Greenland’s most critical glacier is suddenly gaining ice, but that might not be a good thing

20 years later, a Greenland glacier is finally growing

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20 years later, a Greenland glacier is finally growing 00:57

(CNN)Greenland’s largest and most critical glacier, Jakobshavn, is gaining ice, according to NASA researchers.

Although this finding is surprising and temporarily good news for the glacier, limiting its contribution to sea level rise, the reason for the ice accumulation might spell disaster in the long run.
For two decades, Jakobshavn sustained remarkably consistent thinning that scientists thought would continue, if not accelerate, due to large-scale warming of the polar atmosphere and oceans — but that rate dramatically slowed in 2014, and the glacier actually thickened between 2016 and 2017 and again between 2017 and 2018, according to a study published Monday in the journal Nature.
“At first we didn’t believe it,” said Ala Khazendar, the lead NASA scientist on the study. “We had pretty much assumed that Jakobshavn would just keep going on as it had over the last 20 years.”
A close-up of the Jakobshavn glacier.

Jakobshavn Isbrae, the full name of the glacier along Western Greenland’s coast, has been Greenland’s fastest-flowing and largest ice-losing glacier over the past 20 years, making it by far the single largest contributor to sea level rise on the large, mostly frozen island.
In fact, according to Khazendar, the melting from that single glacier alone contributed to global oceans rising an average of 1 millimeter between 2000 and 2010.
And even though Jakobshavn has gained ice at lowest levels where it enters the sea, it has still been contributing to sea level rise because the rate it is melting into the ocean is still greater than the rate that ice is accumulating higher up on the glacier, according to the researchers.
The glacier controls a basin with enough ice, that if melted fully, would raise global oceans by about 2 feet.
It is this threat, and the rapid speed with which Jakobshavn had been shredding ice over the past several decades, that has led droves of scientists to the icy coastline and makes the glacier one of, if not the most, studied glaciers in the world.
Khazendar, along with a team of other scientists at NASA’s Jet Propulsion Laboratory, used a number of datasets from NASA that analyze Greenland’s ice, oceans and atmosphere, including those from recent targeted research missions called Oceans Melting Greenland and Operation Ice Bridge, to determine the likely cause of Jakobshavn’s recent about-face.

Cooler waters chilled Jakobshavn’s advance

Scientists attributed the ice gain to localized ocean cooling.
Between 2014 and 2016, waters up to 2 degrees Celsius (3.6 degrees Fahrenheit) cooler entered Disko Bay, where Jakobshavn glacier enters the water.
Researchers believe that the cooling is related to a natural variation in the climate in the Northern Hemisphere known as the North Atlantic Oscillation, which can warm or cool the northern portions of the Atlantic Ocean in periods of several years (not too dissimilar from the impact that El Niño and La Niña can have on Pacific Ocean temperatures).
A view of the Jakobshavn Glacier from the window of a NASA research plane.

Through detailed observations, Khazendar and team were able to track this cooler water from the open North Atlantic all the way to Disko Bay and found that the timing matched the glacier’s switch towards gaining ice perfectly.
“In the last two or three years, the ocean’s role was dominant,” Khazendar said.
But in the late 1990s, it was much warmer water that entered the bay that melted the ice shelf that had been protecting Jakobshavn glacier, setting off the unparalleled melting that characterized the glacier for the next two decades.
“It is like an experiment 20 years in the making,” Khazendar said.
He said the glacier’s dramatic response to variations in ocean temperature is forcing scientists to reevaluate how sensitive glaciers are to slight changes in the ocean’s climate.

