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The 2019 Greenland Thread

Re: The 2019 Greenland Thread

Unread postby Azothius » Tue 23 Jul 2019, 10:53:50

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Re: The 2019 Greenland Thread

Unread postby jedrider » Tue 23 Jul 2019, 16:20:49

That's like eating an ice cream cone in hot weather.
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Re: The 2019 Greenland Thread

Unread postby dohboi » Thu 25 Jul 2019, 19:20:23

Holy mother of...Looks bad for Greenland melt, if this plays out as predicted:


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Re: The 2019 Greenland Thread

Unread postby Tanada » Thu 25 Jul 2019, 21:10:43

That is a pressure map, not a temperature map. Rule of thumb is because cold air is denser than warm air large cold areas tend to form High pressure cells. Greenland is one of those places.
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Re: The 2019 Greenland Thread

Unread postby Newfie » Fri 26 Jul 2019, 04:04:00

This story is a bit dated but relevant.

https://www.google.com/amp/s/beta.washi ... utType=amp

I was watching West Greenland we closely for a while until I canceled my trip. Also there have been folks here looking to move east to Europe who have been following North Atlantic wx closely.

In June and July there was a pattern of lows sweeping across below Greenland. We would get lots of wind in the Labrador Sea followed by periods of almost dead calm. Almost no wind with an South in it.

The stories, the Arctic ice that sweeps around Cape Favel from the East onto the West Greenland coast was extremely weak this year, would have been a great time to visit, However there were a remarkable number of icebergs coming down the Labrador current, still a great many off Labrador. Consequently the wx in “ice berg alley” was very cold and damp, miserable. That made the initial leg of a Greenland crossing unpleasant.
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Re: The 2019 Greenland Thread

Unread postby yellowcanoe » Fri 26 Jul 2019, 08:20:33

Tanada wrote:That is a pressure map, not a temperature map. Rule of thumb is because cold air is denser than warm air large cold areas tend to form High pressure cells. Greenland is one of those places.


That may be a pressure map but it does look like unusually warm weather is heading to Greenland. https://www.cbc.ca/news/world/un-greela ... 80?cmp=rss
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Re: The 2019 Greenland Thread

Unread postby Azothius » Fri 26 Jul 2019, 15:19:23

UPDATE 2-Europe's record heatwave threatens Greenland ice sheet

https://www.yahoo.com/news/1-europes-re ... 45041.html

The hot air that smashed European weather records this week looks set to move towards Greenland and could cause record melting of the world's second largest ice sheet, the United Nations said on Friday.

Clare Nullis, spokeswoman for the U.N. World Meteorological Organization, said the hot air moving up from North Africa had not merely broken European temperature records on Thursday but surpassed them by 2, 3 or 4 degrees Celsius, which she described as "absolutely incredible".

"According to forecasts, and this is of concern, the atmospheric flow is now going to transport that heat towards Greenland," she told a regular U.N. briefing in Geneva.
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Re: The 2019 Greenland Thread

Unread postby dissident » Fri 26 Jul 2019, 17:48:01

The Greenland ice sheet is over 2 km high and surface temperature maps do not say anything about the temperature at aloft.

Don't worry, the Greenland ice sheet will collapse sooner, rather than later and not due to particular weather events. It is the overall warming of the polar caps and the polar ocean water that is doing it in. Weather is much like noise in that there are warm and cold peaks. The problem is that the cold peaks are not averaging out the warm peaks.
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Re: The 2019 Greenland Thread

Unread postby dohboi » Fri 26 Jul 2019, 19:24:08

How recent was it that at some point nearly the entire surface of Greenland was shown to be melting? Yes, any one of such an event is notable but not damning. But if they start happening every year, then multiple times a year, that would be a clear indicator that we had entered a new regime.
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Re: The 2019 Greenland Thread

Unread postby Plantagenet » Fri 26 Jul 2019, 20:14:34

Its not just more melting at the surface....

