Glaciers

GLACIERS

GLACIERS

Perito Moreno Glacier Patagonia Argentina

GLACIERS

Aletsch Glacier, Switzerland

GLACIERS 

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The word glacier comes from French via the Vulgar Latin glacia, and ultimately from Latin glacies meaning ice. Glaciers are large, slow-moving river of ice, formed from compacted layers of snow, which slowly deforms and flows in response to gravity.

GLACIERS 

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Glacier ice is the largest reservoir of fresh water on Earth, and second only to oceans as the largest reservoir of total water. Glaciers cover vast areas of Polar Regions but are restricted to the highest mountains in the tropics.

GLACIERS 

Geologic features created by glaciers include: • end, lateral, ground, and medial moraines that form from glacially transported rocks and debris; • U-shaped valleys and cirques at their heads, • glacier fringe, which is the area where the glacier has recently melted into water

MORAINE 

Moraines refers to any glacially formed accumulation of unconsolidated debris which can occur in currently glaciated and formerly glaciated regions, such as those areas acted upon by a past ice age.

MORAINE

Moraines clearly seen on a side glacier of the Gorner Glacier, Zermatt, Switzerland.

U-SHAPED VALLEY 

A valley carved by glaciers, or glacial valley, is normally U-shaped. The valley becomes visible upon the recession of the glacier that forms it.

U-SHAPED VALLEY

U-shaped valley in Glacier National Park in Montana, United States.

CIRQUE 

A cirque (French for "circus") is an amphitheatre-like valley, or valley head, formed at the head of a glacier by erosion

CIRQUE

The Lower Curtis Glacier in North Cascades National Park is a well developed "cirque glacier.” If the glacier continues to retreat and melt away, a lake may form in the basin

INTERGLACIAL 

Glacial epochs have come and gone repeatedly over the last million years. Presently, Earth is in a relatively warm period, called an interglacial, exacerbated by global warming with the resulting retreat of the glaciers. The Earth has been cyclically plunged into cold episodes, however, called glacials, in which the extent of glaciers is expanded, colloquially referred to as ice ages.

TYPES OF GLACIERS 

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Alpine glaciers, which are found in mountain terrains, Continental glaciers, which can cover larger areas.

TYPES OF GLACIERS 

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A temperate glacier is at melting point throughout the year, from its surface to its base. The ice of polar glaciers is always below freezing point with most mass loss due to sublimation. Sub-polar glaciers have a seasonal zone of melting near the surface and have some internal drainage, but little to no basal melt.

TYPES OF GLACIERS 

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The smallest alpine glaciers form in mountain valleys and are referred to as valley glaciers. Larger glaciers can cover an entire mountain, mountain chain or even a volcano; this type is known as an ice cap. Outlet glaciers are tongues of ice that extend into valleys below, far from the margins of those larger ice masses. Outlet glaciers are formed by the movement of ice from a polar ice cap, or an ice cap from mountainous regions, to the sea.

TYPES OF GLACIERS 

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Largest glaciers are continental ice sheets, enormous masses of ice that are not visibly affected by the landscape and that cover the entire surface beneath them, except possibly on the margins where they are thinnest. (Antarctica and Greenland) Plateau glaciers resemble ice sheets, but on a smaller scale. They cover some plateaus and high-altitude areas. (Iceland, Western Alaska) Tidewater glaciers are glaciers that flow into the sea. As the ice reaches the sea pieces break off, or calve, forming icebergs.

FORMATION OF GLACIERS 

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The snow which forms temperate glaciers is subject to repeated freezing and thawing, which changes it into a form of granular ice called névé. Under the pressure of the layers of ice and snow above it, this granular ice fuses into denser firn. Over a period of years, layers of firn undergo further compaction and become glacial ice.

FORMATION OF GLACIERS

FORMATION OF GLACIERS

OCCURENCE 

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Glaciers occur on every continent and in approximately 47 of the world's countries. Extensive glaciers are found in Antarctica, Patagonia, Canada, Greenland and Iceland. Mountain glaciers are widespread (in the Andes, the Himalaya, the Rocky Mountains, the Caucasus, the Alps, in Norway, Japan, Turkey and the Iran).

