Skip to comments.Willi Dansgaard dies at 88; scientist who recognized climate record in ice cap
Posted on 02/08/2011 9:27:07 AM PST by Ernest_at_the_Beach
Willi Dansgaard, a Danish paleoclimatologist who was the first to recognize that the Earth's climatic history was stored in the Greenland ice cap, died Jan. 8 in Copenhagen, according to the Niels Bohr Institute at the University of Copenhagen. He was 88.
His research, together with that of Claude Lorius of France and Hans Oeschger of Switzerland, revolutionized scientific knowledge of how the temperature and composition of the atmosphere have changed over the last 150,000 years, demonstrating a clear link between carbon dioxide and methane concentrations and global temperatures.
Their discoveries launched a major global research effort to understand the mechanisms by which these atmospheric changes are linked to changes in the land surface and particularly to changes in ocean circulation and chemistry.
(Excerpt) Read more at latimes.com ...
Read here. Using multiple ice cores with highly resolved stable isotope records, in combination with air temperature data from 13 locations, researchers were able to develop a temperature history going back 1,400 years. They confirmed temperatures were warmer during Medieval Period when CO2 levels were significantly lower, versus the late 20th and early 21st centuries temperatures.
"In describing this record, the seven scientists said that "temperatures during the warmest intervals of the Medieval Warm Period," which they defined as occurring "some 900 to 1300 years ago, "were as warm as or slightly warmer than present day Greenland temperatures." Hence, we conclude that for southwest Greenland, various portions of the MWP (AD 700-1100) were warmer than they have been over the last several years."
"Unprecedented" global warming during late 20th and early 21st centuries? Actually, the real unprecedented warming happened well before the industrial age, as the below charts reveal. Historical Temperatures - Charts/Graphs
The Times Bias even extends into the writing of the notice on the death of a Scientist.
Funny how the LAT chose to “forget” the inconvenient truth in his data that showed that Gore et all are lying, stupid, felonious Obamas....er sleazebag crooks.
By Dr. Tim Ball Monday, December 28, 2009
Climate science is a productive pursuit with Nobel Prizes, an Oscar, billions in research funding, massive tax grabs and wealth for exploiters. Continuation of these activities partly validated the claim the disclosed files from the Climatic Research Unit (CRU) at the University of East Anglia (UEA) are of small consequence.
As I wrote earlier the scandal at CRU (Climategate) is diverting from the real scandal, which is the claim CO2 is causing warming and climate change. Climategate is the greatest orchestrated fraud in scientific history, but claims about CO2 are the greatest fallacy. Climategate lets those who've known what was happening to avoid being ignored as conspiracy theorists.
Everyone incorrectly talks about carbon when they mean CO2, which was the original focus of the claim human industrial activity was causing global warming. Theory assumed CO2 was a greenhouse gas that slowed heat escaping to space. As it increases temperature rises and it would because of increased industrial activity. This became fact immediately and challenging scientists were pushed aside. Mostly by nasty attacks from those who falsified records, rewrote historic records, distorted and misused science and statistics as the leaked CRU emails attest. Now they, their supporters, and all those benefiting, work to perpetuate the massive deception.
Some of this article was presented in a 2008 piece, but the CRU revelations make a revisit important. The summary of work the IPCC represents is only that chosen by the IPCC to achieve their goal. Remember the email comments about including or excluding articles that supported their objective.
Claims now proven false include;
The last claim is basic to the argument that humans are causing warming and climate change by increasing the levels of atmospheric CO2.
In a paper submitted to a US Senate Committee on Commerce, Science, and Transportation hearing Professor Zbigniew Jaworowski explains,The basis of most of the IPCC conclusions on anthropogenic causes and on projections of climatic change is the assumption of low level of CO2 in the pre-industrial atmosphere. This assumption, based on glaciological studies, is false. This means more when you know that Tom Wigley, who is the heart of the CRU gang, introduced the 280 ppm number to the climate science community with a 1983 paper titled, The pre-industrial carbon dioxide level. (Climatic Change 5, 315-320). He based his work on studies by G. S. Callendar (1938) of thousands of direct measures of atmospheric CO2 beginning in 1812. Callendar rejected most of the records, including 69% of the 19th century records and only selected records that established 280 ppm as the pre-industrial level. Here's a plot of the records with Callendar's selections circled.
Selections changed the slope of the trend from declining to increasing. As Jaworowski notes, The notion of low pre-industrial CO2 atmospheric level, based on such poor knowledge, became a widely accepted Holy Grail of climate warming models. The modelers ignored the evidence from direct measurements of CO2 in atmospheric air indicating that in 19th century its average concentration was 335 ppmv.