A reprieve, not a resurrection

The cooling of the Northern Atlantic is a blip on the radar, a localized effect that will eventually turn warmer as the North Atlantic Oscillation flips back. This will take place at the same time as climate change turns up the thermostat on earth’s oceans.
“This is a reprieve,” Khazendar said of the recent thickening of Jakobshavn glacier, “not a resurrection.”
Scientists caution not to read too much into the news of one the most critical glaciers in the world suddenly, and unexpectedly, gaining ice.
“The response of a single glacier does not imply that things have shifted,” said Marco Tedesco, a research professor with Columbia University’s Lamont-Doherty Earth Observatory.
“Greenland is currently [losing] about 270 gigatons (a gigaton is a billion tons) of ice per year…its mass loss has been accelerating over the past decades, with Greenland being the single largest contributor to sea level rise,” Tedesco, who was not involved in the new research, wrote in an email.
Eric Rignot, a glaciologist at the University of California, Irvine and senior research scientist at JPL, noted that “The chances that this will keep going on are very low in my opinion. It is only a matter of time before the glacier starts thinning again — maybe this summer, maybe next year.”
Presidential tweets on climate change notwithstanding, a few cold days in one part of the world does not negate an overall warming trend of the entire planet. We “should not confuse climate with local variability,” said Rignot, who was not involved in the research. “The latter is what we are seeing here.”
The findings show that glaciers are extremely vulnerable to temperatures, both hot and cold, and that is not good news for the future.
Most of the heat from global warming is going straight into the oceans — studies show more than 90% — and that is resulting in global ocean heat levels that are climbing higher every year.
“Next time the warm waters come back to Jakobshavn, they will be even warmer,” Khazendar said.

Melting polar ice sheets will alter weather

Photo of iceberg
Melting ice off the coast of Greenland. Image: By Frank Busch on Unsplash

The global weather is about to get worse. The melting polar ice sheets will mean rainfall and windstorms could become more violent, and hot spells and ice storms could become more extreme.

This is because the ice sheets of Greenland and Antarctica are melting, to affect what were once stable ocean currents and airflow patterns around the globe.

Planetary surface temperatures could rise by 3°C or even 4°C by the end of the century. Global sea levels will rise in ways that would “enhance global temperature variability”, but this might not be as high as earlier studies have predicted. That is because the ice cliffs of Antarctica might not be so much at risk of disastrous collapse that would set the glaciers accelerating to the sea.

The latest revision of evidence from the melting ice sheets in two hemispheres – and there is plenty of evidence that melting is happening at ever greater rates – is based on two studies of what could happen to the world’s greatest reservoirs of frozen freshwater if nations pursue current policies, fossil fuel combustion continues to increase, and global average temperatures creep up to unprecedented levels.

“Under current global government policies, we are heading towards 3 or 4 degrees of warming above pre-industrial levels, causing a significant amount of melt water from the Greenland and Antarctic ice sheets to enter Earth’s oceans. According to our models, this melt water will cause significant disruptions to ocean currents and change levels of warming around the world,” said Nick Golledge, a south polar researcher at Victoria University, in New Zealand.

He and colleagues from Canada, the US, Germany and the UK report in Nature that they matched satellite observations of what is happening to the ice sheets with detailed simulations of the complex effects of melting over time, and according to the human response so far to warnings of climate change.

In Paris in 2015, leaders from 195 nations vowed to contain global warming to “well below” an average rise of 2°C by 2100. But promises have yet to become concerted and coherent action, and researchers warn that on present policies, a 3°C rise seems inevitable.

Sea levels have already risen by about 14 cm in the last century: the worst scenarios have proposed a devastating rise of 130 cms by 2100. The fastest increase in the rise of sea levels is likely to happen between 2065 and 2075.

Gulf Stream weakens

As warmer melt water gets into the North Atlantic, that major ocean current the Gulf Stream is likely to be weakened. Air temperatures are likely to rise over eastern Canada, central America and the high Arctic. Northwestern Europe – scientists have been warning of this for years – will become cooler.

In the Antarctic, a lens of warm fresh water will form over the surface, allowing uprising warm ocean water to spread and cause what could be further Antarctic melting.

But how bad this could be is re-examined in a second, companion paper in NatureTamsin Edwards, now at King’s College London, Dr Golledge and others took a fresh look at an old scare: that the vast cliffs of ice – some of them 100 metres above sea level – around the Antarctic could become unstable and collapse, accelerating the retreat of the ice behind them.

They used geophysical techniques to analyse dramatic episodes of ice loss that must have happened 3 million years ago and 125,000 years ago, and they went back to the present patterns of melt. These losses, in their calculations, did not cause unstoppable ice loss in the past, and may not affect the future much either.

