Vanishing Point
POINT
Chapter
Discover the impacts of glacier melting
Chapter
Chapter
Chapter Vanishing Point
Vanishing Point
Chapter
Chapter
Chapter Vanishing Point
VANISHING POINT
Vanishing Point
Copyright Š (2020) All rights reserved. No part of this publication may be reproduced, stored in retrieval system, or transmitted in any form by any means electronic, mechanical, photocopying, recording or otherwise without permission of copy right holder.
Publisher iUniverse Limited 1663 Liberty Drive, Bloomington, IN Tel + 844-349-9409 News Media Contact iUniverse PR Department media@iuniverse.com
This book is dedicated to people who want to make a difference.
Chapter
Chapter Vanishing Point
Preface melting not only makes the temperatures of ocean and air continue to rise, but also threatens the living environment of human and animals. In order to call attention to the phenomena of glaciers, this book talks about some basic information, such as glaciers formations, glaciers features and glaciers impacts. By reading this book, people can know more about the importance of glaciers and how melting glaciers affect the environment and people’s life.
Vanishing Point Perface
Glaciers are made up of fallen snow that, over many years, compresses into large, thickened ice masses. Glaciers form when snow remains in one location long enough to transform into ice. One of the unique ability for glacier is it can flow. Due to sheer mass, glaciers flow like very slow rivers. Glaciers occupy about 10 percent of the world’s total land area, with most located in polar regions like Antarctica, Greenland, and the Canadian Arctic right now. Glaciers can be thought of as remnants from the last Ice Age, when ice covered nearly 32 percent of the land, and 30 percent of the oceans. Most glaciers lie within mountain ranges that show evidence of a much greater extent during the ice ages of the past two million years, and more recent indications of retreat in the past few centuries. Ice is a protective layer cover over the earth and oceans which reflects excess heat back into spaces and keep the cooler temperature on the planet. Since the early 1900s, there are many glaciers around the world have been melting rapidly. The rapid glaciers
Chapter
Chapter Vanishing Point
Table of Contents
Dedication Preface Introduction
1
Chapter 01 Glaciers Formation
09
Chapter 02 Glaciers Movement
21
Chapter 03 Glaciers Melting
35
Index
53 Vanishing Point
Colophon
Chapter Chapter
1
Chapter Vanishing Point
The Importance of Ice on the Earth
Glaciers are large bodies of ice that exist year-round in high mountains and the polar regions, where they can also be known as ice-sheets or ice-caps. Today, about 10% of land area on Earth is covered with glacial ice. Almost 90% is in Antarctica, while the remaining 10% is in the Greenland ice cap. Glaciers can be thought of as remnants from the last Ice Age, when ice covered nearly 32 percent of the land, and 30 percent of the oceans. In recent years, the greenhouse effect has been affected the shrinking of glaciers around the world. Glacial melt can have global and local effects. Globally, it can lead to rising sea levels and with that, flooding. For example, rapid glacial melt in Antarctica and Greenland influences ocean currents, as massive amounts of very cold glacial-melt water entering warmer ocean waters is slowing ocean currents. And as ice on land melts, sea levels will continue to rise. Locally, glacial melt disrupts water flow to rivers.
Vanishing Point
Ice acts like a protective cover over the Earth and our oceans. These bright white spots reflect excess heat back into space and keep the planet cooler. In theory, the Arctic remains colder than the equator because more of the heat from the sun is reflected off the ice, back into space. Glaciers around the world can range from ice that is several hundred to several thousand years old and provide a scientific record of how climate has changed over time. Through these study, we gain valuable information about the extent to global warning and climate change. Throughout Earth’s history, Glaciers have grown and shrunk depending on the planet’s overall temperature. Glaciers are made up of fallen snow that, over many years, compresses into large, thickened ice masses. Glaciers form when snow remains in one location long enough to transform into ice. What makes glaciers unique is their ability to flow. Due to sheer mass, glaciers flow like very slow rivers. Some glaciers are as small as football fields, while others grow to be dozens or even hundreds of kilometers long.
