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The 2019 Greenland Thread

The 2019 Greenland Thread

Unread postby dohboi » Thu 10 Jan 2019, 12:51:30

Warming of SE Greenland shelf waters in 2016 primes large glacier for runaway retreat

https://www.the-cryosphere-discuss.net/tc-2018-260/
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Methane monster on GIS

Unread postby Whitefang » Fri 11 Jan 2019, 03:40:34

http://www.bristol.ac.uk/news/2019/janu ... hane-.html

An international team of researchers led by the University of Bristol camped for three months next to the Greenland Ice Sheet, sampling the meltwater that runs off a large catchment (> 600 km2) of the Ice Sheet during the summer months.
As reported in Nature, using novel sensors to measure methane in meltwater runoff in real time, they observed that methane was continuously exported from beneath the ice. They calculated that at least six tons of methane was transported to their measuring site from this portion of the Ice Sheet alone, roughly the equivalent of the methane released by up to 100 cows.


Tons of methane……..only 6 for 600 km2, GIS is about 1500000 km2 so that might imply 15000 ton of methane, not that much compared to a Gton. Another day, another feedback...…

Thinking last night on Atlantification, what if there is equal Arctification of the North Atlantic?
The Gyre holds 8000 cubic km, GIS about 4 million but that cannot be released instantly, data already shows that huge cold surface layer of fresh water on top of the warm current flowing northeast.
Would the North Atlantic South East of Greenland be stratified with the onset of current Heinrich event or the start of the Gyre reversal? Weakening of the Golfstream only adds to that effect.
After BOE with the cold pole above central Greenland, Canadian cold from the barren will probably head for Africa along the habits of the new polar vortex, chilling the surface water even more.


Just wondering ya know :roll:

Darn, I cannot wait to see what is happening, yet I do not want what it will cause, abrupt CC, loss of harvest and habitat.
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Re: The Greenland Thread

Unread postby dohboi » Mon 11 Feb 2019, 21:16:54

Arctic Sea Ice Loss in Past Linked to Abrupt Climate Events

https://m.phys.org/news/2019-02-arctic- ... inked.html
A new study on ice cores shows that reductions in sea ice in the Arctic in the period between 30,000 -100,000 years ago led to major climate events.

During this period, Greenland temperatures rose by as much as 16 degrees Celsius.

The results are published today (Monday 11 February) in Proceedings of the National Academy of Sciences (PNAS).


Louise C. Sime el al., "Impact of abrupt sea ice loss on Greenland water isotopes during the last glacial period," PNAS (2019).

...


NASA Finds Possible Second Impact Crater Under Greenland Ice
https://www.eurekalert.org/pub_releases ... 021119.php

A NASA glaciologist has discovered a possible second impact crater buried under more than a mile of ice in northwest Greenland.

His follows the finding, announced in November 2018, of a 19-mile-wide crater beneath Hiawatha Glacier - the first meteorite impact crater ever discovered under Earth's ice sheets. Though the newly found impact sites in northwest Greenland are only 114 miles apart, at present they do not appear to have formed at the same time.

If the second crater, which has a width of over 22 miles, is ultimately confirmed as the result of a meteorite impact, it will be the 22nd largest impact crater found on Earth.



... Following the finding of that first crater, MacGregor checked topographic maps of the rock beneath Greenland's ice for signs of other craters. Using imagery of the ice surface from the Moderate Resolution Imaging Spectroradiometer instruments aboard NASA's Terra and Aqua satellites, he soon noticed a circular pattern some 114 miles to the southeast of Hiawatha Glacier. The same circular pattern also showed up in ArcticDEM, a high-resolution digital elevation model of the entire Arctic derived from commercial satellite imagery.

To confirm his suspicion about the possible presence of a second impact crater, MacGregor studied the raw radar images that are used to map the topography of the bedrock beneath the ice, including those collected by NASA's Operation IceBridge. What he saw under the ice were several distinctive features of a complex impact crater: a flat, bowl-shaped depression in the bedrock that was surrounded by an elevated rim and centrally located peaks, which form when the crater floor equilibrates post-impact. Though the structure isn't as clearly circular as the Hiawatha crater, MacGregor estimated the second crater's diameter at 22.7 miles. Measurements from Operation IceBridge also revealed a negative gravity anomaly over the area, which is characteristic of impact craters.

"The only other circular structure that might approach this size would be a collapsed volcanic caldera," MacGregor said. "But the areas of known volcanic activity in Greenland are several hundred miles away. Also, a volcano should have a clear positive magnetic anomaly, and we don't see that at all."

