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Climate Change

Global Warming

I heard that some glaciers in Alaska are growing, not shrinking. Is this true?

It’s true that many Alaskan glaciers, including, most notably, the Hubbard Glacier, have been advancing in recent years. The reasons for this are complex and may have nothing to do with whether or not climate change is occurring. To simplify what is the rather complicated science of glaciology, there are different types of glaciers. Some glaciers rest in valleys and tend to be more sensitive to changing temperatures. Others, including Hubbard, are known as calving glaciers. They terminate at an ocean and parts of them break away in a stunning spectacle known as “calving.” The five large glaciers in Alaska that are growing, including Hubbard, all have several commonalities: 1) they have previously experienced long periods of retreat only recently reversed (in the past century or so); 2) they all calve on shallow moraine shoals; 3) they all lay at the heads of long fjords; 4) they have positive mass balances that, by sheer force of weight, cause them to expand as gravity pushes down on them; and 5) they have small ablation areas; that is, small surface areas where melting and sublimation occur. Glaciologists note that glaciers with these qualities are not strongly influenced by even long-term temperature changes.



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