How long has it been since the Arctic pole was free of ice?

We know that Larsen ice shelf has been stable for 10s of thousands
of years, and that collapsed - the permafrost has been stable since the
last ice age, and that is melting.
How long has it been since the arctic ocean was ice free?

:)

I'm trying to get a gauge on what the imminent disappearance
of the arctic cap is telling us- going back into history for
comparison.
My sense is that it is something like millions of years.

Cores indicate the Arctic was even warmer then than today. If we're seeing this kind of melt-off with current temps, it's a safe bet that the Arctic melted down then too.

The climatic optimum follwed the ice age, and may have been triggered by freshwater from the post-glacial meltoff screwing with ocean currents. The Arctic stabilized to what we consider "normal" by about 6,000 years ago (it didn't happen all at once).

The portion of the Ayles Ice Shelf (North side of Ellesmere Island) that broke off in 2005 is believed to have ice that is 4500 yrs old.

Paleocene-Eocene Thermal Maximum, which I think was about 55 MYA.

Maybe somebody with a better paleoclimatology background than me could chime in?

:toast:

There is anecdotal evidence for this... farming in Greenland, reports of a (possibly apocryphal) navigable northern passage.

/leebert

the NW Passage is open now isn't it?

:hi:

The settlements have been found and the remains of seeds and plants have been found at those sites. The question is about how universal the medieval optimum really was. There is a lot of evidence indicating that the medieval optimum was a localized event relating to some sort of north Atlantic warming. If that was the case, it's hard to predict what the impact of that warming may have been on the northern ice sheet.

There's also the question of the lack of local oral tradition about a meltoff to contend with. The MCO happened in recorded human history, and yet there is no record from nothern European or Asian peoples discussing an Arctic meltoff. One would assume that if the ice they depended on completely retreated, it would have been a big deal. Big enough that the oral tradition of the meltoff would have survived until someone could have written it down.

This all doesn't prove that the Arctic didn't melt off in medieval days, but it does raise some serious questions. The Holocene Climactic Optimum, ending 6,000 years ago, remains the last melt off that we can conclusively point to as creating a virtually ice free Arctic.

...do you know of any work trying to figure out the extent of the Greenland ice-sheet during the MWP? It would be interesting to compare it to today's ice-sheet, but I don't know if there's any data to base a reconstruction on.