Instability less important

“We’ve shown that ice-cliff instability doesn’t appear to be an essential mechanism in reproducing past sea level changes and so this suggests ‘the jury’s still out’ when it comes to including it in future predictions,” said Dr Edwards.

“Even if we do include ice-cliff instability, our more thorough assessment shows the most likely contribution to sea level rise would be less than half a metre by 2100.”

At worst, there is a one in 20 chance that enough of Antarctica’s glacial burden will melt to raise sea levels by 39 cm. More likely, both studies conclude, under high levels of greenhouse gas concentrations, south polar ice will only melt to raise sea levels worldwide by about 15 cm.

Melting ice sheets may soon unleash ‘climate chaos’: Study

Antarctic-Greenland meltwater could destabilise the climate system and accelerate weather fluctuations in just decades.

Little research has been done on how ice sheet meltwater might affect the climate system itself [AP]
Little research has been done on how ice sheet meltwater might affect the climate system itself [AP]

Billions of tonnes of meltwater flowing into the world’s oceans from the Greenland and Antarctic ice sheets could boost extreme weather and destabilise regional climate in a matter of decades, researchers said.

The melting ice giants, especially the one atop Greenland, are poised to further weaken the ocean currents that move cold water south along the Atlantic Ocean’s floor, while pushing tropical waters northward closer to the surface, scientists reported in the journal, Nature.

Known as the Atlantic Meridional Overturning Circulation (AMOC), this liquid conveyor belt plays a crucial role in Earth’s climate system and helps ensure the relative warmth of the Northern Hemisphere.

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“According to our models, this meltwater will cause significant disruptions to ocean currents and change levels of warming around the world,” said lead author Nicholas Golledge, an associate professor at the Antarctic Research Centre of New Zealand’s Victoria University of Wellington.

The Antarctic ice sheet’s loss of mass, meanwhile, traps warmer water below the surface, eroding glaciers from underneath in a vicious circle of accelerated melting that contributes to sea level rise.

Most studies on ice sheets have focused on how quickly they might shrink from climate change and how much global temperatures can rise before their disintegration becomes inevitable, a threshold known as a “tipping point”.

But far less research has been done on how the meltwater might affect the climate system itself.

More extreme weather

“The large-scale changes we see in our simulations are conducive to a more chaotic climate with more extreme weather events and more intense and frequent heat waves,” said co-author Natalya Gomez, a researcher in the Department of Earth and Planetary Sciences at McGill University in Canada.

Researchers concluded that, by mid-century, meltwater from the Greenland ice sheet will noticeably disrupt AMOC, which has already shown signs of slowing down.

This is a “much shorter timescale than expected”, noted Helene Seroussi, a researcher in the Sea Level and Ice Group at the Jet Propulsion Laboratory in California, who was not involved in the study.

READ MORE

Melting away: Antarctica ice loss increases six-fold since 1979

The findings were based on highly detailed simulations combined with satellite observations of changes to the ice sheets since 2010.

One likely result of the weakened current in the Atlantic will be warmer air temperatures in the high Arctic, eastern Canada and Central America, and cooler temperatures over northwestern Europe.

The Antarctic and Greenland ice sheets, up to 3km thick, contain more than two-thirds of the planet’s fresh water, enough to raise global oceans 58 and 7 metres, respectively, were they to melt completely.

Off the ice cliff

Besides Greenland, the regions most vulnerable to global warming are West Antarctica and several huge glaciers in East Antarctica, which is far larger and more stable.

In a second study published Wednesday in Nature, some of the same scientists offered new projections of how much Antarctica will contribute to sea level rise by 2100 – a hotly debated topic.

A controversial 2016 study suggested the continent’s ice cliffs – exposed by the disintegration of ice shelves that jut out from glaciers over ocean water – were highly vulnerable to collapse, and could lead to sea level rise of a metre by century’s end.

That would be enough to displace up to 187 million people around the world, especially in populous, low-lying river deltas in Asia and Africa, research has shown.