These melting events release huge amounts of water on the surface of the Greenland Ice Sheet in areas where no melting used to occur. The surface water forms rivers that runs across the surface of the ice until they form a moulin, and then the water plunges to the base of the glacier where they lubricate the bed and make the overall ice velocity accelerate.

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The increased melting is changing the whole character of the ice sheet.

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Re: The 2019 Greenland Thread

Unread postby Tanada » Sat 27 Jul 2019, 08:29:44

Plantagenet wrote:Its not just more melting at the surface....

These melting events release huge amounts of water on the surface of the Greenland Ice Sheet in areas where no melting used to occur. The surface water forms rivers that runs across the surface of the ice until they form a moulin, and then the water plunges to the base of the glacier where they lubricate the bed and make the overall ice velocity accelerate.


The increased melting is changing the whole character of the ice sheet.

Cheers!


Moulin's also have the effect of delivering huge volumes of heat directly into the core of the ice sheet. Under the old 'ice cube' model of melting the glaciers can only absorb limited heat from the top and bottom where the weather and geological heating affect the ice. When you add in the Moulin you are taking water that is above the temperature of freezing (obviously) and plunging it vertically through the ice sheet to the base. The water carries heat energy both as latent heat of fusion for each tiny bit warmer than 0C it is. The falling water also carries a huge potential gravitational energy that translates from vertical motion to additional latent heat when it hit the bottom. Jointly these two effects deliver a warm column of energy through the core of the sheet and greatly increase the heating effect at the base of the sheet.

It used to be the case that core samples randomly taken across Greenland showed that the middle of the ice sheet was many degrees below freezing temperature. In those conditions any surface melting that did take place on a small scale drained into crevasses where the fresh water instantly refroze into hard ice by losing its latent heat to the surrounding extremely cold ice. Now all these moulin's operating for decades have added so much energy to the core ice in the mid depths that the ice has warmed to near freezing and the water can pass all the way through to the base. This was a fundamental change in ice sheet dynamics and people still seem to miss it more often than they understand it.
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Re: The 2019 Greenland Thread

Unread postby rockdoc123 » Sat 27 Jul 2019, 11:39:55

There is considerable recent research indicating that the models for Greenland ice loss are missing key ingredients that would change views as to how much "global warming" versus regional conditions contribute.

Basal heat flow is a big one and over the past 4 years or so more and more evidence points to a source of high heat flow that corresponds with rapid ice sheet flow in Greenland:

Rogozhina, I et al, 2016. Melting at the base of the Greenland ice sheet explained by Iceland hotspot history. Nature Geoscience, 9, pp 366-369

Ice-penetrating radar and ice core drilling have shown that large parts of the north-central Greenland ice sheet are melting from below. It has been argued that basal ice melt is due to the anomalously high geothermal flux1, that has also influenced the development of the longest ice stream in Greenland1. Here we estimate the geothermal flux beneath the Greenland ice sheet and identify a 1,200-km-long and 400-km-wide geothermal anomaly beneath the thick ice cover. We suggest that this anomaly explains the observed melting of the ice sheet’s base, which drives the vigorous subglacial hydrology3 and controls the position of the head of the enigmatic 750-km-long northeastern Greenland ice stream5. Our combined analysis of independent seismic, gravity and tectonic data implies that the geothermal anomaly, which crosses Greenland from west to east, was formed by Greenland’s passage over the Iceland mantle plume between roughly 80 and 35 million years ago. We conclude that the complexity of the present-day subglacial hydrology and dynamic features of the north-central Greenland ice sheet originated in tectonic events that pre-date the onset of glaciation in Greenland by many tens of millions of years.


