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Summary of the Glaciation Unit from the RGS

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Summary of the Glaciation Unit from the RGS

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A massive rockslide in Switzerland's Val Bondasca was not a complete surprise. Many parts of Switzerland, two thirds of which is mountainous, are at risk of avalanches and landslides.

Communities in the Alps have been protecting themselves against such natural hazards for years.

Before Wednesday's landslide, sensors on the Piz Cenaglo, high above the Bondasca valley, had already shown that the rock mass was moving. That warning triggered the automatic closure of some sections of road.

The village of Bondo had a narrow escape. The four million cubic metres (141m cubic feet) of mud and rock which thundered down the mountain ended up just centimetres from people's homes.

That wasn't just luck. Bondo has a concrete barrier to protect it from the full force of a landslide, and the river bed in the Bondasca Valley has been widened in the hope of channelling landslides away from populated areas.

But the size of Wednesday's slide was a shock, and some scientists are now warning that the alpine regions can expect more events like this in the future.

Permafrost thaw

The reason is that the high mountains are not as cold as they once were. Marcia Phillips, a permafrost researcher with Switzerland's Federal Institute for Snow and Avalanche Research, has been analysing temperatures all over the Alps.

"We have bore holes at different depths in different terrain and the ones that are in rock walls are showing a distinct warming over the last 10 to 20 years," she explained.

That would not be a problem if the rock was simply rock, but the rock in large sections of the Swiss Alps is cracked and fractured - between the layers of rock there are layers of permafrost. Ice in fact, but ice that is not supposed to melt.

"We have a problem if the temperature rises above -1.5C because the permafrost has a stabilising function," Ms Phillips said.

Compounding the weakening permafrost is another phenomenon associated with global warming - Switzerland's glaciers are noticeably retreating.

The glacier at the base of Piz Cenaglo provided additional stability to the rock above it, but that glacier has shrunk in recent years. So precarious had the mountain become that Marcia and her colleagues had given up on borehole testing and instead resorted to remote monitoring.

"It is cracked and unstable up there," she explained, "It was just too dangerous."

Infrastructure fears

Another headache associated with thawing permafrost is the possible risk to winter tourism. The stanchions of cable cars and chairlifts are very often anchored in permafrost.

The Swiss government already requires intensive monitoring of cable car infrastructure. Lift operators must check regularly for any movement or creep.

Marcia Phillips suggests that, if temperatures do continue to rise, changes may have to be made.

"I could foresee some having to be closed down or rebuilt," she said.

In preparation, the avalanche institute has already produced a book "Building in Permafrost" with guidelines on how to build safely.

"It is possible but very, very expensive," said Ms Phillips.

That is not good news for Switzerland's tourism resorts, already suffering financially because of the strength of the Swiss franc.

For now, though, the focus remains on finding the eight people still missing from Wednesday's landslide, and on protecting those who live in the Bondasca Valley.

The residents of Bondo have been told they cannot go home yet. Four million cubic metres of rock came down but another million, very unstable, still looms above the village.

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Switzerland landslide: Are the Alps melting?

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A massive rockslide in Switzerland's Val Bondasca was not a complete surprise. Many parts of Switzerland, two thirds of which is mountainous, are at risk of avalanches and landslides. Communities in the Alps have been protecting themselves against such natural hazards for years.

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This article highlights how people rely on glaciers for many aspects of their lives

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Asia's mountain glaciers will lose at least a third of their mass through global warming by the century's end, with dire consequences for millions of people who rely on them for fresh water, researchers have said.

This is a best-case scenario, based on the assumption that the world manages to limit average global warming to 1.5C (2.7F) over pre-industrial levels, a team wrote in the journal Nature.

Related: Tibet's fragile ecosystem is in danger. China must change its flawed environmental policy | Lobsang Sangay

"To meet the 1.5C target will be a task of unprecedented difficulty," the researchers said, "and even then, 36% (give or take 7%) of the ice mass in the high mountains of Asia is projected to be lost" by 2100.

With warming of 3.5C, 4C and 6C respectively, Asian glacier losses could amount to 49%, 51% or 65% by the end of the century, according to the team's modelling study.

The high mountains of Asia comprise a geographical region surrounding the Tibetan plateau, holding the biggest store of frozen water outside the poles.

It feeds many of the world's great rivers, including the Ganges, the Indus and the Brahmaputra, on which hundreds of millions of people depend.

Nearly 200 nations adopted the Paris agreement in 2015, which sets the goal of limiting warming to a level "well below" 2C, while "pursuing efforts" to achieve a lower ceiling of 1.5C.

Earth's surface has already warmed by about 1C, according to scientists.

For high warming scenarios, experts predict land-gobbling sea-level rise, worsening storms, more frequent droughts and floods, species loss and disease spread.

The Asian high mountains, the new study said, were already warming more rapidly than the global average.

A global temperature rise of 1.5C would mean an average increase in the region of about 2.1C, with differences between mountain ranges - all of which will warm by more than 1.5C.

The Hindu Kush mountain range would warm by about 2.3C and the eastern Himalayas by 1.9C, the study forecast.

"Even if temperatures stabilise at their current level, [glacier] mass loss will continue for decades to come," the researchers added.

For the high mountain glaciers to survive, "it is essential to minimise the global temperature increase".

Swaths of south Asia and China depend on meltwater from Himalayan glaciers for drinking water, electricity generation and irrigation.

Related: Planet has just 5% chance of reaching Paris climate goal, study says

At the same time, the regions are also vulnerable to more intense flooding from accelerated glacier melt, combined with heavier rains and superstorms boosted by global warming.

A study in July in the journal Nature Climate Change said there was only a 5% chance of holding global warming under 2C. For 1.5C, the odds were about 1%.

On current trends, some experts project Earth is on track to warm by about 3C.

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Asia's glaciers to shrink by a third by 2100, threatening water supply of millions

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Asia's mountain glaciers will lose at least a third of their mass through global warming by the century's end, with dire consequences for millions of people who rely on them for fresh water, researchers have said.

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3. Interesting clip about a film archive preserved under ice!

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3. Interesting clip about a film archive preserved under ice!

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A long-ago buried and forgotten silent film archive has become a new work of art.

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4. Article about Melting of Ice Shelves from beneath!

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4. Article about Melting of Ice Shelves from beneath!

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Scientists have identified a way in which the effects of Antarctic melting can be enhanced.

Their new satellite observations of the Dotson Ice Shelf show its losses, far from being even, are actually focused on a long, narrow sector.

In places, this has cut an inverted canyon through more than half the thickness of the shelf structure.

If the melting continued unabated, it would break Dotson in 40-50 years, not the 200 years currently projected.

"That is unlikely to happen because the ice will respond in some way to the imbalance," said Noel Gourmelen, from the University of Edinburgh, UK.

"It's possible the area of thinning could widen or the flow of ice could change. Both would affect the rate at which the channel forms.

"But the important point here is that Dotson is not a flat slab and it can be much thinner in places than we think it is and much closer to a stage where it might experience major change."

Dr Gourmelen's new study, published in Geophysical Research Letters, uses the European Space Agency's Cryosat and Sentinel-1 spacecraft to make a detailed examination of the thickness and movement of Dotson.

The 70km by 40km ice shelf is the floating projection of two glaciers, Kohler and Smith. As they stream off the west of Antarctica, their fronts lift up and join together, pushing out over the Amundsen Sea.

The shelf acts as a buttress to the ice behind. If Dotson were not present, Kohler and Smith would flow much faster, dumping more of their mass in the ocean, contributing to sea-level rise.

Satellites have long tracked the behaviour of the shelf, but in Cryosat in particular researchers now have an altimeter instrument that is able to retrieve much higher-resolution elevation information than ever before.

Taking the period of its observations from 2010-2016, Dr Gourmelen's team can see that Dotson's surface is lowering on average by about 26cm per year, which suggests the roughly 400m-thick shelf as a whole is thinning by about 2.5m per year.

But Cryosat's sharper vision also reveals that this thinning is concentrated at a surface depression that is roughly 5km wide and 60km long.

It extends from the point where the glacier ice starts to float as it comes off the land, all the way out to the front edge of the shelf where icebergs are calved into the ocean.

What the team is able to show is that this surface depression corresponds to an incised canyon on the underside of the shelf.

The average width of this inverted gorge is 10-15km wide but it cuts up into the shelf by as much as 200m in places. The Edinburgh-led group says all the evidence suggests warm water from the deep ocean around Antarctica has got under the shelf to melt out the canyon.

"We say warm; it's 0.6-0.7 degrees," explains Dr Gourmelen. "It makes its way into the cavity under the shelf along a trough to the grounding line, and then it starts to rotate clockwise and rises. And it comes out on the west side. That's where we see the thinning and the basal melt."

This export of fresh melt-water from the underside of the shelf carries with it a lot of iron from rocks scraped from the continent, and drives strong growth in plankton and other biological activity in front of Dotson.

Just a simple forward projection using the pattern and rates of thinning observed by Cryosat and Sentinel-1 in this study would lead to complete melt-through of Dotson's front in 20 or so years, and its rear in about 40 years.

That is on the order of 170 years earlier than Dotson would thin to zero using the ice-shelf-averaged thinning rate. But as previously stated - the shelf is not a static structure and it will react to the formation of the canyon.

"An ice shelf can be a complicated thing," says co-author Prof Andy Shepherd from Leeds University and principal scientific adviser on the Cryosat mission.

"As you thin them it reduces the traction on the feeding glaciers, allowing those glaciers to speed up; and as they speed up, they should put more ice into the ice shelf so that it thickens again. It is supposed to be a stabilising effect."

Prof Shepherd said a new high-resolution swath mode used by Cryosat at Dotson was now being deployed elsewhere around Antarctica to look for more patterns of enhanced thinning on other ice shelves.

Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos

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Scientists have identified a way in which the effects of Antarctic melting can be enhanced. Their new satellite observations of the Dotson Ice Shelf show its losses, far from being even, are actually focused on a long, narrow sector. In places, this has cut an inverted canyon through more than half the thickness of the shelf structure.

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5. Excellent ARC GIS Storyboard with interactive maps charting the last Glacial Maximum

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5. Excellent ARC GIS Storyboard with interactive maps charting the last Glacial Maximum

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This story map requires JavaScript, but running JavaScript is not currently allowed by your web browser. If you wish to view this story, please enable JavaScript in this browser or try a different browser.

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This story map requires JavaScript, but running JavaScript is not currently allowed by your web browser. If you wish to view this story, please enable JavaScript in this browser or try a different browser.

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6. Article about Venezuela's disappearing glaciers!

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6. Article about Venezuela's disappearing glaciers!

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VENEZUELA is a tropical country, with rainforest in the south and east, and baking savannah stretching towards its northern Caribbean coast. The Sierra Nevada de Mérida mountain range in the north-west offers relief from the heat. In 1991 five glaciers occupied nooks near their peaks. Now, just one remains, lodged into a cwm west of Pico Humboldt. Reduced to an area of ten football pitches, a tenth of its size 30 years ago, it will be gone within a decade or two. Venezuela will then be the first country in the satellite age to have lost all its glaciers.

The retreat of the Humboldt glacier, named for Alexander von Humboldt, a German explorer of the 19th century, is the final stage of a 20,000-year process, the recession of an ice sheet that covered 600 square km (about 230 square miles) of Venezuela in the most recent ice age. Climate change has sped it up.

Scientists want to study the glacier in its final years but Venezuela's tumultuous politics is making that difficult. Carsten Braun, a glaciologist at Westfield State University in Massachusetts, thinks his most recent visit in 2015 was the last by any scientific expedition. Even then, conditions were "a little dicey". Men in military uniform pulled him off a bus and interrogated him. Now, Venezuela's hyperinflation and rampant crime make it too dangerous to travel with the bundles of dollars needed by mountaineering scientists.

It is no longer worth hauling heavy machinery to the glacier to extract samples from it; Humboldt is too small and dirt-caked for that. But Mr Braun would like to dot it with sensors to measure water run-off, and erect weather stations to capture data on wind, temperature and barometric pressure. That would help him understand how weather influences the melting of tropical glaciers. Until Venezuela calms down, Mr Braun will be restricted to monitoring the Humboldt glacier's decline remotely, using satellite imagery, which just reveals how fast it is melting.

That is a loss not just for science but for people in other Andean countries who rely on meltwater from tropical glaciers. In springtime that runoff is an important source of water for residents of Bogotá, Colombia's capital, for example. Closer study of Humboldt's decline might provide knowledge that could help them. Venezuela's ever-deepening crisis makes it impossible for now.

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The death of Venezuela's Humboldt glacier

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VENEZUELA is a tropical country, with rainforest in the south and east, and baking savannah stretching towards its northern Caribbean coast. The Sierra Nevada de Mérida mountain range in the north-west offers relief from the heat. In 1991 five glaciers occupied nooks near their peaks.