Introduction
2
Glaciers
Introduction
Vanishing Point
Glaciers are made up of fallen snow that, over many years, compresses into large, thickened ice masses. Glaciers form when snow remains in one location long enough to transform into ice. What makes glaciers unique is their ability to flow. Due to sheer mass, glaciers flow like very slow rivers. Some glaciers are as small as football fields, while others grow to be dozens or even hundreds of kilometers long. Presently, glaciers occupy about 10 percent of the world’s total land area, with most located in polar regions like Antarctica, Greenland, and the Canadian Arctic. Glaciers can be thought of as remnants from the last Ice Age, when ice covered nearly 32 percent of the land, and 30 percent of the oceans. Most glaciers lie within mountain ranges that show evidence of a much greater extent during the ice ages of the past two million years, and more recent indications of retreat in the past few centuries. An ice cap is a dome-shaped glacier mass flowing in all directions, such as the ice cap on Ellesmere Island in the Canadian Arctic. An ice sheet is a dome-shaped glacier mass exceeding 50,000 square kilometers. The world’s ice sheets are confined to Greenland and Antarrctica.
3
Vanishing Point
4
Alpine Glaciers and Ice Sheets
Introdction
Vanishing Point
A glacier is a huge mass of ice that moves slowly over land. Glaciers fall into two groups: alpine glaciers and ice sheets. Alpine glaciers form on mountainsides and move downward through valleys. Sometimes, alpine glaciers create or deepen valleys by pushing dirt, soil, and other materials out of their way. Alpine glaciers are found in high mountains of every continent except Australia. The Gorner Glacier in Switzerland and the Furtwangler Glacier in Tanzania are both typical alpine glaciers. Alpine glaciers are also called valley glaciers or mountain glaciers.
5
Ice sheets, unlike alpine glaciers, are not limited to mountainous areas. They form broad domes and spread out from their centers in all directions. As ice sheets spread, they cover everything around them with a thick blanket of ice, including valleys, plains, and even entire mountains. The largest ice sheets, called continental glaciers, spread over vast areas. Today, continental glaciers cover most of Antarctica and the island of Greenland. Massive ice sheets covered much of North America and Europe during the Pleistocene time period. This was the last glacial period, also known as the Ice Age. Ice sheets reached their greatest size about 18,000 years ago. As the ancient glaciers spread, they carved and changed the Earth’s surface, creating many of the landscapes that exist today. During the Pleistocene Ice Age, nearly one-third of the Earth’s land was covered by glaciers. Today, about one-tenth of the Earth’s land is covered by glacial ice.
Vanishing Point
A glacier always moves in the same direction whether it is advancing or retreating.
6
Chapter
Chapter Vanishing Point
Vanishing Point
Chapter
Chapter
01
Chapter
Vanishing Point
Glacier Formation
Chapter
Vanishing Point
Chapter
Chapter
Glacier Formation
Chapter
Vanishing Point
Glaciers begin forming in places where more snow piles up each year than melts. Soon after falling, the snow begins to compress, or become denser and tightly packed. It slowly changes from light, fluffy crystals to hard, round ice pellets. New snow falls and buries this granular snow. The hard snow becomes even more compressed. It becomes a dense, grainy ice called firn. The process of snow compacting into glacial firn is called firnification. As years go by, layers of firn build on top of each other. When the ice grows thick enough, about 50 meters, the firn grains fuse into a huge mass of solid ice. The glacier begins to move under its own weight. The glacier is so heavy and exerts so much pressure that the firn and snow melt without any increase in temperature. The meltwater makes the bottom of the heavy glacier slicker and more able to spread across the landscape.
11
Pulled by gravity, an alpine glacier moves slowly down a valley. Some glaciers, called hanging glaciers, don't flow the entire length of a mountain. Avalanches and icefalls transfer glacial ice from hanging glaciers to a larger glacier beneath them, or directly to the valley below. An ice sheet spreads out from its center. The great mass of ice in a glacier behaves plastically, or like a liquid. It flows, oozes, and slides over uneven surfaces until it covers everything in its path.
Consistency and Density
Snow
90% air < 0.1g/cm3
50% air 0.3 to 0.5g/cm3
Firm
30% air 0.5 to 0.7g/cm3
Chapter 01 Glacier Formation
Glacier Ice
Vanishing Point
Granular Ice
20% air as bubbles > 0.7g/cm3
12
Crevasse
Alpine glacier
Chapter
Vanishing Point
Cirque
Glacier ice
13
How Do Glaciers Form
Firn
Ice blocks
Ablation zone Vanishing Point
Kame
Chapter 14
Chapter 01 Glacier Formation
All that ice began to form when snowâ&#x20AC;&#x201D;delicate, feathery crystals of iceâ&#x20AC;&#x201D;fell in areas above the snow line, the elevation above which snow can form and remain all year.
