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New ice core records 120,000 years?

by

30 July 2003

A milestone in deep ice drilling occurred on Thursday, 17 July 2003.1  The deepest ice core in the Northern Hemisphere hit bedrock on the Greenland Ice Sheet at a depth of almost two miles.  The new core was drilled by the North Greenland Ice Core Project (NorthGRIP, or NGRIP for short), which took seven years to drill, after overcoming many problems.2  The ice core is located 203 miles from the highest point on the ice sheet, on a north–north-west trending ice ridge.  European glaciologists had drilled the high point to bedrock back in the early 1990s.  Their ice core was called GRIP.  American scientists had drilled another hole to bedrock at the same time, 18 miles to the west of GRIP, called GISP2.3

The dating of NorthGRIP

The ice core is believed to contain ice that is 120,000 years old at the bottom.1  This date was obtained by matching the oxygen isotope ratio down this core with other ice cores in Greenland.  The oxygen isotope ratio is a general measure of temperature, but many other variables can affect the ratio.  All deep cores drilled into Greenland have a similar broad-scale oxygen isotope pattern.  These cores show three parts: a post-ice age climate with temperatures similar to today, an ice-age climate with temperatures colder than today, and a warmer interval near the bottom of the core.  So the dates of the NorthGRIP core depend upon the dates previously obtained in other Greenland ice cores.

It is important to note that none of these ice cores comes with dates attached.  The dates must be inferred, which means that old age is automatically built into the ice cores based on the evolutionary/uniformitarian paradigm.  There are various methods for dating ice cores, which fall into four general categories: (1) annual layer counting by using several of the measured variables down the core, (2) glaciological flow modeling, (3) use of reference horizons and correlation with other dated time series and (4) comparison with the Milankovitch insolation changes.4

The most scientific method is counting annual layers of ice accumulation down the ice core.  The snow turns to ice by the pressure of subsequent annual layers squeezing out the air between the grains of snow.  The snow is usually turned to ice in the Greenland Ice Sheet at about 200 feet deep.  Annual layers show up quite well at the top of the ice core in a number of measured variables, such as oxygen isotope ratios, dust, various chemicals, and differences in the ice between summer and winter.  It is claimed that one can count these annual layers down the core, like counting tree rings in a tree to determine its age.  In this way, researchers have counted 110,000 annual layers down the GISP2 core and supposedly verified their chronology.

There are a number of problems with this claim of counting 110,000 annual layers, however.5,6 [See Do Greenland ice cores show over one hundred thousand years of annual layers?] Since ice compresses vertically and spreads horizontally with depth, the annual layers thin with depth.  The measured variables become confused by the middle of the ice core, and the confusion is especially noticeable in the ice-age portion of the core.  The annual layer method works well in the upper part of the core for a few thousand years, but it requires some major assumptions to guide the interpretation of the middle and lower parts of the core.  Based on their evolutionary/uniformitarian paradigm, the researchers assume that the ice sheet has been in equilibrium for millions of years.1  Once they make this assumption, they rely on the second and third main methods of measurement—glaciological flow models tied to reference horizons—to provide a first guess for the thickness of annual layers.

In contrast to the evolutionary/uniformitarian model, the Creation/Flood ice-age model7 predicts much thicker annual layers in the lower and middle parts of the ice core, and glaciologists measure subannual or storm layers.  It is known that modern storms duplicate with similar amplitude many of the annual layer signatures.  If you expect a thicker annual layer deeper in the core, these signatures will show up, while those who believe the evolutionary/uniformitarian model assume that compression and diffusion have wiped out the subannual layers.  So, the paradigm determines the age of the ice sheet.

Of course, all climatological systems and ‘dated’ reference horizons are all correlated to the fourth main mechanism for dating cores, Milankovitch insolation changes.  The changes in sunlight absorbed at the surface (insolation) are caused by changes in the earth’s orbital geometry.  These changes are cyclical over past time and are the main reason for postulating multiple ice ages.  The modern Milankovitch dating scheme was first applied to deep-sea cores and subsequently applied to all other climate systems.  Deep ice cores in Antarctica are almost exclusively dated by this method.  There are many problems with the Milankovitch mechanism.8–10  Perhaps the biggest problem is that the periodicity of the earth’s orbital eccentricity every 100,000 years changes the sunlight absorbed at the earth’s surface only a very small amount.  The mechanism is much too weak to cause such dramatic climate change as an ice age. 

Why drill another ice core so close to GRIP?

