Ice cores from Greenland and Antarctica are sacred pillars of evidence, establishing benchmarks of carbon dioxide (CO2) in Earth’s prehistoric atmospheres. But can ice actually preserve atmospheric air (free of contamination or chemical alteration) for thousands, tens of thousands, or hundreds of thousands of years?
Fossil vs. Artifact
A fossil is a remnant or impression of something that existed in past geological ages – an ancient form preserved in its original appearance.
An artifact is a product with an artificial character due to extraneous agency – an object that is left over from a sequence of creative events.
The question is: Do ice cores contain the fossils of Earth’s prehistoric atmospheres, or do ice cores contain artifacts of geophysical processes that continuously remix gases in glacial ice?
In 1992, a group of three otherwise respectable scientists answered this question with a 57-page article that went against the mainstream view . These three dissenters (led by Zbigniew Jaworowski) subsequently endured professional contempt , career endangerment , and harsh criticism . Between 1992 and 2007, Jaworowski produced three more notorious articles condemning ice core science , , .
Mainstream scientists argue convincingly against Jaworowski, and they continue to reject him today. A notable exception is Emeritus Professor of Organic Chemistry, Joel M. Kauffman, who uses Jaworowski’s case to help reexamine the highly controversial issue of human-caused climate change .
Jaworowski and his followers insist that ice cores are invalid media for determining CO2 concentrations in Earth’s prehistoric atmospheres, because:
- Ice sheets are NOT closed systems that trap gases mechanically and preserve them indefinitely. Instead, liquid saline water can exist in ice at temperatures below –70° C, within a permeable ice sheet where a capillary liquid network acts as a sieve to redistribute elements, isotopes and micro-particles.
- Air recovered from old ice is contaminated during field and laboratory operations.
- The widely accepted pre-industrial atmospheric CO2 level of 290 ppm rests on biased rejections of high CO2 readings in ice cores. Early studies on ice cores consistently showed a range of CO2 readings that were higher than later studies – in one case, a study by the same researcher on the same ice core showed different numbers in different years.
D. Raynaud and coauthors  admit that “several processes could cause the gas record measured in ice samples to be different from the original atmospheric composition.” They list the following processes:
- absorption of gases on the surface of snow and ice crystals,
- separation by gravity and molecular diffusion of the gases in the ice column,
- alteration of gas composition by formation of air hydrates at great depths in the ice sheet or by presence of drilling-induced fractures or thermal cracks in ice samples,
- alteration by chemical interaction between gases and ice on long time scales.
Raynaud assures us that researchers can test and calculate the effects of these interfering physical processes, citing papers by Ethridge and Neftel – two of the authors whom Jaworowski contests.
Critique Of Raynaud
In key sentences, Raynaud’s language is obscure and lacking in convincing detail – he appears to elevate strong statements of confidence above decisive descriptions of procedures that eliminate uncertainties in ice-core gas measurements. Raynaud easily dismisses ice-core CO2 testing methods before the 1980’s, claiming that these methods were inappropriate and that reliable results came only later. This argument (if true) overcomes Jaworoski’s objection of suspiciously higher CO2 measurements in ice cores prior to the 1980’s. A similar argument (used by Harro A. J. Meijer against Ernst-Georg Beck rules out much of the 19th century air measurements of CO2. Lack of knowledge, lack of skill, and lack of proper methodology all are mainstream arguments that reject CO2 measurements higher than 290 ppm before the year 1958.
Regarding the soundness of ice core science, Raynaud and coauthors conclude:
“It is now firmly established that after selecting appropriate sampling sites, the ice core record of greenhouse gases provides the most direct evidence for past atmospheric change.”
Expanding on Raynaud’s confidence, Christopher Readinger  writes:
“All of the modern analytical techniques used to extract these proxy records have been developed and honed over time, and with the assistance of better technology and new ideas, more accurate methods of ice core analyses are being developed.”
Looking at Readinger’s end list of limitations, however, a person could easily embrace the doubt that Jaworowski advises.