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Glacial Growth: cracking the ‘Karakoram anomaly’ - Geographical

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Glacial Growth: cracking the ‘Karakoram anomaly’ - Geographical

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Among the Himalaya region, which along with most of the rest of the planet is steadily warming, there lies an aberration which is allowing glaciers in the area to remain stable, even grow in size, rather than melt and shrink

First observed in 2005, the so-called 'Karakoram anomaly' has seen temperatures cooling during both the winter and summer months along the Karakoram mountain range which crosses through India, Pakistan, and China and includes K2, the world's second-highest mountain. This is resulting in the steady accumulation of snow, and, consequently, the growth of some glaciers.

The cause of the anomaly appears to be a vortex of trapped, cold air that circulates through the Karakoram mountains, preventing them from overheating. Combined with the South Asian monsoon, this large-scale circulation system counteracts the summer warming of the rest of the Himalayas, causing the Karakoram range to cool while other areas get hotter.

'This vortex provides an important temperature control,' explains Dr Nathan Forsythe, research associate at Newcastle University, and lead author of a new study trying to understand the mechanics behind the Karakoram anomaly. 'It is therefore important to look at how it has changed and influenced temperature over the last century so we can better understand how a change in the system might affect future climate.'

This phenomenon has also led to stormier weather conditions over the region, while the reduced glacial melt is likely to have affected the flow of several streams, which could be highly significant for the prosperity of people living in lower altitude river valleys. 'This is of huge importance in terms of food security,' continues Forsythe, 'because of the large populations that rely on water resources from snow and ice melt from the mountainous catchments to grow their irrigated crops in the Indus Plains of the Sindh and Punjab states, and provinces of Pakistan and India.'

This was published in the October 2017 edition of Geographical magazine.

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Glacial Growth: cracking the 'Karakoram anomaly' - Geographical

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Among the Himalaya region, which along with most of the rest of the planet is steadily warming, there lies an aberration which is allowing glaciers in the area to remain stable, even grow in size, rather than melt and shrink First observed in 2005, the so-called 'Karakoram anomaly' has seen temperatures cooling during both the winter and summer months along the Karakoram mountain range which crosses through India, Pakistan, and China and includes K2, the world's second-highest mountain.

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BBC - Future - The great thaw of America’s north is coming

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BBC - Future - The great thaw of America’s north is coming

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Vladimir Romanovsky walks through the dense black spruce forest with ease. Not once does he stop or slow down to balance himself on the cushy moss beneath his feet insulating the permafrost.

It's a warm day in July, and the scientist is looking for a box that he and his team have installed on the ground. It's hidden nearly six miles (10km) north of the Geophysical Institute at the University of Alaska in Fairbanks, where he's a professor of geophysics and heads the Permafrost Laboratory.

The box, which is covered by tree branches, contains a data collector connected to a thermometer installed below ground for measuring permafrost temperature at different depths. Permafrost is any earth material that remains at or below 0C (32F) for at least two consecutive years.

Romanovsky connects his laptop to the data collector to transfer the temperature data for this location - called Goldstream III - which he will later add to an online database accessible to both scientists and interested individuals.

"Permafrost is defined on the basis of temperature, the parameter that characterises its stability," Romanovsky says.

The thaw is deepening and expanding, causing the permafrost underneath to become less stable

When the temperature of permafrost is below 0C (32F), for example -6C (21F), it is considered stable and will take a long time to thaw or to change. If it's close to 0C, however, it's considered vulnerable.

Every summer the portion of soil overlaying the permafrost, called the active layer, thaws, before refreezing the following winter. At Goldstream III, on this July day, the summer thaw currently ends at 50cm depth.

As the Earth warms and summer temperatures climb, the thaw is deepening and expanding, causing the permafrost underneath to become less stable.

The consequences, if this thawing continues, will be profound, for Alaska - and for the world. Nearly 90% of the state is covered in permafrost, which means entire villages will need to be relocated, as the foundations of buildings and roads crumble. And if this frozen cache releases the millennia of accumulated carbon it has locked within, it could accelerate the warming of our planet - far beyond our ability to control it.
A vulnerable state
As permafrost thaws, houses, roads, airports and other infrastructure built on the frozen ground can crack and even collapse.

"We are seeing some increased maintenance on existing roads over permafrost," says Jeff Currey, materials engineer for Northern Region of the Alaska Department of Transportation Public Facilities. "One of our maintenance superintendents recently told me his folks are having to patch settling areas on the highways he's responsible for more frequently than they were 10 or 20 years ago."

Similarly, infrastructure built underground - such as those for utilities - is suffering as temperatures rise.

"In Point Lay - on the coast in northwest Alaska - for instance, they're having all sorts of trouble with their water and sewer lines buried in permafrost soil," says William Schnabel, director of the Water & Environmental Research Center at the University of Alaska Fairbanks. "The permafrost soil has thawed and we get water and line breaks because the ground shifts."

The concern is even more pronounced for those living in rural areas who don't have enough funds to combat the effects of thawing permafrost. For those residents it's not just about collapsing buildings, which is common now, but also water supply.

Often as permafrost thaws on the side of a lake that a village might use as water supply, there's a breach and a lateral drain occurs. "It usually requires pretty expensive infrastructure to take water from a lake, bring it to a village and store it and all the components of this infrastructure are vulnerable to thawing permafrost," Romanovsky says.

If a village depends on an affected lake for water, the community members would have to move their infrastructure and sometimes their entire village to another lake, which can be very costly.

Villages like Kivalina in Alaska will have to move within the next 10 years

According to research conducted by US Geological Survey, villages like Kivalina in north-west Alaska will have to move within the next 10 years, Romanovsky explains. "But estimates show cost of moving is about $200m (£150m) per village of 300 people."

Those kinds of sums are only possible with federal government funding - but there are also no guarantees that a new location wouldn't be affected eventually too.

"I think by now there are 70 villages who really have to move because of thawing permafrost," Romanovsky says. "But moving villages to another location on permafrost is very difficult to guarantee for 30 years or so and the federal government doesn't want to pay for something they have to pay for again."

It's possible that building Alaskan settlements on permafrost may also be making the problem worse. "When you think about water and sewers you have to keep those above freezing and when you have permafrost you have to keep that below freezing," Schnabel says. "So you're running relatively warm water through the permafrost and there's going to be some heat dissipation in there."

Similarly, when a road is built, a lot of the vegetation that insulates the permafrost is cleared and then paved over with black covering that increases the amount of absorbed solar radiation. So although the maintenance burden has increased for those like Currey, not all the distress that comes with infrastructure can be solely attributed to a changing climate.
Defrosting a freezer full of carbon
Alaska, no doubt, is on the front lines of climate change, but the issues related to permafrost aren't just specific to The Last Frontier. What happens to the frozen earth material in the 49th state will affect the lower 48, as well as the entire globe.

According to Romanovsky, half of the state's and 90% of interior Alaska's permafrost will thaw if there's a global average rise of 2C in air temperature.

This is especially worrying because an enormous amount of organic carbon is sequestered in permafrost and the overlaying active layer. Since there's not enough heat in frozen soil to help microbes to decompose dying vegetation, over thousands of years organic matter has accumulated in permafrost. Some estimates say the amount of carbon in the permafrost is more than two times than there is in atmospheric carbon dioxide.

"If we maintain our current course of operation, business as usual they call that, then it's pretty certain by 2100 a significant fraction of the permafrost in the upper five metres would thaw out and with it all the organic matter that is currently frozen in the permafrost," says Kevin Schaefer, a research scientist at the National Snow and Ice Data Center at the University of Colorado. "That would indicate a release of carbon dioxide and methane, which would amplify the warming due to the burning of fossil fuels."

If this carbon is released, the amount of CO2 will be three times more than what is in in the atmosphere now

In fact, in a 2012 report published in the journal Nature, Schaefer and his co-authors indicated that past sudden warming events were essentially triggered by the release of carbon dioxide and methane from permafrost some 50 million years ago in Antarctica.

And the projected numbers don't look promising: "Theoretically if this carbon is released to the atmosphere, the amount of CO2 will be three times more than what is in there [in the atmosphere] now," says Romanovsky.

So it's a true feedback loop as it amplifies the warming due to the burning of fossil fuels. And despite the fact that the warming is accelerating, the feedback effects will be gradual, taking time to be noticeable. "It's a very slow feedback," Schaefer says. "Imagine trying to steer a steam ship with a canoe paddle, that's the kind of feedback we're talking about."

Unfortunately, once permafrost starts to thaw, it'll be hard to refreeze it again - at least in our lifetime. Furthermore, once the decay is out of the ground and into the atmosphere, there's no easy way to put that carbon back into the ground.

"The only way to do that would be to lower the global temperature and refreeze the permafrost, which would mean you're removing carbon dioxide from the atmosphere," Schaefer says.

Climate models show that current intergovernmental commitments to reduce warming - as laid out by the Paris Climate Accord - may not be enough, Romanovsky explains.

In a 2016 report published in Nature Climate Change, researchers Sarah Chadburn

and colleagues estimate that even if the climate was stabilised as agreed upon by the 196 parties in 2015, "the permafrost area would eventually be reduced by over 40%".

However, with US President Donald Trump's announcement of withdrawal from the Paris agreement last June, more permafrost loss is likely on the horizon.
The blame game
Alaska is a politically conservative state, so outsiders might assume that residents reject the idea that the planet is warming beyond our control. The truth is more complex.

According to a poll of 750 participants conducted earlier this year by the Alaska Dispatch News, more than 70% of Alaskans are concerned about the effects climate change.

"In Alaska anybody you ask will say 'yes there's warming,'" Romanovsky says. "The farther north you go, northwest especially, the stronger that feeling. Because it's happening, you see it. Of course, the question of who's responsible depends on political beliefs."

At Denali National Park & Preserve, park ranger Anna Moore has witnessed warming affect wildlife across only a couple of years. She's noticed that the Arctic hare, which switches between brown and white coat colours with the seasons can't seem to keep up with the changes as a result of temperature rise, essentially putting itself at risk.

" In the wintertime they get white tips to their hair," Moore says. "As it gets warmer, the snow is melting faster, but their bodies are acclimatised to certain temperature change and so even though the snow is already melting they're still white and in more danger from predators."

Moore says though she believes in climate change and is watching it affect flora and fauna at the park, she considers it a result of both human activities and a natural cycle.

Her colleague Ashley Tench also echoes the sentiment: "I agree with her [on] how it's part man-made and also natural." To that effect, Tench doesn't believe the United States' pullout of the Paris Agreement makes a difference in the climate.

But not everyone in Alaska is on board with that sentiment. To Bill Beaudoin, a retired submariner and educator who's now the proprietor of a bed and breakfast in Fairbanks, it's obvious that humans are to blame and that we should work on reversing the effects of our actions.

People are worried, because of course there's no insurance for thawing permafrost

"I think the Paris climate accord was necessary," he says. "In fact, I didn't think [it was] enough. There's one country, Nicaragua, that didn't sign on to the agreement because they didn't think it was strong enough. I would probably side with Nicaragua on that issue."

No matter who is to blame for the warming and resulting thaw of permafrost, Alaskans are for the most part concerned about their future.

"People are worried, because of course there's no insurance for thawing permafrost," Romanovsky says. "Insurance is not covering damage from permafrost like it does in California for earthquakes."

Back at Goldstream III, Romanovsky notes that at 50cm depth, the temperature of the soil is -0.04C (31.9F). At one metre it's -0.23C (31.5F). The last time he checked the data was in March, where at one metre, the soil temperature measured -1.1C (30F).

He takes his shovel and makes a hole in the ground to look at the soil and check for carbon within. Darker soil indicates accumulated organic carbon. The further down he digs, the colder the soil gets. Romanovsky digs until the shovel hits the permafrost and seemingly can't go any further.

He pushes down a bit more and manages to dig up a bit of the permafrost - about the size of a small coin. Seconds after he holds the frozen soil between his fingers it melts as if it were an ice cube. He returns the dug up dirt back into the hole, disconnects his laptop from the data collector, closes up the box and covers it up with branches and packs up to leave the site. In a week he'll head up north to log the temperature at other sites adding yet more data to one of the most comprehensive permafrost databases in the world.

Meanwhile, bit by bit, America's frozen north is thawing and what happens next is unknown. What's certain is the great thaw will forever change a once-familiar landscape - and likely a planet and its inhabitants too.
Correction: A quote by Bill Beaudoin has been corrected to state that it was Nicaragua that did not originally agree to sign the Paris climate agreement.
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The great thaw of America's north is coming

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Vladimir Romanovsky walks through the dense black spruce forest with ease. Not once does he stop or slow down to balance himself on the cushy moss beneath his feet insulating the permafrost. It's a warm day in July, and the scientist is looking for a box that he and his team have installed on the ground.