The main reason for drilling another ice core so close to GRIP is because of the surprisingly rapid oscillations in the oxygen isotope ratio during the last supposed interglacial, about 120,000 years ago according to the evolutionary/uniformitarian timescale.11 Scientists had previously noted such rapid back-and-forth climate changes in other Greenland ice cores during the glacial period.  The temperature is believed to have shifted up to 38°F (20°C) in a few decades, with some associated effects changing as fast as 1 to 3 years:

‘These millennial-scale events represent quite large climate deviations: probably 20°C [38°F] in central Greenland … .  The events often begin or end rapidly: changes equal to most of the glacial-interglacial differences commonly occur over decades, and some indicators, more sensitive to shifts in the pattern of atmospheric circulation, change in as little as 1–3 years.’12

Such changes in the GRIP ice core are believed to represent the climate around the North Atlantic.

The discovery of such catastrophic changes during the ‘previous interglacial’ in the GRIP core especially alarmed the scientists.  If such catastrophic shifts to a colder climate could occur in the ‘previous interglacial,’ then it could happen in the present interglacial.  The temperature could quickly plunge several tens of degrees, possibly aided by global warming.  We are between ice ages, according to the evolutionary/uniformitarian paradigm.  So, the next ice age could occur soon:

‘If the past is any indication, the earth is at the end of another such warm period, poised to descend into a new ice age.’1

This change could occur suddenly.

However, the American team that drilled the GISP2 core disputes the climatic significance of the interglacial oscillations in the GRIP core, claiming instead that the oscillations represent mixing of ice at the bottom due to glacial flow over rough terrain.13 The main purpose, therefore, for drilling NorthGRIP so close to GRIP was to test whether the temperature-proxy oscillations in the previous interglacial were due to rough bedrock or to catastrophic interglacial climate changes.2  Based on radio-echo soundings, the bedrock below NorthGRIP is smooth, which should eliminate deformations caused by rough bedrock.

NorthGRIP surprises

Since NorthGRIP is so close to GRIP, but with a smooth bedrock surface, the scientists expected that the bottom of the ice would be undisturbed.  So the ‘previous interglacial’ would not be disturbed by a rough bottom.  Any sharp changes in the temperature proxy would then be caused by catastrophic interglacial climate oscillations.  Based on glaciological flow model dating, they expected to find the previous interglacial at about 2750–2850 m deep.  However, this ice still had not been reached by a depth of 3001 m.2 Supposedly this interglacial ice has been reached this summer, but whether they found the climate oscillations or not has not been revealed, as far as I know.

The researchers may not be able to settle the question because of another surprise.  The bottom of the ice showed mysterious undulations up to 200 m amplitude near the bottom in the radio-echo imagery.  So skeptical scientists can still point to temperature oscillations as caused by ice deformation.

A third surprise was that the ice near the bottom was melting.  Since the ice came from central Greenland, the researchers had expected the ice to be frozen to the bed, based on the nearby GRIP and GISP2 cores.  The Greenland Ice Sheet is much more complex than uniformitarian scientists expected, rendering their conclusions extremely tenuous, at best.

References

  1. Grossman, D., Drilling through ice in search of history, The New York Times, p. D2, 22 July 2003.
  2. Dahl-Jensen, D. et al., The NorthGRIP deep drilling programme, Annals of Glaciology 35:1–5, 2002.
  3. Oard, M.J., A tale of two Greenland ice cores, CEN Tech. J. 9(2):135–136, 1995.
  4. Parrenin, F. et al., Dating the Vostok ice core by an inverse method, Journal of Geophysical Research 106(D23):31, 837–31, 851, 2001.
  5. Oard, M.J., Do Greenland ice cores show over one hundred thousand years of annual layers? TJ 15(3):39–42, 2001.
  6. Oard, M.J., Are polar ice sheets only 4500 years old? Acts and Facts 32(7):i–iv, 2003.
  7. Oard, M.J., An Ice Age Caused by the Genesis Flood, Institute for Creation Research, El Cajon, California, 1990.
  8. Oard, M.J., Ice ages: the mystery solved? part I: the inadequacy of a uniformitarian ice age, Creation Research Society Quarterly 21(2):66–76, 1984.
  9. Oard, M.J., Ice ages: the mystery solved? part II: the manipulation of deep-sea cores, Creation Research Society Quarterly 21(3):125–137, 1984.
  10. Oard, M.J., Ice ages: the mystery solved? part III: paleomagnetic stratigraphy and data manipulation, Creation Research Society Quarterly 21(4):170–181, 1985.
  11. Greenland Ice-core Project (GRIP) members, Climate instability during the last interglacial period recorded in the GRIP ice core, Nature 364:203–207, 1993.
  12. Hammer, C., et al., Preface to special issue, Journal of Geophysical Research 102(C12), pp. 26, 315, 1997.
  13. Oard, M.J., Wild ice-core interpretations by uniformitarian scientists, TJ 16(1):45–47, 2002.

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