Antarctica Larson C ice shelf close to becoming one of biggest icebergs ever - or not

Really? The entire ice shelf? It must be true, if the Christian Science Monitor says so:

Antarctica's Larson C shelf is about equal to the area to the state of Delaware. Its collapse might be imminent. 

JANUARY 6, 2017 —Scientists with the British Antarctic Survey now believe that the fracturing of the Larson C ice shelf from the polar cap is imminent, after a rift in the shelf grew vertiginously in the last month of 2016. 

The thread connecting Larson C to the rest of Antarctica is now just more than 65,600 feet long, surveyors from the Britain’s Project Midas say. 

Apart from the ice shelf being about equal in area to Delaware, not one of the statements is correct. They're not simply misquotes. The BAS scientists believe nothing of the kind - their article is titled Giant iceberg set to calve from Larsen C Ice Shelf, and that the calving is imminent. Surveyors from Britain’s Project Midas believe nothing of the kind either. They wrote: (my bold)

Larsen C Ice Shelf poised to calve. 

The Larsen C Ice shelf in Antarctica is primed to shed an area of more than 5000 sq. km following further substantial rift growth. After a few months of steady, incremental advance since the last event, the rift grew suddenly by a further 18 km during the second half of December 2016. Only a final 20 km of ice now connects an iceberg one quarter the size of Wales to its parent ice shelf.

No one but a moron could fail to grasp what those articles stated and meant. CSM author David Iaconangelo clearly isn't a moron, but is what might be euphemistically termed "economical with the truth".

Grist isn't much better - an editor retitles a "cross-post" and reorders images with captions removed to give a very different impression to the linked Climate Central article.

"Antarctica’s fourth biggest ice shelf is on the verge of collapse" shrieks Grist. However, the picture at the top of the page

.... is of the Larsen B disintegration in 2002. There's no caption, nor is it referred to in the text. Below the author's name is stated "Cross-posted from Climate Central". That link is to the article by CC author Andrea Thompson, titled Large Iceberg Poised to Break Off From Antarctica. Does she, or any of her quoted sources think "Antarctica’s fourth biggest ice shelf is on the verge of collapse"? No, this is just Grist once again changing a word or two, or misquoting a link or two, to push its catastrophic view of anything that might be remotely connected to what they think is the coming apocalypse. Also, that picture has been cropped to remove a distance scale at the bottom, as the Larsen B was about the size of the piece splitting from Larsen C. The scale might give the game away.  The one in the CC article, is captioned quite correctly The breakup of Antarctica's Larsen B ice shelf as it looked on Feb. 23, 2002. Click image to enlarge. Credit: NASA

The breakup of Antarctica's Larsen B ice shelf as it looked on Feb. 23, 2002.
Click image to enlarge. Credit: NASA

It's not a "cross-post" - Grist has altered the title, removed image captions, and reordered images from the CC article, to create the impression that the images are of Larsen C. Removing captions, editing images, and showing them out of context to create an impression not intended by the original author is more than breaking the rules of attribution, it's fraud.

Unusually, I find the CC article generally factual, informative, and links back up the text, though there are one or two disputed claims.

Author Andrea Thompson headed her article with this close-up image of part of the rift:

A large rift in Antarctica's Larsen C ice shelf, photographed by NASA's IceBridge mission on Nov. 10, 2016. The rift surged ahead by about 10 miles in late December.
Click image to enlarge. Credit: NASA/John Sonntag

In the Grist "cross-post", that image follows a a paragraph about the disintegration of Larsen B, and has the caption "NASA". The intention is now obvious, and totally unforgivable.

On a more factual note, the rift is about 500m (metres, not miles) wide, 350m deep in the centre, and is currently about 80km long, according to Project MIDAS. Some articles say 80 miles, and if the scale on the graphic below, is accurate, 150 km would be more like it. Not that it matters to you maybe, but I'll check. It's not unusual for genuine mistakes to go unnoticed by authors:

Source: Project MIDAS

The graphic is of more than a little personal significance - I was born just about where the second "s" in Swansea is located top right (although Wales is a little further north, and a lot warmer than its position on that graphic.

