Johns Hopkins Glacier (LingÃÂt: Tsalxaan Niyaadé SÃÂtâÂÂ) is a long glacier located in Glacier Bay National Park and Preserve in the U.S. state of Alaska. It was named, colonially, after Johns Hopkins University in Baltimore, Maryland in 1893 by Harry Fielding Reid. It is one of the few advancing tidewater glaciers of the Fairweather Range.
The glacier begins on the east slopes of Lituya Mountain and Mount Salisbury, and trends east to the head of Johns Hopkins Inlet, southwest of the terminus of Clark Glacier on Mount Abbe, and northwest of Hoonah. It is located near two towns, being 56 miles (90 km) northwest of Gustavus, and 66 miles (106 km) southwest of Haines. Access to the face of the glacier is limited to the Johns Hopkins Inlet.
The peak elevation of the glacier is 1811ft (552 m). The terminus has a height of 225-330 feet (68-100 m) and a width of 1 mile (1.6 km). Many tributary glaciers from the nearby mountains combine to form the Johns Hopkins glacier, creating around 50 medial moraines at the points of contact.
Most glaciers around the world are retreating, meaning they are losing size, volume, or length due to climate change. Tidewater glaciers in Alaska, those that flow from mountains and terminate in water, are especially prone to retreat as most of the ice that feeds them is thinning. Advancing glaciers that are gaining size are rare and usually require special circumstances to occur in this area.
The reason for the John Hopkins Glacier's advancement is the presence of a submarine end moraine that inhibits calving and melting. This leads to less overall mass lost and an increase in thickness of the glacier. In the last 80 years, the terminus of the glacier has advanced 1 mile (1.6 km) and has become 328 feet (100 m) thicker. Additionally, the velocity of the terminus has decreased, unlike most tidewater glaciers which are more rapidly melting.
One disadvantage of this advancing movement is the loss of habitat for harbor seals. Over 2,000 seals aggregate in Johns Hopkins Inlet every summer, making it the largest accumulation of such seals anywhere in Glacier Bay. These seals rely on icebergs, which form from calving glaciers, for molting and pupping, as well as predator avoidance. Therefore, the lack of icebergs formed from the Johns Hopkins glacier's advancing nature poses a threat to the lifestyle of these harbor seals.