What do the Ice Core Bubbles Really Tell Us?

Guest Opinion: Dr. Tim Ball

At a recent public presentation titled “Whither the Weather” the most frequently asked question popped up once gain. “How do they know the temperatures from thousands of years ago, as in the Antarctic ice record.” I gave the standard answer about layers of ice, extraction of air from trapped bubbles and then comparison of the Oxygen 16/18 isotope ratio, which varies with atmospheric temperature. As always, people are dazzled by that, and even though they don’t understand, it sounds plausible. The trouble is that every time I give the answer, it triggers my long-term concerns about the nature of glaciers, glacial ice, entrapment of the bubble, and recovery methods of the air in the bubble. I spent hours discussing all aspects of glaciers and ice cores with the late Dr. Fritz Koerner, one of the few people to study glaciers in the Arctic and Antarctic.

Like all great scientists, he was very aware of the limitations of knowledge, data, and mechanisms in his area of research. I specifically recall him telling me that his work on Baffin and Ellesmere Islands was indicating that temperature changed before CO2 before it was disclosed in the Antarctic record.

The short answer to the question posed in the title to this article is virtually and practically nothing. They definitely do not tell us what is claimed, that is, accurate representation of the state of the atmosphere including temperature in individual years. This is why one of the world’s experts on atmospheric chemistry and ice cores Zbigniew Jaworowski M.D., Ph.D., D.Sc., wrote,

“It was never experimentally demonstrated that ice core records reliably represent the original atmospheric composition.”

Dr. Jaworowski was so respected as an atmospheric chemist that he was chosen to lead the United Nations (UN) investigation into the impact of the Chernobyl disaster. Of course, none of that muted the attacks on him because of his well-reasoned, fully documented views on climate change due to human production of CO2. Undoubtedly, the ad hominems will appear in comments about this article.

Just a few facts about the formation of the glaciers illustrate the problems. Glacier ice forms as precipitation fall above the snow line and accumulates in layers most of which survives the summer melt. These layers build up and change from snow, through firn (granular snow) then meld into layers of ice under the weight and pressure of overlying layers (Figure 1). This process of converting snow to ice takes years and varies depending on a variety of factors but especially temperature. The question is which year does the final bubble represent. How does it remain isolated and insulated from contamination in a very wet, dirty, and constantly changing situation? The answer is it doesn’t, and there is no way of saying that any layer at any level represents a particular year or even a span of years. As I recall Koerner told me that a core sample of eight meters was required at the bottom of Antarctic ice to yield enough sample for a single reading. The problem is at those depths, eight meters of ice represents 10,000 years of compression. How is that useful for climate when a single sample for the entire period of the Holocene Optimum.

Figure 1

A close-up of the layers of one glacier shows the problems of dirt and lack of distinction that occurs even above the glacial ice (Figure 2).

Figure 2.

At an approximate depth of 50 m (150ft), the ice becomes plastic and displays different characteristics than in the Brittle layer. This is why crevasses, that is cracks in the ice surface, only extend down to the Plastic Layer. In that Layer, ice flow deforms and gradually, with depth, most of the gases in the ice are squeezed out. Fischer summarizes the major problems with ice core bubbles as follows,

Due to glacier flow and in the top 50-100 m due to firnification annual layers in the ice become thinner with depth (Fig. 3). This restricts the resolution of ice core parameters in deeper ice and makes dating of ice cores (a crucial prerequisite for the interpretation of climate records) a difficult task.

However, going deeper into the ice sheet, where the hydrostatic pressure is increased, the air bubbles become smaller and smaller due to further deformation (creep) of the ice and the density increases slowly until all bubbles disappear.

The ice at the depth of the bubble enclosure is older than the enclosed air. This ice age/air age difference Δage has to be taken into account when comparing e.g. greenhouse gas concentration and temperature records from the same ice core.

The bubbles at a certain depth are not occluded at the same time. This implies that in a given sample the age of the air in individual bubbles is different. In addition, air needs a few years to diffuse down to the depth of bubble enclosure, also leading to a secondary broadening of the age distribution of the air at a certain depth.

So, the age of the ice is not the same age as the ice that surrounds it, and even the age of the air between bubbles is different. Fischer notes,

The gas records allow only a resolution of decades to a few centuries because of the slow bubble enclosure process (see below).

Apparently, they believe most of these differences are filtered out with statistics, but that doesn’t cover the useless nature of the results. To mask the problems even more, they apply a 70-year smoothing average to the raw data.

Then there is the constant flow of water across and through every portion of the glacier. Not only are glaciers dirty, as you can see in Figure 2, but they are also very wet. Water flows over, through and under them, in small amounts but also in great torrents. Every summer, even above the snow line, there is a period of melt and the water filters down through the snow in all its forms. This water constantly contaminates any bubbles within the ice, so it is virtually impossible for the air in that bubble to be uncontaminated. As Dr. Jaworowski observed,

The basic assumption behind the CO2 glaciology is a tacit view that air inclusions in ice are a closed system, which permanently preserves the original chemical and isotopic composition of gas, and thus that the inclusions are a suitable matrix for reliable reconstruction of the pre-industrial and ancient atmosphere. This assumption is in conflict with ample evidence from numerous earlier CO2 studies, indicating the opposite (see review in Jaworowski et al. 1992b).

