The USGS has been studying glaciers in Glacier National Park since 1850. It is estimated that there were 150 glaciers in the park back then, and when the national park was established in 1910. Today only 25 glaciers remain.
Scientists go back every year to repeat photographs, as well as to examine the ice and the ecology of the landscape to see how glacial retreat is affecting plant and animal species that live there.
All biological organisms require certain nutrients to live. Plants require carbon, hydrogen, and oxygen from air and water, as well as nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, manganese, copper, zinc, nickel, chloride, boron, and molybdenum from soil. Animals require a few others. Conversions and transformations of nutrients in the environment result from chemical reactions, biological activity, or both.