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Major NZ climate report: The five defining figures - NZ Herald

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Major NZ climate report: The five defining figures - NZ Herald

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A sweeping stocktake out today has described the early indicators of a warming New Zealand, now being transformed by a shifting climate, rising sea levels and changing oceans.

The Ministry for the Environment and Stats NZ's latest report, focused on our climate, found our country was experiencing the impacts of excess greenhouse gas emissions in our atmosphere and oceans.

The 60-page report pulled together a mass of data on climate, oceans, soils, emissions, carbon, sea level and UV light.

"We have enough data on measures like annual average temperature to confidently say New Zealand's climate is warming," Government Statistician Liz MacPherson said.

That had been marked, she said, by the quarter of volume that New Zealand's glaciers had lost since 1977.

"National and international data collections on the atmosphere and climate are increasingly comprehensive but there are still some things we don't know at this time, in particular the full impact of climate change on our biodiversity, cultural values and the economy."

Secretary for the Environment Vicky Robertson said the most concerning change was the unprecedented high levels of carbon dioxide, which were leading to increasing global temperatures and changes to our oceans, including rising sea levels and increasing ocean acidity.

"The future impacts of climate change on our lives all depend on how fast global emissions are reduced and the extent to which our communities can adapt to change."

Herald science reporter Jamie Morton looked at five defining figures in the assessment.

1C

Since 1909, our annual average temperature has climbed by 1C - a figure in line with global average temperature increases, which are almost certainly the result of high levels of atmospheric greenhouse gases emitted from human activities.

Although seemingly small, this warming represented a rapid increase over a century, and was already affecting the natural systems on which we depend.

2016 was New Zealand's warmest year since at least 1909, and the five warmest years on record have occurred in the last 20 years.

Globally, 19 of the 20 warmest years occurred within the last 20 years.

Over the 45 years between 1972 and 2016, the number of frost days decreased at 10 of 30 measured sites and increased at one site, while no trend was apparent at the others.

The number of warm days - over 25C - increased at eight and decreased at one, with no trend at the others.

For most of New Zealand, there was no clear evidence that intense rainfall events had changed between 1960 and 2016.

But there were localised trends at some places: the proportion of annual rainfall occurring in intense events decreased in Auckland, New Plymouth, Rotorua, and Taupo, but increased at Napier and Timaru.

Sunshine hours have also increased across New Zealand, largely because of reduced cloud cover, and some locations also experienced changes in seasonal rainfall and extreme wind.

Yet, because New Zealand's climate varied naturally, it was ultimately hard to pick out patterns from short-term observations.

While longer-term data was needed to confirm whether humans were contributing to these sorts of trends, it was clear that further warming in the long term was expected.

How much, exactly?

That depended on the amount of greenhouse has emissions we pumped into the atmosphere over coming years and decades.

Under the Paris Agreement, which aims to rein in future global temperature rise by no more than another 2C, New Zealand has pledged to slash its greenhouse gas emissions by 30 per cent from 2005 levels and 11 per cent from 1990 levels by 2030.

24%

Along with natural variability, the global climate is shifting as a result of increased greenhouse gases and aerosols in the atmosphere from human activities.

While the burning fossil fuels are mainly to blame, changing land use and emissions from other activities, like transport and agriculture, have also been big contributors.

The figures showed how, between 1990 and 2015, New Zealand's gross greenhouse gas emissions rose by 24 per cent, with most of the increase having occurred by 2005.

The bulk of that could be put down to road transport and agricultural production - largely from nitrogen fertiliser use, grazing animal excrement on managed soils, and ruminant cattle belching methane.

Agriculture emissions, mainly methane and nitrous oxide, made up almost half our greenhouse gas emissions in 2015.

But road transport also drove one of the largest increases in emissions - with a 78 per cent increase since 1990.

Over the same time, our net greenhouse gas emissions rose 64 percent, as a result of increasing gross emissions and higher logging rates in production forests.

Net emissions acknowledge the role of carbon sinks, such as growing forests, in removing atmospheric greenhouse gases but also adding them when forests are harvested and land use is changed.

Globally, gross greenhouse gas emissions levels rose by 51 per cent from 1990 to 2013, mainly due to people burning more fossil fuels for electricity generation, heat, transport, manufacturing, and construction.

Carbon dioxide levels in New Zealand's atmosphere have meanwhile increased by nearly a quarter since 1972.

Last year, global concentrations of atmospheric carbon dioxide passed the symbolic level of 400 parts per million - the highest level of carbon dioxide in our atmosphere in at least the last 800,000 years.

The data made it clear that New Zealand was experiencing the effects of past global emissions.

Even if these emissions stopped today, many aspects of climate change would continue for centuries.

The full extent of future global warming depended on the emissions added from this point onward.

22cm

Sea levels around our country had risen by up to 22cm depending on location, over the last century.

The data showed that, since 1916, sea level had climbed by between 14 and 22cm at our four main New Zealand ports.

Over this period, sea level rose an average of 1.8mm a year across monitoring sites.

This was in line with the global record from tide gauges of about 1.7mm a year between 1901 and 2010.

Sea level has been rising around the globe as a result of the world's oceans expanding as they warm and because ice previously stored in glaciers and in parts of the polar ice sheets has been melting.

Globally, sea level rose 19cm between 1901 and 2010.

Rising sea levels and more intense heavy rainfall events associated with climate change are projected to increase coastal flooding and erosion, which may in turn cause damage to coastal ecosystems, housing, and critical infrastructure, such as roading, sewage, and power supply.

The planet's sea level is projected to rise by about 20 to 40 centimetres by 2060.

While New Zealand's sea level rise has aligned with the global average so far, at least one study projected that our sea level may rise a little faster than the global average in the future.

Moreover, with rising seas, we can expect tides, waves, and storm surges to reach further inland more regularly, resulting in more frequent and serious flooding.

There was also a recorded 0.7C increase in sea surface temperature recorded between 1909 and 2009, and acidity of the subantarctic ocean off the Otago coast had increased since 1998.

However, recent satellite data, only available since 1993, showed no trend in sea-surface temperature change in the Tasman Sea and New Zealand's oceanic, subtropical, and subantarctic waters.

This result wasn't not surprising given the short time these data have been available and the year-to-year temperature variations.

Ocean acidification and warming may cause widespread harm to marine ecosystems, for example, by reducing the survival and growth rates of marine species, extending or reducing the range of species, and modifying habitats.

The impacts could occur across New Zealand's entire ocean area, with implications for biodiversity, marine-based industries such as commercial fishing and aquaculture, and Maori customary practice.

25%

There have been more pronounced effects on our natural environment - perhaps none more dramatic than our shrinking glaciers.

New Zealand's mountains are home to 3144 large glaciers, most of them located along the Southern Alps of the South Island, and 18 on the flanks of Mt Ruapehu.

Glacier ice volume is strongly influenced by temperature and precipitation.

From 1977 to 2016, it was estimated our glaciers lost almost 25 percent, or 13.3 cu km, of their ice volume - a trend in step with shrinking glaciers elsewhere in the world.

Since the 1972/73 measurement season, soils at one fifth of sites around New Zealand have been getting drier.

The frequency and intensity of drought in drought-prone regions were expected to increase with climate change, with important implications for our primary industries.

Rising temperatures had also resulted in a greater number of "growing degree days" across the country, which can be used to predict plant, and subsequently, animal growth.
Plant and animal cycles are interdependent across the food chain.

Small changes in the timing of insect reproduction could mean that species further up the food chain miss out on a crucial food source.

The greater the change in timings, the more pressure species further up the food chain experience.

We didn't yet have a detailed understanding of how the changing climate will add to the pressures faced by already vulnerable native flora and fauna.

Our species have evolved in near isolation, forming our country into a biodiversity hotspot home to many species found nowhere else on Earth.

Despite humans only arriving in this country comparatively recently, our biodiversity has declined rapidly because of the cumulative effects of land disturbance, overexploitation of resources, and introduced pest plants and animals.

A changing climate has the potential to exacerbate these existing pressures - and some emerging evidence has already pointed to early effects.

For example, the sex ratios of North Brother Island tuatara were changing - there were now more male offspring in response to warmer nest temperatures.

Numbers of invasive wasps had also increased around the Nelson area because of increasing spring temperatures.

98%

The one piece of good news out of the report was that global production of ozone-depleting substances has dropped 98 per cent from 1986 to 2015.

Ozone is a greenhouse gas that exists throughout our atmosphere.

Four billion years ago, before life on Earth, the planet's atmosphere contained much lower levels of ozone, and much higher levels of UV sunlight reached the planet's surface than today.

It took the development of the ozone layer in the atmosphere for life to be able to withstand the damaging effects of intense UV sunlight.

In the troposphere, the layer of the atmosphere closest to Earth, ozone was typically present only in low concentrations.

Its concentrations were greatest in the second layer of Earth's atmosphere, the stratosphere, and peak at around 25km altitude.

At this level of the atmosphere, ozone is beneficial because it absorbs damaging UV sunlight, reducing the levels experienced at Earth's surface.

For years, the ozone had been depleted by substances - mostly used as refrigerants in air conditioners and refrigerators, and as propellants in aerosol cans - containing synthetic gases, creating a hole.

In the 1980s, scientists were concerned that stratospheric ozone was at risk, with associated increases in UV sunlight reaching Earth's surface.

Increases in UV sunlight due to depleted ozone were observed globally during the 1980s and 1990s, particularly at high latitudes.

Since the 1987 Montreal Protocol was en-acted under the Vienna Convention, the global production of ozone-depleting substances decreased by 98 percent - and the ozone hole has started to shrink in response.

In 2016, the mean maximum size of the ozone hole was 20.9 million square kilometres, a 21 percent decrease from its largest mean maximum size in 2006.

It was possible that the ozone hole would cease to form by the middle of this century, and ozone levels would return to their normal levels, more than 60 years since the world took action to reduce emissions of the harmful substances.

Exposure to ultraviolet (UV) sunlight has positive and negative effects on human health, but importantly for New Zealand, contributes to our high rates of the skin cancer melanoma.

Our high summer UV levels are partly caused by the naturally thinner ozone layer over New Zealand at this time, our clear air, and Earth's orbit, which brings the Southern Hemisphere closer to the sun during summer.

"Although ozone appears to be on a path towards recovery, we need to remain vigilant," said Emeritus Researcher Dr Richard McKenzie, who served on the technical advisory group for the report.

"The situation is delicate at present, and we remain at risk from possible effects from future volcanic eruptions, or non-compliance to the terms of the Montreal Protocol.

"And some of the atmospheric processes are not yet fully understood.

As far as UV radiation is concerned, we need to be especially vigilant.

"New Zealand is the melanoma capital of the world, and any change in UV expected from future recovery in ozone will not change that.

"Changes to personal behaviour are needed."

Climate action 'desperately important'

Environment groups have responded to the report by calling for greater action to curb emissions.

"Most concerning is that net emissions have risen 64 per cent, a function of a decline in planting of new forests," said Gary Taylor, chairman of the Environmental Defence Society.

"That is a wake-up call for all of us and we clearly need to do more offsetting while at the same time substantially increasing our mitigation efforts.

"This will require robust policy changes by Government."

Taylor argued the report confirmed what was already known: New Zealand needed to be better organised do more to meet its 2030 Paris Agreement target.

"The best way to ramp up our efforts is to legislate to set up an independent Climate Commission to plan, recommend, monitor and report on the transition we need to make over the next several decades.

"We need to develop a proper carbon budget, like other countries, to work out the least cost pathway to net zero emissions by mid-century."

Forest and Bird climate advocate Adelia Hallett said it was "desperately important" that our Government and industry leaders acted with urgency.

"We still have a window to keep climate change in check," Hallett said.

"Scientists recently confirmed that it is possible to keep warming under 1.5C, if we make urgent emissions cuts now."

Greenpeace New Zealand executive director Dr Russel Norman noted the report's findings that our country had the second-highest level of emissions per gross domestic product unit of the 35 OECD countries, and the fifth highest emissions per capita.

"This report is an opportunity for us to have a national conversation about how we're going to start reversing these statistics so we can pass on a safe climate to our kids."

He called for an urgent moratorium on new oil exploration.

WWF-New Zealand meanwhile wanted to see a new climate law for New Zealand.

"It's 100 per cent possible for New Zealand to be a world leader in renewable energy," the group's chief executive, Livia Esterhazy, said.

"But we need all political parties, whoever is in government, to support this crucial transition.

"The newly elected Parliament has an opportunity to pass a new climate law like the Zero Carbon Act - to create an expert, non-partisan Climate Commission, to set a science-based target of net zero emissions by 2050, and to give Aotearoa a plan to get there."

Their call for action was echoed by prominent climate scientist Dr Jim Salinger.

"This confirms global warming is alive and well, and that the next Parliament must accelerate action on climate change."

Associate Professor Simon Hales, an environmental epidemiologist at the University of Otago, argued that the report's main message was New Zealand was not living up to its international obligations on climate change.