But the new study challenges those findings.

by Jason Hickel

“Unstable ice-cliffs were proposed as a cause of unstoppable collapse of large parts of the ice sheet,” said lead author Tamsin Edwards, a lecturer in geography at King’s College London.

“But we’ve re-analysed the data and found this isn’t the case.”

Both of the new studies, Edwards said “predict a most likely Antarctic contribution of 15 centimetres” by 2100, with an upward limit of about 40cm.

A special report on oceans by the UN’s Intergovernmental Panel on Climate Change (IPCC), due out in September, will offer a much-anticipated estimate of sea level rise.

The IPCC’s last major assessment in 2013 did not take ice sheets, today seen as the major contributor, ahead of thermal expansion and glaciers, into account because of a lack of data.

A landscape unseen in over 40,000 years

Rapidly receding glaciers on Baffin Island reveal long-covered Arctic landscapes

UNIVERSITY OF COLORADO AT BOULDER

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“A high elevation location might hold onto its ice longer, for example. But the magnitude of warming is so high that everything is melting everywhere now.
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Glacial retreat in the Canadian Arctic has uncovered landscapes that haven’t been ice-free in more than 40,000 years and the region may be experiencing its warmest century in 115,000 years, new University of Colorado Boulder research finds.

The study, published today in the journal Nature Communications [ open access ] <<https://www.nature.com/articles/s41467-019-08307-w>>, uses radiocarbon dating to determine the ages of plants collected at the edges of 30 ice caps on Baffin Island, west of Greenland. The island has experienced significant summertime warming in recent decades.

“The Arctic is currently warming two to three times faster than the rest of the globe, so naturally, glaciers and ice caps are going to react faster,” said Simon Pendleton, lead author and a doctoral researcher in CU Boulder’s Institute of Arctic and Alpine Research (INSTAAR).

Baffin is the world’s fifth largest island, dominated by deeply incised fjords separated by high-elevation, low-relief plateaus. The thin, cold plateau ice acts as a kind of natural cold storage, preserving ancient moss and lichens in their original growth position for millennia.

“We travel to the retreating ice margins, sample newly exposed plants preserved on these ancient landscapes and carbon date the plants to get a sense of when the ice last advanced over that location,” Pendleton said. “Because dead plants are efficiently removed from the landscape, the radiocarbon age of rooted plants define the last time summers were as warm, on average, as those of the past century”

In August, the researchers collected 48 plant samples from 30 different Baffin ice caps, encompassing a range of elevations and exposures. They also sampled quartz from each site in order to further establish the age and ice cover history of the landscape.

Once the samples were processed and radiocarbon dated back in labs at the Institute of Arctic and Alpine Research (INSTAAR) at CU Boulder and the University of California Irvine, the researchers found that these ancient plants at all 30 ice caps have likely been continuously covered by ice for at least the past 40,000 years.

“Unlike biology, which has spent the past three billion years developing schemes to avoid being impacted by climate change, glaciers have no strategy for survival,” said Gifford Miller, senior author of the research and a professor of geological sciences at CU Boulder. “They’re well behaved, responding directly to summer temperature. If summers warm, they immediately recede; if summers cool, they advance. This makes them one of the most reliable proxies for changes in summer temperature.”

When compared against temperature data reconstructed from Baffin and Greenland ice cores, the findings suggest that modern temperatures represent the warmest century for the region in 115,000 years and that Baffin could be completely ice-free within the next few centuries.

“You’d normally expect to see different plant ages in different topographical conditions,” Pendleton said. “A high elevation location might hold onto its ice longer, for example. But the magnitude of warming is so high that everything is melting everywhere now.”

“We haven’t seen anything as pronounced as this before,” Pendleton said.

Greenland’s Melting Ice Nears a ‘Tipping Point,’ Scientists Say

Video

Greenland’s ice is melting so fast that it could become a major factor in sea-level rise around the world within two decades, scientists said in a new study.CreditCreditLucas Jackson/Reuters

Greenland’s enormous ice sheet is melting at such an accelerated rate that it may have reached a “tipping point,” and could become a major factor in sea-level rise around the world within two decades, scientists said in a study published on Monday.

