The GW advocates are fond of pointing to anecdotal evidence like glaciers retreating to substantiate their argument that man-made carbon dioxide is causing global warming. Their argument gets a bit fuzzy more than 30 or 40 years ago, before the SUV so to speak, or more specifically, before the increase in industrial CO2 pointed to by Gore in his documentary An Inconvenient Truth.
I'm fond of pointing out that global warming has been going on for at
least 200 years, if not longer, ever since a period known to history as
The Little Ice Age. Glaciers have been receding for at least the last 200 years. The GW advocates have to find 200 years of man-made causality beyond natural climate change to explain that!
Now we have the beginnings of anecdotal evidence that glaciers are growing again, at least in Alaska. GW has flatlined since 1998 and has dropped in the last two years, probably due to the Pacific Decadel Oscillation, the source of El Nino's and La Nina's, which also appears to be chilling Alaska. The PDO flipped from cool to warm in 1977, and most of the anecdotal evidence for man-made GW comes from the period 1979 to 2006 when the PDO was in a warm phase. It recently flipped back to a cool phase.
Now, a couple of years does not make a change of climate trend, but it does show up the overt and unscientific confirmatory bias of GW advocates who see GW in any climate change.
UPDATE: after ClimateGate, we have begun seeing more balanced reporting. An example is an AP report on Glacier National Park. Glacier Park is used as one of those anecdotes about global warming, since when people visit, they say, "where are all the glaciers?" AP correctly reports that the glaciers had begun melting in 1850, sixty years before it was made a national park. Around the time John Muir was making Yosemite a point of huge interest, George Bird Grinnell was pushing for similar status for Glacier Park. The retreat of the glaciers was noted back then during a similar warming period as we have just come through.
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