"We need to reduce net greenhouse gas emissions, not increase them."

Well designed policies to reduce emissions could have important short-term health benefits, by reducing health risks and by promoting healthy lifestyles, Hales said.

"Mitigating climate change will have long-term health benefits in New Zealand and globally, by reducing extreme climate events, sea level rise, food and water insecurity and the spread of communicable diseases.

"This is especially important for vulnerable Pacific island nations that expect and require New Zealand to support their own efforts to address climate change.

"We require a much better, more quantitative understanding of the likely adverse impacts of climate change on human health than the brief, vague statements in the MfE report."

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Major NZ climate report: The five defining figures

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A sweeping stocktake out today has described the early indicators of a warming New Zealand, now being transformed by a shifting climate, rising sea levels and changing oceans. The Ministry for the Environment and Stats NZ's latest report, focused on our climate, found our country was experiencing the impacts of excess greenhouse gas emissions in our atmosphere and oceans.

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Warm waters melting Antarctic ice shelves may have appeared for the first time in over 7,000 years

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Warm waters melting Antarctic ice shelves may have appeared for the first time in over 7,000 years

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Eastern ice. Shutterstock/Hall

The vast expanse of the Antarctic is a region of the world particularly vulnerable to climate change, where ice loss has the potential to significantly increase sea levels.

Now, for possibly the first time in 7,000 years, a phenomenon known as "upwelling" (the upward flow of warmer ocean water to the surface), is thought to have caused recent ice shelf collapse around the continent - and the glacial thinning associated with it.

Ice shelves floating on water are the oceanic extension of land glaciers and ice sheets, and the primary region for ice loss. As these shelves break apart, the flow of continental ice held up behind them accelerates.

The ocean surrounding Antarctica is extremely cold, but water over 300m deep, Circumpolar Deep Water (CDW), is about 3⁰C above the melting point of ice. Normally, the very cold water above keeps this away from ice shelves. But in some areas, CDW is spilling onto the shallow Antarctic continental shelf, causing the ice to thin.

Ice shelf thinning has accelerated in recent decades, but the picture is not the same everywhere. While the east of the Antarctic has shown modest gains in ice thickness, the west has outstripped this with significant ice loss - up to 18% in vulnerable areas like the Amundsen and Bellingshausen Seas.

The pattern of ice loss and other observations indicate that warmer water upwelling beneath these ice shelves is driving it. But what has caused this upwelling? Is it related to human activity? And how concerned should we be?

Two teams led by scientists from the British Antarctic Survey, both of which I have been working with, set out to tackle these precise questions by focusing on two vulnerable areas. One site is in Pine Island Bay, in the Amundsen Sea, and the other is in Marguerite Bay, in the Bellingshausen Sea.

The aims of the studies are similar - to monitor the extent of upwelling warm water onto the continental shelf over the past 10,000 years, in order to understand when this last occurred and what the impact was.

This involves collecting and sampling "cores" of sediment up to 10m long from the sea bed at a range of depths up to 900m. Obtaining suitable cores is particularly challenging in these remote locations, where glacial dynamics often disturb the sediment.

Core evidence

Much of the evidence for past oceanography comes from tiny shells of amoeboid organisms called foraminifera. A huge variety of species colonise habitats on the sea floor and make up much of the sediment collected. There can be hundreds of shells in just one gram of sediment.

Nature Publishing Group

Forams are extremely valuable, as their shells are made of calcium carbonate precipitated from the ocean water in which they lived. Examining these shells allows us to reconstruct the chemistry of ocean water.

There were two geochemical tracers used for warm CDW in Pine Island Bay - the proportion of carbon isotopes, and the magnesium to calcium ratio controlled by water temperature. Both of these showed CDW was last on the inner shelf over 7,500 years ago.

In Marguerite Bay, shells of another plankton group called diatoms were also analysed. These indicate past productivity and sea surface temperatures. They showed that CDW was persistently on the shelf here over 7,000 years ago, and more sporadically since then.

Tellingly, the enhanced upwelling of warm CDW in both locations negatively impacted the local extent of ice.

Winds of change

Both studies suggest that the cause of the CDW upwelling before 7,000 years ago was a more southerly position of the southern hemisphere westerly winds (SHWW). These winds are thought to drive circulation of the warmer deep water. A recent shift in the position of the SHWW towards the poles could be the cause of greater CDW upwelling in Pine Island Bay since the 1940s.

This coincidence of timing with the onset of industrialisation shows it is possible that human made greenhouse gasses, thought to cause atmospheric warming, are having an impact on the position of the winds, the increase in warm water reaching the surface, and ultimately the melting of more ice in the Antarctic.

Irrespective of the causes of past changes in SHWW positions, the link between winds and ocean upwelling is cause for concern, as future projected global warming may shift SHWW belts and promote further upwelling and melting. More research is now needed to fully understand the link between CDW and past climate, and to estimate the strength of upwelling since the 1940s compared to upwelling before 7,000 years ago. But the emerging picture is one of the potentially increased vulnerability of West Antarctic ice sheets, and possible future sea level rise.

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Warm waters melting Antarctic ice shelves may have appeared for the first time in over 7,000 years

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The vast expanse of the Antarctic is a region of the world particularly vulnerable to climate change, where ice loss has the potential to significantly increase sea levels. Now, for possibly the first time in 7,000 years, a phenomenon known as "upwelling" (the upward flow of warmer ocean water to the surface), is thought to have caused recent ice shelf collapse around the continent - and the glacial thinning associated with it.

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TC - Abstract - Boundary layer models for calving marine outlet glaciers

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TC - Abstract - Boundary layer models for calving marine outlet glaciers

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TC - Abstract - Boundary layer models for calving marine outlet glaciers

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Abstract. We consider the flow of marine-terminating outlet glaciers that are laterally confined in a channel of prescribed width. In that case, the drag exerted by the channel side walls on a floating ice shelf can reduce extensional stress at the grounding line.

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Map Provides High-Resolution Look at Nearly Entire Arctic Region - Eos

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Researchers highlight the value of the time element incorporated into imagery and having a baseline for revisiting and comparing topography.

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Explore the British and Irish Ice Sheet in the Interactive Map

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Explore the British and Irish Ice Sheet in the Interactive Map

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Website with a detailed Study of the Glacial Cairngorms

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Website with a detailed Study of the Glacial Cairngorms

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'Impossible To Save': Scientists Are Watching China's Glaciers Disappear : Parallels : NPR

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'Impossible To Save': Scientists Are Watching China's Glaciers Disappear : Parallels : NPR

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At the end of every summer, scientist Li Zhongqin takes his seasonal hike near the top of a glacier in the Tianshan mountains in China's far northwestern region of Xinjiang.

Li scrambles over a frozen ridge and heads toward a lone pole wedged in the ice. Clouds emerge from a peak above and quickly blow past. He stops to catch his breath. He is at 14,000 feet. The snow is thick. The air is thin.

"This is called a sight rod," he says, grasping the pole. "We come up here each month to check it, to see how fast the glacier's melting. Each year, the glacier is 15 feet thinner."

Li, who heads the Tianshan Mountains Glaciological Station of the Chinese Academy of Sciences, points to a valley beyond a valley of boulders below to another glacier in the distance. "Twenty years ago, when I was a young scientist, these two glaciers were connected," he says. "But now, look: They're completely separate. Things are changing very, very quickly."

Xinjiang, a land of mountains, forests and deserts, is four times the size of California and is home to 20,000 glaciers - nearly half of all the glaciers in China. Since the 1950s, all of Xinjiang's glaciers have retreated by between 21 percent to 27 percent.

In the past 50 years, says Li, the average global temperature has risen by 1 degree Celsius (1.8 degrees Fahrenheit). As a result, these glaciers - split from the original Tianshan No. 1 glacier into No. 1 East and No. 1 West - are retreating by around 30 feet each year.

Li calls out to scientists hiking nearly 1,000 feet above. In their bright parkas, they look like neon-colored ants. They call back, their voices bouncing off an ice and stone amphitheater that cradles the eastern glacier.

Scientists are the only people allowed here. The government has banned tourism on the glacier and shut down factories in the town below, laying off 7,000 workers to try to lessen the impact of pollution.

But local sources of pollution account for just 30 percent of the damage to glaciers, says Li. The other 70 percent is caused by global carbon emissions that have warmed the entire planet.

The central goal of the 2015 Paris Agreement on climate change - which the Trump administration has promised to pull the U.S. out of, but to which China is still a party - is to limit the rise in global average temperature to 2 degrees Celsius (3.6 degrees Fahrenheit). Tianshan is one of those rare places where the impact of climate change policy can be measured and seen.

"If every country sticks to the emissions reductions in the Paris Agreement, these two glaciers will be around for another hundred years," says Li. "If not, then temperatures will continue to rise, and the glacier we're walking on? It'll be gone in 50 years."

And that, says Li, is a problem for this entire region.

These glaciers are the source of the Urumqi River, which provides water for half the city of Urumqi, the largest in the region and home to nearly 4 million people.

But that is not all that is at risk.

"You see that fog coming off the surface?" asks Li, pointing to the top of the glacier. "This glacier creates clouds, which in turn creates rain and snow elsewhere. Without this glacier, this region will start to dry up."

Two hundred miles away, at the foot of the mountain range, conditions couldn't be more different. At a grape orchard near the city of Turpan, it is 70 degrees warmer. This city sits on the edge of the Taklamakan Desert and is considered the hottest place in China - and the lowest, at 500 feet below sea level.

This area gets, on average, half an inch of rain per year. But it's an agricultural powerhouse. Nearly all of China's grapes are grown in this valley. The water this region depends on arrives in the form of snowmelt from faraway glaciers, flowing here through thousands of miles of underground tunnels called karez, an ancient irrigation system built 2,000 years ago. Turpan's karez wells are considered one of the great engineering feats of ancient China.

Down a hole in the parched, yellow earth, cool water from the mountains flows through the karez beneath the vineyard of Magcorjan Abdurehim. The farmer stands in the hot sun, worried.

"Thirty years ago, we had 182 'karez' in my town," he says in Uighur, the region's dominant language. "Now, only 64 of them have water. Each year, several of them run dry."

There used to be nearly 2,000 working karez throughout this region, but that number has shrunk to less than a couple hundred. Melting glaciers in the mountains above Turpan have meant more water flowing into the region, but that has also led to a boom in industrial farms and oil companies competing for water in the karez. The ancient irrigation system is quickly running dry.

Abdurehim shakes his head at the whole affair.

"Water means life. We can't live without it. I'm very worried we're going to run out of it in my lifetime."

The weather isn't helping. In July, the temperature here reached a record 119 degrees. Higher temperatures mean fewer grapes, he says.

It also means fewer glaciers.

At the rate global temperatures are rising, some 55 percent of all the glaciers in Xinjiang - nearly 11,000 - will be gone within 50 years.

"Even if global temperatures stop rising, this glacier will continue to melt," says scientist Li, atop the Tianshan No. 1 East glacier. "So, no, it's impossible to save it."

Li laughs, but it's a laugh that, in Chinese, is a sign of anxiety and defeat. As a glaciologist, Li says his job is changing as quickly as the glaciers themselves. Now, he says, he and other scientists are studying how to slow the melting - and how to prepare this region for a much drier and warmer future.
Yuhan Xu contributed research to this story.

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'Impossible To Save': Scientists Are Watching China's Glaciers Disappear

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At the end of every summer, scientist Li Zhongqin takes his seasonal hike near the top of a glacier in the Tianshan mountains in China's far northwestern region of Xinjiang. Li scrambles over a frozen ridge and heads toward a lone pole wedged in the ice.

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These are the melting glaciers that might someday drown your city, according to NASA - The Washington Post

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These are the melting glaciers that might someday drown your city, according to NASA - The Washington Post

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New York City has plenty to worry about from sea level rise. But according to a new study by NASA researchers, it should worry specifically about two major glacier systems in Greenland's northeast and northwest - but not so much about other parts of the vast northern ice sheet.

The research draws on a curious and counterintuitive insight that sea level researchers have emphasized in recent years: As ocean levels rise around the globe, they will not do so evenly. Rather, because of the enormous scale of the ice masses that are melting and feeding the oceans, there will be gravitational effects and even subtle effects on the crust and rotation of the Earth. This, in turn, will leave behind a particular "fingerprint" of sea level rise, depending on when and precisely which parts of Greenland or Antarctica collapse.

Now, Eric Larour, Erik Ivins and Surendra Adhikari of NASA's Jet Propulsion Laboratory have teased out one fascinating implication of this finding: Different cities should fear the collapse of different large glaciers.

"It tells you what is the rate of increase of sea level in that city with respect to the rate of change of ice masses everywhere in the world," Larour said of the new tool his team created.

The research was published in Science Advances, accompanied by an online feature that allows you to choose from among 293 coastal cities and see how certain ice masses could affect them if the ice enters the ocean. The scientists also released a video that captures some of how it works.

