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Juneau Icefield-Mendenhall Glacier, Sawyer Glacier, the Inside Passage photos by Mario Guerrero & Karen Duquette
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Juneau Icefield, is a spectacular expanse of mountains and glaciating, and the source of all the glaciers in the area, including Mendenhall, Taku, Eagle, Herbert and 38 other glaciers within a 1,500 square mile radius. There are an estimated 100,000 glaciers in Alaska. The Juneau Icefield is the largest icefield in Alaska and the 5th largest in North America. Approximately 100 feet of snow fall each year on the Juneau Icefield. |
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Ice chunks split from
glaciers and fall into the sea or river, a process called calving.
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| The closer we get to Mendenhall Glacier, the more ice chunks. Eventually, there were so many ice chunks in the river, that we couldn't get any closer. | |
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Mario Guerrero & Sandy Guerrero
at Mendenhall Glacier
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Some glacier facts:
Glaciers require very specific climatic conditions. Most are found in regions of high snowfall in winter and cool temperatures in summer. These conditions ensure that the snow that accumulates in the winter isn't lost (by melt, evaporation, or calving) during the summer. Such conditions typically prevail in polar and high alpine regions. There are two main types of glaciers: valley glaciers and continental glaciers (known as ice sheets).
The amount of precipitation (whether in the form of snowfall, freezing rain, avalanches, or wind-drifted snow) is important to glacier survival. In areas such as Antarctica, where the low temperatures are ideal for glacier growth, very low annual precipitation causes the glaciers to grow very slowly.
Motion and change define a glacier's life. Glacial ice advances, then retreats. Glaciers grow and shrink in response to changing climate. Typically glacier movement and shape shifting occur over long periods of time (hundreds to thousands of years), but within historic memory such transformations in fewer than 100 years are not unknown.
Not all glaciers move slowly. For example, surging glaciers experience dramatic increases in flow rate, sometimes traveling as much as ten to one hundred times faster than the normal rate of movement.
By their movement, glaciers mark change and for this reason - among others - scientists study glaciers. By monitoring glaciers over time and around the world, researchers construct valuable records of glacial activity and their response to climate variation.
By comparing contemporary observations with historical and environmental records, such as agricultural records, prehistoric temperature or climate profiles, glaciologists acquire and provide an enhanced understanding of global processes and change.
Today, glaciers and ice sheets store about 75 percent of the world's freshwater
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