THE EFFECT OF GLOBAL WARMING

GLACIAL RETREAT 

Studied by glaciologists, the temporal coincidence of glacier retreat with the measured increase of atmospheric greenhouse gases is often cited as an evidentiary underpinning of anthropogenic (human-caused) global warming.

GLACIAL RETREAT 

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In historic times, glaciers grew during a cool period from about 1550 to 1850 known as the Little Ice Age. Subsequently, until about 1940, glaciers around the world retreated as the climate warmed. Glacier retreat declined and reversed in many cases from 1950 to 1980 as a slight global cooling occurred. Since 1980, glacier retreat has become increasingly rapid and ubiquitous, and has threatened the existence of many of the glaciers of the world.

GLACIAL RETREAT 

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Crucial to the survival of a glacier is its mass balance, the difference between accumulation and ablation (melting and sublimation). Climate change may cause variations in both temperature and snowfall, causing changes in mass balance. A glacier with a sustained negative balance is out of equilibrium and will retreat

GLACIAL RETREAT 

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Excluding the ice caps and ice sheets of the Arctic and Antarctic, the total surface area of glaciers worldwide has decreased by 50% since the end of the 19th century. Currently glacier retreat rates and mass balance losses have been increasing in the Andes, Alps, Himalayas, Rocky Mountains and North Cascades.

GLACIAL RETREAT 

Glacier Ururashraju, at about 15,000 feet in Cordillera Blanca of Peru. (1986 and 1999)

GLACIAL RETREAT 

Grinnell glacier, Glacier National Park, USA, which has receded almost out of sight. (1911 and 2000)

GLACIAL RETREAT 

Glaciers in the Northwest United States have also been shrinking. (Mt. Oregon, 1984 and 2002)

GLACIAL RETREAT 

Alaska's glaciers are receding at twice the rate previously thought (Portage Glacier, 1950 and 2002)

ACCELERATED GLOBAL WARMING 

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Glaciers have a very high albedo, that is they reflect the sunlight back up and out of the atmosphere. As they melted they expose the ground or water beneath them. Both have much lower albedos, they reflect much less sunlight and absorb the energy as heat, speeding up the melting of the glacier surprisingly fast on the local scale. This fast and strong effect on the local scale further helps to increase global warming on a slower but larger global scale.

SEA LEVEL RISE 

With increasing average global temperature, the water in the oceans expands in volume, and additional water enters them which had previously been locked up on land in glaciers, for example, the Greenland and the Antarctic ice sheets for most glaciers worldwide, an average volume loss of 60% until 2050 is predicted.

SEA LEVEL RISE 

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The IPCC report notes that current and future climate change would be expected to have a number of impacts, particularly on coastal systems. Such impacts may include increased coastal erosion, higher storm-surge flooding, inhibition of primary production processes, more extensive coastal inundation, changes in surface water quality and groundwater characteristics.

SEA LEVEL RISE

Sea level rise contributors: Comparison of volume (white), area (grey) and percent contribution to sea level rise (red) by small glaciers and ice caps, and the Greenland and Antarctic Ice Sheets

SEA LEVEL RISE

Small glacier/ice cap contribution: The cumulative contribution to sea level from small glaciers and ice caps (red) plotted with the annual global surface air temperature anomaly (blue)

WATER SCARCITY 

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Sea level rise is projected to increase saltwater intrusion into groundwater in some regions, affecting drinking water and agriculture in coastal zones. Increased evaporation will reduce the effectiveness of reservoirs In some areas, shrinking glaciers threaten the water supply. The continued retreat of glaciers will have a number of different effects.

WATER SCARCITY 

In areas that are heavily dependent on water runoff from glaciers that melt during the warmer summer months, a continuation of the current retreat will eventually deplete the glacial ice and substantially reduce or eliminate runoff.

WATER SCARCITY 

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Essential use of water (washing and drinking) will be limited. A reduction in runoff will affect the ability to irrigate crops and will reduce summer stream flows necessary to keep dams and reservoirs replenished. Glacier runoff is important for hydropower, hence affecting hydroelectric stations.

WATER SCARCITY 

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There will also be impacts on agriculture and aquaculture through decline in soil and water quality. Higher temperatures will also increase the demand for water for the purposes of cooling and hydration.