Rysgaard, S, et al, 2018. High geothermal heat flux in close proximity to the NE Greenland Ice Stream. Scientifi Reports, 8. 1344. doi.org/10.1038/s41598-018-19244-x

The Greenland ice sheet (GIS) is losing mass at an increasing rate due to surface melt and flow acceleration in outlet glaciers. Currently, there is a large disagreement between observed and simulated ice flow, which may arise from inaccurate parameterization of basal motion, subglacial hydrology or geothermal heat sources. Recently it was suggested that there may be a hidden heat source beneath GIS caused by a higher than expected geothermal heat flux (GHF) from the Earth’s interior. Here we present the first direct measurements of GHF from beneath a deep fjord basin in Northeast Greenland. Temperature and salinity time series (2005–2015) in the deep stagnant basin water are used to quantify a GHF of 93 ± 21 mW m−2 which confirm previous indirect estimated values below GIS. A compilation of heat flux recordings from Greenland show the existence of geothermal heat sources beneath GIS and could explain high glacial ice speed areas such as the Northeast Greenland ice stream.


Artemieva, I. 2019. Lithosphere thermal thickness and geothermal heat flux in Greenland from a new thermal isostacy method. Earth Sci Rev, 188, pp 469-481

In East Greenland this anomalous belt merges with a strong GHF anomaly of >100 mW/m2 in the Fjordland region. The anomaly is associated with a strong lithosphere thinning, possibly to the Moho, that requires advective heat transfer such as above active magma chambers, which would accelerate ice basal melting. The anomaly may extend 500 km inland with possibly a significant contribution of ice melt to the ice-drainage system of Greenland.


In addition there is recent suggestion that the disconnect between climate/ice models that predicted continuous increasing melt from Jokobshavn Isbrae (the biggest source of loss from Greenland) and measurements which have shown recent re-advance, slowing and thickening of the ice sheet is a lack of incorporation of regional ocean cooling in the area.

Khazendar, A et al, 2019. Interruption of two decades of Jakobshavn Isbrae acceleration and thinning as regional ocean cools. Nature Geoscience, doi.org/10.1038/s41561-019-0329-3

Jakobshavn Isbrae has been the single largest source of mass loss from the Greenland Ice Sheet over the last 20 years. During that time, it has been retreating, accelerating and thinning. Here we use airborne altimetry and satellite imagery to show that since 2016 Jakobshavn has been re-advancing, slowing and thickening. We link these changes to concurrent cooling of ocean waters in Disko Bay that spill over into Ilulissat Icefjord. Ocean temperatures in the bay’s upper 250 m have cooled to levels not seen since the mid-1980s. Observations and modeling trace the origins of this cooling to anomalous wintertime heat loss in the boundary current that circulates around the southern half of Greenland. Longer time series of ocean temperature, subglacial discharge, and glacier variability strongly suggest that ocean-induced melting at the front has continued to influence glacier dynamics after the disintegration of its floating tongue in 2003. We conclude that projections of Jakobshavn’s future contribution to sea-level rise that are based on glacier geometry are insufficient and that accounting for external forcing is indispensable.
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Re: The 2019 Greenland Thread

Unread postby Plantagenet » Sat 27 Jul 2019, 13:02:31

models for Greenland ice loss are missing key ingredients that would change views as to how much "global warming" versus regional conditions contribute.

...Basal heat flow is a big one and over the past 4 years or so more and more evidence points to a source of high heat flow that corresponds with rapid ice sheet flow in Greenland


Heat flow does indeed influence basalt melting of glaciers. However, there is no evidence that heat flow is increasing under Greenland now, and hence it is illogical to claim that increased surface melting and increases in flow velocity being observed now have anything to do with heat flow, since heat flow hasn't changed.

Image
Basal heat flow has nothing to do with the large recent increases in surface melting in Greenland. Its much more logical to think the huge increases in the areal extent of surface melting in Greenland is controlled by surface meteorological conditions, i.e. global heating.

