using about the same amount of material required to build Dubai’s Palm Islands, would have a 30 percent chance of preventing the West Antarctic Ice Sheet’s collapse.

Building a full wall, a more ambitious endeavor, would have a 70 percent chance of blocking 50 percent of warmer water from reaching the ice.

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Major Antarctic ice sheet shrank when it wasn’t much warmer than now

A small bit of warming compared to the present for enough time melts a lot of ice.

View of a glacier meeting the ocean.

Are the big ice sheets in Antarctica stable in the face of the warming we’ve already committed to? That’s a more serious question than it might sound. The continent is thought to hold enough ice to raise ocean levels by over 55 meters if it were to melt—enough to drown every single bit of coastal infrastructure we have and send people migrating far inland from the present-day shoreline.

But the melting of this ice is a complicated process, one that depends on things like the dynamics of glaciers as they push through coastal hills, the shape of the seafloor where the ice meets it, and the slope of the basins the ice sheets sit in. It’s tough to reason out how much ice would be lost for a given bit of warming. As a result, we’re left with historical comparisons—the last time it warmed by that amount, how much ice did we lose?

This week, we got some new information on this topic courtesy of a detailed study of Antarctica’s Wilkes Subglacial Basin. The work showed that it wasn’t so much the amount of warming the ice experienced; it was how long it stayed warm.

Lots of ice

The majority of the South Pole’s ice is in the East Antarctic Ice Sheet, which has a structure that could leave it prone to instability. The ice sits on rock that’s below sea level in large basins. The water is currently kept out by the large mass of ice that rises above sea level, pushing the rest down. If the ice thinned significantly and ocean water invaded the basin, the ice could float off the rock and break up, dramatically raising sea levels in a relatively short amount of time. The ice hasn’t completely destabilized in millions of years, but there are indications that parts of the East Antarctic Ice Sheet have been lost in the past.

While the Earth has undergone a regular cycle of warmer and glacial periods for the past few million years, the details of the warm periods have varied due to differences in things like orbital configurations and greenhouse gas levels. Their length and maximum temperature differed, meaning we have multiple possible examples of what some degree of future warming might bring to ocean levels, even if the uncertainties are still significant. These mostly tell us that it may not need to get much warmer than the present to see over five meters of additional sea level rise.

The key question addressed in the current paper is “why?”. Is that extra ocean coming from the destabilization of some of Antarctica?

To understand this, researchers relied on sediment cores taken from the ocean near the Wilkes Subglacial Basin, part of the East Antarctic Ice Sheet. (The cores come from a depth of nearly 3.5km.) These cores covered several recent glacial cycles, including two that are especially relevant, as they involved temperatures about 2°C above preindustrial conditions (or 1°C above present) and over six meters of additional sea level. These occurred approximately 125,000 and 425,000 years ago. The cores covered a number of additional cycles, allowing the two to be compared with different conditions.

The cores easily show the difference between glacial and interglacial conditions. To begin with, there are far more signs of life during the interglacials, indicating that the area was probably covered by sea ice during glacial periods; sediments were much siltier during these times. In addition, interglacial periods often contained “dropstones,” which are rocks melted out of the underside of icebergs that drifted through the area.

Isotopes and erosion

To understand where the ice was during each period, the researchers turned to isotopes of the element neodymium, which vary in the different rock layers in Antarctica. They found that during these two critical interglacials, the ratio of different neodymium isotopes changed at the same time that the dropstones and other iceberg debris started appearing. Similar changes had been seen during warm periods in the Pliocene, when we know that the Antarctic lost significant ice.

The authors explain this difference by suggesting that the ice was eroding different rocks once these interglacial periods started; a similar conclusion is supported by strontium isotope data. Currently, the area at the edge of the glaciers, where most of the scoured material originates, is primarily granite. But we know that there’s also large regions of basalt on the continent, and it’s possible that some of these reside in the basin behind the current exit glaciers. That would suggest that the ice retreated significantly from the present coast during these warm periods.

Overall, they identify three different interglacials where this data suggests the ice sheets retreated, and at least one where they did not. The difference between them isn’t the maximum temperature reached during the warm period; instead, in all cases where the glaciers retreated, the elevated temperatures lasted for at least 2,500 years. The present interglacial, which also has not featured a major ice sheet retreat, looks similar to the earlier one where the glaciers also remained stable.

