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Essay on Glaciers and Ice Caps
Essay Contents:
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- Essay on the Introduction to Glaciers and Ice Caps
- Essay on the Formation of Glaciers and Ice Caps
- Essay on the Glacier Responses to Climatic Changes
- Essay on Outlook for Glaciers
- Essay on Glaciers and Natural Hazards
- Essay on Glaciers, Landscapes and the Water Cycle
- Essay on the Effects of Ice Cap Melting
Essay # 1. Introduction to Glaciers and Ice Caps:
Glaciers and ice caps are among the most fascinating elements of nature, an important freshwater resource but also a potential cause of serious natural hazards. Because they are close to the melting point and react strongly to climatic change, glaciers are important indicators of global climate.
Glaciers reached their Holocene (the past 10000 years) maximum extent towards the end of the Little Ice Age (the Little Ice Age extended from the early 14th to mid-19th century.) Since then, glaciers around the globe have been shrinking dramatically, with increasing rates of ice loss since the mid-1980s.
On a time-scale of decades, glaciers in various mountain ranges have shown intermittent readvances. However, under the present climate scenarios, the ongoing trend of worldwide and fast, if not accelerating, glacier shrinkage on the century time-scale is not a periodic change and may lead to the deglaciation of many mountain regions by the end of the 21st century.
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Glacial retreat and melting of permafrost will shift cryospheric hazard zones. This, in combination with the increasing socio-economic development in mountain regions, will most probably lead to hazard conditions beyond historical precedence.
Changes in glaciers may strongly affect the seasonal availability of freshwater, especially when the reduction of glacier runoff occurs in combination with reduced snow cover in winter and earlier snowmelt, less summer precipitation, and enhanced evaporation due to warmer temperatures.
The most critical regions will be those where large populations depend mainly on water resources from glaciers during the dry season and glaciated mountain ranges that are densely populated and highly developed.
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Essay # 2. Formation of Glaciers and Ice Caps:
Glaciers and ice caps formed around the world where snow deposited during the cold/humid season does not entirely melt during warm/dry times. This seasonal snow gradually becomes denser and transforms into perennial firm (rounded, well-bonded snow that is older than one year) and finally, after the air passages connecting the grains are closed off, it is converted to ice. The ice from such accumulation areas then flows under the influence of its own weight and the local slopes down to lower altitudes, where it melts again (ablation areas).
Accumulation and ablation areas are separated by an equilibrium line, where the balance between gain and loss in the ice mass is exactly zero. Where glaciers formed depends not only on air temperature and precipitation, but also on the terrain, which determines how much solar radiation the glacier will receive and where ice and snow will accumulate.
In humid-maritime climates the equilibrium line is at a relatively low altitude because, for ablation to take place, warm temperatures and long melting seasons are needed to melt the thick layers of snow that accumulate each year. These landscapes are thus dominated by ‘temperate’ glaciers with firn and ice at melting temperatures.
Temperate glaciers have a relatively rapid flow, exhibit a high mass turnover and react strongly to atmospheric warming by enhanced melt and runoff. The ice caps and valley glaciers of Patagonia and Iceland the western Cordillera of North America and the mountains of New Zealand and Norway are examples of this type of glaciers. The lower parts of such temperate glaciers may extend into forest valleys, where summer warmth and winter snow accumulation prevent development of permafrost.
In dry continental areas, on the other hand, such as northern Alaska, Arctic Canada, subarctic Russia, parts of the Andes near the Atacama Desert, and many central-Asian mountain chains, the equilibrium line is at a relatively high elevation with cold temperatures and short melting seasons.
In such regions, glaciers far above the tree line can contain—or even consist entirely of—cold firn and ice well below melting temperature. These glaciers have a low mass turnover and are often surrounded by permafrost.
Essay # 3. Glacier Responses to Climatic Changes
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The response of a glacier to climatic change involves a complex chain of processes. Changes in atmospheric conditions (such as solar radiation, air temperature, precipitation, wind and cloudiness) influence the mass and energy balance at the glacier surface.
