Laura:

I agree, good question of when the blackening of the glacier top occurred. Sorta reminds me of the plans Global Cooling concerned scientists had in the 70's to "fix" the cooling in that they were going to color the ice dark colors so the planet would asorb more heat. Hmmm...I wonder if that is the real reason. Maybe this was a secret test case for their experiments. Maybe this whole GW problem is related to this obviously uncontrolled experiment.

Or maybe not and it is just the result of nature.

The majority of glaciers that get so much print time, have only been around for 500-600 years. Since the ending of the LIA these glaciers have been in retreat. During the MWP, many passes in the Alps were wide open for Catholic Pilgrims who made their way to Rome. From 1320-1850, most of these passes closed due to rapid cooling, and copius amounts of precipiatation during all 4 seasons. In the summers, many of these glaciers would melt just enough to allow million of gallons of recent ice melt to burst down the mountain sides. Countless farms, villages, and pasture lands were destroyed this way. What didn't get destroyed, was eventually destoryed by rapidly expanding ice.

Many glaciers world wide have completely melted, only to return when the cold returns; In a period of 2000 years glacier melt, return, and melt again.

It appears that the Patagonian glaciers are so plentiful anybody can pick-and-choose one or the other to prove or disprove Global Warming.

For example the Pio XI glacier advanced for 50 straight years from 1945 to 1995. The Perito Moreno glacier has been used in movies by Al Gore (and by Frank Capra, in 1958) as proof of warming: unfortunately, they both show the phenomenon of calving, usually a characteristic of advancing glaciers.

And of course there are the dramatic pictures of the retreating Upsala glacier, whose story in truth is a bit complicated.

I have written a brief overview of the scientific literature on the topic at this URL: http://omnologos.wordpress.com/2007/03/15/misleading-pictures-wrong-caption/

regards
maurizio

Correct me if I am wrong, but wasn't Scott Pelly the reporter who compared those of us who think global warming is a farce to that of holocaust deniers?....Same old BS from the Comedy BS System!.....Remember?....The network that brought us Dan Rather????.....Excellece in Journalism 101???.....Unbiased reporting???......I laugh at you, CBS!...And may your ratings continue to falter!......

So....if the world gets its drinking water from glacial runoff and there is no water freezing on the glaciers.....am I the only one seeing the pattern here????? You drink water, there is less water to freeze up. The more water the world takes to drink, the less there is for glaciers. Or am I missing something here?

The blackened part will, or should, also show that there were times that part of the world was covered in dirt and possibly volcanic ash, soooooo that means that area was not always covered in ice. Another pattern we aren't supposed to see, maybe cycles in nature that change the ice?

Maurizio, it's interesting that for any given individual glacier one can point a finger at some degree of local natural causation for retreat. The problem is that when one looks at global data on glaciers, it turns out all of those fingers are attached to hands which are engaged in some rather furious waving.

This paper just out in PNAS sheds some interesting light on 20th Century climate change in the Patagonia/Antarctic Peninsula region. Climate is complex, and warming in a given region will affect more than just temperature. In this instance it appears that the dust may be a positive feedback leading to even more glacial retreat than would be the case from the warming alone. It also highlights the observation that global warming-induced drought rather than increased temperature as such is the greater short-term concern.

Dear Steve Bloom,
Do you have any quantitative analysis of the locations and intensities of this oncoming "global warming-induced drought"? Or is this just handwaving while invoking the mantra of "Climate is complex"?

Of course climate is complex and of course regional environments change over time. Given this plus the evidence of warming periods prior to industrialization (unexplained by the AGW mob), how does one justify drastic measures as put forth by the AGW crowd?

here's a novel concept. When do those in the Northern Hemphisphee start to see the warmth return? Oh yeah....they call that spring, and in the fall what does it do. Right, it turns cold. So maybe all this global warming up theory is the fear of Seasons And if I remember my geography correctly...the southern hemisphere sees the exact opposite.