15
Glacier Movement The sheer weight of a thick layer of ice, or the force of gravity on the ice mass, causes glaciers to flow very slowly. Ice is a soft material, in comparison to rock, and is much more easily deformed by this relentless pressure of its own weight. Ice may flow down mountain valleys, fan out across plains, or in some locations, spread out onto the sea. Movement along the underside of a glacier is slower than movement at the top due to the friction with the underlying groundâ&#x20AC;&#x2122;s surface. Where the base of the glacier is very cold, the movement at the bottom can be a tiny fraction of the speed of flow at the surface. Sometimes a glacier slides over a thin water layer at the glacierâ&#x20AC;&#x2122;s base. The water may result from glacial melt driven by pressure of the overlying ice, or from water working its way through glacier cracks to the base. Glaciers can also slide on a soft, watery sediment bed. This basal sliding may account for most of the movement of thin, cold glaciers on steep slopes. Warm, thick glaciers on gentle slopes owe less of their movement to basal sliding.
Vanishing Point
Glaciers periodically retreat or advance, depending on the amount of snow accumulation or evaporation or melt that occurs. This retreat and advance refers only to the position of the terminus, or snout, of the glacier. Even as it retreats, the glacier still deforms and moves downslope, like a conveyor belt. In other words, a retreating glacier does not flow uphill; it simply melts faster than it flows. Alternatively, glaciers may surge, racing forward several meters per day for weeks or even months. In 1986, the Hubbard Glacier in Alaska surged at the rate of 10 meters (32 feet) per day across the mouth of Russell Fjord. In only two months, the glacier had dammed water in the fjord and created a lake.
Chapter 01 Glacier Formation 16
Chapter 01 Glacier Formation
Vanishing Point
Different parts of a glacier move at different speeds. The flowing ice in the middle of the glacier moves faster than the base, which grinds slowly along its rocky bed. The different speeds at which the glacier moves causes tension to build within the brittle, upper part of the ice. The top of the glacier fractures, forming cracks called crevasses. Crevasses are in the top 50 meters (160 feet) of the glacier. Crevasses can be very dangerous for mountaineers. They can open quickly and be very deep. Moulins are another formation that carve into glaciers. A moulin is a deep, nearly-vertical pipeline in the glacier formed by meltwater on top of the glacier falling through a crack in the ice. They are often much deeper than crevasses, going all the way to the bottom of the glacier. Most glaciers move very slowlyâ&#x20AC;&#x201D;only a few centimeters a day. Some, though, can move 50 meters (160 feet) a day. These fast-moving rivers of ice are called galloping glaciers. Where a glacier meets the coast, it becomes a tidewater glacier. Its leading edge lifts and floats in the water, forming cliffs of ice that may be 60 meters (200 feet) high. Chunks of ice at the edge of the tidewater glacier break away into the waterâ&#x20AC;&#x201D;a process called calving. Calving is a violent process. It results in large waves and loud crashes. Floating chunks of glacial ice, broken off during calving, are called icebergs. 17
The glacier moves to lower elevations under the force of gravity by two different processes: internal flow and basal sliding.
Vanishing Point Chapter 01 Glacier Formation Chapter
Chapter
Chapter Vanishing Point
Vanishing Point
Chapter
Chapter
02
Chapter
Vanishing Point
Glacier Movement
Chapter
Vanishing Point
Chapter
Chapter
The Components of A Glacier
Chapter
Vanishing Point
Glaciers are large, perennial accumulation of crystalline ice, snow, rock, sediment. They are dynamic, and several elements contribute to glacier formation and growth. Snow falls in the accumulation area, usually the part of the glacier with the highest elevation, adding to the glacierâ&#x20AC;&#x2122;s mass. As the snow slowly accumulates and turns to ice, and the glacier increases in weight, the weight begins to deform the ice, forcing the glacier to flow downhill. Further down the glacier, usually at a lower altitude, is the ablation area, where most of the melting and evaporation occur. Between these two areas a balance is reached, where snowfall equals snowmelt, and the glacier is in equilibrium. Whenever this equilibrium is disturbed, either by increased snowfall or by excessive melting, the glacier either advances or retreats at more than its normal pace. Glaciers are sensitive indicators of changing climate.