I've read a few articles that say words to the effect that the rift has just been discovered (where did they get that?), but it's been monitored since 2011.

Even the BBC managed to get it right:

Huge Antarctic iceberg poised to break away 

An iceberg expected to be one of the 10 largest ever recorded is ready to break away from Antarctica, scientists say. A long-running rift in the Larsen C ice shelf grew suddenly in December and now just 20km of ice is keeping the 5,000 sq km piece from floating away.
Larsen C is the most northern major ice shelf in Antarctica.
Researchers based in Swansea say the loss of a piece a quarter of the size of Wales will leave the whole shelf vulnerable to future break-up.
Larsen C is about 350m thick and floats on the seas at the edge of West Antarctica, holding back the flow of glaciers that feed into it.
Researchers have been tracking the rift in Larsen C for many years, watching it with some trepidation after the collapse of Larsen A ice shelf in 1995 and the sudden break-up of the Larsen B shelf in 2002.

They even end the piece with

"We are convinced, although others are not, that the remaining ice shelf will be less stable than the present one," said Prof Luckman.
"We would expect in the ensuing months to years further calving events, and maybe an eventual collapse - but it's a very hard thing to predict, and our models say it will be less stable; not that it will immediately collapse or anything like that."
As it floats on the sea, the resulting iceberg from the shelf will not raise sea levels. But if the shelf breaks up even more, it could result in glaciers that flow off the land behind it to speed up their passage towards the ocean. This non-floating ice would have an impact on sea levels.
According to estimates, if all the ice that the Larsen C shelf currently holds back entered the sea, global waters would rise by 10cm.
All that is very much in the future. There are few certainties right now apart from an imminent change to the outline of Antarctica's icy coast.
"The eventual consequences might be the ice shelf collapsing in years to decades," said Prof Luckman,
"Even the sea level contribution of this area is not on anybody's radar; it's just a big geographical event that will change the landscape there."

Prof. Luckman is one of the Project MIDAS team, based in Swansea. I like very much "We are convinced, although others are not...". It shows some humility, the acknowledgement that it's a personal team view. A good note to end on.

UPDATE 10/1/2017

I've been scanning through articles on the British Antarctic Survey website. I've always thought
the BAS to be a reactionary and somewhat alarmist bunch. I had already noticed this, on the page referenced above:

Glaciologist Professor David Vaughan OBE, Director of Science at British Antarctic Survey, said, “The calving of this large iceberg could be the first step of the collapse of Larsen C ice shelf, which would result in the disintegration of a huge area of ice into a number of icebergs and smaller fragments.
“Because of the uncertainty surrounding the stability of the Larsen C ice shelf, we chose not to camp on the ice this season.  Researchers can now only do day trips from our Rothera Research Station with an aircraft nearby on standby.”

In 2015 they said this:

The team, who continue to monitor the ice shelf closely, predict that a collapse could occur within a century, although maybe sooner and with little warning. A crack is forming in the ice which could cause it to retreat back further than previously observed. The ice shelf appears also to be detaching from a small island called Bawden Ice Rise at its northern edge.

"Within a century" - what's changed in the 19 months since that statement? Prof. Vaughan has dramatically changed his view - back in 2015:

Professor David Vaughan, glaciologist and Director of Science at BAS, says:
“When Larsen A and B were lost, the glaciers behind them accelerated and they are now contributing a significant fraction of the sea-level rise from the whole of Antarctica. Larsen C is bigger and if it were to be lost in the next few decades then it would actually add to the projections of sea-level rise by 2100.

On the same page - "within a century" and "the next few decades". However, contradictions like this aren't unusual on the BAS website. Members have very differing views, and careful reading reveals very different "facts" too. The thickness of the Larsen B shelf, which disintegrated in 2002, is given as 200 metres, and on one page a very unlikely and obviously incorrect 1km. That last article I quoted, actually a press release titled New study shows Antarctic ice shelf is thinning from above and below has this lead-in:

The Larsen C Ice Shelf — whose neighbours Larsen A and B, collapsed in 1995 and 2002 — is thinning from both its surface and beneath. For years scientists have been unable to determine whether it is warming air temperatures or warmer ocean currents that were causing the Antarctic Peninsula’s floating ice shelves to lose volume and become more vulnerable to collapse. This new study takes an important step forward in assessing Antarctica’s likely contribution to future sea-level rise. 