The Arctic is warming at twice the average rate of the rest of the planet, and the new research adds to the evidence that the ice loss in Greenland, which lies mainly above the Arctic Circle, is speeding up as the warming increases. The authors found that ice loss in 2012, more than 400 billion tons per year, was nearly four times the rate in 2003. After a lull in 2013-14, losses have resumed.

The study is the latest in a series of papers published this month suggesting that scientific estimates of the effects of a warming planet have been, if anything, too conservative. Just a week ago, a separate study of ice loss in Antarctica found that the continent is contributing more to rising sea levels than previously thought.

Another new analysis suggested that the oceans are warming far faster than earlier estimates. Warming oceans are currently the leading cause of sea-level rise, since water expands as it warms.

Researchers said these findings underscored the need for action to curb emissions of planet-warming gases and avoid the worst effects of climate change.

[A record number of Americans are concerned about global warming, a new poll found.]

Rising sea levels are one of the clearest consequences of global warming; they are caused both by thermal expansion of the oceans and by the melting of ice sheets on land. Current projections say that if the planet warms by two degrees Celsius (3.6 degrees Fahrenheit) over preindustrial times, average sea levels will rise by more than two feet, and 32 million to 80 million people will be exposed to coastal flooding.

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Much of the previous research on Greenland’s ice has dealt with the southeast and northeast parts of the island, where large chunks of glacial ice calve into the sea. The new paper focuses on the ice-covered stretches of southwest Greenland, which has few large glaciers and was not generally considered as important a source of ice loss.

But as the earth warms, the paper concludes, the vast plains of southwestern ice will increasingly melt, with the meltwater flowing to the ocean. Within two decades, it says, the region “will become a major contributor to sea level rise.”

Greenland Is Melting Away

This river is one of a network of thousands at the front line of climate change.

The study, which appears in the Proceedings of the National Academy of Sciences, used satellite data and ground-based instruments to measure Greenland’s ice loss in the 21st century. It looked closely at what seemed to be a pause in the ice loss for about a year, beginning in 2013, that followed a stretch of greatly accelerated melting.

The researchers tied the pause in melting to a reversal of the cyclical weather phenomenon known as the North Atlantic Oscillation. Before the pause, the oscillation was in what is known as its negative phase, which is associated with warmer air hitting west Greenland, along with less snowfall and more sunlight, all of which contribute to ice loss. When the cycle shifted into a positive phase in 2013, an “abrupt slowdown” of melting occurred.

Yet, the slowdown was anything but good news, said Michael Bevis, the lead author of the paper and a professor in the School of Earth Sciences at Ohio State University.

The North Atlantic Oscillation has occurred throughout the historical record, he noted. But before 2000, overall average temperatures were cool enough that the N.A.O.’s positive and negative cycles did not have much of an effect on rates of melting in Greenland.

A scientist repaired a GPS device last summer near Greenland’s Helheim Glacier.CreditLucas Jackson/Reuters
Image
A scientist repaired a GPS device last summer near Greenland’s Helheim Glacier.CreditLucas Jackson/Reuters

Now, the strong effect that the cooler cycle had on the rate of melting — even if it was helpful in stopping ice loss — is a reason for concern, Dr. Bevis said. If the warm cycles of the N.A.O. are associated with huge losses of ice, and the cool cycles only pause the melting, it suggests a threshold has been reached: As average temperatures rise further, melting will be more sustained, and the cooling cycles will have less of an effect in slowing the ice loss.

“If a relatively minor cycle can cause massive melting,” he said, “it means you’ve reached a point of amazing sensitivity” to warmer temperatures, which could represent “the tipping point.”

And so, he said, “One degree of warming in the future will have way more impact than one degree of warming in the last century.”

The new research dovetails with other recent papers on the accelerating melting. Last month a team of researchers published a paper in Nature that used satellite observations, analysis of ice cores and models to show that losses from the Greenland ice sheet have reached their fastest rate in at least 350 years.

At the other end of the earth, the speed of Antarctica’s ice loss is also becoming clearer. A study published last week, also in the Proceedings of the National Academy of Sciences, surveyed four decades of data and found faster losses in some regions than scientists had previously estimated.

