I was forwarded a slide show presentation done by Thomas Lowell et al of the University of Cincinnati titled: Organic Remains from the Istorvet Ice Cap, Liverpool Land, East Greenland: A Record of Late Holocene Climate Change
It was presented last week at AGU’s Greenland Climate Change Past and Present session. It has some very interesting data in it. In summary it has a report on occurrence of subfossil organic remains, with organics recovered in locations presently void of plant growth.
Picture of Istorvet organic remnants at edge of glacier melt.
The preliminary conclusion from the data collected in the field work is that presently the small ice caps at high latitudes in Greenland are retracting to locations where they were at 1000 years ago. The presence of subfossil vegetation was found within 280 vertical meters of ice cap summit and where comparable modern assemblages do not exist. The implication seems to be that there were warmer periods in these areas prior to today, warm enough for plant growth.
According to the study, the organic material in Liverpool Land radiocarbon dates from 400 to 1015 AD. It is interesting to note that the Vikings settled in Greenland around 974 AD and the study indicates that ice cap expansion began around 1015 AD.
While the UC team that did the field work still has more work to do to reconstruct temperatures from this data, the study lends support to the idea that Greenland’s climate was warmer approximately 1000 years ago. One of the organic samples recovered at another location was dated to 910BC. This makes one wonder just how often shifts in Greenland’s climate occurs.
More study is needed, but this is certainly interesting. You can view the abstract here
Anthony,
Are you allowed to post the Greenland Climate Change presentation for downloading? I would like to have it.
Thanks,
Reply: I’m waiting for that
Did he state a causation, or just the facts that melting is not unprecedented.
REPLY: No causation, simply reporting of findings from field work and the implications for the apparent temperatures durign the period.
I am always troubled by folks on both sides of the AGW debate who seem to think a glacier is a thermometer. Like tree-rings, the present extent of glaciation is a proxy for a combination of things of which temperature is only one. Glaciers present a snapshot of a record of precipitation, freezing, melting, sublimation, run-on, runoff, flow due to gravity and perhaps some other effects as well.
Some in the pro-AGW camp seem to think that every glacier is in perfect equilibrium and that minor changes in temperature can be used to explain everything they observe. That is sloppy thinking. So, finding recent organics under an receding glacier is no surprise, but it is also not a guaranteed measure of temperature unless you know the rest of the information a glacier has recorded over the centuries.
I have been wondering for quite a long time about the extent and volume of the Greenland glacier a thousand years back. Especially in relation to sea levels 1000ya as compared with today.
Unfortunately, historical maps are–very–poor prior to the Age of Exploration. The Mercator projection (which distorts size, but is ideal for navigation) did not exist until around 1530. (One of the several very compelling arguments against the Vinland map being genuine is that it is laid out much in the manner of Mercator, and the boreholes match a volume dated 1480).
So it becomes very difficult to determine sea levels, seeing as how the Medieval “T maps” are done on a religious rather than a geographical basis.
I have seen a good many of the ancient maps (I have photostat copies squirreled away), and the coastlines, while somewhat distorted, seem substantially the same as today’s: No “exta land” showing or notable “known features” missing.
But that doesn’t mean an awful lot.
Perhaps a professional paleocartographer should take a look at some of the period maps and try to relate them to what we now know about glacier extent and sea levels. See how it all compares with the archaeological and geological end of it.
[…] The preliminary conclusion from the data collected in the field work is that presently the small ice caps at high latitudes in Greenland are retracting to locations where they were at 1000 years ago. (Watts Up With That?) […]