Message for the present?

So what does that mean for the present? Potentially good things, assuming the world gets its act together and hits the target of limiting climate change to 2°C above preindustrial conditions. The results suggest that we could tolerate at least a thousand years of these sort of temperatures before the Wilkes Subglacial Basin saw significant ice retreat. Which means there is plenty of time to develop technologies that remove carbon dioxide from the air and lower the temperatures to prevent this event (assuming we still have coastal infrastructure we want to preserve).

The bad news is that we’re not currently hitting our targets, raising the prospect that we’ll overshoot the 2°C target, potentially by a wide margin. If that’s the case, then it’s possible we’ll destabilize the East Antarctic Ice Sheet on a shorter time scale and have to scramble to develop negative emissions technologies to remove a lot of CO2.

But even here, there’s a silver lining. The ocean levels during the interglacial periods are nothing like those that would be expected if the East Antarctic Ice Sheet had completely destabilized. So either it has at least semi-stable states in between present conditions and collapsed or the collapse is gradual enough and can be reversed under the right conditions. This means that while we might face sea level rise that’s catastrophic for existing coastal regions, we won’t be looking at a planet remade by 50 meters of additional ocean.

Climate scientist says we have to act soon if we want to protect the southernmost continent.

by Sarah Cahlan /  / Updated 
Image: ANTARCTICA

Antarctica’s ice is melting three times faster today than just a decade ago. Eitan Abramovich / AFP – Getty Images file

Scientists have long known that rising temperatures are melting Antarctica’s vast ice sheet, sending water into the Southern Ocean and raising sea levels around the world. But many were surprised last week by a new study showing that Antarctica’s ice is melting three times faster today than just a decade ago.

In light of the unwelcome news, what lies ahead for Antarctica? Will rising temperatures cause the southernmost continent to lose most or all of its ice — and trigger catastrophic flooding around the world? Or will we find the political will and the scientific know-how to limit the carbon emissions that fuel climate change and keep Antarctica frozen?

For the answers to these and other questions, NBC News MACH spoke with climate scientist Stephen Rintoul, who has done research describing two starkly different scenarios for Antarctica five decades in the future: One shows what will happen if steps are taken to curb the carbon emissions, while the other what happens if we do nothing.

MACH: Why is Antarctica so central to discussions of climate change?

Rintoul: Antarctica is remote, but it’s closely connected to the rest of the world. The volume of ice in Antarctica — if it were all to melt — is enough to raise global sea level by more than 50 meters [more than 160 feet]. Even a small change in the Antarctic ice sheet might make a big change to sea level.

The Southern Ocean also controls how fast climate changes for a given amount of greenhouse gas emissions. That’s because the currents in the ocean take up heat and carbon dioxide from the atmosphere and store it in the interior of the ocean — that acts to slow the pace of climate change. If the Southern Ocean currents were to change in the future, that might either accelerate or decelerate the rate of climate change.

Future scenarios of Antarctica based on carbon emissions.
Future scenarios of Antarctica based on carbon emissions. Courtesy of Stephen Rintoul and Nature

How fast is the Antarctic ice sheet melting?

The new study presents a record of how the Antarctic ice sheet has changed over the last 25 years. This is now the longest and most complete record we have, and it’s still pretty short in the lifetime of an ice sheet. But over the last 25 years, the Antarctic ice sheet has lost about 3 trillion tons of ice.

That’s a very small fraction of the total Antarctic ice sheet — about 0.01 percent. But even that small change has been enough to raise global sea level by a measurable amount, and the rate at which Antarctica is contributing to sea level rise is accelerating. Over the past five years the rate of ice loss from Antarctica is three times what it was 25 years ago.

How much of the ice would need to melt before we notice the effects?

We’re already noticing the sea level rise that has happened to date. The flooding in New York with Hurricane Sandy would not have been as serious as it was if sea level had not risen over the last century or so. And in many coastal environments around the world, we’re seeing an increase in the frequency and the size of coastal flooding. We’re feeling it already even with a global sea level rise which is much smaller than what’s forecast to come in the coming decades.

What happens if we fail to curb carbon emissions?