The upshot is that New York needs to worry about certain parts of Greenland collapsing, but not so much others. Sydney, however, needs to worry about the loss of particular sectors of Antarctica - the ones farther away from it - and not so much about the ones nearer. And so on.

This is the case because sea level actually decreases near a large ice body that loses mass, because that mass no longer exerts the same gravitational pull on the ocean, which accordingly shifts farther away. This means that from a sea level rise perspective, one of the safest things is to live close to a large ice mass that is melting.

"If you are close enough, then the effect of ice loss will be a sea level drop, not sea level rise," said Adhikari. The effect is immediate across the globe.

Indeed, the research shows that for cities like Oslo and Reykjavik, which are close to Greenland, a collapse of many of the ice sheet's key sectors would lower, not raise, the local sea level. (These places have more to fear from ice loss in Antarctica, even though it is much farther away.)

Here's a figure from the researchers showing which parts of Greenland threaten New York the most.

As you can see, the risk is mainly from the northern parts of Greenland and especially from the ice sheet's northeast.

This is revealing because while Greenland has hundreds of glaciers, three in particular are known to pose the greatest sea level risk because of their size and, if they collapse, how they could allow the ocean to reach deep into the remaining ice sheet, continually driving more ice loss. The three most threatening by far are Jakobshavn glacier on Greenland's central western coast, Petermann glacier in its far northwest and Zachariae glacier in the far northeast. Zachariae is partof a massive feature known as the Northeast Greenland Ice Stream, which reaches all the way to the center of the ice sheet and through which fully 12 percent of Greenland's total ice flows.

The new research shows that Petermann, and especially the northeast ice stream, are a far bigger threat to New York than Jakobshavn is.

In a high-end global warming scenario run out for 200 years, the study reported, Petermann glacier would cause 3.23 inches of globally averaged sea level rise, the northeast ice stream would cause 4.17 inches, and Jakobshavn would cause 1.73 inches. Of this total, New York would see two inches of rise from Petermann, 2.83 inches from the Northeast ice stream and just 0.6 inches from Jakobshavn.

This all really matters because in the real world, glaciers are melting at very different rates. Jakobshavn is the biggest ice loser from Greenland and is beating a very rapid retreat at the moment. Zachariae is starting to lose ice and looking increasingly worrisome, but still nothing like Jakobshavn. Petermann is holding up the best, for now, though it has lost large parts of the floating ice shelf that stabilizes it and holds it in place.

You will note that in no case does New York get the full effect of ice loss from any of these parts of Greenland - it's still far too close to the ice sheet. But Miami gets 95 percent of the globe's total sea level rise from the northeast ice stream, while distant Rio de Janeiro gets 124 percent, or over five inches in the scenario above.

The same goes for Antarctica - its melting, too, will have differential effects around the world. And that matters even more because the ice masses that could be lost are considerably larger than in Greenland. Antarctica, like Greenland, is melting at different rates. Substantialice loss is already happening in west Antarctica and in the Antarctic peninsula. Meanwhile, although scientists are watching the far larger eastern Antarctica carefully, so far it's not contributing nearly as much to sea level rise.

Farther away - like, say, New York - Antarctic loss is a big deal. Research has shown that if west Antarctica collapses, the U.S. East Coast would see morethan the average global sea level rise.

The current research does not take into account all aspects of sea level rise. Shifting ocean currents can redistribute the mass of the oceans and change sea level, for instance, and as global warming progresses, it causes seawater to expand, and thus a steady rise in seas.

Overall, though, the new study underscores a common theme of recent climate developments: We are now altering the Earth on such a massive scale that it puts us at the mercy of fundamental laws of physics as they mete out the consequences.
Read more at Energy & Environment: The U.S. has caused more global warming than any other country. Here's how the Earth will get its revenge. Scientists say Greenland just opened up a major new 'floodgate' of ice into the ocean A stunning prediction of climate science - and basic physics - may now be coming true For more, you can sign up for our weekly newsletter here, and follow us on Twitter here.

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These are the melting glaciers that might someday drown your city, according to NASA

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New York City has plenty to worry about from sea level rise. But according to a new study by NASA researchers, it should worry specifically about two major glacier systems in Greenland's northeast and northwest - but not so much about other parts of the vast northern ice sheet.

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Terrawatch: the reawakening of Öræfajökull

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Terrawatch: the reawakening of Öræfajökull

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All eyes have been on Mount Agung for the past week, watching the mesmerising clouds of ash pouring out of this tempestuous Indonesian volcano. Right now, the question is whether it is building for a repeat of the devastating eruption in 1963, when lava and lahars (rivers of water and rock) flooded hectares of land in minutes, killing 1,100 people.

While the news bulletins focus on Agung, geologists are starting to feel jittery about another volcano, thousands of kilometres away in Iceland. The unpronounceable Öræfajökull last erupted in 1727, so we don't have measurements to show how this volcano behaves in the lead-up to an eruption. The glaciated mountain, which is Iceland's highest volcano, is teasing scientists by producing swarms of small earthquakes under its flanks. "Earthquakes are rare at Öræfajökull, so they may indicate a reawakening," says Dave McGarvie, a volcanologist at the Open University.

Three people died during the relatively small eruption in 1727, when a meltwater flood swept their farm away. But the really scary eruption occurred in 1362, when sailors reported pumice "in such masses that ships could hardly make their way through it". Thick volcanic deposits obliterated the rich farmland surrounding the volcano, and ash travelled as far as western Europe.

"It was Iceland's largest explosive eruption since the island was settled, about 1,100 years ago," says McGarvie. But the abandoned farmsteads reveal that this volcano produced many earthquakes before both previous eruptions, giving people time to evacuate. For now, Icelandic scientists have installed extra earthquake monitoring equipment and are listening intently to the rumblings below.

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Terrawatch: the reawakening of Öræfajökull

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All eyes have been on Mount Agung for the past week, watching the mesmerising clouds of ash pouring out of this tempestuous Indonesian volcano. Right now, the question is whether it is building for a repeat of the devastating eruption in 1963, when lava and lahars (rivers of water and rock) flooded hectares of land in minutes, killing 1,100 people.

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These indigenous communities are models for how to adapt to climate change - The Washington Post

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These indigenous communities are models for how to adapt to climate change - The Washington Post

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Jorge Recharte is an anthropologist and director of the Andes Program at The Mountain Institute, an international nonprofit dedicated to mountain communities and their unique cultures and environments.
CANREY CHICO, Peru - When the poisoned river ran red with heavy metals, people from nearby communities didn't believe at first that climate change was to blame. In this small village nestled in the Cordillera Blanca, a majestic mountain range that contains several of the highest peaks in South America, the glaciers melted and metal-rich rocks were exposed to the air for the first time in thousands of years.

The glacial meltwater washing over the exposed rocks carried metals such as lead, arsenic, cadmium and iron into area waterways, turning rivers like the Rio Negro a rust red. This contaminated both soil and water and posed a significant health risk. Over time, people, wildlife and livestock who drank the water became sick, and crop productivity plummeted.

As headlines of global climate change become more alarming, it's easy to forget that climate change is also an intensely local problem. Startling statistics announcing that the snowcaps of the Andes or Alps will disappear before the end of this century conceal the fact that hundreds of smaller glaciers in these mountain ranges have already melted away, leaving a trail of devastation and threatening thousands of families' way of life.

In Peru, the government conducted a national inventory in 2013 and found that between 1970 and 2003, the 19 Peruvian mountain ranges with glaciers lost around 40 percent of their total ice surface. Some very large glacier ranges have already lost a third of their perennial ice, and some smaller glaciers no longer exist at all.

Silently, climate change has started to leave a trail of disasters in these mountains, and that has consequences for major lowland cities that rely, knowingly or not, on mountain ecosystems for food and water, agriculture and livelihoods. In a place like Peru, climate change adaptation begins in the mountains. And alpine communities are scrambling to find ways of adjusting to a new reality.

In the remote mountain villages around the Rio Negro, that adaptation effort took a curious and innovative form. To restore the poisoned river water and contaminated landscape around it, villagers collaborated with scientists from the Mountain Institute and with academic specialists. With training, they built a water purification system that collects the acidic river water in small ponds. Then, using local traditional knowledge, they planted native plant species that could absorb metals from the water.

Involving the communities on the front lines of climate change in this way is vital to finding concrete solutions to local problems; the open dialogue and collegial relationship with the scientists empowered the local community, sparking a palpable sense of pride in both local traditions and scientific solutions to complex climate problems.

And it wasn't the only time traditional knowledge helped restore a landscape degraded by climate change.

In the Nor Yauyos-Cochas Reserve of central Peru, Guadalupe Beraun, a wise and respected grandmother from the small village of Canchayllo, was showing me around the parched pastures where her sheep and cattle used to graze. The mountain peaks towered darkly above us. A small glacier called Wacra used to glisten there, a blinding white against the dark mountain and blue sky beyond. But year after year, it receded, finally disappearing completely around 1990.

Once the glacier was lost, the wetlands started drying up, and sheep and cattle had to be moved down the mountain to pastures that still had a few ponds. Wild vicuna, a relative of llamas, also had to migrate elsewhere. I asked Guadalupe what these drastic, local changes have meant to her. She paused and said, "It's changed my whole way of life. When I walk here now, I long to see vicuna in the grasslands, like before. I used to sing to them to show my happiness and gratitude to this place."

Where Guadalupe lives, people have relied on glacial meltwater to supply their alpine wetlands and grasslands, known as the puna, for as long as anyone can remember. The puna ecosystem extends from around 13,000 feet to 16,000 feet, a belt of pastures above the tree line and below the glaciers. Traditional ways of making a living at this high altitude rely on a healthy ecosystem. Villagers raise sheep, cattle and alpaca and also sheer wild vicuna for their valuable wool. Local farmers grow native potatoes and lesser-known tubers such as oca, olluco and mashua as well as corn, quinoa, broad beans, squash, fodder crops and much more. Their food and water security has always depended on glacial meltwater.

As glaciers receded, dozens of villagers like Guadalupe left their highland pastures years ago and began to over-exploit grasslands at lower elevations. But those pastures, too, were only going to last a few years. Locals were well aware that the puna would continue to degrade, livestock would suffer, and the ecosystem itself would eventually collapse. A more permanent solution - a sustainable adaptation to climate change - had to be found.

Together with scientists from the Mountain Institute and the National Agrarian University in Lima, villagers from Canchayllo and nearby Miraflores planned a "back-to-the-future" solution. Instead of re-inventing the wheel, they chose to honor their ancestors' impressive engineering by restoring ancient, local infrastructure that was used to regulate water in the puna.

The water management systems developed in ancient Peru involved a set of technologies designed to slow or retain water in high alpine territories. The purpose was to keep water available for use as long as possible in the dry season. These ancient systems included dams and reservoirs of different sizes, irrigation canals and large silt traps that kept soil from being eroded in years of intense rain. They also encouraged wetlands to develop. The excess soil in these silt traps could be "harvested" and used in terraces in warm valleys below the puna.

Pre-Inca civilizations in the Andes maintained highland pastures with water technologies that slowed the movement of water through grasses and soils and provided a buffer against flooding and drought. Local wildlife flourished. A steady supply of water supported lush pastures and livestock, who in turn provided manure, used as fertilizer for corn, tubers, hard grains and the hundreds of potato varieties that are native to mountain valleys in the Andes.

Over the centuries, most of this infrastructure was abandoned. Today, older villagers only remember some of the locations and uses. The social and demographic collapse of indigenous cultures after the Spanish conquest of Peru in 1532 helps explain why these ancient socio-technological systems decayed. In more recent times, glacier retreat, changes in precipitation, loss of local labor and shifts away from traditional herding and farming practices have all contributed to the abandonment of this infrastructure and the degradation of the puna ecosystem.

But that's starting to change. Villagers and scientists worked together to restore some of the ancient canals, and the wetlands began coming back to life. Cattle and sheep graze once again in revitalized highland pastures. The approach once again produced a strong sense of pride that traditional knowledge was being used to enable the community to become more resilient to the impacts of climate change.

The disappearing glaciers of the tropical Andes are our preview of what climate change has in store for mountain communities as well as the millions of people in lowland areas whose livelihoods depend on high-elevation ecosystems. We must prepare in our own regions by following the lead of these mountain people and learning from them as agents of change. We should pay close attention; mountains near the equator are our canary in the coal mine. They are the Earth's thermometer - an early indicator of a planetary fever.

I am hopeful and inspired by the mountain communities that live at the foot of receding glaciers. Their creativity, tenacity and resilience come from their deep trust in nature and their kinship with the mountains that surround them. They can teach all of us how to start adapting to a future without glaciers.
This was produced by The WorldPost, a partnership of the Berggruen Institute and The Washington Post. The Mountain Institute's Jesse Chapman-Bruschini translated the article from Spanish.