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Re: The 2019 Greenland Thread

Unread postby dohboi » Sat 27 Jul 2019, 20:59:48

HIgh pressure usually means clear skies and full sun to melt the ever darkening Greenland ice.
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Re: The 2019 Greenland Thread

Unread postby GHung » Sat 27 Jul 2019, 22:46:05

People work really hard to invent reasons why what people see with their own eyes just ain't true.
Blessed are the Meek, for they shall inherit nothing but their Souls. - Anonymous Ghung Person
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Re: The 2019 Greenland Thread

Unread postby rockdoc123 » Sun 28 Jul 2019, 11:58:01

Heat flow does indeed influence basalt melting of glaciers. However, there is no evidence that heat flow is increasing under Greenland now, and hence it is illogical to claim that increased surface melting and increases in flow velocity being observed now have anything to do with heat flow, since heat flow hasn't changed.


Its much more logical to think the huge increases in the areal extent of surface melting in Greenland is controlled by surface meteorological conditions, i.e. global heating.


Well first off it is well documented from areas of high heat flow associated with subduction zones, rifts and hot spots that it is not consistent but rather transient with periods of weaker heat flow interspersed by periods of higher heat flow thought to be related to intermittent movements of magma. Secondly, there is virtually no direct measures of heat flow in Greenland other than very recently, the whole idea of a relationship to plate movement over a stationary hot spot is relatively new. So saying there is no evidence for increasing heat flow is quite misleading.

As to the link between global warming and surface melt in Greenland, my whole point from above was the mass losses in Greenland are much more complex than you seem to think and also what is currently included in the models. Of the various mechanisms of loss glacier dynamics is much more influential than surface mass balance as indicated in:

Mouginot, J, 2019. Forty-six years of Greenland Ice Sheet mass balance from 1972-2018. PNAS, V116. Pp 9239-9244.

The mass loss is controlled at 66 ± 8% by glacier dynamics (9.1 mm) and 34 ± 8% by SMB (4.6 mm). Even in years of high SMB, enhanced glacier discharge has remained sufficiently high above equilibrium to maintain an annual mass loss every year since 1998.


Which means that any impact from basal melt and hence increased speed of ice sheets due to high heat flow will be more important to the overall total mass balance of Greenland than just surface melt.

Eric Rignot pointed this out in commenting on the 2017-2018 melt season:

“The glaciers are still being pushed out of balance,” Eric Rignot, a senior scientist at NASA and an author of the paper, told me. “Even though the ice sheet has [sometimes] been extremely cold and had low surface melt in the last year, the glaciers are still speeding up, and the ice sheet is still losing mass.”
“If there’s a risk of rapid sea-level rise in the future, it will be associated with glaciers speeding up, and not anything happening at the surface,” Rignot said


As well there is a disconnect between global (and even regional) surface temperatures and surface melt in Greenland.

For the period up to the 2016 melt season, the change in surface mass balance (just snow minus surface melt) is shown in

Hall, D. et al, 2018. A multilayer surface temperature, surface albedo and water vapor product of Greenland from MODIS. Remote Sensing, 10(4) 555. DOI: 10.3390/rs10040555

Comparing the maps of surface melt from this publication to HADCRUT4 you see that 2002 and 2012 had the largest surface melt area-wise but although 2002 corresponded to an above trend spike in temperature 2012 was actually well below trend. As well the hottest spike in HADCRUT4 temperature in this series is in 2016 where the area of surface melt is not appreciably different than years such as 2011, 2008, 2000 and 2001 where temperatures were generally below the average trend. And you can’t argue that the picture would be different if we just looked at the northern hemisphere as a plot comparing HADCRUT NH (blue) with global HADCRUT (red) shows and even worse correlation.

Image

Image

Image

For the period immediately following in the 2017-2018 melt season the Danish Meteorologic Institute reported on surface mass balance (again snow accumulation minus surface melt):

For this year, we calculated a total SMB of 517bn tonnes, which is almost 150bn tonnes above the average for 1981-2010, ranking just behind the 2016-17 season as sixth highest on record.
By contrast, the lowest SMB in the record was 2011-2012 with just 38bn tonnes, which shows how variable SMB can be from one year to another.


And their reasoning for why this change happens is the “see-saw” pattern recognized in the North Atlantic Oscillation which is a source of variability for the Atlantic Ocean.