23
Several visible features are common to most glaciers. At locations where a glacier flows rapidly, friction creates giant cracks called crevasses, which may make travel across a glacier treacherous. Other common glacial features are moraines, created when the glacier pushes or carries rocky debris as it moves. These long, dark bands of debris are visible on top and along the edges of glaciers. Medial moraines run down the middle of a glacier, lateral moraines along the sides, and terminal moraines are found at the terminus, or snout, of a glacier. Sometimes one glacier flows into another, creating combined wider moraines. Often these linear deposits of rocks are left behind, almost intact, after the ice in a glacier has melted away. Studying these rocky debris remnants, and the sediments that were once beneath the glacier, is the subject of glacial geology and geomorphology.
Vanishing Point
The process of melt can add components to a glacier, including supraglacial lakes (meltwater surface ponds) and moulins (nearly vertical channels formed by meltwater). Glacier mice sometimes thrive on glacial surfaces. These mice are not rodents, but instead balls of moss containing tiny ecosystems. Blobs of dust or organic debris become the nuclei of glacier mice, and as the clumps are battered by wind, they roll around on glacier surfaces, gathering moss. Examinations of glacier-mice interiors have found springtails, tardigrades, and nematode worms.
Chapter 02 Glacier Movement 24
Movement Features
Chapter 02 Glacier Movement
Vanishing Point
Although glaciers move slowly, they are extremely powerful. Like huge bulldozers, they plow ahead year after year, crushing, grinding, and toppling almost everything in their paths. Forests, hills, and mountainsides are no match for glaciers. Sometimes, glaciers form on volcanoes. When these volcanoes erupt, they are especially dangerous. They send floods of water, ice, and rocks over the land and into the atmosphere Alpine glaciers begin to flow downhill from bowl-shaped mountain hollows called cirques. As the glaciers overflow the cirque, they move downward. They dig deep into the terrain, forming rugged, dramatic landscapes. As they move, glaciers erode or wear away the land beneath and around them. Glaciers carry great amounts of soil, rock, and clay. Some of the boulders they carry are as big as houses.
25
All modeled iceberg trajectories for the full 12 year simulation, colored differently for better distinction of the five size classes introduced by Wesche and Dierking
Vanishing Point Chapter 02 Glacier Movement
bserved giant iceberg trajectories (July 1999 to November 2009) from the QuikSCAT portion of the Antarctic Iceberg Tracking Database
26
LAND-ENDING ICE SHEETS C
(9 TO 99 METERS) PER YEAR,
TERMINATE IN ICE SHELVES M
FROM 1,000 TO MORE THAN
M) PER YEAR. THE GLACIERS
SEA ARE FLOWING THE FAST Vanishing Point
MILES (11 KILOMETERS) PER Chapter 02 Glacier Movement
ARE ACCELERATING.
27
CAN MOVE 30 TO 325 FEET
, WHILE GLACIERS THAT
MOVE MUCH FASTER,
N 5,000 FEET (305 TO 1,600
S THAT DROP OFF INTO THE
TEST WHICH IS UP TO 7 YEAR, AND THEIR SPEEDS Vanishing Point Chapter 02 Glacier Movement 28
Chapter 02 Glacier Movement
Vanishing Point
Horn is a high mountain peak that forms when the walls of three or more glacial cirques intersect
29
Glacier Erratics
Vanishing Point
Glacial erratics is often simply called erratics, or erratic boulders. As a glacier or ice sheet moves, it can erode bedrock. The ice can then pick up, or entrain, the eroded rock. Erratics can range from large boulders to smaller stones and pebbles. As the ice flows, it transports the bedrock debris in the direction of flow. The ice then deposited the entrained sediment once it begins to retreat. Rocks carried hundreds and even thousands of kilometers by glaciers are called glacial erratics. Glacial erratics differ significantly from the landscape in which they were deposited. Embedded, or stuck, in a glacier’s base, these large rocks grind against the ground like the prongs of a rake. They dig long grooves, called striations, in the surface of the Earth. Geologists can tell in what direction an ancient glacier moved by studying striations left in rock. Glaciers eventually deposit their loads of rock, dirt, and gravel. These materials are called moraine. Piles of moraine dumped at a glacier’s end, or snout, are called terminal moraines. Lateral moraine forms along the side of a glacier. Medial moraine appears as dark lines near the center of the glacier. Supraglacial moraine appears on the surface of the glacier— dirt, dust, leaves, and anything else that falls onto a glacier and sticks. Ogives are frozen “waves,” or ridges, on the surface of a glacier.