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Opinion | These indigenous communities are models for how to adapt to climate change

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Jorge Recharte is an anthropologist and director of the Andes Program at The Mountain Institute, an international nonprofit dedicated to mountain communities and their unique cultures and environments. CANREY CHICO, Peru - When the poisoned river ran red with heavy metals, people from nearby communities didn't believe at first that climate change was to blame.

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Needle ice formation and frost heave on Helvellyn resulting from ongoing sub-freezing conditions. @KeeleGeogs

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Needle ice formation and frost heave on Helvellyn resulting from ongoing sub-freezing conditions. @KeeleGeogs https://t.co/P9pQr0ouzU

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Needle ice formation and frost heave on Helvellyn resulting from ongoing sub-freezing conditions. @KeeleGeogs pic.twitter.com/P9pQr0ouzU
— Richard Waller 💙 (@wallersaur) December 9, 2017

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Needle ice formation and frost heave on Helvellyn resulting from ongoing sub-freezing conditions. @KeeleGeogs https://t.co/P9pQr0ouzU

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Needle ice formation and frost heave on Helvellyn resulting from ongoing sub-freezing conditions. @KeeleGeogs https://t.co/P9pQr0ouzU

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Needle ice formation and frost heave on Helvellyn resulting from ongoing sub-freezing conditions. @KeeleGeogs

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El Nino's long reach to Antarctic ice - BBC News

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El Nino's long reach to Antarctic ice - BBC News

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Antarctica may be thousands of kilometres from the central Pacific but events there can have a significant effect on the White Continent's ice.

Scientists have shown how ice shelves - the floating fronts of marine-terminating glaciers - respond to the El Niño phenomenon.

The warming of tropical eastern Pacific seawaters will lead to a change in wind patterns in the polar south.

This promotes snowfall on the shelves, and also melting of their undersides.

These are competing processes, of course. One adds mass; one takes it away.

However, the net outcome is a loss, say scientists. The reason? The ice removed from underneath the floating slabs has a higher density than the fluffy new snow at the surface.

Pressure influence

It is another example of the complexity researchers need to grasp as they try to gauge how Antarctica will react to a warming world.

Although much of the continent is relatively static in its behaviour at the moment, it is losing ice in the west, especially in the Amundsen Sea sector, where glaciers are thinning and accelerating.

The ice being shed in this region - many tens of billions of tonnes a year - adds to global sea-level rise.

Dr Fernando Paolo, from the Scripps Institution of Oceanography, and colleagues report their work in the journal Nature Geoscience .

They analysed more than two decades of satellite radar measurements of ice shelves. The spacecraft have continuously tracked the height of the shelves since 1994.

Once the scientists had removed the long-term negative trend, they found a variable signal that could be tied to the El Niño/Southern Oscillation (ENSO).

This oscillation famously sees surface waters in the eastern tropical Pacific seesaw between warmer than average conditions (El Niño) and cooler than average phases (La Niña).

ENSO is recognised to have global influence, altering patterns of rainfall and drought, for example. And in the southern polar region, it appears to influence atmospheric pressure fields.

One in particular, referred to as the Amundsen Sea Low, governs both regional winds and ocean circulation.

During an El Niño, this fosters higher snowfall rates on shelves, raising their height, but it also pulls more warm water up from the deep which can get under the shelves and melt them.

The combined effect leads to a loss in mass of the shelves. In a big El Niño phase, like the one in 1997/98, this reduction can be equivalent in scale to that stemming from the ongoing, long-term negative thinning trend.

"That means for a short period of time you are adding the two together. And that's key information to put into computer models if you want to properly represent the dynamics of these systems," explained Dr Paolo, who has now moved to the US space agency.

In La Niña years, the reverse happens: less snowfall, but also less melting on the shelves' undersides. This works briefly to slow the ongoing, long-term negative trend.

"Before this we knew that ENSO should affect Antarctica - that it should affect the ocean and the atmosphere around the continent. But this is the first time we've detected that signal on the ice shelves themselves," said Scripps co-author Prof Helen Fricker.

The study shows the value of ongoing satellite measurements in polar regions. Because there can be several years between El Niño events, a single satellite may catch only a couple of occurrences during its operational life.

An unbroken series of satellites is therefore required to capture the big picture.

The European Space Agency (Esa) has managed to do this with its radar satellites ERS-1, ERS-2, Envisat and Cryosat - although that may not be the case for much longer as Cryosat is ageing and any replacement is unlikely to be available until the mid-2020s.

Nasa has not done as well as Esa. It has a allowed a gap to develop between its satellite laser missions, which make very similar observations to radar over the Antarctic and the Arctic.

A major Earth observation report called the " Decadal Survey " was delivered last week through the US National Academies of Sciences, Engineering, and Medicine

The authors said it was "critical" that a satellite capability was maintained to measure ice elevation in the polar regions by either Europe or America.

Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter:@BBCAmos

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Antarctica may be thousands of kilometres from the central Pacific but events there can have a significant effect on the White Continent's ice. Scientists have shown how ice shelves - the floating fronts of marine-terminating glaciers - respond to the El Niño phenomenon.

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Could we retrofit Antarctica’s glaciers to keep them from collapsing? https://t.co/b4MpZjWFwh

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Could we retrofit Antarctica’s glaciers to keep them from collapsing? https://t.co/b4MpZjWFwh

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Could we retrofit Antarctica’s glaciers to keep them from collapsing? https://t.co/b4MpZjWFwh
— internetgeography.net 🌍 (@InternetGeog) January 13, 2018

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Could we retrofit Antarctica’s glaciers to keep them from collapsing? https://t.co/b4MpZjWFwh

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Could we retrofit Antarctica’s glaciers to keep them from collapsing? https://t.co/b4MpZjWFwh

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Could we retrofit Antarctica’s glaciers to keep them from collapsing? https://t.co/b4MpZjWFwh

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As Glacial Lakes Grow, So Do the Risks : Image of the Day

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Throughout the Himalayas, many glaciers are retreating and meltwater lakes are growing, putting people at risk downhill and downstream.

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Fascinating Photos of Glaciers before and after showing retreat

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Fascinating Photos of Glaciers before and after showing retreat

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Before- after - comparison pictures of glacier melting at the Rhone Glacier (Swiss Alps)

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Before- after - comparison pictures of glacier melting at the Rhone Glacier (Swiss Alps)

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Timelapse of Satellite data showing Arctic Sea Ice decline

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Timelapse of Satellite data showing Arctic Sea Ice decline

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Perennial Arctic Sea Ice Decline 1984 – 2016 (4K)

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Animation of Arctic sea ice between 1984 and 2016 showing the rapid decline in perennial sea ice. Perennial sea ice (or multi-year ice) is the portion of the sea ice that survives the summer melt season, may have a life-span of nine years or more, and can grow up to four meters thick.

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Plastic pollution has reached the 'pristine' Arctic

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Plastic waste is increasing in the supposedly pristine wilderness of the Arctic.

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Scientists race to explore Antarctic marine life revealed by giant iceberg

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Scientists race to explore Antarctic marine life revealed by giant iceberg

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A team of international scientists is due to set off for the world's biggest iceberg on Wednesday, fighting huge waves and the encroaching Antarctic winter, in a mission aiming to answer fundamental questions about the impact of climate change in the polar regions.

The scientists, led by the British Antarctic Survey (BAS), are trying to reach a newly revealed ecosystem that had been hidden for 120,000 years below the Larsen C ice shelf on the Antarctic peninsula.

In July last year, part of the Larsen C ice shelf calved away, forming a huge iceberg - A68 - which is four times bigger than London, and revealing life beneath for the first time.

Now scientists say it is a race against time to explore these new ecosystems before they are transformed by exposure to the light.

Marine biologist Dr Katrin Linse from the BAS is leading the mission which sets off on a voyage across the Southern Ocean from the Falklands Islands on Wednesday. They expect to reach the iceberg within a week.

"The calving of A68 provides us with a unique opportunity to study marine life as it responds to a dramatic environmental change," she said. "It's important we get there quickly before the undersea environment changes as sunlight enters the water and new species begin to colonise ... It's very exciting."

Prof David Vaughan, science director at BAS, said: "We need to be bold on this one. Larsen C is a long way south and there's lots of sea ice in the area, but this is important science, so we will try our best to get the team where they need to be."

He said climate change had already affected the seas around Antarctica and is warming some coastal waters.

"Future warming may make some habitats warm. Where these habitats support unique species that are adapted to love the cold and not the warm, those species are going to either move or die. How fast species can disperse, and how fast ecosystems can colonise new areas, is key to understanding where the Antarctic is likely to be resilient, and where it is vulnerable."

Last week the Guardian printed the first images of creatures found in a previously unexplored region of the Antarctic seabed, taken during a Greenpeace research expedition to the Antarctic which is part of a wider campaign to turn a huge section of the region into the world's biggest ocean sanctuary.

Speaking onboard the Greenpeaceship Arctic Sunrise, the group's head of oceans, Will McCallum, saidthere was "still so much left to learn about ocean life here in the Antarctic".

"From hidden ecosystems revealed by calving icebergs, to our research missions to the seafloor which have found an abundance of rare and vulnerable species - this place is bursting with life and a vast Antarctic Ocean sanctuary would help us protect it in all its forms."

There is growing concern about the possible impact of climate change in the Antarctic.

Earlier this month, a report revealed that melting ice sheets in Greenland and Antarctica are speeding up the already fast pace of sea level rise.

The research published by the National Academies of Sciences said, at the current rate, the world's oceans will be on average at least 60cm (2ft) higher by the end of the century.

However it found that the process is accelerating, and more than three-quarters of the acceleration since 1993 is due to melting ice sheets in Greenland and Antarctica, the study shows.

Experts say the area around the Antarctic peninsula has seen widespread ice shelf decay and collapse in recent decades, leading to "glacier acceleration" and increased discharge of ice from the Antarctic continent into the sea.

However scientists are wary of attributing the calving of the Larsen C iceberg directly to global warming.

Adrian Luckman, professor of glaciology at Swansea University and leader of a project studying the state of the ice shelf, said: "Whilst the Larsen C ice shelf has reduced in area since records began, suggesting that over the long-term the environment of the Antarctic peninsula is becoming less able to support ice shelves, we have no evidence to link this particular calving event to changing conditions. Iceberg calving is a natural part of the ice shelf cycle and, whilst large, the calving of A68 is not unprecedented."
Topics

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Scientists race to explore Antarctic marine life revealed by giant iceberg

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A team of international scientists is due to set off for the world's biggest iceberg on Wednesday, fighting huge waves and the encroaching Antarctic winter, in a mission aiming to answer fundamental questions about the impact of climate change in the polar regions.

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The glacier that keeps collapsing - BBC News

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The glacier that keeps collapsing - BBC News

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The Perito Moreno glacier in Argentina is one of very few globally that grows rather than shrinks

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Underwater melting of Antarctic ice far greater than thought, study finds

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Hidden underwater melt-off in the Antarctic is doubling every 20 years and could soon overtake Greenland to become the biggest source of sea-level rise, according to the first complete underwater map of the world's largest body of ice.

Warming waters have caused the base of ice near the ocean floor around the south pole to shrink by 1,463 square kilometres - an area the size of Greater London - between 2010 and 2016, according to the new study published in Nature Geoscience.

The research by the UK Centre for Polar Observation and Modelling at the University of Leeds suggests climate change is affecting the Antarctic more than previously believed and is likely to prompt global projections of sea-level rise to be revised upward.

Until recently, the Antarctic was seen as relatively stable. Viewed from above, the extent of land and sea ice in the far south has not changed as dramatically as in the far north.

But the new study found even a small increase in temperature has been enough to cause a loss of five metres every year from the bottom edge of the ice sheet, some of which is more than 2km underwater.

"What's happening is that Antarctica is being melted away at its base. We can't see it, because it's happening below the sea surface," said Professor Andrew Shepherd, one of the authors of the paper. "The changes mean that very soon the sea-level contribution from Antarctica could outstrip that from Greenland."

The study measures the Antarctic's "grounding line" - the bottommost edge of the ice sheet across 16,000km of coastline. This is done by using elevation data from the European Space Agency's CryoSat-2 and applying Archimedes's principle of buoyancy, which relates the thickness of floating ice to the height of its surface.

Melting Antarctic ice sheet graphic

The greatest declines were seen in west Antarctica. At eight of the ice sheet's 65 biggest glaciers, the speed of retreat was more than five times the rate of deglaciation since the last ice age. Even in east Antarctica, where some scientists - and many climate deniers - had previously believed ice might be increasing based on surface area, glaciers were at best stable and at worst in retreat when underwater ice was taken into account.

"It should give people more cause for concern," said Shepherd. "Now that we have mapped the whole edge of the ice sheet, it rules out any chance that parts of Antarctica are advancing. We see retreat in more places and stasis elsewhere. The net effect is that the ice sheet overall is retreating. People can't say 'you've left a stone unturned'. We've looked everywhere now."

