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In a critique (or possibly a rant) against modern climate science, Swiss geologist Christian Schlüchter makes a very specific claim that Alpine glaciers were essentially non-existent (or very much smaller than they are today) in Roman times. From a blog translating his original interview:

...the glaciers during the Roman times were at least 300 to 500 meters higher than today. “The mean temperature was one and half degree Celsius above that of 2005. The current development is nothing new in terms of the earth’s history.”

More specifically:

Early in the interview Schlüchter reminds us that during Roman times in the Alps “the forest line was much higher than it is today; there were hardly any glaciers. Nowhere in the detailed travel accounts from Roman times are glaciers mentioned.”

There are a number of contentious criticisms of climate science and some highly debatable claims about causality (is it all about the sun?). And I can't think of an easy way to verify Roman temperatures that wouldn't be controversial.

But the claim that Alpine glaciers were much smaller is surely a matter of history and should be verifiable from historical sources. So, is his claim that they were much smaller in Roman times correct?

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    Off-hand, if they are referring to the Roman Warm Peiord the claim is plausible but I'd have to do some research to verify everything. – rjzii Jun 9 '14 at 23:25
  • This gives a great example of how to exercise skepticism of blogs. The blog linked by @matt_blak is titled "Giant Of Geology/Glaciology Christian Schlüchter Refutes CO2…Feature Interview Throws Climate Science Into Disarray", however google translate suggests he actually said "The CO 2 played no role in the melting of glaciers? CO 2 plays a role. But you can not explain it for the sole reason, without explaining the motions of glaciers in the 1980s.". Nobody claims that all climate change is due to CO2, that is a blatant straw man. – Dikran Marsupial Jun 19 '14 at 18:58
  • The translation isn't great, but it looks to me like he was asked some very leading questions, which have then been cherry picked by blogs such as the one @matt_black refers to. It is a shame that this sort of thing happens, but google translate is a useful tool for the skeptic. The translations are not all that great, but you can see what the author chose not to include in the blog. – Dikran Marsupial Jun 19 '14 at 19:02
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This paper seems to suggest that the Romans didn't have a specific term for glacier, but their travel writers did describe things that are plausibly glaciers. This would imply that the claim "Nowhere in the detailed travel accounts from Roman times are glaciers mentioned." is ill-informed if not actually factually incorrect. This also implies that we can't expect to be able to unambiguously verify glacial extents from historical sources, and certainly can't use the absence of evidence that Schlüchter's claim is correct.

Does this mean that Alpine glaciers were smaller in Roman times? There seems to be some evidence that they were, e.g. Roman coins revealed by glacier retreat (reported by the BBC), however that doesn't mean the Romans didn't traverse the glacier, rather than that it wasn't there, or that the glacier had not transported them from higher up the mountain. However later in the article, we read "The fact that we still find these 5,000-year-old pieces of leather tells us they were protected by the ice all this time, and that the glaciers have never been smaller than in the year 2003 and the years following." which directly refutes the claims.

It is worth noting that the BBC article also says "The site is exactly at the point where the glacier responds most sensitively to short-term climate change and temperature variations," he explains. "So if we get more carbon datings from this site, we can get the most precise picture of short-term glacier fluctuations for the past six or 7,000 years.". This suggests we should be cautious in interpreting such regional changes in glaciers as strong evidence regarding global climate.

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The only easy way to "verify" Roman Warm Period temperatures is through proxies. And we need many proxies from many different locations to begin to estimate global temperature as opposed to just the local/regional temperature. Different proxies may also respond to different temperature timescales and variables other than just temperature are typically involved. It's an area of ongoing research, that's for sure. One of these proxies is actually glaciers.

Although Schluchter's work is certainly helpful to the wider body of literature and may provide more information about the local climate of his study area, he is going beyond the applicability of his data by discussing global climate. And the worst part is that he thinks his data, by itself applicable to local climate, somehow negates all other temperature reconstructions that found different answers. He also made statements regarding "growth" of glaciers in the 1980s; this can also be verified as inaccurate (see Skeptical Science). This is just a brief list of issues with Schluchter's statements, however there are many more issues. As expected, his statements are spreading like wildfire with very limited skepticism, at least among some people.

  • Welcome to Skeptics!. Your first paragraph has no references, and seems to be avoiding the question. The question is specifically about glaciers. The second paragraph attacks the source with no substantiation. The only reference doesn't address anything earlier than the 20th Century. – Oddthinking Jun 20 '14 at 5:15

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