Arctic Glacier Facts Largest Ice Sheet Greenland Ice Sheet Avg. Thickness About 5000 feet Amt. of Earth's freshwater 10% Point of glacial motion When about 60 feet thick Research methods Ice cores, satellite imagery, aerial surveys, seismic tests Did you know? Glaciers form where the mean winter snowfall exceeds mean summer melting. Glacial ice can range in age from several thousands to millions of years old. Tiny air bubbles trapped in glacial ice preserve bits of Earth's atmosphere from thousands of years ago. Ice cores allow scientists to reconstruct past eras, showing how and why climate changed. Glacial motion can be difficult to predict; in 1986, the Hubbard Glacier in Alaska's Russell Fjord suddenly began to surge at the rate of 30 feet per day, creating a sizeable lake at the mouth of the fjord.

Glaciology in the Arctic

The Arctic region has attracted significant glaciological study and attention, particularly in regard to climatic fluctuations. The use of sensitive remote monitoring instruments and computer modeling has enabled scientists to record and predict subtle changes in ice masses. Glaciers and ice sheets can be effective indicators of environmental change -- a form of early warning -- providing scientists with clues about past and future climatic events.

Glacial ice can range in age from several thousands to millions of years, making it valuable for climate research. To see a long-term climate record, an ice core is drilled and extracted from the glacier. These cores are continuous records providing scientists with important information about past climates. By analyzing various components of cores, particularly trapped air bubbles, scientists can determine past atmospheric composition, temperature variations, and types of vegetation. This is how scientists know that there have been several Ice Ages. By finding out how and why climate has changed in the past, scientists can predict how it might change in the future.

With 10% of the world's total freshwater reserves, the Greenland Ice Sheet is the largest Arctic glacial mass. Aerial surveys of the Ice Sheet provide evidence for changes in ice thickness or patterns of movement. Currently there is much debate about whether the ice sheet has lost or gained mass. In fact, recent ice cores drilled at the summit of the ice cap have shown increased snowfall perhaps due to rising temperatures. Glaciers in other areas are monitored by field measurements and with the use of satellite imagery to determine ice velocities and overall glacial motion. Much research is concerned with the chemistry, dynamics, and history of ice formation and glacial processes.

In addition to climate information, glaciologists are also concerned with the effect glacial processes have on the landscape. Many areas of the Arctic have been shaped by repeated glaciations. In the North American and western Eurasian Arctic, ice sheets have scoured the landscape like giant bulldozers, tearing away topsoil and broken rock. In areas with hard crystalline granite bedrock, the glaciers left the land dotted with depressions that filled with water and became lakes. Glaciers that eroded the bedrock below sea level at the coast created deep, winding fjords. In other areas, the glaciers piled extensive moraines and sedimentary deposits on top of the bedrock.