The research team combined satellite data and eight radar surveys captured during a 15-year period from 1998–2012. They found that Larsen C Ice Shelf lost an average of 4 metres of ice, and had lowered by an average of one metre at the surface. 

Lead author, Dr Paul Holland from British Antarctic Survey (BAS), says:
“What’s exciting about this study is we now know that two different processes are causing Larsen C to thin and become less stable. Air is being lost from the top layer of snow (called the firn), which is becoming more compacted — probably because of increased melting by a warmer atmosphere. We know also that Larsen C is losing ice, probably from warmer ocean currents or changing ice flow. 

“If this vast ice shelf — which is over two and a half times the size of Wales and 10 times bigger than Larsen B — was to collapse, it would allow the tributary glaciers behind it to flow faster into the sea. This would then contribute to sea-level rise.”
The Antarctic Peninsula is one of the fastest warming regions on Earth, with a temperature rise of 2.5°C over the last 50 years.

"Air is being lost", "probably because of increased melting by a warmer atmosphere". Here's a plot of the "warmer atmosphere" since 1995:

Larsen C - GISS unadjusted data.

I don't think so. What's amazing, is that many glaciologists and climate scientists never keep up-to-date with the latest data, but rely on published papers, many of which are out of date within a few years. I read something a dated a few weeks ago by a glaciologist, publishing regularly in this field, who cited "the continuing warming on the Antarctic Peninsula". An Ostrich is a large flightless bird, claimed to occasionally put its head in the sand. Some scientists are sightless birds, with their heads continually in the sand. More on the "continued warming" (/sarc off) soon.

All you need to know about glaciers, or maybe not

I could dedicate an entire  separate blog to rubbishing Guardian articles about the environment, climate change and the like. But for now, it amuses me to just pick the worst articles for this blog. Take today's article for instance, by one Wendell Tangborn. Who he? The Guardian has a mini résumé:

Wendell Tangborn has worked with glaciers for 55 years, beginning with South Cascade Glacier in Washington in 1960. Currently, his main interest is mass balance. He has developed a computer model that calculates a glacier's mass balance from routine weather observations and has published over 40 papers in glaciology. He lives on Vashon Island in Washington State.

He's "worked with glaciers"? I'll let that one pass, but it conjures up all sorts of strange images...
I don't doubt he's published over 40 papers in glaciology, but a Google Scholar search reveals that most of them concern the North and South Cascade Mountains that stretch from just over the Canadian border west of Vancouver (Canadian Cascades), through Washington and Oregon and into northern California. He is not an expert on glaciers worldwide, as the record of his published papers shows.

Glacier melt shows a climate change tipping point. We must pay attention 

Fossil fuel burning must taper off dramatically and be replaced with renewable sources of energy if we are going to survive as a species on this planet 

Mountain glaciers and humans have coexisted for roughly 200,000 years, but that long idyll appears to be ending. The earth’s 190,000 glaciers, sentinels of climate change that appear to be more sensitive to the climate than are humans, are disappearing at an unprecedented pace, the canaries in climate change’s coal mine.

There is evidence for many glaciers worldwide being in retreat, and there are estimates, but no one actually knows how many. Wendell's being rather less than truthful by implying here that all are in retreat. To cap it all, the "canary in the coal mine" appears here too. That coal mine must have hundreds of canaries in it by now, put there by many dozens of claims about climate, sea-level rise, coral reefs, glaciers - the list goes on and on. They can't all be "the canary in the coal mine".

It is all being driven by human activities, and it has been happening for three decades. The fate of both humans and glaciers will depend on drastically reducing carbon dioxide emissions during the next decade. 