Ice cores provide the historic record and samples from Mauna Loa provide the recent record. Both are drastically smoothed thus eliminating variability. This was done to tie in with the pre-industrial levels. Ernst Beck confirmed Jaworowski's research in a September 2008 article in Energy and Environment and validated all the 19th century records. In a devastating conclusion Beck writes,Modern greenhouse hypothesis is based on the work of G.S. Callendar and C.D. Keeling, following S. Arrhenius, as latterly popularized by the IPCC. Review of available literature raise the question if these authors have systematically discarded a large number of valid technical papers and older atmospheric CO2 determinations because they did not fit their hypothesis? Obviously they use only a few carefully selected values from the older literature, invariably choosing results that are consistent with the hypothesis of an induced rise of CO2 in air caused by the burning of fossil fuel.
Pre-industrial levels were 50 ppm higher than those used in the IPCC computer models. Models also incorrectly assume uniform atmospheric distribution and virtually no variability from year to year. Beck found, Since 1812, the CO2 concentration in northern hemispheric air has fluctuated exhibiting three high level maxima around 1825, 1857 and 1942 the latter showing more than 400 ppm. Here is a plot from Beck comparing 19th century readings with ice core and Mauna Loa data.
Difference in variability of the 19th century measures, ice core records and Mauna Loa are apparent. Ice core records are subjected to a 70-year smoothing average eliminating a great deal of information. For example, the Mauna Loa record covers 50 years (1958 - 2009), not enough for even a single point. Elimination of high readings prior to the smoothing makes the loss even greater. As with all known records the temperature changes before the CO2, here by approximately 5 years.
Elimination of data occurs with the Mauna Loa readings, which can vary up to 600 ppm in the course of a day. Beck explains how Charles Keeling established the Mauna Loa readings by using the lowest readings of the afternoon. He ignored natural sources, a practice that continues. Beck presumes Keeling decided to avoid these low level natural sources by establishing the station at 4000 meters up the volcano. As Beck notes Mauna Loa does not represent the typical atmospheric CO2 on different global locations but is typical only for this volcano at a maritime location in about 4000 m altitude at that latitude.(Beck, 2008, 50 Years of Continuous Measurement of CO2 on Mauna Loa Energy and Environment, Vol 19, No.7.) Keeling's son continues to operate the Mauna Loa facility and as Beck notes, owns the global monopoly of calibration of all CO2 measurements. Since Keeling is a co-author of the IPCC reports they accept Mauna Loa without question.
Jaworowski estimates the ice core readings are at least 20% low, which is reasonable given the CO2 levels for 600 millions years using geologic evidence. Further evidence of the effects of statistical smoothing and the artificially low ice core readings are provided by measurements of stomata. Stomata are the small openings on leaves that vary directly with the amount of atmospheric CO2. A comparison of a stomata record with the ice core record for a 2000-year period illustrates the issue.
Stomata data on the right show higher readings and variability than excessively smoothed ice core record on the left. The stomata record aligns with the 19th century measurements as Jaworowski and Beck assert. A Danish stomata record shows levels of 333 ppm 9400 years ago and 348 ppm 9600 years ago.
EPA declared CO2 a toxic substance and a pollutant. Governments prepare carbon taxesand draconian restrictions crippling economies for a completely non-existent problem. Failed predictions, discredited assumptions, incorrect data did not stop insane policies. Climategate revealed the extent of corruption so more people understand malfeasance and falsities only experts knew or suspected. More important, they are not rejected as conspiracy theorists. Credibility should have collapsed, but political control and insanity persists at least for a little while longer.
Directeur de recherche émérite du CNRS au Laboratoire de glaciologie et géophysique de l'environnement, Université Joseph Fourier, Saint-Martin-d'Hères, France.
Research Interests :
He has taken part in more than 20 expeditions to the polar regions, primarily to Antarctica. He is distinguished by his ability to organise internationally co-operating teams, for example in the drilling of the Vostok core in which Russian, French and American scientists worked together in interdisciplinary teams to recover ice cores. We owe to Claude Lorius the insight that the air trapped in old ice cores might contain a record of the composition of the atmosphere in the past. Subsequently, the international and interdisciplinary work that he inspired has led to the realization that over periods of hundreds of thousands of years, the climate and the biogeochemical cycles of the planet are synchronized together as two parts of a single "Earth system". The discovery by Lorius and his associates of the systematic changes in atmospheric composition that accompanied the Quaternary glacial cycles ranks as one of the outstanding achievements in global biogeochemistry during the 20th century".