Chapter 02 Glacier Movement 30
Glacier Features
Chapter
Vanishing Point
When glaciers began their final retreat 10,000 years ago, they left behind many landscape features, such as lakes, valleys, and mountains. Many hollowed-out areas carved by glaciers became lakes. Bowl-shaped cirques, where most alpine glaciers form, became mountain lakes. These alpine lakes are called tarns. Glaciers can also create lakes by leaving depressions in the earth. The lakes were once stream valleys. Along the streams, the glacier scooped out troughs that now contain deep lakes. Glacial retreat created other features of the landscape. Materials deposited by a glacier as it retreats are called ground moraines. The jumble of rock, gravel, and dirt making up ground moraines is called till. Much of the fertile soil in the Great Plains of North America was formed from layers of till left by ancient ice sheets. Glacial valleys exist on almost every continent. These valleys are scooped out as a glacier scrapes through them. There are no glaciers in Australia, but Mount Kosciuszko still has glacial valleys from the last Ice Age.
31
Vanishing Point
Distinctive mountain formations called aretes and horns are the result of glacial activity. An arête is a sharp ridge of rock that forms when two glaciers collide. Each glacier erodes a glacial valley on either side of the arête. Glacier National Park in the U.S. state of Montana is filled with deep glacial valleys and sharp arêtes. An arête where three or more glaciers meet to form a peak is called a horn. These tall, singular landforms are also called pyramidal peaks. Roche moutonnee is a smooth, rounded rock formation created as a glacier crushes and rearranges rocks in its path. Roche moutonnee is visible in many hilly areas as outcroppings of flat rock. In contrast to alpine glaciers, ice sheets do not create landscape features as they spread. They tend to smooth out the land beneath them.
Chapter 02 Glacier Movement 32
Chapter
Chapter Vanishing Point
Vanishing Point
Chapter
Chapter
03
Chapter
Vanishing Point
Glacier Meltiing
Chapter
Vanishing Point
Chapter
Chapter
37
Chapter Vanishing Point
Glacier Benefits
Vanishing Point
Glaciers provide people with many useful resources. Glacial till provides fertile soil for growing crops. Deposits of sand and gravel are used to make concrete and asphalt. The most important resource provided by glaciers is freshwater. Many rivers are fed by the melting ice of glaciers. The Gangotri Glacier, one of the largest glaciers in the Himalayan Mountains, is the source of the River" Ganges River. The Ganges is the most important source of freshwater and electricity in India and Bangladesh. Glaciers provide vast quantities of drinking water that can be relied on in arid conditions. For populations living in La Paz, Bolivia, they get their fresh water from snow melt. But when precipitation levels are low, glacial melt provides the much needed water supply. Remove the glaciers, and the water supply will dry up in the dry season, forcing these communities to move out of this hospitable environment. Glaciers also provide ice. Glaciers dug basins for most of the worldâ&#x20AC;&#x2122;s lakes and carved much of the Earthâ&#x20AC;&#x2122;s most spectacular mountain scenery. The dramatic, diverse landscape of Yosemite Valley, California, was sculpted entirely by glaciers during the last Ice Age.
Chapter 03 Glacier Melring 38
Glacier Retreat
Chapter 03 Glacier Melring
Vanishing Point
Glaciers require very specific climatic conditions. Most are found in regions of high snowfall in winter and cool temperatures in summer. These conditions ensure that the snow that accumulates in the winter is not lost during the summer. Such conditions typically prevail in polar and high alpine regions. Glacier retreat, melt, and ablation result from increasing temperature, evaporation, and wind scouring. Ablation is a natural and seasonal part of glacier life. As long as snow accumulation equals or is greater than melt and ablation, a glacier will remain in balance or even grow. Once winter snowfall decreases, or summer melt increases, the glacier will begin to retreat. Some biological processes, such as microbes on the surface of a glacier, can reduce the glacierâ&#x20AC;&#x2122;s ability to reflect sunlight back into space. These bioalbedo processes can hasten glacier retreat.
39
As they flow, glaciers plow up or push aside rocks and debris, which is then left behind when the glacier recedes. Then, as large glaciers retreat, the underlying ground surface is typically abraded of most materials, leaving only scars and debris on the underlying bedrock surface. Over the past 60 to 100 years, glaciers worldwide have tended to retreat. Tidewater glaciers, which flow through valleys out to sea, are susceptible to retreat at the point where the ice meets relatively warm ocean water. Alpine glaciers, due to their relatively small size and lack of stability, seem particularly susceptible to retreat.
Vanishing Point
A glacier retreats when its terminus does not extend as far downvalley as it previously did. Glaciers may retreat when their ice melts or ablates more quickly than snowfall can accumulate and form new glacial ice. Higher temperatures and less snowfall have been causing many glaciers around the world to retreat recently.