Although the newly found impact craters in northwest Greenland are only 114 miles apart, they do not appear to have been formed at the same time. From the same radar data and ice cores that had been collected nearby, MacGregor and his colleagues determined that the ice in the area was at least 79,000 years old. The layers of ice were smooth, suggesting the ice hadn't been strongly disturbed during that time. This meant that either the impact happened more than 79,000 years ago or -- if it took place more recently -- any impact-disturbed ice had long ago flowed out of the area and been replaced by ice from farther inland.

Open Access: Joseph A. MacGregor et al. A Possible Second Large Subglacial Impact Crater in Northwest Greenland, Geophysical Research Letters (2019).

(Thanks to vox at asif for these)
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Re: The Greenland Thread

Unread postby Whitefang » Fri 01 Mar 2019, 13:19:00

https://www.youtube.com/watch?v=WGmJgJ1d02Y

Between 60,000 and 22,000 years ago there were numerous abrupt temperature fluctuations recorded by oxygen and nitrogen isotopes (paleo-thermometer proxies) in Greenland ice cores. Temperatures over parts of Greenland rose by up to 16.5 C within a decade or two, in the largest of these so-called Dansgaard-Oescher (D-O) Oscillations. I chat on the latest science, about how a lack of Arctic sea-ice was the primary factor. This is crucial info to help us figure out what will happen to Greenland when we have no surrounding sea ice left.



DO events are 95% correlated to sea ice loss, sea surface temperature being the most important aspect, number in CC.
Part 2 of video from last week.

https://www.youtube.com/watch?v=SA1y73Dje4U

Glaciers on Greenland and Antarctica are rapidly melting due to Abrupt Climate Change, and melt rates are doubling with a period of roughly 7 years. This is exponential, after 7 years melt rates are double (2x), after 14 years rates are 4x, after 21 years rates are 8x, etc...In this video and the next I discuss consequences that are rarely considered, like reduced gravitational pull near the glaciers, isostatic rebound, and reduction of vertical ocean mixing from surface freshwater lensing effects, leading to increased basal ice sheet melting.



Gravitational effects.....interesting facts on ice sheet collapse
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Re: The Greenland Thread

Unread postby vtsnowedin » Fri 01 Mar 2019, 14:43:34

I note that humans had nothing to do with the DO event of 11,000years ago which raised temps 8 degrees C.
From the wiki article:
In the Northern Hemisphere, they take the form of rapid warming episodes, typically in a matter of decades, each followed by gradual cooling over a longer period. For example, about 11,500 years ago, averaged annual temperatures on the Greenland ice sheet warmed by around 8 °C over 40 years, in three steps of five years (see,[3] Stewart, chapter 13), where a 5 °C change over 30–40 years is more common.
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linky

Unread postby Whitefang » Fri 01 Mar 2019, 15:50:03

https://en.wikipedia.org/wiki/Dansgaard–Oeschger_event/

Causes[edit]
The processes behind the timing and amplitude of these events (as recorded in ice cores) are still unclear. The pattern in the Southern Hemisphere is different, with slow warming and much smaller temperature fluctuations. Indeed, the Vostok ice core was drilled before the Greenland cores, and the existence of Dansgaard–Oeschger events was not widely recognised until the Greenland (GRIP/GISP2) cores were done; after which there was some reexamination of the Vostok core to see if these events had somehow been "missed".[verification needed]


A closeup near 40 kyr BP, showing reproducibility between cores
The events appear to reflect changes in the North Atlantic Ocean circulation, perhaps triggered by an influx of fresh water.[5]
The events may be caused by an amplification of solar forcings, or by a cause internal to the earth system – either a "binge-purge" cycle of ice sheets accumulating so much mass they become unstable, as postulated for Heinrich events, or an oscillation in deep ocean currents (Maslin et al.. 2001, p25).
More recently, these events have been attributed to changes in the size of the ice sheets [6] and atmospheric carbon dioxide [7]. The former determines the strength of the Atlantic Ocean circulation via altering the northern hemisphere westerly winds, gulf stream, and sea-ice systems. The latter modulates atmospheric inter-basin freshwater transport across Central America, which changes the freshwater budget in the North Atlantic and thus the circulation. They further suggest the existence of a window of AMOC bistability ('sweet spot' for abrupt climate changes) associated with ice volume and atmospheric CO2, accounting for the occurrences of D-O type events under intermediate glacial conditions in the late Pleistocene.


