View attachment 297926
All the signs had to be removed because.. the glaciers are still there..... and GROWING!
Glacier National Park Quietly Removes Its ‘Gone by 2020’ Signs
Melting Glaciers - Glacier National Park (U.S. National Park Service)
In 1966, the park had 35 named glaciers large enough to be considered active. By 2015, only 26 named glaciers remained. The average area reduction was 39 percent, though some lost as much as 85 percent. This trend of glacier retreat is expected to continue as temperatures rise.
As usual you present a very short history, to make misleading conclusions. Lets try the entire interglacial period instead:
"At the Last Glacial Maximum (approximately 20,000 years ago), GNP was almost entirely encased in ice, with glaciers filling mountain valleys and extending onto the plains (Carrara, 1989). All but the tallest peaks were covered by glaciers. Geologic evidence suggests that by approximately 11,500 years ago, the GNP landscape was nearly ice free (Porter and others, 1983). Lake sediment records suggest that, since approximately 6,500 years ago, small glaciers have been present and active (Munroe and others, 2012).Comprehensive mapping of glacial moraines (fig. 3) indicates that there were 146 small mountain glaciers in GNP at the Little Ice Age glacial maximum near the mid-19th century (Fagre and Martin-Mikle, 2019). Since then, every glacier has decreased in area (Fagre and others, 2017). The rate of retreat, however, is not uniform across GNP glaciers, likely because of variations in glacier geometry, elevation, ice thickness, wind effects on snow, snow avalanches (fig. 4), and shading (Florentine and others, 2018)."
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