IMPACTS ON ECOSYTEMS 

Many species of freshwater and saltwater plants and animals are dependent on glacier-fed waters to ensure a cold water habitat that they have adapted to.

IMPACTS ON ECOSYTEMS 

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Some species of freshwater fish need cold water to survive and to reproduce, and this is especially true with Salmon and Cutthroat trout. Ocean krill, a cornerstone species, prefer cold water and are the primary food source for aquatic mammals such as the Blue whale.

THERMOHALINE CIRCULATION 

The term thermohaline circulation (THC) refers to the part of the large-scale ocean circulation that is thought to be driven by global density gradients created by surface heat and freshwater fluxes. The adjective thermohaline derives from thermoreferring to temperature and -haline referring to salt content, factors which together determine the density of sea water.

THERMOHALINE CIRCULATION

THERMOHALINE CIRCULATION 

As average temperatures rise worldwide, glaciers and sea ice are melting, and evaporation and precipitation patterns are shifting. With more fresh water pouring in some regions and more evaporation in others, parts of the ocean are becoming fresher, while others are becoming saltier at a visible pace.

THERMOHALINE CIRCULATION 

If the North Atlantic loses too much salinity, one of the primary forces driving ocean circulation could weaken. Fresher water is less dense than salty water, so it does not sink in saltier water. If waters were to stop sinking in the North Atlantic, existing currents could slacken or change course, leading to altered climate patterns.

THERMOHALINE CIRCULATION 

A slackening of the conveyor could slow or change the course of the Gulf Stream, a warm current that gives northwestern Europe a milder climate than it would normally have so far north, plunging Europe into a colder era.

IMPACTS ON ICE SHEET DYNAMICS 

Ice sheet dynamics describe the motion within large bodies of ice, such those currently on Greenland and Antarctica. Ice motion is dominated by the movement of glaciers, whose gravity-driven activity is controlled by two main variable factors: the temperature and strength of their bases.

IMPACTS ON ICE SHEET DYNAMICS 

It is clear that increasing temperatures are resulting in reduced ice volumes globally, due to the melting of glaciers. Rising sea levels will also reduce the stability of ice shelves, which have a key role in reducing glacial motion. Some Antarctic ice shelves are currently thinning by tens of meters per year, and the collapse of the Larsen B shelf was preceded by thinning of just 1 meter per year.

IMPACTS ON ICE SHEET DYNAMICS 

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Increasing global temperatures take around 10,000 years to directly propagate through the ice before they influence bed temperatures, but may have an effect through increased surfacal melting, producing more supraglacial lakes, which may feed warm water to glacial bases and facilitate glacial motion. Observations, while currently limited in scope, do agree with these predictions of an increasing rate of ice loss from both Greenland and Antarctica.

CATASTROPHES 

As temperatures rise, a global meltdown has begun. The melting of glaciers can lead to worldwide problems and catastrophes. • Water Scarcity • Sea Level Rise

CATASTROPHES 

As sea levels rise, oceans throughout the world are also becoming hotter. Warmer seas fuel more intense hurricanes. Already, major catastrophes brought on by the process of melting ice, rising seas and intensifying storms have occurred in coastal communities around the world: New Orleans, for example

CATASTROPHES 

Increased extreme weather means more water falls on hardened ground unable to absorb it, leading to flash floods instead of a replenishment of soil moisture or groundwater levels.

CATASTROPHES 

The rising oceans may swallow some lands forever

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Glacial lakes will burst

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Debris and ice will fall in avalanches

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Rivers will flood

CATASTROPHES 

Water wars between countries or states may occur. (Water war describes an armed conflict motivated around the use or possession of water resources within a state’s boundary or between two different states.)

SUMMARY 

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The rise of global temperature greatly affect glaciers. Since 1860, glacial retreats and disappearances increased. The rapid melting of glaciers is a harbinger of other problems.

SUMMARY 

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As glaciers melt, sea level rise. Sea level rise increased the salinity of major water resources, affecting drinking water and agriculture in coastal zones. Melting of glaciers decreased the albedo of the Earth, helping increased global warming.

SUMMARY 

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Several species that depends on glacial-fed waters will be greatly affected. The food chain will also be disrupted. Glacial retreat decrease the salinity of some areas affecting the climate.

GLACIERS 

Prepared by: • Jericho Olea • Joseph Carlo Pang