Most of the world’s glaciers began changing in the late 1980s from relative stability to negative mass balances. Mass balance is the difference between growth from snow accumulation and shrinkage from snow and ice melting. The relatively abrupt change to negative glacier mass balances strongly suggests a climate tipping point, when the climate changes from one stable state to another.

Total rubbish - it's been happening at an increasing pace since the end of the "Little Ice Age" in the mid 19th. century. The World Glacier Inventory says that systematic glacier monitoring on a large scale began in 1894. The World Glacier Monitoring Service published a comprehensive report in 2008 titled "Global Glacier Changes: facts and figures" available here. On page 14 of the pdf is shown this figure:

     Fig. 5.9 The cumulative specific mass balance curves are shown for
     the mean of all glaciers and 30 ‘reference’ glaciers with (almost)
     continuous series since 1976. Source: Data from WGMS.

It should be obvious that "Most of the world’s glaciers began changing in the late 1980s from relative stability to negative mass balances." is baloney. There was no "relatively abrupt change" at all, hence no "climate tipping point". This is not science at all - it's politics. Perhaps it's true of some, or even all of the glaciers he's studied - the list isn't very long, judging by the abstracts of his papers, and certainly far, very far, from global.

There are other compelling signs that a climate tipping point has been reached. One of the most critical is the loss of the floating sea ice cover in the Arctic Ocean. In 2014, the late-summer extent of sea ice in the north polar seas was the lowest since satellite measurements began in 1979. Before 1979, evidence based on shipping and whaling charts suggests it has not been this low for at least hundreds of years. Paleo climatologists believe that Arctic sea ice cover last melted completely during summers about 125,000 years ago, during a warm period between ice ages.

More rubbish - in fact there is plenty of evidence pre-1979 that large parts of  the Arctic currently under ice were ice-free in late summer; newspaper articles and reports from ship's captains, whalers and explorers.

Reduction of northern-hemisphere sea ice means that more incoming sunlight is absorbed into darker ocean water instead of being reflected by ice and then re-radiated into the atmosphere as heat. This, in turn, reduces the extent of the annual northern-hemisphere snow cover, which further accelerates global warming. A related effect that could be even more environmentally devastating is the release of methane from permafrost and seafloor hydrates as the ocean warms. Another tipping-point indicator is the Greenland and West Antarctic ice sheets, which have shown signs of disintegrating during the past two decades. Just partial melting of these ice sheets will raise sea level several meters.

There is evidence that the warmer ocean water actually freezes quicker next winter precisely because it does radiate into the atmosphere, but not as heat, Wendell, but as long-wave infrared. He really knows his stuff, this Wendell.

He then says "Just partial melting of these ice sheets will raise sea level several meters". Depends just how much "partial" means, don't it? I've found out a little more about our Wendell - try this:

Tracking glaciers the Tangborn way 

Wendell Tangborn thinks he has invented a better mousetrap. He's still waiting for the scientific world to beat a path to his door. 

Sitting in a cramped home office overlooking the (rising) waters of Puget Sound, Tangborn talks about his plan to monitor 200 glaciers around the world to see whether or not — and, if so, how quickly — they're melting away. He has already done detailed reports on seven, including Juneau's incredible shrinking Mendenhall Glacier. He's working on 40 more, and hoping one or more foundations will supply enough money to hire the three people he'd need to keep track of all 200. 

People often cite the waxing or waning of glaciers to prove that the earth is or is not getting warmer. But according to Tangborn, no one is looking systematically at a large number of glaciers so that trends become obvious and the glaciers which are behaving contrary to the trends can be seen clearly as outliers.

What? "No one is looking systematically..."? The man's an ostrich with his head in the sand, or perhaps in a glacier crevasse. So in 2013 he'd reported on just seven glaciers out of his target 200. That target, using his own figure above of  190,000 would be just 0.1% of the total. Just how does he do it with his "better mousetrap"?

Basically, he uses temperature and precipitation data from fixed weather stations to calculate a glacier's "mass balance" — that is, the difference between the winter accumulation of snow and the summer melting of snow and ice. A positive balance means the glacier is growing; negative means it's shrinking. 

