If ice is 3,000 years old what does that tell you about melting patterns after the glaciation period?
In a question yesterday it was mentioned that the chunk of ice that broke off of an ice shelf near Alberta Canada was 3,000 years old.
I feel there's some significance here when you think about when we came out of the last Glaciation period about 10,000 years ago.
I just want everyone to think about this a bit and about the Ice Melting and Reforming pattern this would represent during the interglacial period that we're in now.
2008-07-31T05:59:12Z
But since this ice was only 3,000 years old and not 100,000 years old, doesn't it also tell you that this area had melted and broken up before and refroze during this interglacial period?
Anonymous2008-07-31T07:43:02Z
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We've had warming, thus melting, off and on since the end of the Ice Age, and 3000 years ago it was cooling somewhat after the Holocene Maximum, thus new ice shelves formed.
The Alps have been ice free or close to it three or four times since the HM. Glacial retreat in the Alps is revealing artefacts used during past warm periods. Tree lines were higher in other mountain ranges at different times.
Similarly, most of the oldest coral reefs are 700 years old or less - dating back to the onset of the LIA.
"But since this ice was only 3,000 years old and not 100,000 years old, doesn't it also tell you that this area had melted and broken up before and refroze during this interglacial period?"
EXACTLY.
Does that disprove man-made warming today?
No.
It does mean that the mere fact of warming is not by itself proof of its cause.
ice was slowly building up. More was produced in winter than melted in summer. That's the source of the 3000 year old ice.
Because of our production of greenhouse gases causing warming (the righthand edge of the graph is darn near a vertical line up), that pattern is now reversed. The average mass of the Arctic ice cap throughout the year is now dramatically less than it was at any time in the past 100 years.
In reality unless ice is trapped inside a mountain valley like most of the Greenland and Antarctica ice is it will eventually flow to the sea and break off as ice bergs. It has been doing that for millions of years and will continue so until the sun goes nova.
Unless we are in a full-blown ice age, ice does not just sit in one spot forever. It is going to flow downhill and ultimately break off. This is typically a slow process, depending on whether or not the Earth is in a warming or cooling period, volcanic activity under the ice, ocean currents....etc. Ice shelves have and will continue to occasionally break off..... this has occurred 'naturally' for millions of years.
It tells me that that 3000 year old ice moved to a point where the pressure was enough to crack it and break it off the ice shelf. Glaciers move. That's just the way it is. Always has been, always will be.