The ice core evidence that the concentration of atmospheric carbon dioxide is closely linked to Earth's climate has been fundamental to the present concern of the scientific community over the consequences of rising atmospheric carbon dioxide due to human activity. Lorius was one of the first scientists to recognize this threat and to warn of the potential threat that human activities pose to the Earth system.
The source for the CO2 Claim perhaps???
Hans Oeschgers letter to ESPR
Jaworowskis article in ESPR is so hard to locate, it wouldnt be too unreasonable to suspect that the journal is not eager now for people to take much notice of it. But it did get noticed by one giant in climate science Hans Oeschger.
Prof. Oeschger was the founder of the Division of Climate and Environmental Physics at the Physics Institute of the University of Bern. His name is attached to the Oeschger Counter that enabled Carbon-14 dating to be applied to geophysical problems, and to the Dansgaard-Oeschger 1,500 year cycle of slow cooling and abrupt warming observed in sediments and ice cores. He was active and influential in climate science until his death in 1998. His assessment of the Jaworowski article was blunt.
ESPR - Environ Sci. & Pollut. Res. 2 (1) 1995, pp. 60-61
It is with great hesitation that I write in reply to the paper by JAWOROWSKI, this paper deserves little attention. But unfortunately, he has succeded in publishing similar articles in journaIs and thus has induced considerable confusion regarding the reconstruction of ancient atmospheric compositions by the analysis of air occluded in polar ice of known age. We hope that this reply will help to clarify the issue. JAWOROWSKI is correct in one point. The glacier studies of ice cores are fundamental for one of the most important issues of the century and are of great importance for succeeding centuries.
I have been personally involved in the development of this field since its inception. In the early stages I was involved directly in experiments; later the experimental and analysis work was conducted by my collaborators and students. ii in this article I speak of we, I refer to the ice core team at the University of Bern. In the following I first give a short overview of the history of ice core research.
Although we knew since the nineteen fifties that human activities might change the climate of the Earth, it was not until the mid seventies we realised that mankind was faced with a serious problem. Using a new model for the exchange of CO2 between atmosphere and ocean, we were able to consistently describe the uptake excess of CO2 by the ocean, as well as the distribution in the ocean of 14C produced by cosmic radiation, and 14C stemming from nuclear weapon tests. We became convinced that, for the expected future anthropogenic CO2 emission, the atmospheric CO2 concentration would rise in a predictable manner. (In fact, using the estimated actual fossil CO2 emissions as input, the CO2 increase of the past 20 years corresponds to within 10% of the predictions based on such models.) At that rime an urgent question concerned the preindustrial atmospheric CO2 concentration and the early history of the CO2 increase, but also the question of whether the atmospheric CO2 concentration of the preindustrial time was stable or whether there were also natural variations in CO2 concentration.
The US-CO2 programme was planned at an ERDA meeting in Miami in the late seventies. At that time we proposed a reconstruction of the CO2 history by measuring the gases trapped in polar ice. This idea was met with a great deal of scepticism and we were aware that the changes for success were limited because of a wide spectrum of problems, including those which JAWOROWSKI describes in his paper. On the other hand, we were aware of the urgency of the greenhouse problem and concerned that the science community would fail to conduct the most relevant studies aimed at the assessment of the rising greenhouse effect.
The project to reconstruct the history of the greenhouse gases was conducted; it was, and is, very successful - much above expectation. The CO2 concentrations measured on the SIPLE core, Antarctica, serve as a measure of that success. They illustrate (JAWOROWSKI, Fig. 5 a, p. 168) the history of atmospheric CO2 increase since the middle of the 18th century. Another important result was the observation of low CO2 concentrations of the gases extracted from ice-age ice. The low glacial CO2 concentrations have been confirmed in ice cores with different physical and chemical properties both from Greenland and Antarctica and independently from 13C measurements on carbonate of foraminifera shells in ocean cores and, yet again, more recently in moss samples.