And I don’t think I need to point to all the papers which have discussed the fact Greenland went through a similar rapid loss phase back in the thirties which was followed by a period of ice growth in the forties and fifties.

Hence my comments above that the overall picture is much more complex than many want to believe.
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Re: The 2019 Greenland Thread

Unread postby Plantagenet » Sun 28 Jul 2019, 16:27:26

...it is well documented from areas of high heat flow associated with subduction zones, rifts and hot spots that it is not consistent but rather transient with periods of weaker heat flow interspersed by periods of higher heat flow thought to be related to intermittent movements of magma.


You have forgotten your geology, if you ever knew any to begin with.

Greenland is not at the border of a tectonic plate and contrary to your false claims Greenland isn't currently associated with a subduction zone, rift zone or a hot spot, and also contrary to your false claims there is no known movement of magma occurring under Greenland.

The area of somewhat higher high heat flow in east central Greenland is a residual feature left over from the Triassic, when the ancient mega-continent of Pangea began to rift apart. The Triassic Period extended from ca. 251.9 million years ago (Mya), to the beginning of the Jurassic Period 201.3 Mya, and Pangea progressively pulled apart as the Atlantic mid-oceanic ridge began to form during this time period. The Icelandic hot spot provided a local heat flow boost, and part of Greenland has somewhat greater heat flow then average because millions of years ago it was once near the Iceland hot spot. But now its hundreds of miles away from the Icelandic hot spot and there is no local hot spot or other magmatic source that can produce short term variations in heat flow, contrary to what you are claiming.

Furthermore, acceleration of glacier melt and glacier flow velocities are occurring all over Greenland, not just in the east central area. That means the phenomena causing it is affecting all of Greenland, not just local areas. That is consistent with the commonly accepted scientific idea that global warming is changing the ablation patterns, hydrology, and glacial flow mechanics of the Greenland Ice Sheet.

To summarize, your phony claims are nothing but BS, as usual.

Finally, since entertainment falls within my purview here, I am posting a short video showing how Pangea rifted apart and Greenland formed, starting over 200 million years ago.

Image

Do you get it now?

Cheers!
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Re: The 2019 Greenland Thread

Unread postby Plantagenet » Sun 28 Jul 2019, 17:36:48

Tanada wrote:Moulin's ... have the effect of delivering huge volumes of heat directly into the core of the ice sheet. Under the old 'ice cube' model of melting the glaciers can only absorb limited heat from the top and bottom where the weather and geological heating affect the ice. When you add in the Moulin you are taking water that is above the temperature of freezing (obviously) and plunging it vertically through the ice sheet to the base. The water carries heat energy both as latent heat of fusion for each tiny bit warmer than 0C it is. The falling water also carries a huge potential gravitational energy that translates from vertical motion to additional latent heat when it hit the bottom. Jointly these two effects deliver a warm column of energy through the core of the sheet and greatly increase the heating effect at the base of the sheet.

It used to be the case that core samples randomly taken across Greenland showed that the middle of the ice sheet was many degrees below freezing temperature. In those conditions any surface melting that did take place on a small scale drained into crevasses where the fresh water instantly refroze into hard ice by losing its latent heat to the surrounding extremely cold ice. Now all these moulin's operating for decades have added so much energy to the core ice in the mid depths that the ice has warmed to near freezing and the water can pass all the way through to the base. This was a fundamental change in ice sheet dynamics and people still seem to miss it more often than they understand it.


Exactly right. You summarized the processes involved perfectly.

The addition of significantly more water at the base of the glacier changes the ice sheet dynamics and leads to more sliding and higher ice velocities. That in turn results in more glacier ice flowing to tidewater more rapidly, where it calves away, or more glacier ice flowing down to lower elevations where it melts. Both result in more rapid loss of ice and glacier mass, more rapid shrinking of the Greenland Ice Sheet, and more rapid transfer of water to the oceans where it contributes to sea level rise.

