In 1850, at the end of the Little Ice Age, there were an estimated 150 glaciers in the area that is now Glacier Park. By 1968, these had been reduced to around 50. Today the number of glaciers in the park is 25, many of which are mere remnants of what they once were. Rapid retreat of mountain glaciers is not just happening in the park, but is occurring worldwide.
https://www.nps.gov/glac/learn/education/glaciers.htm
In polar and high-altitude alpine regions, glaciers generally accumulate more snow in the winter than they lose in the summer from melting, evaporation, or calving. If the accumulated snow survives one melt season, it forms a denser, more compressed layer called firn.
http://nsidc.org/cryosphere/glaciers/life-glacier.html
Glacier retreat, melt, and ablation result from increasing temperature, evaporation, and wind scouring. Ablation is a natural and seasonal part of glacier life. As long as snow accumulation equals or is greater than melt and ablation, a glacier will remain in balance or even grow. Once winter snowfall decreases, or summer melt increases, the glacier will begin to retreat.
http://nsidc.org/cryosphere/glaciers/life-glacier.html
Over the past 60 to 100 years, glaciers worldwide have tended to retreat. Alpine glaciers, which are typically smaller and less stable to begin with, seem particularly susceptible to retreat. Over 90 percent of the measured alpine glaciers in the world are retreating, in almost every major glaciated region.
http://nsidc.org/cryosphere/glaciers/life-glacier.html
During the maximum point of the last ice age, glaciers covered about 32 percent of the total land area. From the 17th century to the late 19th century, the world experienced a “Little Ice Age,” when temperatures were consistently cool enough for glaciers to advance in many areas of the world.
http://nsidc.org/cryosphere/glaciers/quickfacts.html
Glaciers are formed when more snow falls in winter than melts in summer. As snow accumulates over many seasons it becomes ice. The weight from snow and ice causes the bottom layers to move, fashioning a frozen river of snow and ice that slowly flows across the landscape, eroding and shaping it into unique landforms. When this process is reversed, the glaciers retreat back up the mountain.
https://www.nps.gov/glac/learn/education/glaciers.htm
In the very few places in the world where glaciers are advancing (or have some oscillation), then for most it is due to more precipitation in the neve overwhelming the increasing temperatures at the terminus (which by definition is where temperatures are too hot for ice to persist unless its terminating into water).
https://www.skepticalscience.com/himalayan-glaciers-growing.htm
Most of the world’s glaciers are found near the poles, but glaciers exist on all of the world’s continents, even Africa. Australia does not have any glaciers; however, it is considered part of Oceania, which includes several Pacific island chains and the large islands of Papua New Guinea and New Zealand.
http://nsidc.org/cryosphere/glaciers/life-glacier.html
The Kutiah Glacier in Pakistan holds the record for the fastest glacial surge. In 1953, it raced more than 12 kilometers (7.5 miles) in three months, averaging about 112 meters (367 feet) per day. Satellite images caught this large iceberg, named A54, calving off of what remains of the Larsen Ice Shelf in Antarctica.
http://nsidc.org/cryosphere/glaciers/quickfacts.html
The largest glacier in the world is the Lambert-Fisher Glacier in Antarctica. At 400 kilometers (250 miles) long, and up to 100 kilometers (60 miles) wide, this ice stream alone drains about 8 percent of the Antarctic Ice Sheet. Antarctic ice is up to 4.7 kilometers (3 miles) thick in some areas.
http://nsidc.org/cryosphere/glaciers/quickfacts.html
when did glaciers melt
Glaciers melted in the summer. Glaciers melt in summer.