Now to the paper of JAWOROWSKI: For years he emphasizes only the difficulties of these studies, formulates the underlying assumptions which sometimcs are only partly fulfilled and criticizes the work performed hitherto in an unscrupulous manner. He does this without any appreciation for the development of expertise in this field over several decades. Thus he extrapolates from contamination problems in improvised pioneering experiments in the late sixties to more recent (1992) similar experiments on the Greenland ice cap for which special equipment was developed. Some of his statements are drastically wrong from the physical point of view, e.g. the statement that CO2 at 70 m depth in the ice begins to change into solid clathrates. Another example concerns the gas-occlusion process in firn and young ice. This process has been studied in detail theoretically and experimentally. The theory of diffusion of gases in firn and the occlusion at the firn-ice transition has been confirmed impressively by the detection of a gravitational enrichment of the heavier gases and of the heavier isotopes of a gas. This enrichment depends, in the first instance, on the depth of the firn-ice transition. It enables the reconstruction of the history of gas enclosure depth during the last glacial-interglacial cycle. But JAWOROWSKI maintains that the age of the ice and that of the occluded gases are the same and shifts the CO2 increase revealed from studies of the SIPLE core (Fig. 5 a) - which in the uppermost part overlaps convincingly with the atmospheric measurements by ca. 100 years back in time (assuming identical ages for the ice and the gases in the ice). Fig. 5 b speaks for itself; why should there be such a drastic increase of CO2 and of CH4 (Fig. 5 a) in the middle of the 19th century?
The teams of researchers involved in ice core studies have a high standing within the scientific community. The early increases of the greenhouse gases are used to initiative the models simulating climatic change and help to understand the source and sink problem related to the greenhouse gas increases of the last 150 years. The low glacial greenhouse concentrations are an essential boundary condition for climate modelling experiments of the Earth during a glacial period. The papers by JAWOROWSKI, and the one by HEYKE quoted in this paper, are not taken seriously by the science community. The problem with these publications is that a broader circle of persons interested in the Global Change issue will receive the impression that the assessment of the problem is partly based on doubtful information, that there are serious weaknesses in experimental procedures, that the whole Global Change problem does not need to be taken so seriously and that there is no urgency regarding the control of CO2 emission. The time lost now is crucial for attempts to limit the anthropogenic climatic change to a range with more absorbable negative consequences.
The study of the history of Earth system parameters is an on-going process; an increasing number of laboratories have become involved and interact with each other. As it is the case in any field of science, the state of art is continuously critically assessed and attempts are made to improve the quality of the research. Ice-core information is fundamental for the assessment of one of the most urgent problems of our time. Based on my experience during decades of involvement in this field, I consider the chances as very small that the major findings from greenhouse gas studies on ice cores are fundamentally wrong; and I find the publications of JAWOROWSKI not only to be incorrect, but irresponsible.
Hans Oeschger, Ph. D. Professor of Physics
University of Bern
Chl-3012 Bern, Switzerland
Why 1500 years??
He’s polluting his sample.
Zbigniew Jaworowski is a Polish physicist, and alpinist.
Zbigniew Jaworowski is chairman of the Scientific Council of the Central Laboratory for Radiological Protection in Warsaw and former chair of the United Nations Scientific Committee on the Effects of Atomic Radiation (198182) . He was a principal investigator of three research projects of the U.S. Environmental Protection Agency and of four research projects of the International Atomic Energy Agency. He has held posts with the Centre d'Etude Nucleaires near Paris; the Biophysical Group of the Institute of Physics, University of Oslo; the Norwegian Polar Research Institute and the National Institute for Polar Research in Tokyo.
Jaworowski's works on ice cores were published in Jaworowski (1994, 1992) and in reports Jaworowski (1990, 1992). Jaworowski has suggested that the long-term CO2 record is an artifact caused by the structural changes of the ice with depth and by postcoring processes.
However, Jaworowski's views are rejected by the scientific community. Increases in CO2 and CH4 concentrations in the Vostok core are similar for the last two glacial-interglacial transitions, even though only the most recent transition is located in the brittle zone. Such evidence argues that the atmospheric trace-gas signal is not strongly affected by the presence of the brittle zone. Similarly Hans Oeschger[dead link] states that "...Some of (Jaworowski's) statements are drastically wrong from the physical point of view".
CO2: The Greatest Scientific
Scandal of Our Time
by Zbigniew Jaworowski, M.D., Ph.D., D.Sc., March 2007
Read pdf paper of this strong critique of the IPCC from EIR Science 16 March 2007. (Note typo error near top of page 50 . After 'The Near Future', the "..2 million years.." should be 1 million.
| The data from shallow ice cores, such as those from Siple, Antarctica[5, 6], are widely used as a proof of man-made increase of CO2 content in the global atmosphere, notably by IPCC. These data show a clear inverse correlation between the decreasing CO2 concentrations, and the load-pressure increasing with depth (Figure 1 A). The problem with Siple data (and with other shallow cores) is that the CO2 concentration found in pre-industrial ice from a depth of 68 meters (i.e. above the depth of clathrate formation) was too high. This ice was deposited in 1890 AD, and the CO2 concentration was 328 ppmv, not about 290 ppmv, as needed by man-made warming hypothesis. The CO2 atmospheric concentration of about 328 ppmv was measured at Mauna Loa, Hawaii as later as in 1973, i.e. 83 years after the ice was deposited at Siple.
| An ad hoc assumption, not supported by any factual evidence[3, 9], solved the problem: the average age of air was arbitrary decreed to be exactly 83 years younger than the ice in which it was trapped. The corrected ice data were then smoothly aligned with the Mauna Loa record (Figure 1 B), and reproduced in countless publications as a famous Siple curve. Only thirteen years later, in 1993, glaciologists attempted to prove experimentally the age assumption, but they failed.
