There are at least 35 named glaciers in Glacier National Park (U.S.). At the end of the Little Ice Age about 1850, the area containing the national park had 150 glaciers. There are 25 active glaciers remaining in the park today. Since the latest interglacial period began 10,000 years ago, there have been regular climate shifts causing periods of glacier growth or melt-back. The glaciers are currently being studied to see the effect of global warming. The glaciers in the park have been in a general state of retreat since at least the year 1850, which is oftentimes cited as the end of the Little Ice Age, when midlatitude glaciers reached their largest historical maximum. Though believed in the early 2000s that most of the glaciers in the park would disappear by the year 2020, more recent stu