How Glaciers Reflect Climate Change

Glaciers serve as one of the most valuable proxy tools in which to study climate change because they can range in age from hundreds to several thousands of years old. When a core is extracted from a glacier, the bubbles are analyzed in it, just as they are in ice cores. Analysis of the oxygen content reveals what the composition of the atmosphere was like at the time that layer of snow fell on the glacier. In addition, analyzing the 18O/16O ratio reveals what the temperature was like. Vegetation

Cirque Main glacier Medial floor moraine

^Cirques Arête spurs

Landscape Produced by a Receding Glacier

Esker

Terminal moraine

Ground moraine

Kettles

Ground moraine

Kettles

Landscape Produced by a Receding Glacier

Esker

Terminal moraine

Moraine

Drum I ins

Esker

Landforms as a Result of Past Glaciation

Kettle lakes

C Infobase Publishing

Drum I ins

Moraine

Esker and other debris trapped in the ice that was carried along with the glacier can also be used to unlock secrets about what the past climate was like. Dust reveals information about the wind conditions, salt content can give evidence of windiness near oceans, and sulphuric acid content relays information about nearby volcanic activity.

As scientists such as Dowdeswell and paleoclimatologists at the NSF, USGS, National Ice Core Laboratory, NASA, and NOAA Paleoclimatol-ogy Research Center trace Earth's history back from one ice age to another, they are able to build a temperature chronology and determine by how many degrees the planet warmed up during each interglacial period and cooled off during each glacial interval. It is because glaciers are so dynamic and responsive to temperature change that they are good indicators today of temperature changes occurring worldwide in the face of global warming. The fact that so many of the world's glaciers are currently melting reflects a change taking place in the climate right now. The following lists what some of the world's glaciers are currently experiencing:

• In the Peruvian Andes, Qori Kalis Glacier is losing as much ice in one week as it used to lose during an entire year.

• The Alaskan glaciers are losing an average of six feet (1.8 m) of thickness each year.

• The glaciers in the European Alps are expected to be gone by the end of the 21st century.

• Mount Kilimanjaro's glacier in Africa is expected to be gone in about a decade.

• The glaciers that supply drinking water to northern India and western China will no longer be able to provide this life-sustaining service in just a few years.

• The glaciers in Canada's and Montana's Glacier National Park will all be melted in the next few decades.

(opposite page) There are several diagnostic features of a glacial landscape that climatologists use to identify areas that were glaciated in the past. Recognizing these features gives them insight as to what the climate was once like.

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