The results could prompt an upward revision of sea-level rise projections. 10 years ago, the main driver was Greenland. More recently, the Antarctic's estimated contribution has been raised by the Intergovernmental Panel on Climate Change. But its forecasts were based on measurements from the two main west Antarctic glaciers - Thwaites and Pine Island - a sample that provides an overly narrow and conservative view of what is happening when compared with the new research.

The study's lead author, Hannes Konrad, said there was now clear evidence that the underwater glacial retreat is happening across the ice sheet.

"This retreat has had a huge impact on inland glaciers," he said, "because releasing them from the sea bed removes friction, causing them to speed up and contribute to global sea level rise."
Topics

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Underwater melting of Antarctic ice far greater than thought, study finds

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Hidden underwater melt-off in the Antarctic is doubling every 20 years and could soon overtake Greenland to become the biggest source of sea-level rise, according to the first complete underwater map of the world's largest body of ice.

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Touring the Lake District with an 80-year-old guidebook

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In 1939, the newly established Penguin Books published six guides to various English counties, complete with touring maps, aimed at the middle-class motorist. Emma Jane Kirby has been driving around the UK with those first-edition guides in her hand to see how Britain has changed since the start of World War Two. Next stop: the Lake District.

"No other countryside in the world," boasts my guide's author, W T Palmer, "can offer such variety, to suit all tastes and pockets."

It would be wrong of me to suggest I had developed a favourite county during my tour of England with the 1939 Penguin guides, but I think I can say that if I had the chance to go back in time to meet just one of the books' authors, I'm pretty sure I'd plump for W T Palmer.

Some of the other authors' waspish humour is certainly more amusing and their observations perhaps more perspicacious but what I like so much about Mr Palmer is that rather than showing off his knowledge or casting judgement on the peculiar eating or dancing habits of the locals, he just seems terribly concerned that everyone coming to the Lake District in 1939 should have a jolly nice holiday. Yes, everyone.

Even the less well-off.

"Youth hostels are established in our area for the benefit of youngsters who are compelled to take holidays on small means... the movement has been accused of bringing a newer and poorer type of guest and keeping away more profitable people. So far this cannot be proved."

Borrowdale Youth Hostel, noted W T Palmer with some excitement, was just about to open as he penned his guide. In fact the whole youth hostel movement, of which he was a fervent supporter, had only begun a few years previously.

As I drive warily over the Fisher-Price-sized stone bridge in my stocky 21st Century hire car, a small group of YHA guests clad in sturdy walking boots and serious-looking cagoules wave their Ordnance Survey maps at me as I pass. To the right of the original low-slung wooden building, a barefoot, blonde young man, his hair crusted into dreadlocks, pets a dog in front of some trendy pod-like wooden cabins.

"That was always the whole point of the hostel movement," grins YHA archivist Duncan Simpson as he ushers me into Borrowdale's bar and orders us coffee.

"At a shilling a night, it allowed everyone to get a holiday in the countryside and provided an opportunity for all classes and backgrounds to mix. You could be a bishop bunked next to a steel worker. And while there weren't those pods outside, you were allowed to bring your own tent."

He shows me the carpeted dormitories and the pristine shower blocks - most of the youth hostels in W T Palmer's day could boast only of the possibility of nearby "river bathing".

But basic comforts - or the lack of them - did not seem to mar his enthusiasm. In fact he devoted a whole chapter of his guide to hostelling.

A couple of people are clearing up the remnants of their late breakfast in the communal kitchen, and in the games room the barefoot young man and his friend are laughing over a last game of table tennis before heading to the hills.

"It's exactly like in 1939," says Duncan. "Everyone would be out walking during the day... and of course there was no bar to hang around in in 1939 - alcohol wasn't allowed."

But surprisingly, there were women. (Palmer chastely calls them "maidens".) By 1939 half of the guests in the Lake District hostels were female and I tell Duncan Simpson that Palmer writes obliquely that the Lake hostels hold a "high reputation for freedom, which attracts more and more visitors to the chain".

Duncan laughs and tells me that's why there was plenty of local - and national - opposition.

"Youth hostels were luring people into the countryside in mixed groups and away from church on Sundays," he tells me. "And they gave people not only the freedom to get out in the open, but also the freedom to meet the opposite sex without chaperones!" He shakes a finger at me.

"But there were rules," he insists. "To make sure people were well-behaved."

Find out more

Read Emma Jane Kirby's account of following the 1939 Penguin guides to Kent, Derbyshire and Cornwall

Listen to her report from the Lake District at 13:00 on Tuesday 3 April 2018 on BBC Radio 4's The World at One

Or catch up later on the BBC iPlayer

I'm not sure that W T Palmer was a true libertarian - every third page of his guide robustly reminds readers of the rules and regulations of the popular 1930s sports of fell walking and rock climbing, and the climber's responsibilities.

"Rock climbing has become an important, if select, sport in the Lake District... it must be impressed that the sport is both difficult and dangerous... any inexperienced person venturing on these forbidding slabs, sheer cracks and fangs of rock, invites disaster and mishap."

As mountaineering instructor Zac Poulton and I start our ascent up Blencathra, the sky ruptures and spills a spiteful torrent of freezing rain and sleet on top of us.

"In '39, climbers were much hardier, really pushing themselves psychologically," says Zak amiably, over his shoulder, as I trail miserably behind him.

"They'd climb using any rope they could find, ropes that wouldn't have been tested... they'd steal mother's washing line... These days we climb with several hundred quids' worth of metal dangling from our harness so we can anchor ourselves to the rock."

A bullying wind comes to join the rain. Zak and I were meant to meet in kinder weather yesterday but he was delayed for five hours after coming across a woman who had slipped on snow and smashed into some boulders descending Helvellyn. He's amazed there were not more accidents in W T Palmer's day, especially as the 1930s climbers would have been climbing either in hobnailed boots or the new rubber-soled plimsolls that were coming over from Europe.

"They wouldn't have had all the waterproof kit we've got," says Zak nodding at my breathable coat. "It would have been tweed jacket, ex-Ministry of Defence smocks and woollen jumpers. If you wanted to climb in the Lakes, you were going to get wet and cold - it was the old British attitude; one must suffer for one's sport!"

Climbing, however, is clearly not my sport and so we turn around, ignoring W T Palmer's boast that he once "tramped" 85 miles in the Lake District in just 25 hours and 30 minutes.

As we trudge back down towards the car we chat about how Palmer seemed both fascinated by rock climbing but also rather fearful. Defrosting later in a Keswick cafe, I look at the back flyer of my Penguin guide and learn with a shiver that he lost his great-grandfather on Shap Fell during a storm.

I also learn that his father was a drover - and his strong affinity and respect for the fells and their farmers permeates the book. Penrith, says Palmer proudly, is an important and "distinguished" agricultural centre.

"You wanted quality, here she is now!' sing-songs the auctioneer at Penrith and District Farmers Market as a startled sheep surges into the pen, flashing the red mark on her fleece. "Seventy-five pounds I'm bid. Who'll give me £80?"

The elderly farmer beside me growls into his sausage sandwich.

"Sheep aren't as hard as they used to be," he says. "Back in the day, we never took them off the moor - now we bring them down into the lowlands and they've gone a lot softer."

I show him the 1939 guide I'm using to tour his county and tell him that 80 years ago its author assured readers that most shepherds and farmers went about "their daily work in the saddle".

"I've got petrol in my horse today," he quips. "It's called a quad bike." He wipes some tomato ketchup from his chin on to his sleeve.

"Other than that," he says after a moment's reflection, "it's still the same."

A younger farmer, here to sell last year's lambs, disagrees.

"It's all about quantity and low price today. I'm 33 but I'd rather have lived in my granddad's time in farming rather than face what's coming now, definitely."

The sheep in the holding pen start bleating, perhaps sensing that whatever price they command this morning, the day isn't going to end well for them.

"Has it improved in 80 years?" asks a fell farmer rhetorically. "No. Because then there'd be a lot of people working on a farm together." He takes off his tweed deerstalker hat and wipes his forehead. "Now it's a lonely job, believe me."

I daren't mention the local celebrity shepherd, James Rebanks, and the 107,000 followers of his Twitter account, the Herdwick Shepherd - but I feel quite sure that W T Palmer would be delighted that his beloved sheep were big on social media.

Comfort is easy to come by in Cumbria. The county's sweet tooth is so notorious that local shops sell "bags for life" bearing the logo, The Cake District.

"There are many dishes peculiar to Lakeland which should be enjoyed... Kendal mint cakes, Grasmere gingerbread, Hawkshead wigs are worth trying," writes our guide.

"I am the only person now with the original recipe for Hawkshead Wigs," says chef Mark Whitehead, tipping caraway seeds into a bowl.

He shrugs.

"I'm afraid your guide would be hard pushed to find a wig in Cumbria nowadays - the only bakery in Hawkshead shut down years ago."

Thought originally to be an offering to the Norse god Wigga, wigs are a sort of rich bread spiced with caraway seeds, and made not with water but with milk and butter.

Until a few years ago Mark used to get up at 5am every morning to bake wigs for customers of a cafe he ran, serving them with local cheese and his own Hawkshead Relish or Cumberland sausage. Not any more.

"The problem is, that having all that butter and milk in them they go stale quickly," he explains kneading the sticky dough. "Plus they also take four hours to make - who's got time for that these days?"

W T Palmer encouraged his readers to take a three-hour tour on one of Windermere Lake's steamers. Starved of time, local historian Roger Bingham and I have opted for the 45-minute island spin from Bowness. Over the loudspeaker our tour guide is giving a running commentary in a thick foreign accent. Roger motions towards the quayside where scores of Japanese tourists are pouring off coaches.

I'm afraid, in the 1930s, the locals saw her as a la-dee-dah off-comer who dressed as a tramp
Roger Bingham, on Beatrix Potter

"Even though the war was coming, in 1939, this place would have had huge crowds on the promenade in their Sunday best," he says. "The workers would come in charabancs from Lancashire... but Westmorland in 1934 had more cars than anywhere else on Earth!"

We chat about how Palmer, perhaps in his bid to give everyone one last nice holiday, steadfastly omitted to make any mention of the war that everyone knew was coming; by spring 1939, the Westmorland Gazette was full of news about blackout practices and air-raid precautions.

The accented voice over the loudspeaker interrupts to inform us we are nearing Beatrix Potter's house. There's a crackling of waterproofs as tourists rush to pull cameras and phones from their pockets.

"I'm afraid, in the 1930s, the locals saw her as a la-dee-dah off-comer who dressed as a tramp," says Roger Bingham. "And she wasn't nice to children. Whether she had a pet rabbit and was nice to Peter, I don't know."

The two ladies beside us who have been surreptitiously ear-wigging our conversation look crushed.

"Still," adds Roger thoughtfully, "she was buying up a lot of Lakeland farms in the 1930s to give to the National Trust - she did a lot of good here."

Perhaps W T Palmer just wasn't much of a bunny man but he doesn't mention the Potter canon at all in his guide. He is however extraordinarily proud of another local writer - Hugh Walpole.

"Lakeland is full of literary homes and haunts... in the new time Sir Hugh Walpole has settled in the country and many of his best novels deal with the Herries and other Lakeland families and landmarks."

Eric Robson, chairman of Radio 4's Gardeners' Question Time and a huge fan of Walpole's, shrugs his shoulders as we study the noble-looking bust of the author in Keswick's museum.

"How he fitted in here, is a mystery," he muses. "Cumbrians are a blunt crew - and here was a gay, spendthrift intellectual... but he caught the essence of this place and its people and he knew his cast. Cumbrian people recognised he was their voice on the world stage."

Six months after the publication of his meticulous guide, Britain and France declared war with Germany and the Penguin County Guides were pulled from the shelves

We peer at two handwritten manuscripts displayed in a glass case. The writing is distinctly scruffy and childish.

"He also couldn't spell and had no grasp of grammar!" laughs Eric.

If you're of a literary bent and yet are scratching your head over the name Hugh Walpole, don't be too hard on yourself. In the 1930s, when Walpole was writing a novel a year (he produced 50 in his lifetime), he was selling 20,000 copies of each novel in hardback within the first two weeks of publication. John Buchan reviewed his Lakeland trilogy, saying the work was the best English novel since Thomas Hardy's Jude The Obscure.

But he's been out of print for years and it's difficult to find a copy of his novels even in second-hand bookshops. So what on Earth happened to crush this literary Lakeland giant who in the late thirties was touring America and pulling bigger audiences than Dickens had, 80 years earlier?

"The war!" smiles Robson. "The war brought in a new generation of writers who wanted to break down the mould of literature as we knew it and Walpole was a representative of the old hierarchy they wanted to tear down."

On the end page of W T Palmer's 1939 book, there's an illustration of two exhausted but very contented little penguins, reposing on their haversacks.