The notion of low pre-industrial CO2 atmospheric level, based on such poor knowledge, became a widely accepted Holy Grail of climate warming models. The modelers ignored the evidence from direct measurements of CO2 in atmospheric air indicating that in 19th century its average concentration was 335 ppmv (Figure 2). In Figure 2 encircled values show a biased selection of data used to demonstrate that in 19th century atmosphere the CO2 level was 292 ppmv. A study of stomatal frequency in fossil leaves from Holocene lake deposits in Denmark, showing that 9400 years ago CO2 atmospheric level was 333 ppmv, and 9600 years ago 348 ppmv, falsify the concept of stabilized and low CO2 air concentration until the advent of industrial revolution .
Improper manipulation of data, and arbitrary rejection of readings that do not fit the pre-conceived idea on man-made global warming is common in many glaciological studies of greenhouse gases. In peer reviewed publications I exposed this misuse of science [3, 9]. Unfortunately, such misuse is not limited to individual publications, but also appears in documents of national and international organizations. For example IPCC not only based its reports on a falsified Siple curve, but also in its 2001 report used as a flagship the hockey curve of temperature, showing that there was no Medieval Warming, and no Little Ice Age, and that the 20th century was unusually warm. The curve was credulously accepted after Mann et al. paper published in NATURE magazine. In a crushing criticism, two independent groups of scientists from disciplines other than climatology [16, 17] (i.e. not supported from the annual pool of many billion climatic dollars), convincingly blamed the Mann et al. paper for the improper manipulation and arbitrary rejections of data. The question arises, how such methodically poor paper, contradicting hundreds of excellent studies that demonstrated existence of global range Medieval Warming and Little Ice Age, could pass peer review for NATURE? And how could it pass the reviewing process at the IPCC? The apparent scientific weaknesses of IPCC and its lack of impartiality, was diagnosed and criticized in the early 1990s in NATURE editorials [18, 19]. The disease, seems to be persistent.
The basis of most of the IPCC conclusions on anthropogenic causes and on projections of climatic change is the assumption of low level of CO2 in the pre-industrial atmosphere. This assumption, based on glaciological studies, is false. Therefore IPCC projections should not be used for national and global economic planning. The climatically inefficient and economically disastrous Kyoto Protocol, based on IPCC projections, was correctly defined by President George W. Bush as fatally flawed. This criticism was recently followed by the President of Russia Vladimir V. Putin. I hope that their rational views might save the world from enormous damage that could be induced by implementing recommendations based on distorted science.
Rehashing whether CO2 is the influence on warming and what can be determined from Ice Cores....
Was referring to his pipe smoke contaminating his core sample.:)
Ha...not a careful scientist then....!
Full of links.....could use a directory.
For some implied links at post # 15...use the link at the top of the #15 post.
Climate Change and GISP2
During the past few decades, researchers have established the existence of a climate system on Earth that is characterized by complex integration and feedback. The sun and all the parts of the Earth - the oceans, the atmosphere, the land masses, the snow and ice masses, all life, and the inner earth - are parts of this system. Changes in any one part of the system affect all the others and ultimately result in climate change. Climate change is actually a continuous process, but in the past the changes have ranged from the slow and gradual to the surprisingly fast and dramatic. This much we have learned about the climate system; but beyond this we are less knowledgeable. How do the parts of the system interact? How will specific changes in one part affect the others and, ultimately, the climate? What patterns of processes occur to produce the changes we have observed such as the cycle of glacial advances and retreats? What climate changes will occur as a result of our activities?
Humanity's production of CO2, nitrous oxide, sulfuric and nitric acids, CFC's and other "greenhouse" gases, as well as our direct impact on large ecosystems, makes understanding the climate system an imperative. From what we do know now, our activities could raise the average temperature a few to several degrees centigrade over he next few decades in addition to altering weather patterns. If so, the potential exists for severe, or catastrophic, disruption of the EarthÕs living and climate systems.