Under continued high emissions, one of the most serious consequences by 2070 is that the floating ice shelves around the edge of Antarctica will have started to thin and weaken and break up. As the ice flows off the Antarctic continent, it reaches the ocean, and some of it starts to float — those are the floating ice shelves. They act like a buttress or a barrier that helps restrict the flow of ice from the Antarctic into the ocean. If we weaken those ice shelves or remove them, more ice flows into the sea. That increases sea levels.

By 2070 under that scenario, the Antarctic contribution to sea level will have increased by about 27 centimeters. If we want to avoid that scenario, we need to make a decision to reduce emissions sharply within the next decade.

Antarctica in 2070 if we don't curb carbon emissions.
Antarctica in 2070 if we don’t curb carbon emissions. Courtesy of Stephen Rintoul and Nature

How would rising seas affect us?

It doesn’t sound like very much, but the effect of storms or high sea level events is more serious because it comes on top of a higher baseline. And so, the frequency of coastal flooding increases with time and the magnitude of coastal flooding increases with time as the average sea level rises.

A study estimates that the damage caused by coastal flooding in about 150 coastal cities will reach a trillion dollars a year within the next 50 years — if we don’t protect the coast. And the cost of protecting the coast will be about $50 billion a year. It doesn’t take a huge amount of sea level rise before we’re coping with a flood event that used to happen once a century now happening once a decade.

What if we take effective steps to reduce carbon emissions?

Antarctica in 2070 looks much like it does today if we follow the low-emissions trajectory. The point of the paper is that we have a choice. It’s not too late to choose the low-emissions scenario. But we do need to act very soon because if we continue along the present trajectory of relatively high greenhouse gas emissions, within 10 years or less it becomes impossible to get back to that low-emissions scenario.

One way to think about it is that to keep temperatures below a certain threshold — say, to keep warming below 2 degrees [Celsius] like the Paris [COP21] agreement set out to do. We have a budget of carbon that we’re allowed to spend, and we’ve already spent about two-thirds of that budget. The longer we continue to emit high levels of CO2, and spend that budget, the less we have left for the rest of time. And so, it really is important to turn that emissions trajectory downward as soon as we possibly can to buy us more time.

What will it take to make that happen?

I don’t downplay the challenge of fully realizing that low-emissions trajectory. And the longer we wait to turn emissions around and start decreasing the amount of greenhouse gases we emit, the more difficult it becomes, the more costly it becomes and the more quickly we need to do it.

The causes for optimism, and there are some, are that some groups in nations, industries, communities and regions are starting to take this seriously. They’re taking it seriously both because they appreciate the consequences of not acting but also that they see opportunities in a low-carbon economy. It means we don’t have to wait for the political system at the national level to reach agreement that we’re going to get serious about action. We can do it in smaller steps taken by many individuals and groups around the world.

Antarctica is melting faster than we knew. Here’s what it will take to save it.

[We don’t need to save just “it”, but all life on the planet…]
Climate scientist Stephen Rintoul says we have to act soon if we want to protect the southernmost continent.
by Sarah Cahlan /  / Updated 
Image: ANTARCTICA

Antarctica’s ice is melting three times faster today than just a decade ago. Eitan Abramovich / AFP – Getty Images file

Scientists have long known that rising temperatures are melting Antarctica’s vast ice sheet, sending water into the Southern Ocean and raising sea levels around the world. But many were surprised last week by a new study showing that Antarctica’s ice is melting three times faster today than just a decade ago.

For the answers to these and other questions, NBC News MACH spoke with climate scientist Stephen Rintoul, who has done research describing two starkly different scenarios for Antarctica five decades in the future: One shows what will happen if steps are taken to curb the carbon emissions, while the other what happens if we do nothing.

MACH: Why is Antarctica so central to discussions of climate change?

Rintoul: Antarctica is remote, but it’s closely connected to the rest of the world. The volume of ice in Antarctica — if it were all to melt — is enough to raise global sea level by more than 50 meters [more than 160 feet]. Even a small change in the Antarctic ice sheet might make a big change to sea level.

The Southern Ocean also controls how fast climate changes for a given amount of greenhouse gas emissions. That’s because the currents in the ocean take up heat and carbon dioxide from the atmosphere and store it in the interior of the ocean — that acts to slow the pace of climate change. If the Southern Ocean currents were to change in the future, that might either accelerate or decelerate the rate of climate change.