Six months after the publication of his meticulous guide, Britain and France declared war with Germany and the entire Penguin County Guides series with their detailed maps - which would have been a gift for foreign agents - were pulled from the shelves. Special Forces requisitioned Borrowdale Youth Hostel; Hugh Walpole and Beatrix Potter would be dead within 18 months; the holidays were well and truly over.

I sit in the fading light in Hawkshead graveyard and listen to the church bells chime.

"Return to your lodgings," advises W T Palmer gently. "You have had a full day."

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How much has the Lake District changed in 80 years?

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In 1939, the newly established Penguin Books published six guides to various English counties, complete with touring maps, aimed at the middle-class motorist. Emma Jane Kirby has been driving around the UK with those first-edition guides in her hand to see how Britain has changed since the start of World War Two.

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oth the north pole and the south pole are situated in the middle of huge ice deserts which are melting around the edges under the influence of human activity. The difference that matters between them is that the ice of the Arctic floats: if it melted nothing much would happen to aggregate sea levels. The ice of Antarctica, like that of Greenland, rests on land. If it all were to melt, as it has done in the far distant past, sea levels could rise by as much as 60 metres. That is most unlikely to happen. What is possible, though, is that the smaller portion of the continent, west Antarctica, which is divided from the rest by a mountain range, could lose much of its ice. Even that would be catastrophic. A significant retreat in west Antarctica, as seems to be already under way, could raise sea levels by between one and three metres by the end of this century. Children now alive will see that happen across their lifetimes. That is what is meant by the urgency of global warming.

This week saw the publication of fresh research showing that the glaciers of west Antarctica are retreating faster than they were at the end of the last ice age, when water levels also rose significantly. The ice sheet is not one homogeneous mass, but a collection of glaciers all moving slowly but inexorably towards the sea. Their retreat is happening underwater, and invisibly, as the ocean erodes the foot of the glacier, known as the "ground line", where its contact with the sea floor ends. Beyond that point, long tongues of ice stick out into the ocean, providing the coastline that we can see and map. But the capacity of the ice sheet to lock up water depends on the position of the ground line. As that retreats, invisibly, the sea level rises and the whole of the ice sheet grows less stable, something which makes further sea rise still more likely.

Previous surveys have concentrated on a few of the glaciers that are an obvious danger but the research released this week analysed satellite data covering the whole of the coastline of west Antarctica to reach its worrying conclusions. The problem is worsened by the shape of the seabed on which the glaciers now rest. It does not slope towards the deep ocean, but inwards, forming a bowl of which the far side is the mountain range that divides the continent. That means that the process of erosion will be working downhill as it moves inwards, with faster and less predictable results.

The present danger was discovered by measuring the thickness of the ice sheet from space and deducing from this the shape of the glacier beneath. This is much easier than knowing what to do. The contrast between the exquisite technological sophistication employed in the diagnosis of the problem and the lack of international coordination or political sophistication when it comes to solving it, illustrates the crisis of technological civilisation. As a species we have shown enough cleverness to disrupt the world's climate, but may not have enough to remedy the damage that we've done. Things are of course made very much worse by the presence in the White House of an aggressively ignorant and anti-science administration.

Predicting the future of these changes isn't an exact science, which is one of the things which makes them so frightening, but neither is it entirely guesswork. Ignorance about the size of the threatened rise in sea levels is no excuse for inaction. We know it's coming. We know it will be disruptive. We don't know if it will be catastrophic. But the possibility must spur us into drastic action on fossil fuels. Keep them in the ground.

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The Guardian view on Antarctica: the worrying retreat of the ice | Editorial

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oth the north pole and the south pole are situated in the middle of huge ice deserts which are melting around the edges under the influence of human activity. The difference that matters between them is that the ice of the Arctic floats: if it melted nothing much would happen to aggregate sea levels.

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Geography videos about glacial processes and landforms. These videos are developed with links to various specifications including Geography GCSE Glaciation, Geography IGCSE Glaciation, Geography AS-level Glaciation, Geography A-level Glaciation, Geography IA-level Glaciation, Geography National 5 Glaciation, Geography Higher Glaciation.

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Virtual Reality Tours of Glaciated Landscapes

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Virtual Reality Tours of Glaciated Landscapes

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Welcome to VR Glaciers and Glaciated Landscapes

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VR Glaciers and Glaciated Landscapes is a new resource that provides on-demand, simulated fieldwork to glaciers and glaciated landscapes. Its primary role is in supporting class and lab-based teaching of glaciers and glaciation in schools, colleges and universities.

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Excellent Resource on all things Glacier - and Antarctica

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Excellent Resource on all things Glacier - and Antarctica

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Welcome to AntarcticGlaciers.org

Antarctic glaciers are beautiful and awe-inspiring. They affect us through their connections with the ocean and sea level, and environmental change is having rapid consequences in Antarctica.

Antarctica is the world's largest ice sheet, covering ~14,000,000 km ². Much of the Antarctic ice sheet surface lies above 3000 m above sea level. This massive thickness of ice drowns whole mountain ranges, and numerous volcanoes exist underneath the icey exterior. Antarctica is the world's fifth largest continent, and it is, on average, the highest and coldest continent.

Antarctica provides a unique record of the Earth's past climate, through the geomorphological record of glacier moraines, through ice cores, through deep sea sediment cores, and through past records of sea level rise.

The Antarctic Continent

The Antarctic continent comprises three ice sheets: the Antarctic Peninsula Ice Sheet, the West Antarctic Ice Sheet, and the East Antarctic Ice Sheet. Most of Antarctica is covered by ice (~98%), with ice-free areas on, for example, nunataks (high mountains poking through the ice sheet), James Ross Island and Alexander Island on the Antarctic Peninsula, and the McMurdo Dry Valleys in East Antarctica.

The Antarctic Ice Sheet is drained by fast-flowing ice streams, which respond quickly to climate change; they can thin, accelerate, recede, or even stop flowing entirely. Beneath the thick skin of ice, there is flowing water and subglacial lakes. Despite the aridity and cold temperatures, there is life on the ice, in the ice and underneath the ice.

Antarctic glaciers terminate on land or in the sea, as floating ice shelves or grounded or floating outlet glaciers. The Antarctic Ice Sheet contains 25,400,000 km ³ of ice, which, if it melted, would be equivalent to a sea level rise of 58 m[1]. The ice sheet is over 4000 m thick in places, and in places, the West Antarctic Ice Sheet is grounded more than 1500 m below sea level[2]. The coldest temperature ever recorded on Earth was at Vostok: -89.2°C on 21 st July 1983. The Dry Valleys of Antarctica are the most similar place on Earth to the desolate landscapes of the Moon and Mars.

Geography A-Level

This website aims to introduce some key concepts in Antarctic glaciology and glacial landscapes and systems more broadly. These ideas are explored in our Science Themes, and include descriptions of different types of glacier, ice shelves, and ice streams. This website also explores the recent rapid environmental changes happening today in Antarctica, and how changes in atmospheric and ocean temperatures has led to ice-shelf collapse, rapid glacier recession and sea level rise.

Pages that are particularly relevant to the UK A-Level curriculum are highlighted with a yellow flash.

Click through each of the Science Themes on the website to discover more about Antarctic glaciers. Italicised words are defined in the Glossary. Alternatively, ask a me a question through twitter (@Antarcticglacie) or Ask a Scientist!

Website authors

This website was written by Dr Bethan Davies from Royal Holloway, University of London, as part of an ongoing commitment to education, outreach and impact, and Dr Jacob Bendle, also from Royal Holloway, who is an expert in the Patagonian Ice Sheet, with guest contributions from others. For more information on authors, see the About page.

Funding

We acknowledge funding from the Quaternary Research Association, Scientific Committee for Antarctic Research, Royal Holloway University of London and the British Society for Geomorphology. For more information, see the About page.

1. Lythe, M.B., Vaughan, D.G., and the BEDMAP Consortium. 2001. BEDMAP: a new ice thickness and subglacial topographical model of Antarctica. Journal of Geophysical Research, 2001. 106(B6): p. 11335-11351.

2. Joughin, I. and Alley, R.B., 2011. Stability of the West Antarctic ice sheet in a warming world. Nature Geosci, 2011. 4(8): p. 506-513.

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Antarctic glaciers are beautiful and awe-inspiring. They affect us through their connections with the ocean and sea level, and environmental change is having rapid consequences in Antarctica. Antarctica is the world's largest ice sheet, covering ~14,000,000 km 2. Much of the Antarctic ice sheet surface lies above 3000 m above sea level.

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Virtual field trip (& video), to help students understand the formation of drumlins by subglacial processes, on @timeforgeog. Developed in partnership with @esriuk & @KeeleGeogs #GCSE #Alevel #Geography #NorthYorkshire #GIS @GIS4Schools @The_GA @ESTA_UK

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Antarctic: 'No role' for climate in Halley iceberg splitting

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When a giant iceberg breaks away from near Britain's Halley research base, it won't be because of climate change.

Scientists Jan De Rydt and Hilmar Gudmundsson have spent years studying the area and say the calving will be the result of natural processes only.

The Antarctic station, which sits on a floating platform of ice, was moved in 2017 to get it away from a large chasm.

That crack is now expected to dump a berg the size of Greater London into the Weddell Sea.

It's not clear precisely when this will happen, but the breakaway looks imminent, prompting the British Antarctic Survey (BAS) to withdraw its staff from Halley as a precaution.

As soon as the calving does occur, though, it can be guaranteed that one of the first questions everyone will ask is: what was the influence of climate change?

And the Northumbria University team believes it will be able to answer with high confidence: "There was none."

Jan De Rydt and Hilmar Gudmundsson have built a model to describe the behaviour of the floating ice platform, which is known as the Brunt Ice Shelf.

The Brunt is essentially an amalgam of glacier ice that's flowed off land and pushed out to sea at a rate of about 400m per year.

Incorporating satellite and surface-gathered data, the team's model reveals how stress is distributed across the 150-250m-thick structure. And it predicts accurately where cracks are likely to develop and the path they will take.

"It all fits together; it's a very compelling piece of work," says Prof Gudmundsson.

"It shows that the chasm started to grow because of the stresses building up, and they built up because of the natural growth of the ice shelf. The ice shelf itself created this chasm."

The Brunt has never been in quite so advanced a position. The famous explorer Sir Ernest Shackleton mapped its ice front in 1915 and the modern cliff edge is well beyond what he saw. A calving seems overdue.

The chasm is not the only major split in the Brunt, however. To the east of Halley is a crack dubbed Halloween, after its discovery on 31 October 2016. This fissure is likely to produce its own berg at some point, but, again, this behaviour can be described simply by the developing stresses in the shelf.

"There is no indication from oceanographic or atmospheric data that the climate is changing in the Brunt area," Dr De Rydt told BBC News.

"Our ocean observations are limited but whatever we have doesn't indicate anything unusual; and our model shows that what we are seeing can be perfectly explained by natural changes in the geometry of the ice shelf."

The Northumbria pair were previously employed at BAS and it was their work that informed the survey's decision to move Halley and the choice of where to put it - 23km upstream of the chasm. Had the base not been shifted, it would now be in a very precarious position.

It was forward-thinking that now looks very smart.

BAS has once more ordered the base be closed for the period from March to November.

There's some uncertainty over how exactly the shelf will react in a large calving event, and the survey doesn't want to be mounting rescue missions in the darkness of a polar winter. This would be extremely hazardous.

With no-one on the ice surface, notice of any breakaway will have to come from automated in-situ instrumentation and from spacecraft observations.

The EU's Sentinel-1 radar satellites pass overhead every few days and their precision measurements can discern not only the propagation of cracks, but also the subtle deformation in the ice as it moves.

This remote-sensing data is processed by the ENVEO (Environmental Earth Observation) company, in Innsbruck, Austria; and ENVEO staff are co-authors on a new paper with the Northumbria team that is under review in The Cryosphere journal.

Although the model has skilfully forecast the actions of cracks on the Brunt Ice Shelf, what it can't do is predict the actual date for a calving event.

The chasm shaping the 1,500-sq-km would-be iceberg has maybe 3-4km to go before it cuts completely through the Brunt shelf. This last thread could go tomorrow, or it may hang on for months.

"In this particular case, extrapolation may be the simplest way to think about it," said Prof Gudmundsson.

"The chasm's been growing at about 1-2km a year and we haven't really seen any slow-down in winter. It's almost through already, but I would say it should happen within a year."

Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos

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When a giant iceberg breaks away from near Britain's Halley research base, it won't be because of climate change. Scientists Jan De Rydt and Hilmar Gudmundsson have spent years studying the area and say the calving will be the result of natural processes only.

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Alaska heatwave: Anchorage hits record temperature

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Alaska sees record temperatures in heatwave

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Several places in southern Alaska are experiencing record temperatures, including its largest city.