40
Glacier Melting
Chapter 03 Glacier Melring
Vanishing Point
Ice acts like a protective cover over the Earth and our oceans. These bright white spots reflect excess heat back into space and keep the planet cooler. In theory, the Arctic remains colder than the equator because more of the heat from the sun is reflected off the ice, back into space. Glaciers around the world can range from ice that is several hundred to several thousand years old and provide a scientific record of how climate has changed over time. Through their study, we gain valuable information about the extent to which the planet is rapidly warming. They provide scientists a record of how climate has changed over time. Today, about 10% of land area on Earth is covered with glacial ice. Almost 90% is in Antarctica, while the remaining 10% is in the Greenland ice cap. Rapid glacial melt in Antarctica and Greenland also influences ocean currents, as massive amounts of very cold glacial-melt water entering warmer ocean waters is slowing ocean currents. And as ice on land melts, sea levels will continue to rise.
41
The processes that remove snow, ice, and moraine from a glacier or ice sheet are called ablation. Ablation includes melting, evaporation, erosion, and calving. Glaciers melt when ice melts more quickly than firn can accumulate. Earthâ&#x20AC;&#x2122;s average temperature has been increasing dramatically for more than a century. Glaciers are important indicators of global warming and climate change in several ways. Melting ice sheets contribute to rising sea levels. As ice sheets in Antarctica and Greenland melt, they raise the level of the ocean. Tons of fresh water are added to the ocean every day. Large additions of fresh water also change the ocean ecosystem. Organisms, such as many types of corals, depend on salt water for survival. Some corals may not be able to adjust to a more freshwater habitat. The loss of glacial ice also reduces the amount of fresh water available for plants and animals that need fresh water to survive. Glaciers near the Equator, such as those on the tropical island of Papua or in South America, are especially at risk.
Cumulative mass balance (meters of water equivalent)
0 -5 -10 -15 -20 -25
Number of glaciers meastured
-30 1940
1950
1960
1970
1980
1990
2000
2010
2020
1950
1960
1970
1980
1990
2000
2010
2020
50 25 0 1940
Vanishing Point
This figure shows the cumulative change in mass balance of a set of â&#x20AC;&#x153;referenceâ&#x20AC;? glaciers worldwide beginning in 1945. The line on the upper graph represents the average of all the glaciers that were measured. Negative values indicate a net loss of ice and snow compared with the base year of 1945. For consistency, measurements are in meters of water equivalent, which represent changes in the average thickness of a glacier. The small chart below shows how many glaciers were measured in each year. Some glacier measurements have not yet been finalized for the last few years, hence the smaller number of sites.
Chapter 03 Glacier Melring 42
Chapter 03 Glacier Chapter Melring
Vanishing Point
EVEN IF WE SIGNIFICAN IN THE COMING DEC A THIRD OF THE WO GLACIERS WILL MEL 2100. WHEN IT COME THE OLDEST AND TH ARCTIC IS ALREADY G
43
NTLY CURB EMISSIONS CADES, MORE THAN ORLDâ&#x20AC;&#x2122;S REMAINING LT BEFORE THE YEAR ES TO SEA ICE, 95% OF HICKEST ICE IN THE GONE. Vanishing Point Chapter 03 Glacier Melring 44
Causes of Glacier Melting
Chapter
Vanishing Point
The melting of the glaciers, a phenomenon that intensified in the 20th century, is leaving our planet iceless. Human activity is the main culprit in the emission of carbon dioxide and other greenhouse gases. The sea level and global stability depend on how these great masses of recrystallized snow evolve. A glacier is a large mass of snow and ice that has accumulated over many years and is present year-round. A glacier flows naturally like a river, only much more slowly. At higher elevations, glaciers accumulate snow, which eventually becomes compressed into ice. At lower elevations, the â&#x20AC;&#x153;riverâ&#x20AC;? of ice naturally loses mass because of melting and ice breaking off and floating away (iceberg calving) if the glacier ends in a lake or the ocean. When melting and calving are exactly balanced by new snow accumulation, a glacier is in equilibrium and its mass will neither increase nor decrease.
