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Sea ice covers an area of almost 16 million square kilometers of the Arctic seas during its maximum extent in winter.Each summer the pack ice (Arctic ice cover)melts and shrinks in area,and,at a minimum,extends over about 9 million square kilometers.The sea ice is an important part of the climate of the Arctic,and indeed of the whole world,because it has a large effect on the way the surface of the Arctic is heated.Sea ice is highly reflective-we see this by the need to wear sunglasses when walking over snow or ice.Water,on the other hand,appears rather dark by comparison.Where sea ice covers the Arctic seas,much radiation from the Sun is reflected back into the atmosphere.However,where open water is present,most of that radiation is absorbed and acts to heat the water.As the water heats up,more ice can be melted,and so on.This is called a positive feedback effect and is one of the key reasons why scientists are monitoring both the extent and the thickness of Arctic sea ice today.If sea ice covers a progressively smaller part of the Arctic seas in a world that may be affected by greenhouse gases,then this positive feedback could be critical to the rate at which our planet warms up. Another important aspect of the formation of sea ice is that when water freezes,a large proportion of its salt content is rejected (forced out into the surrounding water).Indeed,it is possible to melt old sea ice and drink the water.However,the seawater produced in areas where sea ice forms is both very cold and also of high salinity (salt content).The presence of so much salt produces some of the densest water found in the world's oceans,and this water sinks to ths seafloor as a result.In fact,the very dense waters produced by sea ice freezing in the Arctic are a vital factor in driving the circulation of the oceans,because these waters flow to the deepest parts of the ocean floor.Some areas of the Arctic seas are places of intense sea ice production,where upwelling (the movement of above-freezing water from the lower depths of the ocean to the surface)or strong winds consistently keep the sea open year-round.One example is the North Water at the head of Baffin Bay.New sea ice can,therefore, continue to form throughout the winter in such open-water areas, which are known as polynyas,from the Russian language.
Sea ice also presents a number of hazards to human activity in the waters around the Arctic islands.In the heroic era of nineteenth-and early-twentieth-century exploration of the Arctic archipelagos (groups of islands),the presence of sea ice in many passages between islands made travel by sea difficult and dangerous.The British navy, for example,sent several tens of ships to the Canadian Arctic during the first half of the nineteenth century in an attempt to find a navigable passage connecting the north Atlantic and Pacific Oceans,referred to as the Northwest Passage,as a route for trade with Asia.However, this period of exploration coincided with some of the coldest weather of the last few thousand years,which is known as the Little Ice Age. The ice conditions encountered by many of these ships were appalling.A number of vessels became trapped in sea ice as the short summers came to an end,and several were crushed when pressure built up in the sea ice as it was driven by strong winds.The great dangers inherent in these early explorations of the islands and passages in,for example,the Canadian north are exemplified by the remarkable story of Sir John Franklin and his crews of the ships Erebus and Terror,who disappeared in the late 1840s and whose fate has never been finally established.By contrast,the Norwegian explorer Roald Amundsen was the first to navigate a ship through the Northwest Passage,and he did so only in 1903-06,when the climate had warmed up after the Little Ice Age and sea ice conditions had become less severe. 1. ►Sea ice covers an area of almost 16 million square kilometers of the Arctic seas during its maximum extent in winter.Each summer the pack ice (Arctic ice cover)melts and shrinks in area,and,at a minimum,extends over about 9 million square kilometers.The sea ice is an important part of the climate of the Arctic,and indeed of the whole world,because it has a large effect on the way the surface of the Arctic is heated.Sea ice is highly reflective-we see this by the need to wear sunglasses when walking over snow or ice.Water,on the other hand,appears rather dark by comparison.Where sea ice covers the Arctic seas,much radiation from the Sun is reflected back into the atmosphere.However,where open water is present,most of that radiation is absorbed and acts to heat the water.As the water heats up,more ice can be melted,and so on.This is called a positive feedback effect and is one of the key reasons why scientists are monitoring both the extent and the thickness of Arctic sea ice today.If sea ice covers a progressively smaller part of the Arctic seas in a world that may be affected by greenhouse gases,then this positive feedback could be critical to the rate at which our planet warms up.