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Air temperature plays a predominant role, as it is related to the radiation balance and turbulent heat exchange, and it determines whether precipitation falls as snow or rain. Over a time period of years and decades, changes in energy and mass balance cause changes in volume and thickness, which in turn affect the flow of ice through internal deformation and basal sliding.
This dynamic reaction eventually leads to changes in the length of the glacier—the advance or retreat of glacier tongues. In short, the glacier mass balance (the change in vertical thickness) is the direct signal of annual atmospheric conditions—with no delay—whereas the advance or retreat of glacier tongues (the change in horizontal length) is an indirect, delayed and filtered signal of climatic change.
The advance or retreat of a glacier is, though, an easily- observed and strong signal of climatic change, as long it is observed over a long period. If the time interval of the analysis is longer than the time it takes as a glacier to adjust to a change in climate, the complications involved with the dynamic response disappear.
Over a period of decades, cumulative length and mass change can be directly compared. Special problems are encountered with heavily debris-covered glaciers with reduced melting and strongly limited ‘retreat’, glaciers that end in deep-water bodies causing enhanced melting and calving, and glaciers undergoing periodic mechanical instability and rapid advance (‘surges’) after extended periods of stagnation and recovery. But glaciers that are not influenced by these special problems are recognized to be among the best indicators of global climate change.
They essentially convert a small change in climate, such as a temperature change of 0.1 °C per decade over a longer time period, into a pronounced length change of several hundred metres or even kilometres—a signal that is visible and easily understood.
Essay # 4. Outlook for Glaciers:
The total increase of global mean air temperature of about 0.75°C since 1850 is clearly manifested in the shrinking of glaciers and ice caps worldwide. The sensitivity of glaciers in humid-maritime areas to this warming trend has been found to be much higher than that of glaciers in dry-continental areas.
According to climate scenarios for the end of the 21st century, changes in global temperature and precipitation ranges between +1.1 and +6.4°C and -30 and +30 per cent, respectively. Such an increase in mean air temperature will continue the already dramatic glacier changes.
Cold continental-type glaciers will react in the first instance with warming of the ice and firm temperatures, whereas glaciers with ice temperatures at the melting point will have to convert the additional energy directly into melting.
Low-latitude mountain chains like the European Alps or the Southern Alps of New Zealand, where glaciers are typically medium-sized and found in quite steep mountains, will experience rapid glacier changes in adaptation to the modified climate.
A modelling study shows that the European Alps would lose about 80 per cent of their glacier cover if the summer air temperatures rise by 3°C, and the precipitation increase of 25 per cent for each 1°C would be needed to offset the glacial loss.
In heavily glacier-covered regions like Patagonia (Argentina, Chile) or the St. Elias Mountains (Alaska), the landscape is dominated by relatively large and rather flat valley glaciers. Because long, flat valley glaciers have dynamic response time beyond the century scale 10, 11, rapid climate change primarily causes (vertical) thinning of ice rather than (horizontal) retreat and area reduction.
For such cases, conditions far beyond equilibrium stages, perhaps even run-away effects from positive feedbacks (mass balance/altitude), must be envisaged. Down wasting or even collapse of large ice bodies could become the most likely future scenarios related to accelerating atmospheric temperature rise in these areas, and have already been documented.
Under the present climate scenarios, the ongoing trend of worldwide and fast, if not accelerating, glacier shrinkage on the century time scale is of non- periodical nature and may lead to the deglaciation of large parts of many mountain regions in the coming decades.
Essay # 5. Glaciers and Natural Hazards:
Changes in glaciers may well lead to hazardous conditions, particularly in the form of avalanches and floods, and thus have dramatic impacts on human populations and activities located in glacierized mountain regions. The majority of glacier hazards affect only a limited area—often only a few square kilometres—and mostly pose a danger to densely populated mountain regions such as the European Alps. In some cases, however, glacier hazards have far-reaching effects over tens or even hundreds of kilometres and thus also affect less densely populated and developed mountain regions.