The program must be customized for every glacier. Tangborn must take account of the topography and total area of the glacier's surface. Once he plugs that into the program, he can sit in his office and get information that's as reliable as the data produced the old-fashioned way — the way he did it for many years — by climbing around on the ice with probing rods and shovels. 

For each glacier, Tangborn has to find a weather station that produces results in line with actual observations. That isn't necessarily the weather station right next door to the ice. Austrian scientists can't believe that Tangborn's using a weather station in Innsbruck to monitor the Vernagtferner glacier, which is 100 kilometers away, rather than a station close to the site. But, says Tangborn, somehow local weather phenomena keep the closer station from producing useful numbers.

This is clearly his "mass balance model", but he doesn't always use local weather data, but scratches around until he gets a fit with reality, or his reality at least. Innsbruck's elevation is 574m, the lowest point (the snout) of the Vernagtferner glacier is 2790m above sea level. He's using a weather station 100 km away, and more than 2000 metres lower, because "local weather phenomena keep the closer station from producing useful numbers". But it's the "local weather phenomena" which directly affect the glacier; no other weather phenomena can possibly affect it. Remember "He's still waiting for the scientific world to beat a path to his door.", and they haven't. I wonder why. Perhaps you can work it out for yourself.

More Signs Of Accelerating Sea Level Rise - what signs?

Maybe it's me, maybe there's some other meaning of the word "signs" I was previously unaware of. Maybe Forbes writer John McQuaid picked no.243 instead of no.244 from his collection of alarmist headlines. I leave you to judge - here's the entire piece.

More Signs Of Accelerating Sea Level Rise

Evidence continues to mount that recent estimates of sea level rise from global warming were wrong, and that the potential inundation to come may be much worse than previously contemplated, possibly exceeding an average of 3 feet worldwide. This from a new study published in Nature Climate Change focusing on the latest opinions of scientists studying the world’s largest ice sheets in Greenland and Antarctica, where recent, unexpectedly fast melting has raised alarms:

The study found that the ice sheets are likely to contribute a median estimate of 29 centimeters (11.4 inches) of sea level rise by 2100, with a 5 percent chance that it could exceed 84 centimeters (33 inches). When combined with other contributors to sea level rise, such as melting mountain glaciers and thermal expansion of seawater, this implies a “conceivable risk” that sea levels could rise more than 1 meter by 2100.

What’s significant here is that the 1 meter figure, once a highly unlikely, worst-case scenario, has moved decisively into the realm of possibility. It’s still unlikely, according to the scientists surveyed. But current alarming trends mean it has become a lot less so. That said, a lot of uncertainty remains; scientists are unclear on why the melting has accelerated, or if that trend will continue. But given what we’ve seen so far, it’s the official IPCC estimates for sea level rise will likely be revised upward, putting additional pressure on governments to act.

It’s still early in the century, of course, and some urban areas are starting to grapple with changes to infrastructure, coastal settlement, and other issues. But the evidence suggests that the march of disaster will probably continue to outrun attempts to prevent it.

The last sentence of the abstract of the "new study" says

On the critical question of whether recent ice-sheet behaviour is due to variability in the ice sheet–climate system or reflects a long-term trend, expert opinion is shown to be both very uncertain and undecided.

So John McQuaid has decided that "the potential inundation to come may be much worse than previously contemplated" even though the scientists themselves say they don't know whether the trends they identified did indeed reflect a long-tern trend or (natural) variability in the ice-sheet climate system. They updated the ice-sheet component in predictions in AR4 - they didn't validate them. They even say "It's still unlikely" but John (Now working on a book about the science of taste, to be published by Scribner) McQuaid knows better because "current alarming trends mean it has become a lot less so".

What trends (note the "s")? WashPo bleats "2012 hottest year on record in contiguous U.S., NOAA says". Apparently the egg-heads (hard-boiled in the extreme heat perhaps) at NOAA "described the data as part of a longer-term trend of hotter, drier and potentially more extreme weather". Hang on - I was promised "more signs" and I'm served with just one. I was assured of "alarming trends" but have a single dusted off, polished-up old (but somehow confirmed) trend dished up? Aren't short-servings illegal in the good-old US of A?