45
In many areas, glaciers provide communities and ecosystems with a reliable source of streamflow and drinking water, particularly in times of extended drought and late in the summer, when seasonal snowpack has melted away. Freshwater runoff from glaciers also influences ocean ecosystems. Glaciers are important as an indicator of climate change because physical changes in glaciersâ&#x20AC;&#x201D; whether they are growing or shrinking, advancing or recedingâ&#x20AC;&#x201D;provide visible evidence of changes in temperature and precipitation. If glaciers lose more ice than they can accumulate through new snowfall, they ultimately add more water to the oceans, leading to a rise in sea level (see the Sea Level indicator). The same kinds of changes occur on a much larger scale within the giant ice sheets that cover Greenland and Antarctica, potentially leading to even bigger implications for sea level. Small glaciers tend to respond more quickly to climate change than the giant ice sheets. Altogether, the worldâ&#x20AC;&#x2122;s small glaciers are adding roughly the same amount of water to the oceans per year as the ice sheets of Greenland and Antarctica. During the last two decades, they added more water overall to the oceans than the ice sheets did Vanishing Point Chapter 03 Glacier Melring 46
47
Chapter 03 Glacier Melring Vanishing Point
Effects of Glacier Melting Melting glaciers add to rising sea levels, which in turn increases coastal erosion and elevates storm surge as warming air and ocean temperatures create more frequent and intense coastal storms like hurricanes and typhoons. Specifically, the Greenland and Antarctic ice sheets are the largest contributors of global sea level rise. Right now, the Greenland ice sheet is disappearing four times faster than in 2003 and already contributes 20% of current sea level rise. How much and how quickly these Greenland and Antarctic ice sheets melt in the future will largely determine; how much ocean levels rise in the future. If emissions continue to rise, the current rate of melting on the Greenland ice sheet is expected to double by the end of the century. Alarmingly, if all the ice on Greenland melted, it would raise global sea levels by 20 feet.
Vanishing Point
Today, the Arctic is warming twice as fast as anywhere on earth, and the sea ice there is declining by more than 10% every 10 years. As this ice melts, darker patches of ocean start to emerge, eliminating the effect that previously cooled the poles, creating warmer air temperatures and in turn disrupting normal patterns of ocean circulation. Research shows the polar vortex is appearing outside of the Arctic more frequently because of changes to the jet stream, caused by a combination of warming air and ocean temperatures in the Arctic and the tropics. The glacial melt are witnessing today in Antarctic and Greenland is changing the circulation of the Atlantic Ocean and has been linked to collapse of fisheries in the Gulf of Maine and more destructive storms and hurricanes around the planet.
Chapter 03 Glacier Melring 48
Chapter 03 Effect
Chapter 03 Glacier Melring
Vanishing Point
What happens in these places has consequences across the entire globe. As sea ice and glaciers melt and oceans warm, ocean currents will continue to disrupt weather patterns worldwide. Industries that thrive on vibrant fisheries will be affected as warmer waters change where and when fish spawn. Coastal communities will continue to face billion-dollar disaster recovery bills as flooding becomes more frequent and storms become more intense. People are not the only ones impacted. In the Arctic, as sea ice melts, wildlife like walrus are losing their home and polar bears are spending more time on land, causing higher rates of conflict between people and bears.
49
When solar radiation hits snow and ice, approximately 90% of it is reflected back out to space. As global warming causes more snow and ice to melt each summer, the ocean and land that were underneath the ice are exposed at the Earthâ&#x20AC;&#x2122;s surface. Because they are darker in color, the ocean and land absorb more incoming solar radiation, and then release the heat to the atmosphere. This causes more global warming. In this way, melting ice causes more warming and so more ice melts. Global warming is causing soils in the polar regions that have been frozen for as much as 40,000 years to thaw. As they thaw, carbon trapped within the soils is released into the atmosphere as carbon dioxide and methane. These gases, which are released to the atmosphere, cause more warming, which then thaws more the frozen soil.
