My search-fu appears to be somewhat lacking…
Do the results from ice cores around the world correllate with regard to atmospheric bubbles? E.g. do the ice cores from (say) the Himalayas correllate with those from Greenland and the Antarctic?
What do the Antarctic cores say about the Antarctic ozone hole? Likewise Arctic ones?
Glaciers, as in the Himalayas, are “rivers of ice”" that move downslope and melt at their terminal end. Hence glacial ice is usually not all that old (although the glacier itself may have existed for a long time). To get an extended climate record you need ice that has been in one place for a very long time, as in the ice caps of Greenland and Antarctica.
Atmospheric bubbles in ice cores are used to look at past levels of gases such as carbon dioxide in the atmosphere, not the “ozone hole,” which concerns mainly the uppermost levels of the atmosphere. The ozone hole is only a few decades old so long ice cores wouldn’t be necessary to study it in any case.
I think the idea is to test the hypothesis that ozone holes are a cyclic natural phenomenon. If there were evidence of an ozone hole ten thousand years ago, for instance, that would imply that they’re not strictly anthropogenic.
And even though ice cores don’t sample the atmosphere at ozone height, it’s still conceivable that they might carry some indicator of surface UV levels, which would in turn be an indicator for the thickness of the ozone layer.
Are you aware of any such studies, or hypotheses, or are you just speculating?
I don’t know whether it’s ever been addressed in the scientific literature, but I have seen the speculation in the popular press. Unfortunately, I can’t recall any specific instances.
Regardless of the source, though, it’s a testable scientific hypothesis.
What kind of signature, specifically, would you expect to find in ice cores regarding past UV levels?
Specifically, I don’t know if there are any, or what they would be if there were. I said it was a testable hypothesis, not an easily testable hypothesis. If nothing else, we could test it by ceasing all production of halogen compounds, waiting a few millenia, and seeing if the hole is still around (which would still be easy, compared with, say, testing the String Model).
Don’t you mean, ‘we have only known about it for a few decades’?
Anyway, the questions were mostly seperate.
What concerns me for the first question is that we have several widely seperated areas with long-standing ice - I thought there was such in the Himalayas as well as the glaciers, but colour me educated - so if we’re looking at data from one source, we should be able to corroborate it with the other sources. I’m remembering that with dendrochronology they can date wood pretty accurately by looking at the tree rings and thinking that something similar might be doable with ice cores. If we can’t corroborate (as in not technically possible rather than the data does not corroborate) - or haven’t - then surely ice core data should be classed as unreliable? But my search-fu is lacking on this. Are we drawing all sorts of conclusions from unverified data?
Secondly, with regard to the ozone holes, it might be one reason why the ice cores do not corroborate, but if there were a consistent and logical mismatch, then we could deduce when and where the ozone hole was. But perhaps there are insufficient ice core sample locations?
No. We know it didn’t exist a few decades ago.
One could presume that the fact that the majority of the scientific community regards ice core data as reliable evidence indicated that the correlation has already been proven solid, and not presume that they make a habit of wild speculations. But then again, I’m not impressed with the academic rigor of a lot of science in other areas I see in the last decade or so, so evidence is always welcome.
This article from the American Chemical Society from nearly a decade ago seems to give a fairly simple yet detailed overview of the methodology and interpretation of ice cores.
maybe you can use it to inform yourself enough to decide if the data correlates to your liking.
Cite. But that doesn’t mean that there weren’t earlier holes.
What is your hypothesis for why they would have existed? What mechanism do you propose?
Now, that’s good stuff. Thank you.
So, we have only three survey sites in Antarctica.
This actually answers my first question: it’s not actually possible to directly correllate the ice cores from Greenland and Antarctica, but indirect correllation can be done.
I have no hypothesis that they did or did not exist. I’m simply asking the question.
Ice cores have shown that solar flares caused ozone depletion in 1859. However, this is a completely different mechanism than that involved in the creation of the present ozone hole.
The cause of modern ozone depletion is pretty well understood at this point to be chlorofluorocarbons, which are human-produced. Naturally occuring sources of chlorine, such as volcanoes and oceans, produce it in a form that is easily washed out of the atmosphere, in contrast to CFCs, which persist. Unless it can be established that there was some natural source of CFCs in the past, earlier episodes of ozone depletion would have little relevance to this one.
And that’s #2. I wonder if ice cores show other, earlier depletions?
However, ice cores are not the only climatological record we have.
This article about a core from a couple of years ago mentions the fact that the marine sediment record matches fairly well with ice core records. It also mentions some other interesting information.
When you talk about corroborating the data, are you talking about the dating of the layers? As I understand it, that can be corroborated with dates of known volcanic eruptions - ash residues of the right composition are found in the layers we would expect to find it if our assessment of the age is correct.
The excellent link scotandrsn supplied shows that this cannot be done to the same degree of accuracy.