Those egg-heads seem to think that one warm year "confirms a trend". Don't take any advice on stock-market investments from these guys - they'd have you shivering and hungry on a street-corner in no time flat. Wait - there are still people hungry and shivering on street corners since Sandy struck NY. Sandy confirmed a trend too - a reducing trend in land-falling hurricanes on the eastern seaboard. Short-order writer McQuaid takes this weeks cake for hyperbole. I'd better rephrase that - hyperboles - he wouldn't understand that word if I omitted the "s".

At last! Greenland research confirms common sense

We've been told for years that the Greenland ice-sheet is "melting faster than expected", so contributing more meltwater to sea-level rise. We've been told that meltwater percolates to the base of glaciers, providing lubrication that speeds up movement of the ice towards the sea. This last claim has always seemed to me to be counter-intuitive - glaciers may be melting at the surface in summer, but surely the ice temperature drops with depth? Surely the meltwater would freeze before it reached the rock at the base of the ice? It seems that simple common sense backed by actual research (none of the "experts" postulating meltwater lubrication had taken any measurements) has triumphed over scientific supposition. A paper published in Nature just over a week ago (9th. November 2012) is revealingly titled Greenland ice-sheet contribution to sea-level rise buffered by meltwater storage in firn (J. Harper, N. Humphrey, W. T. Pfeffer, J. Brown & X. Fettweis). The abstract reads

Surface melt on the Greenland ice sheet has shown increasing trends in areal extent and duration since the beginning of the satellite era. Records for melt were broken in 2005, 2007, 2010 and 2012. Much of the increased surface melt is occurring in the percolation zone, a region of the accumulation area that is perennially covered by snow and firn (partly compacted snow). The fate of melt water in the percolation zone is poorly constrained: some may travel away from its point of origin and eventually influence the ice sheet’s flow dynamics and mass balance and the global sea level, whereas some may simply infiltrate into cold snow or firn and refreeze with none of these effects. Here we quantify the existing water storage capacity of the percolation zone of the Greenland ice sheet and show the potential for hundreds of gigatonnes of meltwater storage. We collected in situ observations of firn structure and meltwater retention along a roughly 85-kilometre-long transect of the melting accumulation area. Our data show that repeated infiltration events in which melt water penetrates deeply (more than 10 metres) eventually fill all pore space with water. As future surface melt intensifies under Arctic warming, a fraction of melt water that would otherwise contribute to sea-level rise will fill existing pore space of the percolation zone. We estimate the lower and upper bounds of this storage sink to be 322±44 gigatonnes and 1,285(+388-262) gigatonnes, respectively. Furthermore, we find that decades are required to fill this pore space under a range of plausible future climate conditions. Hence, routing of surface melt water into filling the pore space of the firn column will delay expansion of the area contributing to sea-level rise, although once the pore space is filled it cannot quickly be regenerated.

Co-author Neil Humphrey of Wyoming University is quoted in the university news sheet

“We’re not saying Greenland is not melting,” Humphrey says. “What we’re saying is it will be one to two decades longer before we start seeing the melt.”

That’s because Humphrey and other researchers’ data -- collected on the western flank of the Greenland Ice Sheet from 2007-2009 -- shows that the water generated by repeated recent melt events penetrates deeply into the snow and firn (partially compact snow). This fills the pore space and diminishes the amount of meltwater that actually runs off into the ocean.

As future surface melt intensifies due to Arctic warming, a fraction of meltwater -- that would otherwise add to the rise in sea levels -- fills tens of meters of existing pore space of the percolation zone. The percolation zone is a region of the accumulation area that is perennially covered by snow and firn, Humphrey says.

What happens to the water that "penetrates deeply into the snow and firn"?

“The snow is so deep and so cold that, even though it’s melting, the melt infiltrates into the lower, colder snow and refreezes,” Humphrey says. “We calculate there is one to two decades of pore space within the snowpack. You get denser snowpack. After 10 or 20 years, it (the pore space) fills up.”