He adds that additional assumptions are equally invalid.

1. No liquid phase occurs in the ice at a mean annual temperature of −24°C or less (Berner et al. 1977, Friedli et al. 1986, Raynaud and Barnola 1985).

2. The entrapment of air in ice is a mechanical process with no differentiation of gas components (Oeschger et al. 1985).

3. The original atmospheric air composition in the gas inclusions is preserved indefinitely (Oeschger et al. 1985).

4. The age of gases in the air bubbles is much younger than the age of the ice in which they are entrapped (Oeschger et al. 1985), the age difference ranging from several tens to several ten-thousands of years.

More than a decade ago, it was demonstrated that these four basic assumptions are invalid, that the ice cores cannot be regarded as a closed system, and that low pre-industrial concentrations of CO2, and of other trace greenhouse gases, are an artifact, caused by more than 20 physical-chemical processes operating in situ in the polar snow and ice, and in the ice cores. Drilling the cores is a brutal and polluting procedure, drastically disturbing the ice samples (Jaworowski 1994a, Jaworowski et al. 1990, Jaworowski et al. 1992a, and Jaworowski et al. 1992b).

It is interesting to note parallels in bad science between the ice core procedures and the computer models. They are based on false assumptions, inadequate untested data and are not validated. Sadly, it is a common theme of the deception that is human-caused global warming (AGW). I urge everybody to read Jaworowski’s article completely because it ties the ice core debacle into the wider debacle of international climate science.

I recall when the French scientists led by Petit, Jouzel, et al., announced the reconstruction of temperature, CO2, and Deuterium levels based on ice core data. One of them, as I recall Jouzel, warned about rushing to judgment. It was approximately five years later that research showed that temperature changes preceded CO2 changes, not as assumed, yet that is the theme still generally pushed to the public.

In the ice cores, the isotopically determined temperature signal and the signal of CO2 air concentrations are out of phase by hundreds to several thousands of years (Jaworowski et al. 1992b), with the temperature increases always preceding the rising CO2 levels, not the reverse (Caillon et al. 2003, Fischer et al. 1999, Idso 1988, Indermuhle et al. 2000, Monnin et al. 2001, and Mudelsee 2001).

All other measures agree with this juxtaposition regardless of the time period or length of record. But, even allowing for this, we have the problem that Jaworowski, nor anyone else to my satisfaction can answer.

Only recently, many years after the ice-based edifice of anthropogenic warming had reached a skyscraper height, did glaciologists start to study the fractionation of gases in snow and ice (for example, Killawee et al. 1998), and the structure of snow and firn which might play a first-order role in changing gas chemistry and isotopic profiles in the ice sheets (Albert 2004, Leeman and Albert 2002, and Severinghaus et al. 2001). Recently, Brooks Hurd, a high-purity-gas analyst, confirmed the previous criticism of ice core CO2 studies. He noted that the Knudsen diffusion effect, combined with inward diffusion, is depleting CO2 in ice cores exposed to drastic pressure changes (up to 320 bars—more than 300 times normal atmospheric pressure), and that it minimizes variations and reduces the maximums (Hurd 2006).

This is illustrated by comparing for the same time period, about 7,000 to 8,000 years before the present, two types of proxy estimates of CO2. The ice core data from the Taylor Dome, Antarctica, which are used to reconstruct the IPCC’s official historical record, feature an almost completely flat time trend and range, 260 to 264 ppmv (Indermuhle et al. 1999). On the other hand, fossil leaf stomata indices2 show CO2 concentrations ranging widely by more than 50 ppmv, between 270 and 326 ppmv ( Wagner et al. 2002).

The stomata record Jaworowski refers to is shown in Figure 3, shown for clarification with the original caption.

Figure 3

The range of variability of the stomata fits the record for the 90,000 19^th century direct atmospheric readings studied by Beck. It also fits the pre-manipulated record at Mauna Loa.

Jaworowski is saying that, like dendrochronology was misused for dendroclimatology, glaciology and specifically ice core research was coopted by the global warming hysteria created by the Intergovernmental Panel on Climate Change (IPCC). Ice cores were manipulated and massaged using inadequate assumptions, lack of understanding of physical and chemical mechanisms, and masked by statistics to produce a result.

This difference (between stomata and cores) strongly suggests that ice cores are not a proper matrix for reconstruction of the chemical composition of the ancient atmosphere.

Like so many of these claims of scientific certainty about past climate reconstructions, the ice core bubbles claims bear little scrutiny. They confirm A. N. Whitehead’s warning;

“There is no more common error than to assume that, because prolonged and accurate mathematical calculations have been made, the application of the result to some fact of nature is absolutely certain.”