Evidence[edit]
The best evidence for Dansgaard–Oeschger events remains in the Greenland ice cores, which only go back to the end of the last interglacial, the Eemian interglacial. Ice core evidence from Antarctic cores suggests that the Dansgaard–Oeschger events are related to the so-called Antarctic Isotope Maxima by means of a coupling of the climate of the two hemispheres, the Bi-polar Seesaw.[1] If this relationship holds also for the previous glacials, Antarctic data suggest that D-O events were present in previous glacial periods as well. Unfortunately, current ice core records from Greenland extend only through the last most recent glacial period so direct evidence of D-O events in earlier glacial periods from Greenland ice is unavailable. However, work by Stephen Barker and colleagues has shown that the existing Greenland record can be reconstructed by deriving the Antarctic ice core record. This allows for the reconstruction of an older Greenland record through the derivation of the nearly million-year-long Antarctic ice core record.[2]
Effect[edit]
In the Northern Hemisphere, they take the form of rapid warming episodes, typically in a matter of decades, each followed by gradual cooling over a longer period. For example, about 11,500 years ago, averaged annual temperatures on the Greenland ice sheet warmed by around 8 °C over 40 years, in three steps of five years (see,[3] Stewart, chapter 13), where a 5 °C change over 30–40 years is more common.
Heinrich events only occur in the cold spells immediately preceding D-O warmings, leading some to suggest that D-O cycles may cause the events, or at least constrain their timing.[4]
The course of a D-O event sees a rapid warming of temperature, followed by a cool period lasting a few hundred years.[5] This cold period sees an expansion of the polar front, with ice floating further south across the North Atlantic Ocean.[5]


Humans were not yet into large scale agriculture yet the NH were prone to abrupt CC, the Northern Atlantic seems to be very fragile, easy to do a flip flop from one stable state to the other.
I think the Heinrich events followed the DO warmings, not preceding as the wiki writing claims, a typo?
But now with 8 billion, bit less, humans the situation is even more unstable. Less trees to begin with, more junk to clean up. 8)
Last edited by Tanada on Fri 01 Mar 2019, 22:53:37, edited 1 time in total.
Reason: fixed broken link
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Re: The Greenland Thread

Unread postby vtsnowedin » Fri 01 Mar 2019, 19:27:07

You are missing the point or ignoring it.
If it happened 11,000 years ago without human interference it may well be happening today reguardless of human interaction and if that is the case any human actions for or against it may well be useless and ineffectual.
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ignorance is bliss

Unread postby Whitefang » Sat 02 Mar 2019, 18:52:15

vtsnowedin wrote:You are missing the point or ignoring it.
If it happened 11,000 years ago without human interference it may well be happening today reguardless of human interaction and if that is the case any human actions for or against it may well be useless and ineffectual.


I needed some time to reflect so I did ignore your point of view, your position.
The issue of who did it, US with such and such carbon emissions, Europe, China and the rest, humanity as a whole.
What can be done to solve the problem or accept abrupt CC as a predicament.

From our studies I would say the arctic is driving abrupt CC and nothing can stop the disappearance of the GIS or sea ice.
But that does not mean humanity started something irreversible when we took the Earth, land and water for ours to manage more and more complex machines for more people. Our cult is a heat engine, drive through a city from the country and the temperature rises a few degrees. The cause of the current 6th extinction is human action.

The abrupt changes in the past did not lead to a hothouse but just a temporary bit warmer period, interglacial that with time and natural variations went back to a glacial.
Never before did GHG increase this much, geologically in the blink of an eye, the methane hydrates bomb comes on top of that.
So an already fragile depleted ecosystem that is no match for an extremely abrupt CC.

The only thing keeping the system working as before is the last bit of spread out sea ice and what is left of the giant ice shelves that once covered the NH. Sea ice can be gone anytime.
So basicly I think we all took more than we need, no excuse for anyone, and that our indulgence lead to our fall as in going down now. But I do not mean to be judgemental, I have indulged like almost everybody, still do :oops: .
We are responsible for our actions, each and everyone of them.
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Re: The Greenland Thread

Unread postby Newfie » Sun 03 Mar 2019, 11:02:28

Very nice post Witefang.
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Re: ignorance is bliss

Unread postby vtsnowedin » Sun 03 Mar 2019, 14:41:05

Whitefang wrote:
The abrupt changes in the past did not lead to a hothouse but just a temporary bit warmer period, interglacial that with time and natural variations went back to a glacial.
.

I suppose it comes down to the definition of hot house.
From Wiki on D-O events:
In the Northern Hemisphere, they take the form of rapid warming episodes, typically in a matter of decades, each followed by gradual cooling over a longer period. For example, about 11,500 years ago, averaged annual temperatures on the Greenland ice sheet warmed by around 8 °C over 40 years, in three steps of five years (see,[3] Stewart, chapter 13), where a 5 °C change over 30–40 years is more common.

