Geo-Joint: Glacier National Park

Glacier National Park

Original Image: Emily Hildebrand

While a small rise in temperature may make you feel a bit warmer, it doesn’t change much about your surroundings if you live in a temperate place.  But if your neighborhood experiences extreme cold and you live with a lot of ice, that small rise in temperature may begin to change the very look of your landscape.  When winter snowfall (usually in a mountainous area) exceeds summer snowmelt, ice accumulates.  When it has exceded about 25 acres in size,  and begins to flow downhill, we call it a glacier.  Glaciers typically advance and retreat seasonally depending upon short-term fluctuations in temperature and precipitation.  Snow obviously adds to the glacier, while rain diminishes it. When the climate changes enough however, what was once a very icy landscape becomes bare rock, with serious implications for the local flora and fauna.

Intensive studies at Glacier National Park in northwestern Montana confirm what the eye can see, that the alpine glaciers there are shrinking and in some cases, disappearing altogether.  Perhaps more striking than the deflation of the massive glaciers in Greenland, the smaller and more southerly glaciers in Montana are shrivelling up quite noticeably.  The craggy mountains of Glacier National Park were carved by a glacial period that ended some 12,000 years ago.  The glaciers you see there on your vacation today were formed only about 7,000 years ago.  Scientists can tell from moraines (the piles of rock and soil debris left behind by melting glaciers) that the ice in the park reached a maximum relatively recently, around 1850.  Data collected over the last century shows that summer temperatures have been rising, and winter snowfall declining generally, since 1900.  Of the 150 glaciers that existed in 1850, only 26 remain, and almost all are much diminished.  The cyclical variations of climate such as the Pacific Decadal Oscillation (an ocean-derived temperature fluctuation) have sometimes fed this glacier-unfriendly change, but of late the general warming has accelerated, and more rapidly than had been predicted.  Scientists now forecast the loss of all the park’s glaciers by 2030.

glacerchange

Image: USGS

What does it matter, beyond the loss of scenic white fields cascading down lofty mountain peaks?   Glaciers store water year-round, and slow summer melting feeds streams and rivers even if one year’s meager snowfall delivers insufficient runoff.  This is of benefit not only to human water needs, but for plants and animals, especially fish, which depend upon a reliable flow.  Summer rain may make up for some lack of glacial melt but that water is of a higher temperature and less suitable for organisms that have evolved to require colder temperatures for survival.   Within the park, besides the increased melting of the glaciers, climate change has altered the water content of the snowpack and brought earlier spring melting.  Warmer temperatures have encouraged the population of the mountain pine beetle, leading to increased tree mortality and subsequent fire danger.  Fire is also facilitated by the drier conditions brought on by the loss of glacial meltwater.

Unlike the melting of the tundra in faraway Alaska, Glacier National Park is a highly visible and closer-to-home example that our world is changing rapidly, with losses that affect both scenic vistas and the web of life.

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