It's getting a little hard for the press to keep up with the required twice-weekly global warming scare story, so, a few days ago, NBC reached into the recycling bin for an old chestnut: Glaciers are melting at our national treasure, Glacier National Park, and it's a result of pernicious human influence on the atmosphere. On the program, reporter Jim Avila claimed that "the temperature's gone up an average 3 1/2 degrees in the park during the last 110 years."
A closer, more scientific look at the data reveals a different picture. The way we take reliable estimates of temperature is to measure it over a broad area--usually several counties--with an array of thermometers. This is the methodology used by the National Climatic Data Center, the country's "official" climate repository. They have divided the nation into a couple of hundred "Climatological Divisions" (CDs). Their professionals and volunteers monitor calibrated instruments within each division, and then monthly and annual temperatures are calculated by averaging the readings.
At our latitude, glaciers melt in the summer. Beginning in September and ending in May, it snows frequently at Glacier Park, which is one of the reasons for its glaciers, to begin with. You can download the history of the Western Montana Climatological Division ("Montana CD 01") for yourself, at http://www.wrcc.dri.edu. This site is the academically lustrous Desert Research Institute at the University of Nevada and "wrcc" is the Western Regional Climate Center, headed by Dr. Kelly Redmond, one of America's most careful and savvy climatologists.
All of the CD records have a common starting point in 1895. Inspection of the entire summer history yields no statistically significant warming whatsoever in Montana 01. Ditto for the annual record, although that is not as important as the summer readings. In other words, Glacier's glaciers are being melted by temperatures that show no summer warming distinguishable from natural year-to-year variability over the last 107 years.
With climate data, it's easy to play the standard game of picking a starting point in the record to prove a point. Precisely, one can come up with 3 1/2 degrees of warming by looking at data beginning in 1950, rather than considering the entire history.
The reality is that Glacier Park's glaciers are melting today because the summer temperature is the same, on average, as it was when the record begins, 107 years ago. They were melting then, too, which was before people burned much fossil fuel, altering the earth's natural greenhouse effect. They started to melt as the region emerged from what is sometimes called the "Little Ice Age," a cold period that ended in the middle of the 19th century.
This incident recalls similarly breathless and shoddy reporting two years ago about the melting of the hemisphere's largest ice complex, the Greenland ice cap, and its outflow glaciers. The overall ice balance turns out to be nearly neutral, but the southern end is melting. We also have a large number of surprisingly good climate records at and near the regions of maximum melting. There hasn't been any warming for a long time. Every graduate student who has ever passed a comprehensive exam in climatology knows that temperatures have been going down in this region for about 70 years. Like Glacier National Park, southern Greenland also warmed in the 19th century with the climb-out from the Little Ice Age.
For what it's worth, some knowledgeable people think that this decline in regional temperature is caused by global warming (and others do not). But it is getting colder up there, even as the glaciers retreat. As scientists who study Greenland speculated two years ago, the melting rate must have been prodigious in the early part of the 20th century (or nearly 100 years ago) when Greenland was warmer than it is now.
Why didn't NBC check the regional temperature records for western Montana? Instead of recycling an old story, they could have produced a much better one--real news--by showing that Glacier's' glaciers have been melting like this for well over a century and are doing so without any net regional summer warming in the last 100 years.
It's a fact that many other glaciers around the world are melting because of local and regional changes that correlate with human combustion of fossil fuels, but not the disappearing ice fields of Glacier National Park.