Vanishing Point
Chapter 03 Effect
50
Chapter
Chapter Vanishing Point
Vanishing Point
Chapter
Chapter
Index A
B
Index
Vanishing Point
C
53
Ablation ¦ 14, 21, 37 Abraded ¦ 39 Accumulate ¦ 14, 21, 37, 49 Antarctica ¦ 2, 41, 46 Alpine ¦ 5, 13, 37 Aretes ¦ 32 Arctic ¦ 2, 43 Asphalt ¦ 36 Atmosphere ¦ 49 Avalanchess ¦ 5 Basal sliding ¦ 16 Basins ¦ 36 Bedrock ¦ 30, 39 Boulder ¦ 30 Biological ¦ 37 Brittle ¦ 16 Bowl-shaped ¦ 23 Bulldozer ¦ 23 Calving ¦ 41 Chatter Marks ¦ 5 Cliff ¦ 5 Climatic ¦39 Cirque ¦ 13, 29 Coastal ¦ 47 Coast ¦ 47 Collapse ¦48 Collide ¦ 32 Corals ¦ 41 Continental glaciersm ¦5 Continent ¦ 39 Crevasse ¦ 13, 17 Culprit ¦ 45 Cumulative ¦ 41
D
Dam ¦ 27 Dense ¦ 5 Distinctive ¦ 31 Dome-shaped ¦ 3 Drumlins ¦ 21 Dug ¦ 36
E
Ellesmere Island ¦ 3 Entrain ¦ 30 Equilibrium ¦ 21 Erratic ¦ 2, 30 Eroded rock ¦ 30 Erosion ¦ 41 Emission ¦ 44, 47 Evaporation ¦ 37, 41 Extended ¦ 46
F
Fertile ¦ 36 Firn ¦ 13 Firnification ¦ 13 Fisheries ¦ 48 Fjord ¦ 16
G Galloping glaciers ¦ 17 Gangotri Glacier ¦ 36 Ganges River ¦ 36 Giant ¦ 46 Global warming ¦ 41 Gravity ¦ 2, 16 Gravel ¦ 31 Great Plains ¦ 31 Greenland ¦ 2, 3, 41 Gulf ¦ 48
H
I
Horns ¦ 32 Himalayan Mountains ¦ 36 Hubbard Glacier ¦ 16 Hurricanes ¦ 47
Icebergs ¦ 17 Ice blocks ¦ 13 Ice-caps ¦ 2, 3 Ice pellets ¦ 5 Ice sheets ¦ 5, 27 Indicators ¦ 41, 46 Implications ¦ 46
J
Jet stream ¦ 48 Jumble ¦ 31
K
Kame ¦ 14 Krakatoa ¦ 16
L
P
Papua ¦ 41 Peak ¦ 32 Piedmont ¦ 16 Pipeline ¦ 16 Pleistocene ¦ 5 Plow up ¦ 39 Polar ¦ 2 Precipitation ¦ 36, 46 Prevail ¦ 39 Prongs ¦ 30 Pyramidal ¦ 30
R
Recrystallized ¦ 44 Retreats ¦ 16, 37 Runoff ¦ 46 Russell Fjord ¦ 16 Roche moutonnee ¦ 32
S
Sea level ¦ 41 Snout ¦ 16 Snowfall ¦ 39 Snowpack ¦ 46 Solar radiation ¦ 49 Spectacular ¦ 36 Stream ¦ 31 Streamflow ¦ 46 Striation ¦ 30 Surging ¦ 16, 36, 41 Susceptible ¦ 39
T
Terminal moraine ¦ 30 Terminate¦ 27 Terminus ¦ 16 Tidewater ¦ 37 Till ¦ 31 Trajectories ¦ 26 Tropical ¦ 41 Trough ¦ 26 Typhoonse ¦ 47
M Maine ¦ 48
Matterhorn ¦ 16 Moraine ¦ 30, 41, Moulins ¦ 16 Mount Kosciuszko ¦ 31
W Wind scouring ¦ 37 X
Y
Yosemite Valley ¦ 4
Z
Q
Landform ¦ 32
V
N Ogive ¦ 30 Organisms ¦ 41 Outcroppings ¦ 32
Vanishing Point
O
Index
U 54
Colophon Display and Headings Typeface Gibson Designed by Jamie Chang, Kevin King, Patrick Griffin, and Rod McDonald Published in 2011 by Canadian type
Chapter
Vanishing Point
Body Text Typeface ITC Galliard Pro Designed by Matthew Carter Published in 1978 by ITC Tools and software Adobe Creative Cloud InDesign, Illustrator Designer Jiarong Lu Photography Sourced from Unsplash
Chapter
Chapter Vanishing Point
Vanishing Point
Chapter
Chapter
This book talks about the causes of the melting glaciers and its impacts of natural ecosystems, biodiversity, and living environment of human and animals. The goal of this project is to call attention to the growing environmental problems and take action to change the situation.
Chapter
Vanishing Point
Ice is a protective layer cover over the earth and oceans which reflects excess heat back into spaces and keep the cooler temperature on the planet. Since the early 1900s, there are many glaciers around the world have been melting rapidly. The rapid glaciers melting not only makes the temperatures of ocean and air continue to rise, but also threatens the living environment of human and animals.
Chapter