The long-term average annual economic loss from glacier disasters or related mitigations costs are estimated to be in the order of several hundred million U.S. dollars. The largest disasters have killed more than 20,000 people, for instance the Huascaran rock-ice avalanches in Peru in 1970 or the Nevado del Ruiz lahars (rapidly flowing volcanic debris flows) in Colombia in 1985.
A systematic assessment of hazards can only be achieved by identifying the physical processes involved. Generally speaking, the most important types of hazards are as follows: glacier floods, hazardous processes associated with glacier advance or retreat, ice and rock avalanches, periglacial debris flows, and ice-volcano interactions.
Particularly severe disasters have often resulted from a combination of these processes or chain reactions. Glacier lake outburst floods represent the largest and most extensive glacial hazard, that is, the hazard with the highest potential for disaster and damage (up to 100 million m3 break-out volume and up to 10,000 m3 per second runoff).
The Himalayas, Tien Shan and the Pamirs, the Andes, but also the European Alps are among those regions most severely affected by this type of hazard. Glacier floods are of particular concern in view of the rapidly retreating glaciers and the corresponding formation and growth of numerous glacier lakes.
In terms of hazard, ice and rock avalanches may be roughly grouped by volume. Avalanches with volumes smaller than 1 million m3 are mostly of concern to densely populated and developed mountain regions such as the European Alps.
Avalanches with a volume of 1 to 100 million m3 or even more have usually more far-reaching effects and the potential to completely devastate mountain valleys. The most recent such disaster occurred in 2002 in the Caucasus with a 100 million m3 ice-rock avalanche that extended more than 30 km downstream and killed more than 100 people.
These types of mass movements and the relationship between their magnitude and their frequency have recently become more and more important in research because of concerns that they may become more frequent with continuing atmospheric warming, permafrost degradation and related destabilization of steep glaciers and rock walls.
Debris flows from periglacial areas have frequently caused damage to life and property in mountain areas. Unconsolidated sediments, uncovered by glacier retreat during the recent decades, and degradation of stabilizing permafrost in debris slopes are the main sources of the largest debris flows observed in the European Alps.
Ice-capped volcanoes pose particularly severe hazards because large mass movements (avalanches, lahars) may result from the interactions between material that erupts from the volcanoes with ice and snow. Alaska, the Cascades and the Andes are among the regions most-affected by hazards posed by the interaction between volcanoes and glaciers.
Chain reactions and interactions between the afore mentioned processes play a crucial role in determining the magnitude and frequency of glacier-related hazards. As one example, outbursts of naturally or artificially dammed mountain lakes were caused by impact waves from rock and ice avalanches and this led to failure of the dams.
Such potential process interactions have to be assessed carefully in order to predict related consequences. Two present global developments and their regional expressions will strongly affect the potential impact of current and possible future glacier hazards: climate change and socio-economic development.
First, atmospheric warming has an increasingly dramatic effect on mountain glaciers, and strongly influence the development of related hazards. For example, potentially unstable glacial lakes often formed in glacier fore fields dammed by frontal moraines which were left behind by retreating glaciers. Steep slopes of unconsolidated debris are a potential source for debris flows when they are no longer covered by glacier ice or cemented by ground ice.
Fresh ice break-off zones may evolve in new places from glacier retreat, while existing danger zones may cease to be active. Atmospheric warming also affects permafrost thickness and distribution. The thickness of the active layer (that is, the layer above the permanently frozen ground that thaws during the summer) may increase, the magnitude and frequency of rockfalls may increase or evolve at locations where such events were historically unknown. Lateral rock- walls can be destabilized by glacier retreat as a result of the stress changes induced.
In general, climate change is expected to bring about a shift of the cryospheric hazard zone. It is difficult, however, to ascertain whether the frequency and/or magnitude of events have actually increased already as a consequence of recent warming trends. Nevertheless, events with no historical precedence do already occur and must also be faced in the future.
