There’s definitely neat stuff going on in the arctic these days. I havent read much about the Ayles ice shelf, but

I suspect that the 3000 year old ice was part of the ice sheet initially, which gradually flowed into the floating ice shelf

One thing that might be worth pointing out about glacier change is that glaciers and ice shelves are constantly recirculating ice, the same way a river recirculates water — the river may have been there for centuries, but the water is exchanged weekly to monthly.  While the ice shelve has been there a long time, the actual ice is changing constantly. The reason I mention this is that there is a dynamic component to glaciers, and these dynamics are related to some degree by climate.

For example, over the past few years, a trend has started with the glaciers that have been draining the Greenland ice sheet, where they have begun a sudden acceleration in recent years. It began with the southern-most glaciers and is working its way north, with glaciers more than doubling in speed and ice berg discharge. What’s likely happening here is that a point of instability has been exceeded that was initially triggered by climate change but is now decoupled from it. Some of these glaciers are moving more than 10 km/year and retreating almost as fast; this makes measurements very difficult and somewhat dangerous. These glaciers will continue to speed up and discharge more ice bergs largely independent of climate, until such time as they find a way to slow themselves down, like retreating through a narrow constriction.

There’s a meeting on arctic glaciers happening in Switzerland next week and we’ll learn what the latest is then: www.phys.uu.nl/%7Ewwwimau/research/ice_climate/iasc_wag/activities.html

Good point - ice is indeed constantly renewing itself, but as you say, the 3,000 year old ice must have originally been compacted on land before flowing out over the water. Parts of the mid-Greenland ice caps may contain water which froze many many thousands of years ago; see Roy Koerner’s site at www.science.gc.ca/default.asp?Lang=En&n=D4359403-1&edit=off

I’ve been doing some research into the addition of fresh water to the salinated sea water and what the result of that will be. Its amazing to me to see how interconnected all these factors are. Its one of the things that makes it hard to understand. I was standing in line for an ice cream yesterday (well, it was 65 degrees after all!) and the youngish people behind me in line were commenting on how “weird and awesome” the weather is, and how its probably climate change, and then they riffed on all the impossible science fiction weather scenarios their imaginations could drum up–such as snow until August and then summer in winter, etc. What was interesting about this conversation was how the every weather changes suddenly seemed not unlike science fiction–where the ordinary becomes improbable.