Future scenarios of Antarctica based on carbon emissions.
Future scenarios of Antarctica based on carbon emissions. Courtesy of Stephen Rintoul and Nature

How fast is the Antarctic ice sheet melting?

The new study presents a record of how the Antarctic ice sheet has changed over the last 25 years. This is now the longest and most complete record we have, and it’s still pretty short in the lifetime of an ice sheet. But over the last 25 years, the Antarctic ice sheet has lost about 3 trillion tons of ice.

That’s a very small fraction of the total Antarctic ice sheet — about 0.01 percent. But even that small change has been enough to raise global sea level by a measurable amount, and the rate at which Antarctica is contributing to sea level rise is accelerating. Over the past five years the rate of ice loss from Antarctica is three times what it was 25 years ago.

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How much of the ice would need to melt before we notice the effects?

We’re already noticing the sea level rise that has happened to date. The flooding in New York with Hurricane Sandy would not have been as serious as it was if sea level had not risen over the last century or so. And in many coastal environments around the world, we’re seeing an increase in the frequency and the size of coastal flooding. We’re feeling it already even with a global sea level rise which is much smaller than what’s forecast to come in the coming decades.

What happens if we fail to curb carbon emissions?

Under continued high emissions, one of the most serious consequences by 2070 is that the floating ice shelves around the edge of Antarctica will have started to thin and weaken and break up. As the ice flows off the Antarctic continent, it reaches the ocean, and some of it starts to float — those are the floating ice shelves. They act like a buttress or a barrier that helps restrict the flow of ice from the Antarctic into the ocean. If we weaken those ice shelves or remove them, more ice flows into the sea. That increases sea levels.

By 2070 under that scenario, the Antarctic contribution to sea level will have increased by about 27 centimeters. If we want to avoid that scenario, we need to make a decision to reduce emissions sharply within the next decade.

Antarctica in 2070 if we don't curb carbon emissions.
Antarctica in 2070 if we don’t curb carbon emissions. Courtesy of Stephen Rintoul and Nature

How would rising seas affect us?

It doesn’t sound like very much, but the effect of storms or high sea level events is more serious because it comes on top of a higher baseline. And so, the frequency of coastal flooding increases with time and the magnitude of coastal flooding increases with time as the average sea level rises.

A study estimates that the damage caused by coastal flooding in about 150 coastal cities will reach a trillion dollars a year within the next 50 years — if we don’t protect the coast. And the cost of protecting the coast will be about $50 billion a year. It doesn’t take a huge amount of sea level rise before we’re coping with a flood event that used to happen once a century now happening once a decade.

What if we take effective steps to reduce carbon emissio[ns?

Antarctica in 2070 looks much like it does today if we follow the low-emissions trajectory. The point of the paper is that we have a choice. It’s not too late to choose the low-emissions scenario. But we do need to act very soon because if we continue along the present trajectory of relatively high greenhouse gas emissions, within 10 years or less it becomes impossible to get back to that low-emissions scenario.

One way to think about it is that to keep temperatures below a certain threshold — say, to keep warming below 2 degrees [Celsius] like the Paris [COP21] agreement set out to do. We have a budget of carbon that we’re allowed to spend, and we’ve already spent about two-thirds of that budget. The longer we continue to emit high levels of CO2, and spend that budget, the less we have left for the rest of time. And so, it really is important to turn that emissions trajectory downward as soon as we possibly can to buy us more time.

What will it take to make that happen?

I don’t downplay the challenge of fully realizing that low-emissions trajectory. And the longer we wait to turn emissions around and start decreasing the amount of greenhouse gases we emit, the more difficult it becomes, the more costly it becomes and the more quickly we need to do it.

The causes for optimism, and there are some, are that some groups in nations, industries, communities and regions are starting to take this seriously. They’re taking it seriously both because they appreciate the consequences of not acting but also that they see opportunities in a low-carbon economy. It means we don’t have to wait for the political system at the national level to reach agreement that we’re going to get serious about action. We can do it in smaller steps taken by many individuals and groups around the world.