Ice cores, cylinders of ice drilled out of glaciers and polar ice sheets, have played an important role in revealing what we know so far about the history of climate. Today, United States scientists are embarking on a new ice coring project in Greenland with a wide range of state of the art analyses in the hopes of resolving questions about how the climate system functions. Drilling for The Greenland Ice Sheet Project Two* (GISP2) began in 1989. When they reach the bottom of the ice sheet, 3000+ meters thick, in 1992 they will have recovered the longest, most detailed, continuous record of climate available from the northern hemisphere stretching back 200,000 years or more through two glacial/interglacial (cold/warm) cycles.
While long ice core records exist from Antarctica, fewer comparable records exist from the northern hemisphere. The newest theories1 on the transitions between glacial (cold) and interglacial (warm) periods involve changing circulation patterns in the North Atlantic Ocean. The modern ocean circulation pattern includes the well known Gulf Stream. This flow of water brings significant amounts of heat, in the form of warm water, from the tropics to the North Atlantic. When it reaches the North Atlantic and cools, by giving its heat off to the atmosphere, it becomes dense enough to sink to the bottom. This water flows slowly through the depths of the Atlantic to the Indian and Pacific oceans and eventually returns, approximately 1000 years later, to the North Atlantic. It is surmised that during glacial periods this circulation was shut off, changing temperatures in the polar regions. Because CO2 is soluble in seawater, the cessation of this circulation also has important implications for CO2 in the atmosphere. Since the North Atlantic is where this circulation is driven - the cooling, sinking water sets the circulation in motion - it has become a region of significant interest and means that GISP2 will provide a unique record for evaluating these theories.
As an example of the changes to be investigated, the GISP I core (a predecessor to GISP2) has revealed evidence of extremely rapid rises in temperature on the order of several degrees centigrade in several decades2. While the location of the GISP I core precludes further illumination of this event, if such rapid changes can be investigated during GISP2, the mechanisms by which such a change could occur can be understood. Furthermore, our understanding of the relationship between changes in the "greenhouse" gases (such as CO2 and methane (CH4)) and temperature can be investigated by examining the timing and magnitude of their change during different climatic periods.
How Ice Cores Record a History of Climate
How can a history of climate be reconstructed from an ice core? When snow falls it carries with it the compounds that are in the air at the time, compounds ranging from sulfate, nitrate and other ions, to dust, radioactive fallout, and trace metals. When snow falls in a place where temperatures above freezing are rare (there is only a hint of any melting at the GISP2 site in the 750 year record recovered to date), such as in polar regions or at high altitude, the snow from one year falls on top of the previous year without melting.
As each yearÕs snowfall is buried by successive years' snowfall, the constituents contained in the snow are buried along with it. By drilling down from the surface of an ice sheet and analyzing snow from greater and greater depths, a history of the compounds in the air can be obtained. Further, snow that is deeper than 80 meters at the GISP2 site turns into ice from the weight of the snow above it, and trapped in the ice are small bubbles of air. Thus, in addition to trapping compounds from the air, an ice sheet traps a small sample of the air itself. This trapped air is also analyzed and provides information about the composition of the atmosphere at the time the ice formed.
Like ice cores, deep sea cores have also provided information about climate, but from accumulated sediments on the ocean floor. Unlike ice cores, which provide direct climate information, sediment cores provide indirect information. An example of this indirect evidence is the method for determining temperature. When sediment cores are analyzed researchers painstakingly sort out plankton shells which twist in different directions depending on the temperature of the water they grew in. By counting the number of shells that twist each way the temperature of the surface water at the time that they grew can be determined. Understanding the behavior of these plankton in the modern world is necessary to produce a historical record of temperature for the ocean.
Sediments also accumulate very slowly relative to snow on an ice sheet. This results in much longer records from sediment cores, but a much reduced ability to resolve short term changes. While periods of hundreds to thousands of years might be resolved in a sediment core, annual and even seasonal resolutions are possible with ice cores. On the other hand, sediment cores can provide records which are as long as several million years compared with the several hundred thousand years of ice cores. Because of these differences, sediment cores and ice cores provide complimentary climate information; ices cores provide high resolution, direct information and sediment cores lower resolution, less direct records, but from much longer time periods.
GISP2 is located at the highest point on the Greenland ice sheet (38¡ 28' W, 72¡ 35'N, 3208 meters above sea level) on the "ice divide" of central Greenland. Ice on the west of the roughly north south divide passing through the "summit" flows to the west and ice to the east flows east. Here the ice moves almost vertically down to the bottom and the annual layers get progressively thinner and thinner as they get deeper. This is the optimal place for drilling. It will yield the longest continuous record available from the ice sheet and each yearÕs snowfall will be thinned the least providing the greatest detail.