The second important change in glacier-related risks concerns the increasing economic development in most mountain regions. Human activity is increasingly encroaching upon areas prone to natural hazards. Related problems affect both developed and developing countries. The latter (such as in Central Asia, the Himalayas or the Andes), however, often lack resources for adequate hazard mitigation policies and measures.
Cost-efficient, sound and robust methods are therefore needed to regularly monitor the rapid environment and land-use changes in high mountains to identify the most vulnerable areas. This is equally important for developed countries in the European Alps.
Expensive protective structures need to be built in the past to reduce the risk. Public funds increasingly struggle to keep pace with it—and to ensure sufficient protection from—the rapid environmental changes and their consequences in mountain areas. Integrating climate change effects and robust process models into risk studies will help ensure that politics and planning can adapt to environmental conditions that change with increasingly high rates.
Essay # 6. Glaciers, Landscapes and the Water Cycle:
Landscapes around many high-mountain regions also in vast lowlands were moulded and sculpted by large ice bodies during the most recent part of Earth’s history—the Ice Ages—over the last few million years. The detection, in the first half of the 19th century, of corresponding traces from glacier erosion and of erratic boulders far from mountain chains led to the formulation of the Ice Age theory by Louis Agassiz and colleagues.
It was soon understood that large ice sheets had formed over North America and even entirely covered Scandinavia, lowering global sea level by more than 100 m, greatly modifying coastlines of all continents and dramatically affecting the courses of large rivers and the global ocean circulation.
This new knowledge constituted a fundamental breakthrough in our understanding of the climate system as an essential part of living conditions on Earth. Ice Age landforms have become a unique heritage, reminding us of the consequences of global temperature changes of just a few degrees. Curiosity and romantic enthusiasm characterize many historical reports and paintings of glaciers and high mountain landscapes.
Very often, glaciers are portrayed as an expression of ‘wild, non-destroyable’ nature, sharply contrasting with the cultivated landscape of human habitats. Glacierized mountain areas therefore became—and still are—major tourist attractions in many parts of the world. In fact, the ‘clean white of the eternal snow’ on high mountain peaks is often seen as a beautiful treasure and used as a precious symbol of intact environments. This is why the current shrinking, decay and even complete vanishing of glaciers evokes such an emotional response.
Apart from their symbolic value, glaciers are also among the best natural indicators of climate change. Their development can be observed by everybody— and the physical process, the melting of ice under the influence of warm temperatures, can intuitively be understood. The impacts of accelerated atmospheric warming are thus changing the public perception of glaciers: they are increasingly recognized as a warning signal for the state of the climate system.
Continued atmospheric warming will inevitably lead to the deglaciation of many currently glacierized landscapes-, especially in low-latitude mountain chains. In many places, lakes have already been formed. Such lakes may replace some of the lost landscape attractiveness, but their beauty may come at a dangerous price. On slopes, vegetation and soils take decades and even centuries or sometimes millennia to follow the retreating ice and cover the newly exposed terrain.
As a consequence, the zones of bare rock and loose debris will expand. Vegetation (especially forests) and ice both have a stabilizing effect on steeply inclined surfaces. During the expected long transitional period between glacier vanishing and forest immigration, erosion (including large debris flows) and instability (including large rockfalls and landslides) on slopes unprotected by ice or forest will increase substantially.
The perennial ice of glaciers is an important part of the water cycle in cold regions. It represents a storage component with strong effects on river discharge and fresh water supply. Such effects indeed make high mountain chains ‘water towers’ for many large areas and human habitats.
Climatic change will lead to pronounced changes in this system. At time scales of tens and hundreds of millennia, the growth and decay of continental ice sheets, large ice caps and glaciers during periodical ice ages profoundly affect the global water cycle.
Within annual cycles of temperature and precipitation, glacial meltwater feeds rivers during the warm/dry season. In the Andes of Peru, the Argentinean Pampas or the Ganzhou Corridor of China, this contribution to river flow is the predominant source of freshwater for large regions surrounding the corresponding mountain areas. Meltwater from glacierized mountain chains with rugged topography is also intensively used for hydropower generation.
