The Great Greenland Snow Job – 03 – Hewing the Holocene Hockey Stick

Hewing the Holocene Hockey Stick

In 1966 the mainstream mathematical flow model for ice sheets was defined by John Nye’s 1957 paper The distribution of stress and velocity in glaciers and ice sheets and according to the Nye Model the Camp Century “ice 20 metres above the bottom was estimated at 16,000 years” old.

Nye’s considerations led to a simple formula giving the age t of the ice z metres above the bedrock as a function of the ice sheet thickness H and the annual surface accumulation l (H).

With H = 1390 m and l (H) = 35 cm of ice per year at Camp Century the age of the ice 20 metres above the bottom was estimated at 16,000 years.

Frozen Annals Greenland Ice Cap Research – 2005 – Willi Dansgaard
http://www.iceandclimate.nbi.ku.dk/publications/FrozenAnnals.pdf/

A block of ice resting upon a rough slope forms a theoretical model of a glacier or an ice-sheet, the sides of the glacier valley being ignored.

The Distribution of Stress and Velocity in Glaciers and Ice-Sheets – J. F. Nye – 1957
The Royal Society – Proceedings A
http://rspa.royalsocietypublishing.org/content/239/1216/113.abstract

The 16,000 year estimate produced by the Nye Model was rejected outright by Willi Dansgaard because he believed the age of the Greenland Ice Sheet exceeded the 40,000 year limitation associated with radiocarbon dating.

Carbon-14 dating of the ice core was not possible, particularly not the deep layers, partly because there was not enough ice available, and partly because this dating technique only reaches 40,000 years back in time, at best.

We needed an ice flow model.

Frozen Annals Greenland Ice Cap Research – 2005 – Willi Dansgaard
http://www.iceandclimate.nbi.ku.dk/publications/FrozenAnnals.pdf/

Therefore, demonstrating a singular flare for confirmation bias, Willi Dansgaard developed his own Sandwich Model that produced a far more acceptable estimate of 160,000 years for the Camp Century ice situated 20 metres above the bottom.

The sandwich model.
However, the bottom temperature at Camp Century was measured by CRREL at -13˚C indicating that the ice is frozen to the bottom, thus moving very slowly down there, if at all, so Nye’s formula could not be valid for the deeper parts of “cold glaciers”.

Instead, we calculated a slightly more complicated formula for the age assuming that the horizontal ice velocity in the bottom 400 metres increases linearly from zero at bedrock to a value equal to the surface velocity all the way up to the surface.

According to the new calculation ice situated 20 metres above the bottom should be 160,000 years old, i.e. 10 times older than suggested by Nye’s formula for temperate glaciers.

The new one rests upon an approximation to the real ice flow in cold glaciers frozen to the bedrock. And yet, calculated ages of ice at the greatest depths are not reliable, if only because the bottom 25 metres of ice contains silt, which influences the flow properties considerably.

Frozen Annals Greenland Ice Cap Research – 2005 – Willi Dansgaard
http://www.iceandclimate.nbi.ku.dk/publications/FrozenAnnals.pdf/

Camp Century - Nye vs Dansgaard

A Flow Model and a Time Scale for the Ice Core from Camp Century, Greenland
W. Dansgaard and S. J. Johnsen – Journal of Glaciology – Vol 8 No 53 – 1969
http://www.igsoc.org:8080/journal/8/53/igs_journal_vol08_issue053_pg215-223.pdf

Confirmation bias, also called myside bias, is the tendency to search for, interpret, or prioritize information in a way that confirms one’s beliefs or hypotheses.

It is a type of cognitive bias and a systematic error of inductive reasoning.

People display this bias when they gather or remember information selectively, or when they interpret it in a biased way.

The effect is stronger for emotionally charged issues and for deeply entrenched beliefs.

People also tend to interpret ambiguous evidence as supporting their existing position.

https://en.wikipedia.org/wiki/Confirmation_bias

Curiously, Willi Dansgaard assumed the horizontal ice velocity “in the bottom 400 metres increases linearly” although Lyle Hansen had explicitly reported in 1966 that the temperature gradient was only “linear in the bottom 300 meters”.

The minimum temperature was -24.6°C at 154 meters,
and the bottom temperature was 13.0°C.

The temperature gradient is linear in the bottom 300 meters,
indicating a geothermal heat flow of 1.00 microcalorie/cm2/sec.

Deep Core Drilling in Ice and Core Analysis at Camp Century, Greenland, 1961-1966
B. Lyle Hansen and C. C. Langway Jr.
U. S. Army Cold Regions Research & Engineering Laboratory
Antarctic Journal September-October 1966
https://s3.amazonaws.com/Antarctica/AJUS/AJUSvIn5/AJUSvIn5p207.pdf

Camp Century - Temperature Profile

Willi Dansgaard’s fortuitous selection of this 400 metre [from the bottom] value was clearly pivotal to his chronology because at 400 metres [from the bottom] the blade of the Holocene Hockey Stick dramatically moves away from the shaft.

DEFINITION of ‘Hockey Stick Chart’

A line chart in which a sharp increase or decrease occurs over a period of time.