As already indicated, ice cores provide a more direct record of climate than sediment cores. They also provide a staggering breadth of information. One of the cornerstones of ice core research is the d18O (delta-O-18) isotopic record (16O and 18O are isotopes of oxygen; they are the same chemically, but have slightly different weights). Water in the oceans contains primarily oxygen with an atomic weight of 16 (16O, oxygen-16). A small fraction however is 18O, 12% heavier than "typical" oxygen. Water molecules with 18O are the same as regular water in most respects except that because it is heavier, it does not evaporate as readily and condenses slightly more easily than water with 16O. Depending on the temperature of evaporation and how far the water has had to travel before it fell as snow on the summit of Greenland, the ratio of 18O to 16O will vary. This ratio, known as d18O, can be measured very accurately using a mass spectrometer. Over short time scales the change in temperature from summer to winter produces a very clear oscillation in the 18O/16O ratio. This oscillation is used to determine the age of the core at different depths, simply by counting the oscillations. Over longer time periods, this ratio indicates the average temperature of the regions between the evaporation site and the coring site. GISP2 investigators are also analyzing for the ratio of 1H/2H (Hydrogen to deuterium) which will allow even finer detail about source temperature and condensation history to be obtained. Dr Pieter Grootes of the University of Washington and Dr. Jim White of the University of Colorado, Boulder are working on these isotope measurements for GISP2.
The major ions found in snow also have annual signals. Some ions such as sodium (Na+) and chloride (Cl-) are principally derived from the sea. Others such as sulfate (SO4=) come from human, biological, and volcanic activity as well as from the sea. The burning of fossil fuels in the northern hemisphere produces sulfate and nitrate (NO3-) and can be seen as high levels of these compounds in the ion record from previously drilled, shallow Greenland ice cores3. The ion record from an ice core reveals important information about the source of the air to the drill site (which is critical for interpreting other measurements), volcanoes (which produce sulfate and chloride), and changes in the activities that produce the ions such as fossil fuel combustion. Dr. Paul Mayewski (Chief Scientist for GISP2), Dr. Wm. Berry Lyons, and Dr. Mary Jo Spencer of the University of New Hampshire and Dr. Eric Saltzman of the University of Miami produce the ion record for GISP2.
Another property of the core is being studied by Dr. Julie Palais of the University of New Hampshire and Dr. Michael Ram of University of New York at Buffalo. The amount of dust carried to Greenland varies with the amount of land where dust can be picked up by the wind, the strength of the wind, and also, with volcanic activity and fires. Like the isotopes and ions, there is an annual signal of dust in the core. A dust peak is often found in the spring section of an annual layer. Like isotopes these can be counted to determine the age of the core. Volcanoes can produce large quantities of particles and leave a record in the ice. Scanning electron micrographs of the particles from a particularly large dust peak in an ice core may reveal that it is from a known volcano and allow a firm date to be placed on that section of core. For prehistoric times, the dust record is a key tool for reconstructing a history of volcanic activity. Further at the end of a glacial advance there is often a period of dustiness as the glaciers retreat and leave large unvegetated land areas. These periods can be detected by high levels of dust in the core.
An important baseline measurement is electrical conductivity. This research is done by Dr. Ken Taylor of the Desert Research Institute in Reno, Nevada. Electrical conductivity measurements (ECM) of the core is a very rapid method to indicate how acidic the core is without the chemical detail of the ion analyses. The value of the measurement is that it can be done for the whole length of the core in high resolution and provide an immediate picture of the core and allow quick detection of interesting areas, such as a volcanic eruptions. Because it is a high resolution, continuous measurement it can be used, along with the other measurements, for time frequency analysis in order to identify cycles in the climate signal.
The relationship between CO2, other "greenhouse" gases and global warming is of great importance and much debated. The ice core record from Vostok, Antarctica shows a near perfect correlation between CO2 and temperature4. Several groups are analyzing the gas bubbles from the core. Dr. Martin Wahlen of the New York State Department of Health will be measuring CO2 concentrations in addition to methane (CH4), nitrous oxide (N2O), and other gases. Dr. Alex Wilson of the University of Arizona is determining CO2 concentrations and carbon-14 (14C) dating the CO2 in the ice to help determine the age of the core. This information will indicate, for example, not only how much CO2 was in the air at any given time but, based on its isotopic signature,what its source was. Dr. Michael Bender of the University of Rhode Island, in addition to the other gas investigators, will be making special analyses of the isotopic composition of the bubbles. These studies will reveal fine details about how gases might change in the ice with time.