However, after this healthy dose of science, the prof. drops into the realm of fantasy (is he concerned about protecting his funding?)

“While other people (scientists) are predicting up to a one-half foot sea rise by 2050, we’re actually saying our data shows that any rise that will occur will be delayed by one or two decades,” says Humphrey of the paper he termed as “controversial.” “A half-foot rise is significant. Half of Florida would be under water. New Orleans would be gone.”

A "half-foot" is of course six inches, or 15 cm. Is he really suggesting that half of Florida is just 15 cm above current high tides? Just when I thought that scientists were abandoning advocacy in favour of traditional research and actual fact.....

Making it up (1) - "Study finds Greenland's ice cover is sliding into the ocean"

This is the start of a new series to run in parallel with "Disconnects in Logic". Both have and will be a source of amusement and debunking hyperbole, unjustified conclusions and predictions, and plain outright lies at the same time.

"Click Green" (you're ahead of me, I can tell) trumpets the apocalyptic headline "Study finds Greenland's ice cover is sliding into the ocean" . The contradiction between headline and article is striking - it's becoming common when the environment, wildlife, "climate change" or "global warming" are discussed, or new research summarised. Apart from the fact that most of the Greenland ice sheet covers the depressed interior of the landmass, and has as much chance of "sliding into the ocean" as a pool ball in a pocket has of "sliding onto the table", what does the first paragraph actually say?

Like snow sliding off a roof on a sunny day, the Greenland Ice Sheet may be sliding faster into the ocean due to massive releases of meltwater from surface lakes, according to a new study by the University of Colorado Boulder-based Cooperative Institute for Research in Environmental Sciences.

As usual, the caveat is "may be", which as so often is the case in alarmist articles, becomes "is" in the headline.

During a typical catastrophic lake drainage, about 1 million cubic meters of meltwater - which is equivalent to the volume of about 4,000 Olympic swimming pools - funnels to the ice sheet's underside within a day or two. Once the water reaches the ice sheet's belly that abuts underlying rock, it may turn the ice-bed surface into a Slip 'N Slide, lubricating the ice sheet's glide into the ocean. This would accelerate the sea-level rise associated with climate change.

Alternatively, however, the lake drainages may carve out sub-glacial "sewers" to efficiently route water to the ocean. "This would drain the ice sheet's water, making less water available for ice-sheet sliding," Colgan said. That would slow the ice sheet's migration into the ocean and decelerate sea-level rise.

"Alternatively, however..." means they don't know, and what's more, the researchers openly admit it.

"Lake drainages are a wild card in terms of whether they enhance or decrease the ice sheet's slide," Colgan said. Finding out which scenario is correct is a pressing question for climate models and for communities preparing for sea-level change, he said.

So they, we, (and the "Click Green" author) don't actually know what's happening. All that is known is that the meltwater "lakes" suddenly disappear, and it's assumed they've drained away. I say assumed, because

For the study, the researchers developed new feature-recognition software capable of identifying supraglacial lakes in satellite images and determining their size and when they appear and disappear. "Previously, much of this had to be double-checked manually," Colgan said. "Now we feed the images into the code, and the program can recognize whether a feature is a lake or not, with high confidence and no manual intervention."

If such a lake "disappears" then, it might be because the water's drained away, as postulated, or possibly it's refrozen, and wouldn't be recognised by the software. First they don't know what the drainage mechanism is, whether meltwater is actually "lubricating" the base of the ice, and the real "sceptic in the room", don't even know if the lake hasn't simply refrozen. Headline fail, alarmism alert, interesting study, shame about the lack of any firm conclusions.

I really aught to start a third new series "Displaying Your Ignorance", 'cos I LOL when I saw this "schoolboy howler" on redOrbit - "Greenland Slipping Away"

Massive releases of meltwater from surface lakes may be causing Greenland to slide ever faster into the ocean, according to a new study by the University of Colorado Boulder-based Cooperative Institute for Research in Environmental Sciences (CIRES).

What's Greenland sliding on I wonder, Santa's Sleigh? Hold on tight, Greenlanders! Wheeee!