<ul><li>WHAT ARE GLACIERS ? </li></ul><ul><li>Glaciers are large masses of snow recrystalized ice & rock debris that accumulate in great quantities & begin to flow outwards & downwards under the pressure of their own weight. </li></ul><ul><li>Glaciers are also known as 'rivers of ice' because they are not stationary but moving constantly like the water of a river; only much slower, from a few millimeters a day to a few meters a day. </li></ul>
<ul><li>HOW ARE THEY FORMED ? </li></ul><ul><li>Glaciers are formed by snow. </li></ul><ul><li>The weight and size of the glacier keeps increasing. </li></ul><ul><li>The lower layers and are more brittle, forming deep </li></ul><ul><li>cracks (crevasses) as they move. </li></ul>Low and high contrast images of the Byrd Glacier DO NOT CLICK ON PICTURES
Is Ice Glaciers Melting Normal? It is normal for ice glaciers to melt. Ice glaciers either break off into smaller icebergs and melt directly into the sea, or melt on land and form rivers that will empty into the sea. Sea water is evaporating constantly and is replaced by melting glacier water. A problem here occurs when the snow replenishing it is less than the melted water. This is exactly what is happening with most of the glaciers around the world today, gradually reducing the size of the glacier, at the same increasing the sea water level.
TYPES OF GLACIERS :- • Alpine & continental glaciers. • The smallest alpine glaciers are found in mountain valleys & are referred to as valley glacier. • The largest glaciers are continental ice-sheets. • Antarctica & Greenland are the only places where continental ice-sheets currently exists.
The modest sea-level rise seen during the 20th century led to erosion and the loss of 100 sq km of wetlands per year in the U.S. Mississippi River Delta
ANATOMY (STRUCTUTRE) The Upper Grindelwald Glacier and the Schreckhorn, in Switzerland, showing accumulation and ablation zones
Signs warning of the hazards of a glacier in New Zealand
“ Earth at night” This is a "Blue Marble" image from NASA, "Earth at night" is superimposed on this (NASA/GSFC), Using the lights as an indication of population density. The squares on the map highlight a representative number of cities within the regions of glacier-fed areas. All of these areas derive some benefit from melting glaciers
Causes: A rise in the temperature of the air around the glacier. Increasing accumulation of dust [from volcanic eruptions for one example] on the glacier's surface. The "dirtier" the surface of the glacier's ice, the less sunlight it reflects, and the more sunlight it absorbs, increasing its surface temperature, and causing increased melting.
The Effects Of Melting Ice Glaciers <ul><li>GLOBAL WARMING </li></ul><ul><li>FRESH WATER STORAGE </li></ul><ul><li>REDUCED AGRICULTURAL OUTPUT </li></ul><ul><li>Shortage of Electricity (Hydroelectric) </li></ul><ul><li>Excessive Flooding </li></ul><ul><li>Rise in Sea-level </li></ul><ul><li>Animal, Bird, and Fish Habitat Loss </li></ul><ul><li>Coral Reefs will Vanish </li></ul><ul><li>Earth Will Get Recontaminated </li></ul><ul><li>Melting Ice Glaciers Affects the Whole World </li></ul>
SOLUTION It is now clear that the Earth is warming rapidly due to man-made emissions of carbon dioxide and other heat-trapping gases, which blanket the planet and cause temperatures to rise Climate change is already happening, but we can strive to keep global warming within tolerable limits if we act now. To limit global warming to a maximum of 2ºC over pre-industrial levels
The Perito-Moreno Glacier, showing cracks in brittle upper layer