Cheers!
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Re: The 2019 Greenland Thread

Unread postby rockdoc123 » Sun 28 Jul 2019, 19:13:11

Furthermore, acceleration of glacier melt and glacier flow velocities are occurring all over Greenland, not just in the east central area. That means the phenomena causing it is affecting all of Greenland, not just local areas. That is consistent with the commonly accepted scientific idea that global warming is changing the ablation patterns, hydrology, and glacial flow mechanics of the Greenland Ice Sheet


And the areas of high heat flux are not just confined to one area in Greenland (as the following map shows).

Martos, Y. M., 2018. Geothermal heat flux reveals the Iceland hotspot track underneath Greenland. Geoph Res Lett, 45, doi.org/10.1029/2018GL078289

Image

In fact the high heat flux areas correspond to the origin areas of very important ice sheets such as the Northeast Greenland Ice Sheet and the Jakoshavn Isbrae sheet is also sitting in an area of high geothermal heat flux (and hot water vents) and that particular ice sheet is responsible for large historic losses from Greenland. I had already pointed to the paper that suggested Jokoshavn Isbare losses were heavily controlled by regional climate with cooling and warming in surrounding waters a major factor.

And as is pointed out in a number of the papers you are completely full of BS with regards to some scientific idea that global warming has changed ablation patterns, hydrology and glacial flow patterns…it is regional climate that is at work here. The disconnect from global temperatures and surface melt is informative in that manner. Did you just ignore that because it doesn’t fit with your view point?

But now its hundreds of miles away from the Icelandic hot spot and there is no local hot spot or other magmatic source that can produce short term variations in heat flow, contrary to what you are claiming. 


I did not state that there was a hot spot currently present in Greenland, please show me where I said that. The crust has thinned as a consequence of passage over the Iceland hot spot which is why the heat anomaly is present. I posted that article above and much earlier in this same thread (and there are about a dozen other published papers to back that up). And apparently, you are not very aware of how geothermal flux works anywhere where the crust is thinner and it can be observed. In continental areas where crust is usually very thick the heat flow tends to be more constant as fluctuations in activity in the asthenosphere are baffled by older colder crust but where the crust is thinner we see all sorts of effects including hot water vents, magma, volcanism etc. Which is what you are seeing in Greenland where it passed over the hotspot and in adjacent areas where it is becoming well documented. Heat transmitted from the asthenosphere is not constant as was shown in the Rysgaard et al 2018 paper which I referenced above. Here is a diagram from that paper that points to that fact with HF on its own in 2006 not at the level to cause large melt but from 2009 onwards it would be.

Image

Bottom line is surface melt in Greenland is not well correlated with either global or northern hemisphere atmospheric temperatures but seems to be more related to variation in the NAO (as pointed out in various papers). Basal melt seems to be important to the velocity of ice sheets and basal melting is impacted by high geothermal heat flux which helps lubricate ice sheets and can result in increased speeds when coupled with a gravitational spreading gradient which would occur with increased snowpack in ice sheet headlands. Ice sheet dynamics are much more important to the overall mass balance of the GIS than surface processes and it has been shown by numerous papers that a part of those ice sheet dynamics are dependant on basal heating from high heat flux and warming/cooling effects at ice exit areas as a consequence of NAO variability.

Oversimplifying what is going on in Greenland in an attempt to support your very basic understanding of global climate change does nobody a service.
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Re: The 2019 Greenland Thread

Unread postby Plantagenet » Sun 28 Jul 2019, 19:42:02

.. the areas of high heat flux are not just confined to one area in Greenland


Yes, but the increased melting and accelerated ice velocities are happening EVERYWHERE in Greenland. Your suggestion that accelerated glacier flow is related to high heat flow areas doesn't make any sense since there is no correlation between areas of high heat flow and the ubiquitous and extensive changes occurring in Greenland.

Thats the third time I've explained that simple idea to you.

Do you get it now?
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