Studies of the trace metal content of the core will help to resolve the debate about large meteor strikes on Earth by detecting iridium, a product of meteor strikes. Dr. Ed Boyle of MIT, whose work on sediment cores has been important in linking climate change and ocean circulation5, will be analyzing for iridium, an element found in abundance in extraterrestrial material, as well as a broad suite of other elements.
Physical characteristics of the core reveal annual layers resulting from the temperature difference between summer and winter as well as detecting any deformation of the glacier that could affect the record. Dr. Richard Alley of The Pennsylvania State University and Dr. Tony Gow and Dr. Deborah Meese of the Cold Regions Research and Engineering Lab in Hanover, New Hampshire produce the physical record of GISP2.
The Outlook for the Future
After four summers of drilling and the equivalent of decades of analyses all squashed into five years of intense work, what will GISP2 produce? A new view of Earth history will have evolved - the most detailed view of the last 200,000 years ever seen. This view will literally be a "time machine" that will tap a reservoir of information barely recognized as a resource two decades ago. Theories about climatic change will have been tested and perhaps even more importantly, new views of the history of climate will spawn that are perhaps not even possible to guess about today. We cannot look into the future yet, but we can look to the past. From the past we gain perspective, a different view of who we are, what we can do and the environment of which we are a part. By 1992 as the last of the 3000 meters of core come to the surface, a group of scientists, technicians, engineers, and students will have sampled the atmosphere as it was during the onset of the Industrial Revolution, at the earliest periods of modern civilization, and into the last major ice age, through to the last warm period and into the previous major ice age. Unknown natural cycles may become clear, new interactions between the atmosphere and climate may reveal themselves. From this view of the past, the magnitude of human involvement will be placed in sharper perspective and our view of the Earth system will be probed yet farther.
Retrieving a 3000 meter core is not a simple task. Ice must be retrieved from great depths and pressures. Information about the drill's angle, depth, power consumption, must all be relayed to the surface during drilling, and slight flaws in the drill barrel can damage the core The Polar Ice Coring Office (PICO) of the University of Alaska, Fairbanks provides the state-of-the-art drilling technology for recovering this deep core and has spent several years developing a drill capable of working at these depths. The 20 meter long drill consists of a specialized drill head, a core barrel, chip catcher, motor, instrument package, and anti-torque knives all suspended from a 4000 meter cable. The drill is lowered to the bottom of the bore hole where a section of core between 2 and 6 meters long is cut, broken off at the base and winched back to the surface. This core is then sent to a "science trench", a large room cut out of the snow for processing and analyzing the core, while the drill goes down the hole for more ice.
Because the concentrations of the compounds being measured in the ice are very low it would be easy to contaminate the ice samples. The touch of a bare hand would hopelessly contaminate a final ice sample. Once the core sections are in the science trench they are passed through a "core processing line"; a series of stations where the core is processed, sampled and packed for shipment back to laboratories in the United States. The outside of the core is cut first for use in isotopic analyses which are not easily contaminated then the cleaner, inside pieces of the core are rinsed briefly in ultra-pure water under clean conditions and packaged for shipment. Scientists must wear special "clean suits" over their warm clothing to insure that they themselves do not contaminate the samples.
* The Greenland Ice Sheet Project Two (GISP2) is being carried out by scientists from: the U. S. Army Cold Regions Research and Engineering Laboratory in Hanover, NH, Carnegie Mellon University the Desert Research Institute in Reno, Nevada, The Massachusetts Institute of Technology, Ohio State University, Pennsylvania State University, the New York State Department of Health, the State University of New York at Albany, the State University of New York at Buffalo, Lamont-Doherty Geological Observatory of Columbia University, University of Arizona, University of Colorado, University of Miami, University of New Hampshire, University of Rhode Island, University of Washington, the U. S. Geological Survey in Tacoma, Washington, and the University of Wisconsin.
GISP2 is funded by the United States National Science Foundation Division of Polar Programs as a part of the Arctic System Science Initiative (ARCSS). The University of New Hampshire coordinates GISP2 scientific activities. Logistical and drilling support is provided by the Polar Ice Coring Office (PICO) at the University of Alaska in Fairbanks. Permission to work in Greenland is generously provided by The Commission for Scientific Research in Greenland and the governments of Denmark and Greenland and is gratefully acknowledged. The 109th TAG Air National Guard, Schenectady, NY, and the U. S. Air Force Military Airlift Command from McGuire Air Force Base in New Jersey provide air transport. Support at Sondrestrom Air Base in Greenland is provide by the U.S. Air Force Space Command.