The shrinking and even vanishing of mountain glaciers in scenarios of atmospheric temperature rise is likely to cause both small and large meltwater streams to dry out during hot and dry summers. This drying out may become more frequent at mid- latitudes, where human populations are often dense and the need for fresh water is growing.
Earlier, snowmelt and perhaps also reduced snow cover from winter time could result in severe consequences for both ecosystems and related human needs: decreasing river flow, warmer water temperatures, critical conditions for fish and other aquatic forms of life, lower groundwater levels, less soil humidity, drier vegetation, more frequent forest fires, stronger needs for irrigation water, and rising demands for energy (such as air conditioning) coupled with reduced hydropower generation and less river cooling for nuclear power plants. These consequences are all likely to be interconnected and related to growing conflicts of interest.
Perhaps the most critical regions will be those where large populations depend on water from glaciers during the dry season, such as in China and other parts of Asia, including India, together forming the Himalaya-Hindu Kush region, or in the South American Andes. But it will also affect mountain ranges which are densely populated and highly developed, such as the European Alps and the regions in the vicinity of its rivers.
Glacier changes, as important and pronounced part of climate-induced changes in mountain landscapes, are not only the clearest indication of climatic change—they also have the potential of having a strong impact on the seasonal availability of fresh water for large, densely populated regions and, hence, on the fundamental basis of ecosystem stability and economic development.
Essay # 7. Effects of Ice Cap Melting:
The polar regions, the Arctic and Antarctica, have large ice masses. As the temperature of the Earth increases, the polar caps are thinning, breaking and melting. NASA, with the help of satellite technology, projects the possibility of ice-free summers in the Arctic by the end of the 21st century. Loss of the polar caps has a global impact on animal life, including that of humans.
The effects can be described under the following heads:
1. Loss of Smaller Bodies of Water:
The Ward Hunt Ice Shelf used to be the largest single block of ice in the Arctic, but it cracked and splintered at the beginning of this decade. The enclosed freshwater lake was lost as it drained into the ocean, no longer protected by the Ward Hunt Ice Shelf.
2. Changes to Animal and Marine Life:
The loss of the polar caps affects the feeding habits and migration patterns of animals. Indigenous people and animals, including whales, polar bears, penguins, seals and walruses, will find it increasingly difficult to hunt for food. Some animals, though, will benefit from the increased water volume and higher temperatures, such as pollock, salmon and other fish whereas others, like clams and crabs, are unlikely to survive.
Warmer waters also bring new predators. Coral reefs are most vulnerable, impacting shoreline erosion as well as the production of antibiotics and other disease-fighting drugs. Sustained coral bleaching may lead to the death of corals.
3. Acceleration of Global Warming:
In one big cycle, as the Arctic ice decreases, the volume of open water—and therefore the absorption of solar energy by that water—increases. Ocean temperatures rise as a result, causing a further decrease in ice. Reducing snow and ice in the Arctic leads to higher global temperatures, which leads to faster melting of ice. The warming is furthered by an increase in greenhouse gases from warmer ocean waters, soil and vegetation.
4. Rising Sea Levels:
The Arctic polar cap is like a floating sheet of ice. Thus, melting Arctic ice will not affect sea level, like a melting ice cube doesn’t change the water level in a glass. However, the large masses of ice in Greenland and Antarctica rest on land. The melting of these ice masses, as well as glaciers, does contribute to rising sea levels.
Rising sea levels threaten low-lying areas from the Maldives 10 Shanghai and up to the U.S. Heavily populated areas could be forced inward because of coastal flooding. Higher sea levels also contribute to lower and contaminated bodies of freshwater.
5. Changes to Weather Patterns:
Loss of Arctic ice causes warmer winters in areas that normally experience freezing temperatures. Warmer summers could result in drier lands, robbing moisture of soil. Higher temperatures may lead to more frequent, more extreme weather such as hurricanes, severe rainstorms and blizzards.