2. ►Sea ice covers an area of
almost 16 million square kilometers of the Arctic seas during its maximum
extent in winter.Each summer the pack ice (Arctic ice cover)melts and shrinks
in area,and,at a minimum,extends over about 9 million square kilometers.The sea
ice is an important part of the climate of the Arctic,and indeed of the whole
world,because it has a large effect on the way the surface of the Arctic is
heated.Sea ice is highly reflective-we see this by the need to wear sunglasses
when walking over snow or ice.Water,on the other hand,appears rather dark by
comparison.Where sea ice covers the Arctic seas,much radiation from the Sun is
reflected back into the atmosphere.However,where open water is present,most of
that radiation is absorbed and acts to heat the water.As the water heats
up,more ice can be melted,and so on.This is called a positive feedback effect
and is one of the key reasons why scientists are monitoring both the extent and
the thickness of Arctic sea ice today.If sea ice covers a progressively smaller
part of the Arctic seas in a world that may be affected by greenhouse
gases,then this positive feedback could be critical to the rate at which our
planet warms up. 3. ►Another important aspect of the formation of sea ice is that when water freezes,a large proportion of its salt content is rejected (forced out into the surrounding water).Indeed,it is possible to melt old sea ice and drink the water.However,the seawater produced in areas where sea ice forms is both very cold and also of high salinity (salt content).The presence of so much salt produces some of the densest water found in the world's oceans,and this water sinks to ths seafloor as a result.In fact,the very dense waters produced by sea ice freezing in the Arctic are a vital factor in driving the circulation of the oceans,because these waters flow to the deepest parts of the ocean floor.Some areas of the Arctic seas are places of intense sea ice production,where upwelling (the movement of above-freezing water from the lower depths of the ocean to the surface)or strong winds consistently keep the sea open year-round.One example is the North Water at the head of Baffin Bay.New sea ice can,therefore, continue to form throughout the winter in such open-water areas, which are known as polynyas,from the Russian language.
4. ►Another important aspect
of the formation of sea ice is that when water freezes,a large proportion of
its salt content is rejected (forced out into the surrounding water).Indeed,it
is possible to melt old sea ice and drink the water.However,the seawater
produced in areas where sea ice forms is both very cold and also of high
salinity (salt content).The presence of so much salt produces some of the
densest water found in the world's oceans,and this water sinks to ths seafloor
as a result.In fact,the very dense waters produced by sea ice freezing in the
Arctic are a vital factor in driving the circulation of the oceans,because
these waters flow to the deepest parts of the ocean floor.Some areas of the
Arctic seas are places of intense sea ice production,where upwelling (the
movement of above-freezing water from the lower depths of the ocean to the
surface)or strong winds consistently keep the sea open year-round.One example
is the North Water at the head of Baffin Bay.New sea ice can,therefore,
continue to form throughout the winter in such open-water areas, which are
known as polynyas,from the Russian language. 5. ►Another important aspect of the formation of sea ice is that when water freezes,a large proportion of its salt content is rejected (forced out into the surrounding water).Indeed,it is possible to melt old sea ice and drink the water.However,the seawater produced in areas where sea ice forms is both very cold and also of high salinity (salt content).The presence of so much salt produces some of the densest water found in the world's oceans,and this water sinks to ths seafloor as a result.In fact,the very dense waters produced by sea ice freezing in the Arctic are a vital factor in driving the circulation of the oceans,because these waters flow to the deepest parts of the ocean floor.Some areas of the Arctic seas are places of intense sea ice production,where upwelling (the movement of above-freezing water from the lower depths of the ocean to the surface)or strong winds consistently keep the sea open year-round.One example is the North Water at the head of Baffin Bay.New sea ice can,therefore, continue to form throughout the winter in such open-water areas, which are known as polynyas,from the Russian language.