The continent has presented a mixed story in recent years, with researchers measuring substantial losses in some regions but stability and even gains in others. But the new paper found considerable losses of glacial ice in East Antarctica, previously considered to be relatively stable. As a whole, Antarctica lost about 40 billion tons of ice per year in the 1980s, but it has been losing roughly 250 billion tons per year in the past decade.

That new paper adds to a body of recent research showing that Antarctica’s ice loss is accelerating, including a study in June that found that the rate of ice loss had tripled since 2007. Scientists estimate the Antarctic melting will contribute six inches to sea-level rise by 2100.

Luke D. Trusel, a glaciologist at Rowan University and an author of last month’s Nature paper on Greenland, said the new research by Dr. Bevis and his colleagues “provides clear and further illustration of how sensitive Greenland now is” to global warming.

“What’s happening today is well beyond the range of what could be expected naturally,” he said. “The human fingerprint on Greenland melting today is unequivocal.”

Still, he said, most estimates of a tipping point for Greenland ice loss cite higher average temperatures than are currently occurring, more along the lines of 1.5 or two degrees Celsius above preindustrial levels. Global average temperatures have already increased by about one degree Celsius (1.8 degrees Fahrenheit).

A co-author of the Nature paper, Sarah B. Das, a scientist at the Woods Hole Oceanographic Institution, agreed that Dr. Bevis’s study reinforced her own team’s conclusions and showed “how quickly Greenland is disappearing.” The common finding, she said, is that climate change has brought Greenland to a state in which “a little bit of a nudge is going to have an outsized impact,” causing enormous melting.

But, she said, “I take issue with using ‘tipping point’ to describe the accelerating mass loss Greenland is experiencing,” because “it makes it appear as if we have passed, or soon will pass, the point of no return.” She said she saw reasons for hope.

Dr. Trusel agreed that talk of tipping points could discount the humans’ ability to mitigate global warming. “We may be able to control how rapidly the ice sheet changes in the future,” he said.

“By limiting greenhouse gas emissions we limit warming, and thus also limit how rapidly and intensely Greenland affects our livelihoods through sea-level rise,” he added. “That, it seems, is our call to make.”

For more news on climate and the environment, follow @NYTClimate on Twitter.

John Schwartz is part of the climate team. Since joining The Times in 2000, he has covered science, law, technology, the space program and more, and has written for almost every section.

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.

Studies Warn of Increasing Sea Level Rise

The most recent gathering of scientists at the American Geophysical Union in Washington, DC, brought deeply troubling news about the Antarctic.

Jeremy Shakun, a paleoclimatologist at Boston College, told Science that the large increase in the loss of ice mass in Antarctica in the last decade or two could already be the beginning stage of the process of collapse of the Western Antarctic Ice Sheet.

Ice loss in the Antarctic has tripled in just the last decade alone, and is currently losing 219 billion metric tons of ice annually. That number is up from 73 billion metric tons per year as of a decade ago.

“The big uptick in mass loss observed there in the past decade or two is perhaps the start of” the larger-scale collapse of the glaciers, Shakun told Science.

If that is the case, the world must begin preparations immediately for sea levels that will rise far more abruptly than previously expected, with ocean waters rising as fast as 2.5 meters every one hundred years.

The aforementioned discovery presented at the annual meeting of scientists also revealed that during the last brief warm period between Earth’s ice ages, which took place 125,000 years ago and when global temperatures were barely higher than they are today in our greenhouse-warmed planet, sea levels were six to nine meters (20 to 30 feet) higher than they are right now.

That amount of sea level rise means that New York, Boston, Miami, Tampa, New Orleans, Jakarta, Singapore, Osaka, Tokyo, Mumbai, Kolkata, Dhaka and Ho Chi Minh City are among the many cities that will, sooner or later, have to be moved or abandoned entirely to the sea.

East Antarctica Is Melting From Below

Eastern Antarctica has always been seen as a place virtually impervious to melting, and has often been referred to as the “last bastion” of stable ice on the planet.

However, recent data has shown that a group of glaciers covering 13 percent of the coastline of that side of the frozen continent are melting from below due to warming oceans.