The line connecting the data points resembles a hockey stick, with the “blade” formed from data points shifting diagonally and the “shaft” formed from the horizontal data points.

Hockey stick charts have been used as a visual to show dramatic shifts, such as global temperatures and poverty.

http://www.investopedia.com/terms/h/hockey-stick-chart.asp

Camp Century - The last 100 metres

A Flow Model and a Time Scale for the Ice Core from Camp Century, Greenland
W. Dansgaard and S. J. Johnsen – Journal of Glaciology – Vol 8 No 53 – 1969
http://www.igsoc.org:8080/journal/8/53/igs_journal_vol08_issue053_pg215-223.pdf

The refined and polished Holocene Hockey Stick was then publicly unleashed in 1969.

One Thousand Centuries of Climatic Record from Camp Century on the Greenland Ice Sheet
A correlation of time with depth has been evaluated for the Camp Century, Greenland, 1390 meter deep ice core.
Oxygen isotopes in approximately 1600 samples throughout the core have been analyzed.
Long-term variations in the isotopic composition of the ice reflect the climatic changes during the past nearly 100,000 years.
Climatic oscillations with periods of 120, 940, and 13,000 years are observed.

One Thousand Centuries of Climatic Record from Camp Century on the Greenland Ice Sheet – W. Dansgaard, S. J. Johnsen, J. Møller, C. C. Langway Jr. – Science Vol 166 – 1969
http://www.sciencemag.org/content/166/3903/377

Camp Century - Sandwich Model

A Flow Model and a Time Scale for the Ice Core from Camp Century, Greenland
W. Dansgaard and S. J. Johnsen – Journal of Glaciology – Vol 8 No 53 – 1969
http://www.igsoc.org:8080/journal/8/53/igs_journal_vol08_issue053_pg215-223.pdf

The commanding officer, major Morris, suspected us of modesty (a true misconception), so he doubled up.

Frozen Annals Greenland Ice Cap Research – 2005 – Willi Dansgaard
http://www.iceandclimate.nbi.ku.dk/publications/FrozenAnnals.pdf/

These findings were greeted with scepticism and there was much debate about the integrity of the Greenland record…

The Ice Age – A Very Short Introduction
Jamie Woodward – 2014 – Oxford University Press

Camp Century - Thule Cross Section

It is hardly surprising that Willi Dansgaard’s papers were sceptically received because the “simple assumptions” upon which his Sandwich Model rests are startling [to say the least].

Assumption : Camp Century can be modelled using the Sandwich Model.

This is an extremely problematical assumption because the Sandwich Model is fundamentally an apex model that could be used as a rough approximation for Summit Camp [3,216 metres] at the apex of the Greenland Ice Sheet.

However, Camp Century [1,885 metres] is not at the apex of the ice sheet and the Sandwich Model specifically assumes that all sections of the Camp Century ice core originate from a location at the same altitude as Camp Century.

This is clearly a very dubious assumption.

Camp Century - Modelling

Assumption : The ice sheet rests on a “horizontal subsurface”.

Clearly, this assumption is invalid for the Greenland Ice Sheet.

Camp Century - Horizontal Subsurface

This assumption is also invalid for Camp Century.

Camp Century - Slope

Assumption : Unchanged rate of accumulation.

Willi Dansgaard acknowledged that this was “one of the weaknesses of our sandwich model”.

After the talk at the Nobel symposium a colleague praised me for the consistency by having reckoned on unchanged accumulation rate throughout the whole lapse of time without guessing on its value under glacial conditions.

I found it difficult to accept the praise, because one of the weaknesses of our sandwich model was just that the accumulation under glacial conditions was obviously lower than in warm periods.

By then, however, nobody knew how much lower, so we desisted from guessing.

Frozen Annals Greenland Ice Cap Research – 2005 – Willi Dansgaard
http://www.iceandclimate.nbi.ku.dk/publications/FrozenAnnals.pdf/

Assumption : Unchanged thickness and flow pattern over time.

The assumption that the Greenland Ice Sheet suddenly materialised in its fully developed form is [to put it politely] not a real world assumption.

Ice Sheet Growth

Regardless of these issues the 1969 version of the Holocene Hockey Stick [somehow] still stands as a tribute to Willi Dansgaard [and the power of Settled Science] because in 2005 he deemed it to be “correct, by and large, through the upper 85 % of the core, i.e. back to 14,000 years B.P. (before present)”.

Camp Century - Fine Tuning

Frozen Annals Greenland Ice Cap Research – 2005 – Willi Dansgaard
http://www.iceandclimate.nbi.ku.dk/publications/FrozenAnnals.pdf/

The Settled Science of the Earth Sciences is truly a wondrous thing to behold.

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Gallery | This entry was posted in Catastrophism, Glaciology, Great Greenland Snow Job, Greenland, History. Bookmark the permalink.

4 Responses to The Great Greenland Snow Job – 03 – Hewing the Holocene Hockey Stick

  1. One of the biggest problems is the vertical exaggeration of the height/thickness. Drawn up correctly to scale and a quite different behaviour of ice flow might present itself.

    Scale

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