6. Reduced Crop Production:
Warmer weather resulting from the melting ice can lead to reduced food production. Both winter and summer crops will be affected by changes to weather patterns.
7. Impact on Human Life:
People with waterfront property may lose their homes or businesses in heavily populated areas. Infrastructure, such as buildings, roads and airports, could have an impact. At the same time, although some cities might suffer reduced land masses as melting ice leads to flooding, the increased water expands fishing, shipping and offshore drilling opportunities.
8. Global Warming and Ice Caps:
Global warming is causing the polar ice caps to melt at an alarming rate. The rapidly melting polar ice caps caused by global warming have drastic consequences for the environment. The dangers of global warming and the ice caps melting will threaten all aspects of life.
The polar ice caps of the world are extremely sensitive to climate changes. The consequences global warming will be having on this region is causing the ice caps to melt at an alarming rate. Global warming is causing the temperatures in the areas to rise twice as fast as other areas of the world. This is causing the ice to melt quickly and alter the environment.
The 3,000-year-old Ward Hunt Ice Self is greatly dangered by global warming. This shelf has now split in half and larger pieces of ice continue to split from it. The polar ice is melting at a rate of 9 per cent each decade. At this rate, the ice will soon be gone. Once the ice is gone, serious changes to the environment will begin to occur drastically.
The melting polar ice caps caused by global warming will alter the entire planet. As the ice on the polar regions melt, the temperatures in the regions will drastically increase. This will occur because the snow and ice covering that usually protects the ground will be depleted.
The dangers of global warming continue to cause the ice sheets from this area to break free and melt in the sea, sea levels all over the world will rise. The ice caps melting is very threatening to the areas of the world in low-lying regions. The higher sea levels will cause coastal flooding and coastal erosion. This can then contaminate fresh water supplies.
If fresh water supplies are contaminated, the ecosystems in those water bodies will be threatened. The dangers of global warming also alter weather patterns. Weather patterns are easily affected by the melting polar ice caps. This can harm food supplies. As the weather patterns change, the growing seasons for many crops can be altered. Crops will be damaged and even ruined from the changes in the weather.
As the ice continues to melt, temperatures all over the globe will continue to rise. Once the ice has melted completely, global temperatures will increase even more. This will lead to warmer winters and hotter summers.
The effect global warming is having on the polar ice caps is alarming for all areas of the globe. There is no region that will be safe from global warming if the ice completely melts.
Some Glacier and Ice Cap Facts:
i. Glaciers store about 69% of the world’s freshwater, and if all land ice melted the seas would rise about 70 metres (about 230 feet).
ii. During the last ice age (when glaciers covered more land area than today) the sea level was about 400 feet lower than it is today. At that time, glaciers covered almost one-third of the land.
iii. During the last warm spell, 125,000 years ago, the seas were about 18 feet higher than they are today. About three million years ago the seas could have been up to 165 feet higher.
iv. North America’s longest glacier is the Bering Glacier in Alaska, measuring 204 kilometres long.
v. Glacial ice can be very old—in some Canadian Arctic ice caps, ice at the base is over 100,000 years old.
vi. The land underneath parts of the West Antarctic Ice Sheet may be up to 2.5 kilometres below sea level, due to the weight of the ice.
vii. Antarctic ice shelves may calve icebergs that are over 80 kilometres long.
viii. The Kutiah Glacier in Pakistan holds the record for the fastest glacial surge. In 1953, it raced more than 12 kilometres in 3 months, averaging about 112 metres per day.
ix. Glacial ice often appears blue when it becomes very dense. Years of compression gradually makes the ice denser over time, forcing out the tiny air pockets between crystals. When glacier ice becomes extremely dense, the ice absorbs all other colours in the spectrum and reflects primarily blue, which is what we see. When glacier ice is white, that usually means that there are many tiny air bubbles still in the ice.