The Hubbard Glacier is North America's largest tidewater glacier. Here are some facts about it!
- It is 76 miles long,7 miles wide, and 600 feet tall at its terminal face (350 feet exposed above the waterline and 250 feet below the waterline).
- The Hubbard Glacier starts at Mt. Logan (19,850 ft) in the Yukon Territory of Canada and ends within Wrangell-St. Elias National Park & Preserve. Mt. Logan is the 2nd tallest mountain on the North American continent.
- The glacier was named in 1890 for Gardiner Hubbard, the first president of the National Geographic Society.
- The Hubbard Glacier is currently advancing (last 100 years), while most Alaskan glaciers are retreating (95% ). This is not in contradiction with current global temperature increases. The Hubbard Glacier will advance during times of warming climate and retreat in time of colder climates. The current rate of advance is approximately 80 feet per year.
- The glacier's rate of overall forward velocity is much higher, but the advance is due to its calving.
- The ice you see at the terminal face is approximately 450 years old and is over 2000 feet thick at some locations.
2002 and 1986 - Gilbert Point
100 years ago - 2 miles east of Osier Island
200 years ago - retreated past Haenke Island
300 years ago - retreated to Pt. Blizhni
700 years ago - advanced to fill the entire Yakutat Bay
Why Does the Hubbard Glaicer Advance and Retreat?
During the summer of 2002 the Hubbard Glacier near Yakutat pulsed forward, closing Russell Fiord from the sea. The massive ice dam that formed was later breached and washed out by water retained behind it, reconnecting the fiord to the ocean. Rather than being an event that took hundreds of years, this drama played out in the course of a couple of months.
Glaciers will always try to reach a balance between the amount of ice they gain to the amount of ice they lose (equilibrium). Simply, when the glacier gains more ice than it loses, it will advance. Conversely, when a glacier loses more ice than it gains, it retreats.
Glaciers gain ice by accumulating snow and burying it to transform into glacial ice. This is a four-part transformation; first snow, then to an ice called neve, then to a denser ice called firn, and finally to glacial ice. This transformation is due to burial pressure applied from the snow accumulating above. Once the ice becomes more than 150 feet thick the ice can behave plastically, and start to flow under the influence of gravity.
The Hubbard Glacier is currently advancing while most glaciers are retreating worldwide. The Hubbard Glacier will and does react in an opposite fashion to most glaciers in a warming climate. As the global temperature increases, more precipitation is created locally. As this precipitation hits the St. Elias Mountains, it rises and cools, changing to snow. This increase of precipitation is what allows the Hubbard Glacier to advance.