. Based on procedures A and B, what has happened to the glaciers in recent years?

Based on procedures A and B, the glaciers have lost thickness and have retreated in recent years.

Explanation:

The long-term "benchmark" glacier program managed by the U.S. Geological Survey monitors climate, glacier geometry, glacier thickness, glacier motion, and stream runoff (procedure A) in the ways  to understand the consequences of climate change through monitoring the balance  between accumulation and melting, which results in the change in glacial thickness of ice over the 40 year record from  1965 to 2005.

The Taku and Norris Glaciers as well  as land contours and the positions of the edge of each glacier at different times since 1890 (procedure B) show that glaciers  gain and lose snow and ice each year, and this causes the glacier

to advance but when the snow and ice melt, the glacier retreats and moves up the hill.

The glaciers have shown a significant reduction in the thickness as well as the coverage area. This indicates that not only the depth of the glaciers have decreased, the they have also shrunk over the normal size.

Explanation:

The procedures A and B are basically the referencing of the glaciers with the benchmark. So the instance A is the benchmark thickness and surface coverage of the glaciers. where as the point B is the thickness and surface coverage of the glaciers at any given time after the benchmark.

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