Now 8 deg. C for forty years is a lot more then what we have been repeatedly told is more then enough to cross multiple tipping points and kill us all. But the ice core evidence in Greenland shows it was not enough to melt all the ice in Greenland hence the existence of the cores. The cores do stop at the beginning of the last glacial period showing that Greenland was ice free in the period between the last two glacials while Antarctica was not.
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Re: The Greenland Thread

Unread postby Newfie » Sun 03 Mar 2019, 16:34:16

Earth average vs local conditions
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Re: The Greenland Thread

Unread postby vtsnowedin » Sun 03 Mar 2019, 17:48:59

Newfie wrote:Earth average vs local conditions
Perhaps. I haven't researched it enough to exclude that.
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Re: The Greenland Thread

Unread postby Newfie » Sun 03 Mar 2019, 19:57:01

VT,

I’ve not read on it deeply either but that is my understanding. There have been some local dramatic events. But when you average it out then in summation they are much smaller. And that makes sense. We have a great deal of flesh to day variation. Also week to week. Month to month is averaged out more. Year to year even more. Would it not also work that way geographically? I would be very surprised to hear the entire Earth rose 8°C over a short time scale. It’s much more believable that there was a local significant bump in temps that didn’t not move the average vermuch over a short time scale. I mean, all that heat would need to be transported on or off the planet. Much easier to believe it was moved around ON the planet.
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Re: The Greenland Thread

Unread postby vtsnowedin » Sun 03 Mar 2019, 21:32:13

The Eemain interGlacial which was the warm period before the last ice age had temps. that world wide were less then the 8 deg. C+ of these D-O events. Again from Wiki:
Global temperatures
The Eemian climate is believed to have been about as stable as that of the Holocene.[citation needed] Changes in the Earth's orbital parameters from today (greater obliquity and eccentricity, and perihelion), known as Milankovitch cycles, probably led to greater seasonal temperature variations in the Northern Hemisphere.[citation needed] Although global annual mean temperatures were probably several degrees warmer than today, during summer months, temperatures in the Arctic region were about 2-4 °C higher than today.[6] The warmest peak of the Eemian was around 125,000 years ago, when forests reached as far north as North Cape, Norway (which is now tundra) well above the Arctic Circle at 71°10′21″N 25°47′40″E. Hardwood trees such as hazel and oak grew as far north as Oulu, Finland.

Interesting to note that in this long lasting warm period the sea level rise was 20 to 30 feet higher then it is today,
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Re: The Greenland Thread

Unread postby Newfie » Mon 04 Mar 2019, 10:51:45

VT,

It doesn’t address that element. Perhaps a lot of ice was locked up in the Antarctic. I mean it had to be somewhere right? And it also matters where you measure SLR.
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Re: The Greenland Thread

Unread postby vtsnowedin » Mon 04 Mar 2019, 12:54:27

Newfie wrote:VT,

It doesn’t address that element. Perhaps a lot of ice was locked up in the Antarctic. I mean it had to be somewhere right? And it also matters where you measure SLR.

I think the 20 to 30 foot range covers both the potential accuracy of the measurements and the variations of where on the planet they are taken. Some features like coral atolls sink over time while in other places shore lines are rising due to mountain building from plate tectonics subduction. I think the significance of it is that it was 20 to 30ft., not 80 to 100 feet or more as many from the Al Gore school of climate change have predicted will come from the same amount of temperature rise.
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Re: The Greenland Thread

Unread postby Newfie » Mon 04 Mar 2019, 14:24:20

Now just think about what you are saying for a minute. If all the GIS melted, as you seem to be implying, where did the water go?
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Re: The Greenland Thread

Unread postby vtsnowedin » Mon 04 Mar 2019, 16:17:46

Newfie wrote:Now just think about what you are saying for a minute. If all the GIS melted, as you seem to be implying, where did the water go?
Into that thirty feet of sea level rise.
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Re: The Greenland Thread

Unread postby Newfie » Mon 04 Mar 2019, 17:02:47

Wiki says a complete melt of the GIS would result in a 23’ SLR.

Not 80’.
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Re: The Greenland Thread

Unread postby vtsnowedin » Mon 04 Mar 2019, 21:23:28

Newfie wrote:Wiki says a complete melt of the GIS would result in a 23’ SLR.

Not 80’.

The 80 to 100 predictions assume a lot more of Antarctica ice will melt also.
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