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Ice Loss in Antarctica Triples in 10 Years

MARK KARLIN, EDITOR OF BUZZFLASH AT TRUTHOUT

antarcticajpg2Ice melt in Antarctica is increasing. (Photo: Tak)

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http://buzzflash.com/commentary/ice-loss-in-antarctica-triples-in-last-ten-years

In the midst of a presidential administration and Republican majority in Congress that deny the reality of global warming, factual research continues to indicate the looming disaster of climate change. However, due to the mainstream corporate media focus on the spectacle of Trump, there is little sustained coverage of the peril that awaits us, even though the warning signs are occasionally reported on. Furthermore, the “alternative facts” of the climate deniers stifle intensive coverage of the ruinous future due to relative inaction on reducing carbon and methane emissions.

On June 13 The Washington Post reported on a study that has just been released:

Antarctica’s ice sheet is melting at a rapidly increasing rate, now pouring more than 200 billion tons of ice into the ocean annually and raising sea levels a half-millimeter every year, a team of 80 scientists reported Wednesday.

The melt rate has tripled in the past decade, the study concluded. If the acceleration continues, some of scientists’ worst fears about rising oceans could be realized, leaving low-lying cities and communities with less time to prepare than they had hoped.

The result also reinforces that nations have a short window — perhaps no more than a decade — to cut greenhouse-gas emissions if they hope to avert some of the worst consequences of climate change.

In the period from 2012-2017, Antarctica lost 219 billion tons of ice each year, according to The Post. The article reveals a stunning comparison to that figure: “From 1992 through 1997, Antarctica lost 49 billion tons of ice annually.” That’s an increase of 170 billion tons of ice melt.

With a continued rise in sea levels, as The Post notes, cities and communities that are located on the ocean are in jeopardy. Rising sea levels will gradually erode the shorelines of these population centers and eventually flood them. These include such major cities in the United States as New York, Miami and Los Angeles. In fact, the entire Eastern and Western seaboard are being threatened in the absence of reversing climate change. Ominously, there is no emergency and comprehensive plan that would reverse this trend. The Paris accord — which Trump pulled out of — has voluntary goals for nations and falls short of fully tackling the accelerating global warming threat.

As an article in this week’s Time about the new revelations notes:

In Antarctica, it’s mostly warmer water causing the melt. The water nibbles at the floating edges of ice sheets from below. Warming of the southern ocean is connected to shifting winds, which are connected to global warming from the burning of coal, oil and natural gas, Shepherd said.

More than 70 percent of the recent melt is in West Antarctica.

Twila Moon, a research scientist at the National Snow and Ice Data Center who wasn’t part of the studies, said “ice-speaking, the situation is dire.”

Dire indeed. However, beyond the media focus on Trump as ringmaster of a circus, there is an additional challenge in coming to terms with climate change. In a society that responds to what is happening today and has little interest in safeguarding the future, the warning signs of the devastating effect of global warming appear, to many, to be too distant in their implications. The United States is not a nation that places a priority on what might occur down the road. Mainstream corporate news coverage emphasizes what is happening contemporaneously, not problems of the future.

The Associated Press story on the study emphasizes how thorough and evidence-based the research is: “Unlike single-measurement studies, this team looks at ice loss in 24 different ways using 10 to 15 satellites, as well as ground and air measurements and computer simulations, said lead author Andrew Shepherd of the University of Leeds in England.”

Shepherd also squarely laid the blame on climate change:

“Under natural conditions we don’t expect the ice sheet to lose ice at all,” Shepherd said. “There are no other plausible signals to be driving this other than climate change.”

These are the facts, not the “alternative facts,” and they should be the cause of sustained alarm and remediation. Otherwise, we are left with the likes of climate deniers brushing back the mass media on reporting on the impending threat.

Imbie, the organization that released the study, notes on its website:

Sea level rise is likely to continue at an even faster rate during the 21st century. It is also predicted to affect more than 95% of the world’s oceans by 2100, with 70% of coastlines experiencing rising sea levels.

As noted earlier, we are not a country that has long-term vision about preventing disasters. Furthermore, we are up against a Republican wall of opposition to acknowledging that climate change is made by humans. Take Senator James Inhofe (R-OK), a leading climate denier, who said in a 2017 floor speech in the Senate:

The hoax is that some in the far left believe man controls changes in the climate and we’ve endured eight years of an administration that buys into the alarmists’ mentality that the world is coming to an end due to man-made gases. That’s the hoax.

No, it’s not a hoax. It’s an attempt to salvage the planet based on scientific — not spurious — facts.