And disturbingly, 2017 was the hottest year on record for the oceans, and the fifth year in a row that oceans set a record for how warm they had become due to human-caused climate change.

It is already known that the Western Antarctic Ice Sheet is experiencing serious retreat with a three-fold increase in acceleration having been reported in recent years. But NASA scientist Catherine Walker used measurements of ocean temperatures and computer modeling to show that the heat being delivered to certain glaciers in the Eastern Antarctic was coming from warming oceans.

“The finding has very serious repercussions for climate change and particularly sea-level rise,” Chris Fogwill, a professor at Keele University in England told The Guardian. “It has the potential to mean that our sea-level projections could be [in] an order of magnitude higher than we’re anticipating.”

Given the remoteness of the Eastern part of Antarctica, it hasn’t been studied nearly as much as the rest of the Antarctic.
Hence, since there is little data on it thus far, we should expect more bad news of melting as more studies are published on the region.

The NASA data, coupled with the study mentioned at the American Geophysical Union, show that the speed of sea level rise from melting Antarctic glaciers is consistently increasing each year.

At the current trajectory, 17.7 trillion metric tons of ice will be shed in the Antarctic by 2100. This assumes the current rate of loss will remain linear — an unrealistic assumption given that the rate is increasing annually.

ARCTIC REPORT CARD DETAILS EFFECT OF RECORD MELTING ON GLOBAL ENVIRONMENTAL CHANGES

The Arctic report, in its 13th edition, explains changes, impacts of melting on the ecosystem & marine life.

https://www.firstpost.com/tech/science/arctic-report-card-details-effect-of-record-melting-on-global-environmental-changes-5714191.html

Global warming is heating the Arctic at a record pace, driving broad environmental changes across the planet, including extreme storms in the United States and Europe, a major US scientific report said Tuesday.

Persistent heat records have assaulted the fragile Arctic for each of the past five years — a record-long warming streak, said the 2018 Arctic Report Card, released by the National Oceanic and Atmospheric Administration (NOAA).

The mounting heat in the north is upsetting typical weather patterns, a trend that “coincides” with severe winter storms in the eastern United States and an extreme cold snap in Europe in March, it said.

“Continued warming of the Arctic atmosphere and ocean are driving broad change in the environmental system in predicted and, also, unexpected ways,” warned the report.

“New and rapidly emerging threats are taking form and highlighting the level of uncertainty in the breadth of environmental change that is to come.”

Emily Osborne, program manager of NOAA’s Arctic Research Program, told reporters the Arctic “is experiencing the most unprecedented transition in human history.”

The report was released at the American Geophysical Union’s annual conference in Washington, just weeks after another damning climate assessment by federal scientists which US President Donald Trump dismissed, saying he did not “believe” it.

Asked by reporters if he had personally briefed Trump on the latest Arctic findings, NOAA acting administrator Timothy Gallaudet said he had not, but he insisted that NOAA has the White House’s support when it comes to scientific research.

Temperature records

Arctic air temperatures for the past five years, from 2014 to 2018, “have exceeded all previous records since 1900,” when record-keeping began, said the peer-reviewed report compiled by 81 scientists working for governments and academia in 12 nations.

This warming trend “is unlike any other period on record,” it said.

During the latest period studied, October 2017 through September 2018, annual average temperature in the Arctic was 3.1 Fahrenheit (1.7 Celsius) higher than the 1981–2010 average.

“The year 2018 was the second warmest year on record in the Arctic since 1900 (after 2016),” it said.

The Arctic also saw the second-lowest overall sea-ice coverage and the lowest recorded winter ice in the Bering Sea.

Another key measure of ice cover is its age, and the old, thick kind is rapidly disappearing across the Arctic.

Last year, old ice made up less than one percent of the ice pack.

Over the past 33 years, very old Arctic ice has declined by 95 percent.

Snow cover is decreasing on land, and river discharge is increasing. Vegetation in the Tundra region is growing, but the populations that graze on them are dying off. Image courtesy: NOAA

Snow cover is decreasing on land, and river discharge is increasing. Vegetation in the Tundra region is growing, but the populations that graze on them are dying off. Image courtesy: NOAA

Jet stream

The Arctic continues to heat up at twice the rate of the rest of the planet, but the effects are far from isolated, and are now spilling over into the mid-latitudes.