6. ►Sea ice also presents a number of hazards to human activity in the waters around the Arctic islands.In the heroic era of nineteenth-and early-twentieth-century exploration of the Arctic archipelagos (groups of islands),the presence of sea ice in many passages between islands made travel by sea difficult and dangerous.The British navy, for example,sent several tens of ships to the Canadian Arctic during the first half of the nineteenth century in an attempt to find a navigable passage connecting the north Atlantic and Pacific Oceans,referred to as the Northwest Passage,as a route for trade with Asia.However, this period of exploration coincided with some of the coldest weather of the last few thousand years,which is known as the Little Ice Age. The ice conditions encountered by many of these ships were appalling.A number of vessels became trapped in sea ice as the short summers came to an end,and several were crushed when pressure built up in the sea ice as it was driven by strong winds.The great dangers inherent in these early explorations of the islands and passages in,for example,the Canadian north are exemplified by the remarkable story of Sir John Franklin and his crews of the ships Erebus and Terror,who disappeared in the late 1840s and whose fate has never been finally established.By contrast,the Norwegian explorer Roald Amundsen was the first to navigate a ship through the Northwest Passage,and he did so only in 1903-06,when the climate had warmed up after the Little Ice Age and sea ice conditions had become less severe.
7. ►Sea ice also presents a number of hazards to human activity in the waters around the Arctic islands.In the heroic era of nineteenth-and early-twentieth-century exploration of the Arctic archipelagos (groups of islands),the presence of sea ice in many passages between islands made travel by sea difficult and dangerous.The British navy, for example,sent several tens of ships to the Canadian Arctic during the first half of the nineteenth century in an attempt to find a navigable passage connecting the north Atlantic and Pacific Oceans,referred to as the Northwest Passage,as a route for trade with Asia.However, this period of exploration coincided with some of the coldest weather of the last few thousand years,which is known as the Little Ice Age. The ice conditions encountered by many of these ships were appalling.A number of vessels became trapped in sea ice as the short summers came to an end,and several were crushed when pressure built up in the sea ice as it was driven by strong winds.The great dangers inherent in these early explorations of the islands and passages in,for example,the Canadian north are exemplified by the remarkable story of Sir John Franklin and his crews of the ships Erebus and Terror,who disappeared in the late 1840s and whose fate has never been finally established.By contrast,the Norwegian explorer Roald Amundsen was the first to navigate a ship through the Northwest Passage,and he did so only in 1903-06,when the climate had warmed up after the Little Ice Age and sea ice conditions had become less severe.
8. ►Sea ice also presents a number of hazards to human activity in the waters around the Arctic islands.In the heroic era of nineteenth-and early-twentieth-century exploration of the Arctic archipelagos (groups of islands),the presence of sea ice in many passages between islands made travel by sea difficult and dangerous.The British navy, for example,sent several tens of ships to the Canadian Arctic during the first half of the nineteenth century in an attempt to find a navigable passage connecting the north Atlantic and Pacific Oceans,referred to as the Northwest Passage,as a route for trade with Asia.However, this period of exploration coincided with some of the coldest weather of the last few thousand years,which is known as the Little Ice Age. The ice conditions encountered by many of these ships were appalling.A number of vessels became trapped in sea ice as the short summers came to an end,and several were crushed when pressure built up in the sea ice as it was driven by strong winds.The great dangers inherent in these early explorations of the islands and passages in,for example,the Canadian north are exemplified by the remarkable story of Sir John Franklin and his crews of the ships Erebus and Terror,who disappeared in the late 1840s and whose fate has never been finally established.By contrast,the Norwegian explorer Roald Amundsen was the first to navigate a ship through the Northwest Passage,and he did so only in 1903-06,when the climate had warmed up after the Little Ice Age and sea ice conditions had become less severe.
9. Sea ice covers an area of almost 16 million square kilometers of the Arctic seas during its maximum extent in winter.⬛Each summer the pack ice (Arctic ice cover)melts and shrinks in area,and,at a minimum,extends over about 9 million square kilometers.⬛The sea ice is an important part of the climate of the Arctic,and indeed of the whole world,because it has a large effect on the way the surface of the Arctic is heated.⬛Sea ice is highly reflective-we see this by the need to wear sunglasses when walking over snow or ice.⬛Water,on the other hand,appears rather dark by comparison.Where sea ice covers the Arctic seas,much radiation from the Sun is reflected back into the atmosphere.However,where open water is present,most of that radiation is absorbed and acts to heat the water.As the water heats up,more ice can be melted,and so on.This is called a positive feedback effect and is one of the key reasons why scientists are monitoring both the extent and the thickness of Arctic sea ice today.If sea ice covers a progressively smaller part of the Arctic seas in a world that may be affected by greenhouse gases,then this positive feedback could be critical to the rate at which our planet warms up. 10.
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