SummitPost.org

Might be of interested to SP members.

http://news.yahoo.com/s/ap/20061205/ap_ ... ng_in_alps

Not meant to be a P&P dabate-type post, but I thought it was interesting.

In the June, 2004, edition of the "Die Alpen", the offical magazine of the Swiss Alpine Club, there was anarticle that detailed research in Switzerland that established that when Hannibal was crossing the Alps with his elephants, the Alps were much warmer than today and had actually few glaciers. How? By the tree trunks and other things that are coming exposed by the currently receding glaciers. There has been apparently a regular cycle of warming has lasted anywhere from 100 to 1800 years. So is this present "global warming" caused or accelerated by humans or is this part of a cycle that is actually a precursor to the next mini or full ice age soon to come? Stay tuned...

Moni wrote:In the June, 2004, edition of the "Die Alpen", the offical magazine of the Swiss Alpine Club, there was anarticle that detailed research in Switzerland that established that when Hannibal was crossing the Alps with his elephants, the Alps were much warmer than today and had actually few glaciers. How? By the tree trunks and other things that are coming exposed by the currently receding glaciers. There has been apparently a regular cycle of warming to the point of few European glaciers that has lasted anywhere from 100 to 1800 years. So is this present "global warming" caused or accelerated by humans or is this part of a cycle that is actually a precursor to the next mini or full ice age soon to come? Stay tuned...

First, I'm not committed to any particular view on anthropogenic global warming.

But in N America as well, some glaciers first formed only 700-500 years ago during the first part of the "Little Ice Age" (LIA). Those glaciers are now retreating very quickly. The LIA is a rather poorly defined period world-wide -- e.g. some say it really ended (in some places) only 150 years ago, and in some places, it didn't seem to do much at all.

These "recent" oscillations are really fairly small amplitude compared to the large changes that have taken place since the last real ice age, when sea level was ~120 m lower (i.e., 20k years back). The LIA was too short and low intensity to greatly affect global sea level -- at least, within the poor resolution of historical measurements. So the folks whose villages got run over by glaciers probably felt LIA was a big deal, but LIA was nothing compared to a period of continental ice sheets.

I've tried to keep up with the debate(s) on the tree-ring geothermometer. The "thermometer" is often calibated against historical temperature measurements, which only go back to about 1750, and the correlation (of ring isotopic composition & thickness with temperature) doesn't seem that good. There is a lot of statistical treatment of the data, and unfortunately, the studies are not "blind" -- that is, the researchers are humans with subliminal leanings about the "correct" answer. Nor are the pre-1900 T measurements all that reliable. Ring thickness is affected by other things beside temperature -- e.g., drought.

What were we talking about?