That’s because a warmer Arctic reduces the north-south temperature difference, which provides the main fuel for the polar jet stream, or a river of strong wind, at levels where jet aircraft fly, NOAA said.

In this warming environment, the jet stream has become wavier, a pattern that “allows warm air to penetrate farther north and cold air to plunge farther south, compared to when the jet is strong and relatively straight,” said the report.

Scientist now see evidence that this changing jet stream may be sparking extreme storms.

Examples include “the heat wave at the North Pole in autumn 2017, a swarm of severe winter storms in the eastern United States in 2018, and the extreme cold outbreak in Europe in March 2018 known as the ‘Beast from the East.'”

Reindeer, marine life

Meanwhile, warmer Arctic temperatures are wreaking havoc on the Arctic ecosystem, decimating reindeer and caribou populations, allowing harmful algae blooms to move northward and sickening marine life, said the report, now in its 13th year.

“Considerable concentrations of algal toxins have been found in the tissues of Arctic clams, seals, walrus, and whales and other marine organisms,” it said.

Even though melting ice has freed up more land for grazing, herds of caribou and wild reindeer across the Arctic tundra have declined by 56 percent over the last two decades, cutting populations from 4.7 million to 2.1 million.

“The long-term warming trend may be taking a toll on some of the Arctic’s most majestic animals,” said Howard Epstein, professor of environmental sciences at the University of Virginia.

Scientists attribute the decline to increased frequency of drought, which affects quality of the tundra, and longer and hotter summers which can lead to more parasites.

Another new focus of the report involved the emerging threat of marine microplastics, which scientists have discovered are accumulating in the Arctic at higher concentrations than anywhere else in the world.

“This pollution — from plastics produced and discarded in more populated areas of the world — is likely traveling with ocean currents to the Arctic,” said Karen Frey, professor of geography at Clark University.

Microplastic contamination has increased over the last decade, and is a concern because seabirds and marine life can ingest debris, sickening them and interfering with a key food and income source for people who consume them, she said.

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

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The icy realm of Greenland is getting hot under the collar.

The melting of Greenland’s massive ice sheet has now accelerated, scientists announced Wednesday, and shows no signs of slowing down, according to a new study.

“Melting of the Greenland ice sheet has gone into overdrive,” said Luke Trusel, a glaciologist at Rowan University and lead author of the study. “Greenland melt is adding to sea level more than any time during the last three and a half centuries, if not thousands of years,” he said.

Ice loss from Greenland is the single largest contributor to global sea-level rise, which is predicted to lead to inundation of low-lying islands and coastal cities around the world over the next several decades and centuries.

At the moment, conservative estimates of global sea level rise predict an additional half a meter or more by the end of the century, according to German news agency Deutsche Welle (DW). Alun Hubbard, a professor of glaciology at Aberystwyth University in Wales, told DW that even an increase of half a meter is “a terrible disaster for humanity – especially coastal regions of the planet.”

“From a historical perspective, today’s melt rates are off the charts, and this study provides the evidence to prove this” said co-author Sarah Das, a glaciologist at the Woods Hole Oceanographic Institution.

Specifically, the melt rate over the past two decades was 33 percent higher than the 20th-century average, and 50 percent higher than in the pre-industrial era before the mid-1800s.

According to the journal Nature, in just one year (2012), enough ice melted into water to fill up some 240 million Olympic swimming pools.

To determine how much Greenland ice has melted in past centuries, the research team used a drill the size of a traffic light pole to extract ice cores from the ice sheet itself. Ice cores contain records of past melt intensity, allowing researchers to extend their records back to the 1650s.

Researchers say the rate of melting at their drilling sites is representative of trends across Greenland.

Another expert – NASA oceanographer Josh Willis – told Mashable that “it’s one more nail in the coffin of climate denial.” Willis, who was not involved in the research, added “I don’t know how many more nails we need.”

The study was published Wednesday in the peer-reviewed British journal Nature.