Top Glaciologists: Alps Ice-Free 6,000 Years Ago When CO2 Lower
Dr. Sebastian Lüning earlier today released his latest Klimaschau report, No. 6 [Video at the end]. In the first part, he looks at glaciers in the Alps over the course of much of the Holocene.
It turns out that Most of the Alps were ice-free 6,000 years ago, glaciologists have discovered.
In his video, the German geologist presents a new paper authored by glaciologists Bohleber et al, 2020 of the Austrian Academy of Science.
The Austrian-Swiss team discovered from ice cores that the 3,500-meter high Weißseespitze summit was ice-free 5,900 years ago.
Much warmer in the early Holocene
Lüning next shows why the Alps were ice-free 6,000 years ago by using a chart by Heiri et al 2015, which shows it was some 2°C warmer than today.
Beginning some 10,000 years ago, after the Ice Age ended, all glaciers below 4,000 meters elevation in the East Alps melted away over the years that followed.
Then beginning 6,000 years ago, cooling started again and the glaciers returned (neoglaciation). Today, temperatures in the Alps are still well below early Holocene levels.
Today’s glacial retreat very much in debate
Roughly 5,300 years ago, Ötzi succumbed to injuries just a few kilometers from the Weißseespitze, says Lüning.
“The historical glacier melt show that today’s glacier retreat is not a new phenomenon. Whether or not there will be another complete melting of the East Alps glaciers remains a scientific debate.”
Also, you’ll find many more non-alarmist articles on glaciers here.
All images cropped from Klimaschau, Ausgabe 6
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Jerry Krause
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Hi Kyle and PSI Readers,
I take this opportunity to review what I know about glaciation. First and foremost: It has to snow a lot to form a deep layer of glacier ice. I consider there are two classes of glaciers: mountain (severely sloped) and level (slightly sloped). And I do not yet claim to know much about the latter.
An observed fact (I believe) is that the snow which falls on the steep slopes of mountains has a tendency to slide down the steep slopes to a lesser slope where the snow (fresh snow flakes or packed snow) piles up to a greater depth.
The greater depth is a critical factor because I know pressure melts ice even if the temperature of the ice is less than its melting temperature. So, at some point, as the snow piles up, it beginning to melt at its base. If the base is merely porous packed snow, the melting will create a cavity, reducing the pressure at the bottom of the formed cavity and the liquid water will refreeze if the temperature is slightly below ice’s melting temperature. By this crudely explained mechanism snow is converted to solid ice.
As thicker layers of solid ice are formed the pressure upon this solid ice base will begin to melt it again. And now a cavity will not form and the liquid water will need to percolate down through a porous ground or if ground surface is solid rock, the liquid water need to begin to drain downslope at the interface between rock and ice.
Now on more fact I have experienced: wet ice is very slippery.
Zoe, I also claim to know about geothermal energy. So, pressure is not the only factor which will melt the ice at the base of a glacier.
Have a good day, Jerry
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Jerry Krause
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Hi PSI Readers,
Is it happenstance the the following three articles touch each other here at PSI? ‘Top Glaciologists: Alps Ice-Free 6,000 Years Ago When CO2 Lower’ ‘A Critique Of Geological Society Of London Scientific Statement On Climate’ ‘Sea-Level Rise? Hundreds Of Pacific Islands Getting Bigger’
I have made comments to each of these articles but I consider the glaciers of the Alps focuses our attentions’ most directly upon the scientific issue of climate change. And as I pondered what had written about the glaciers of the Alps I saw that I had ignored the GEOGRAPHY of the Alps.
Kyle had even supplied a map of the Alps, But I forget so often. A portion of the Alps has a NORTH-SOUTH orientation and a portion has an EAST-WEST orientation. And just to the south of both are nearby seas of warm water. And it should not surprise any one who studies climate that climates of localize ares can be quite different because of what I term ‘geography’.
The first thing I recognized that I have overlooked was that there were North facing steep slopes upon which there is never direct insolation of solar radiation. Another thing I finally remembered was that although that a snow surface has an high albedo, I have observed how in the spring that direct solar radiation (at about 45N latitude) begins to significantly melt snow at midday and at about 4pm the melted water begins to refreeze (given a generally cloudless sky). Of course, the snow on a steep north slope is not melted. So, I expect, but don’t know, that the glaciers of the Alps which are a somewhat permanent are found on these north slopes and not on the south slopes. Except where the Alp range is north-south the south peaks shade the south slope of the northern peaks.
I believe that general speculations like this suggests where a scientist should direct his/her attentions to actually observe what is being generally reasoned.
Like when Kyle wrote: “Roughly 5,300 years ago, Ötzi succumbed to injuries just a few kilometers from the Weißseespitze, says Lüning.”. Details (words) are important. I have never climbed mountains but I claim to know that when climbing mountains ‘a few kilometers’ is not an insignificant factor.
We must ask: where specifically was he found? South, north, east, or west? We must ask: Did the glacier on which he was climbing slide down (a few kilometers) the steeper upper slopes to the lower, less steep, slopes where he was found? We must ask: when Luning says ‘a few kilometers’ is he referring to vertical distance, horizontal distance, or a combination of both. Long ago Louis Elzevir wrote: “Intuitive knowledge keeps pace with accurate definition.” In SCIENCE we must accurately define what we are writing or reasoning (pondering).
But most important of all we must have extensive dialogues (discussions); not only disconnected articles and comments here and there.
Please join me in a discussion of what Kyle wrote and of what I am sharing.
Have a good day, Jerry
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