Category Geography

WHY ARE GLACIERS IMPORTANT?

Glaciers are a very important source of fresh water. Melting glacier ice keeps many of Earth’s rivers flowing. Glaciers create fertile valleys for farming and their deposits are also rich in resources.

Glaciers are keystones of Life on Earth. As giant freshwater reservoirs, they support the planet’s life systems and influence our day-to-day lives, even for communities who live far away from them. However, glaciers are disappearing.

The disappearance of glaciers makes visible the invisible. It makes tangible the current climate change that can be hard to perceive in other ecosystems. The recent evolution of glaciers found in World Heritage sites paints a true picture of their decline in a warming planet.

A study led by Jean-Baptiste Bosson in 2019 shows that most World Heritage glaciers have lost a significant portion of their mass since 1900; some even completely disappeared, as in Africa or the Alps. The study predicts that glaciers could disappear from almost half of World Heritage sites by 2100 if business-as-usual emissions continue.

Credit: International Union for Conservation of Nature

Picture Credit : Google 

WHAT ARE FJORDS?

Fjords are very deep, long and narrow inlets with steep sides or sheer cliffs, seen along the coasts of Norway, New Zealand and Canada. A fjord is formed when the sea comes in to fill the U-shaped valley left by a glacier after it has retreated.

A fjord is a long, deep, narrow body of water that reaches far inland. Fjords are often set in a U-shaped valley with steep walls of rock on either side.

Fjords are found mainly in Norway, Chile, New Zealand, Canada, Greenland, and the U.S. state of Alaska. Sognefjorden, a fjord in Norway, is more than 160 kilometers (nearly 100 miles) long.

Fjords were created by glaciers. In the Earth’s last ice age, glaciers covered just about everything. Glaciers move very slowly over time, and can greatly alter the landscape once they have moved through an area. This process is called glaciation.

Glaciation carves deep valleys. This is why fjords can be thousands of meters deep. Fjords are usually deepest farther inland, where the glacial force was strongest.

Some features of fjords include coral reefs and rocky islands called skerries.

Some of the largest coral reefs are found at the bottom of fjords in Norway. They are home to several types of fish, plankton and sea anemones. Some coral reefs are also found in New Zealand. Scientists know much less about these deep, cold-water reefs than they do about tropical coral reefs. But they have learned that the living things in cold-water reefs prefer total darkness. Organisms in cold-water reefs have also adapted to life under high pressure. At the bottom of a fjord, the water pressure can be hundreds or even thousands of kilograms per square meter. Few organisms can survive in this cold, dark habitat.

Skerries are also found around fjords. A skerry is a small, rocky island created through glaciation. Most of the Scandinavian coastline is cut into thousands of little blocks of land. These jagged bits of coastline are skerries. The U.S. states of Washington and Alaska also have skerries.

Even though skerries can be hard to get around in a boat, fjords are generally calm and protected. This makes them popular harbors for ships.

Credit:  National Geographic Society

Picture Credit : Google

WHAT IS THE STUDY OF GLACIERS CALLED?

Glaciology is the study of natural forms of ice, particularly glaciers, and phenomena related to ice. It includes the study of how glaciers are formed and depleted, how they move, and how they affect the physical landscape, the climate, and living organisms. It is one of the key areas of polar research. It also involves research into glacial history and the reconstruction of past glaciation, thus providing insights into the ice ages. The apparent presence of ice on Mars and Jupiter’s moon Europa brings in an extraterrestrial component to the field.

Thus, glaciology is an interdisciplinary earth science, integrating geophysics, geology, physical geography, geomorphology, climatology, meteorology, hydrology, biology, and ecology. The impact of glaciers on humans adds the fields of human geography and anthropology. A person who studies glaciers is called a glaciologist.

Credit: New World Encyclopedia

Picture Credit : Google 

WHY DO GLACIERS LOOK BLUE?

Glacial ice is a different color from regular ice. It is so blue because the dense ice of the glacier absorbs every other color of the spectrum except blue — so blue is what we see!

It’s Not Just Frozen Water!

Sometimes the glacial ice appears almost turquoise. Its crystalline structure strongly scatters blue light. The ice on a glacier has been there for a really long time and has been compacted down so that its structure is pretty different from the ice you normally see. Glacial ice is a lot different from the frozen water you get out of the freezer.

It’s Not Just Frozen Snow!

Glacial ice is not just frozen compacted snow. There are other things in the ice that make it much different from the ice in your home. Glaciers move through rock and soil as they carve their way down a slope. This means the ice is going to have a lot more ingredients than just water.

Credit: Alaska Satellite Facility

Picture Credit : Google 

WHAT ARE THE CRACKS IN GLACIERS CALLED?

Crevasse, fissure or crack in a glacier resulting from stress produced by movement. Crevasses range up to 20 m (65 feet) wide, 45 m (148 feet) deep, and several hundred metres long. Most are named according to their positions with respect to the long axis of the glacier. Thus, there are longitudinal crevasses, which develop in areas of compressive stress; transverse crevasses, which develop in areas of tensile stress and are generally curved downstream; marginal crevasses, which develop when the central area of the glacier moves considerably faster than the outer edges; and bergschrund crevasses, which form between the cirque and glacier head. At the terminus of the glacier many crevasses may intersect each other, forming jagged pinnacles of ice called seracs. Crevasses may be bridged by snow and become hidden, and they may close up when the glacier moves over an area with less gradient.

Credit: Britannica

Picture Credit : Google 

HOW DO GLACIERS FORM?

In places high above the snow line, where more snow gathers than melts, it gets tightly packed. New snow falls and buries the old snow, which turns more dense and grainy. This is called firn and the process is called firnification. Layers of firn build up on top of each other and as they get thick and heavy, the grains of firn merge into huge mases of ice. Over time, the tightly compacted ice becomes so heavy and exerts so much pressure that the glacier slowly starts to move and slide downhill.

Glaciers are huge masses of ice that cover the basement rock. They are found only in regions where snow cover is permanent, that is, at the poles and at high altitude.

At low temperatures, snow does not melt. It accumulates and is compacted into ice. This gradual metamorphosis, which can take several decades, results in the formation of an enormous mass of ice, several dozen meters thick–a glacier.

Propelled by its own weight, a mountain glacier may become detached from the rock wall and slide downward. It slowly flows into the valley like a river of ice. As it descends, the glacier picks up rocks and debris, which accumulate in the form of mounds, called moraines.

If the climate warms, the glacier melts. We say that it recedes. It leaves behind a profoundly eroded landscape composed of wide, flat bottom valleys and many lakes.

Credit: Britannica

Picture Credit : Google