This summer we went on a cruise to southeastern Alaska with the Celebrity Infinity. On the way we passed the Hubbard glacier for some photos. Hubbard Glacier is the largest tidewater glacier on the North American continent. It has been thickening and advancing toward the Gulf of Alaska since it was first mapped by the International Boundary Commission in 1895 (Davidson, 1903). This is in stark contrast with most glaciers, which have thinned and retreated during the last century. This atypical behavior is an important example of the calving glacier cycle in which glacier advance and retreat is controlled more by the mechanics of terminus calving than by climate fluctuations. The Hubbard Glacier is North America’s largest tidewater glacier. 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). This would correspond to about a 33 story skyscraper or about twice as tall as Niagara Falls. It is hard to get a proportion of how big it really is when viewing it since you just see a wall of blue ice.
The Hubbard Glacier ice margin has continued to advance for about a century. In May 1986, the Hubbard Glacier surged forward, blocking the outlet of Russell Fjord and creating “Russell Lake”. All that summer, the new lake filled with runoff; its water level rose 25 metres (82 ft), and the decrease in salinity threatened its sea life. Around midnight on October 8, the dam began to give way. In the next 24 hours, an estimated 5.3 cubic kilometres (1.3 cu mi) of water gushed through the gap, and the fjord was reconnected to the ocean at its previous level. This was the second largest glacial lake outburst flood in recorded history, and had the equivalent flow of about 35 Niagara Falls. The fjord could become dammed again, and perhaps permanently. If this happens, the fjord could overflow its southern banks and drain through the Situk River instead, threatening trout habitat and a local airport.
There were only a few 5–10 foot icebergs floating around, all of them with blue ice. The glacier routinely calves off icebergs the size of a ten-story building. Where the glacier meets the bay, most of the ice is below the waterline, and newly calved icebergs can shoot up quite dramatically, so that ships must keep their distance from the edge of the glacier in Disenchantment Bay. Blue ice occurs when snow falls on a glacier, is compressed, and becomes part of the glacier. Air bubbles are squeezed out and ice crystals enlarge, making the ice appear blue. Small amounts of regular ice appear to be white because of air bubbles inside them and also because small quantities of water appear to be colorless. In glaciers, the pressure causes the air bubbles to be squeezed out, increasing the density of the created ice. Large quantities of water appear to be blue, as it absorbs other colors more efficiently than blue. A large piece of compressed ice, or a glacier, similarly appears blue.
The day we visited, it was overcast but not raining, limiting visibility. The Hubbard Glacier is so large it actually influences local weather and overcast skies are actually quite common.
More Pictures Hubbard Glacier
It takes about 400 years for ice to traverse the length of the glacier, meaning that the ice at the foot of the glacier is about 400 years old. I hope you enjoyed the post, please leave a comment.