Таяние ледников в Гренландии

Гренландия — второй по размеру ледниковый массив на Земле после Антарктиды. Таяние гренландских ледников вызывает большой интерес и тревожит ученых, так как данный процесс опасен для жителей прибрежных районов всего мира. Дело в том, что если весь лед Гренландии растает, то уровень Мирового океана может подняться до 6 метров. Таяние ледников постоянно изучается. Когда в одном из удаленных уголков Гренландии установили камеру, удалось запечатлеть невероятно величественное, прекрасное и одновременно ужасающее зрелище…

(39 фотографий)

lednik_1 lednik_2

The "North Lake" was the first site that was selected in 2006 for the deployment of scientific instruments for measuring changes in ice motion caused by melt water reaching the base of the ice sheet. The lake is only partially full in this picture. When entirely full, the lake was nearly 4-km (2.5 miles) wide and more than 40 feet deep. The entire lake drained in about 90 minutes 16 days after this picture was taken.

The «North Lake» was the first site that was selected in 2006 for the deployment of scientific instruments for measuring changes in ice motion caused by melt water reaching the base of the ice sheet. The lake is only partially full in this picture. When entirely full, the lake was nearly 4-km (2.5 miles) wide and more than 40 feet deep. The entire lake drained in about 90 minutes 16 days after this picture was taken.

Twila Moon and Ian Howat prepare a rubber raft for a lake survey to determine depth with a sonar and to deploy instruments that measure lake level. After the discovery of how fast the lakes can actually drain (90 minutes), the use of boats was discontinued on this project. Instead lake level loggers were deployed and retrieved at times when the lakes were empty.

Twila Moon and Ian Howat prepare a rubber raft for a lake survey to determine depth with a sonar and to deploy instruments that measure lake level. After the discovery of how fast the lakes can actually drain (90 minutes), the use of boats was discontinued on this project. Instead lake level loggers were deployed and retrieved at times when the lakes were empty.

lednik_5

An ice penetrating radar is deployed from a string of four kayaks to survey a section of the Petermann glacier in Greenland. Three scientists, Jason Box, Richard Bates and Alun Hubbard, are working in partnership with Greenpeace. They fit a radar transmitter, receiver and antennas to the kayaks, to obtain valuable data on the processes operating over floating ice shelves. This will reveal more of the complex nature of the ice thickness, basal melt-rates and insight into the breakup at the front section of Petermann. The team paddles the kayaks whilst running the radar, over the carefully selected 25 kilometer course along a meltwater channel which runs down the middle of the glacier's floating ice shelf.

An ice penetrating radar is deployed from a string of four kayaks to survey a section of the Petermann glacier in Greenland. Three scientists, Jason Box, Richard Bates and Alun Hubbard, are working in partnership with Greenpeace. They fit a radar transmitter, receiver and antennas to the kayaks, to obtain valuable data on the processes operating over floating ice shelves. This will reveal more of the complex nature of the ice thickness, basal melt-rates and insight into the breakup at the front section of Petermann. The team paddles the kayaks whilst running the radar, over the carefully selected 25 kilometer course along a meltwater channel which runs down the middle of the glacier’s floating ice shelf.

lednik_7

Hours after this image was taken from a helicopter flying over the lake, this lake drained to the base of the ice sheet in about 90 minutes. The linear feature extending from the middle left edge of the image into the lake appears to be part of the 3+km (1.8 mile)  long crack that drained the lake the previous year and appears to have been active in the impending drainage.

Hours after this image was taken from a helicopter flying over the lake, this lake drained to the base of the ice sheet in about 90 minutes. The linear feature extending from the middle left edge of the image into the lake appears to be part of the 3+km (1.8 mile) long crack that drained the lake the previous year and appears to have been active in the impending drainage.

GLACIAL ICE SHEET, GREENLAND - JULY 17:  Water is seen on part of the glacial ice sheet that covers about 80 percent of the country is seen on July 17, 2013 on the Glacial Ice Sheet, Greenland.  As the sea levels around the globe rise, researchers affilitated with the National Science Foundation and other organizations are studying the phenomena of the melting glaciers and its long-term ramifications. The warmer temperatures that have had an effect on the glaciers in Greenland also have altered the ways in which the local populace farm, fish, hunt and even travel across land.  In recent years, sea level rise in places such as Miami Beach has led to increased street flooding and prompted leaders such as New York City Mayor Michael Bloomberg to propose a $19.5 billion plan to boost the city’s capacity to withstand future extreme weather events by, among other things, devising mechanisms to withstand flooding.  (Photo by Joe Raedle/Getty Images)

GLACIAL ICE SHEET, GREENLAND — JULY 17: Water is seen on part of the glacial ice sheet that covers about 80 percent of the country is seen on July 17, 2013 on the Glacial Ice Sheet, Greenland. As the sea levels around the globe rise, researchers affilitated with the National Science Foundation and other organizations are studying the phenomena of the melting glaciers and its long-term ramifications. The warmer temperatures that have had an effect on the glaciers in Greenland also have altered the ways in which the local populace farm, fish, hunt and even travel across land. In recent years, sea level rise in places such as Miami Beach has led to increased street flooding and prompted leaders such as New York City Mayor Michael Bloomberg to propose a $19.5 billion plan to boost the city’s capacity to withstand future extreme weather events by, among other things, devising mechanisms to withstand flooding. (Photo by Joe Raedle/Getty Images)

lednik_10

The large channel that used to drain this lake is visible as it extends from the lake toward a nearby crevasse field  (upper left) where the moulin is located. Hydro-fractures start when water finds and fills an initial crack. If such a fracture cannot form beneath a lake, the lake often will overflow  to find a crack near the shoreline. The water spilling into this crack  then hydro-fractures to the bed.

The large channel that used to drain this lake is visible as it extends from the lake toward a nearby crevasse field (upper left) where the moulin is located. Hydro-fractures start when water finds and fills an initial crack. If such a fracture cannot form beneath a lake, the lake often will overflow to find a crack near the shoreline. The water spilling into this crack then hydro-fractures to the bed.

With its drainage channel dammed, the north-north lake did not drain last summer ( http://bigice.apl.washington.edu/photos/Greenland09A-2.jpg) and in July 2010 it contained melt from one and half summers. The ice cover that formed over the winter shows the approximate extent of the lake at the end of summer in 2009.

With its drainage channel dammed, the north-north lake did not drain last summer ( http://bigice.apl.washington.edu/photos/Greenland09A-2.jpg) and in July 2010 it contained melt from one and half summers. The ice cover that formed over the winter shows the approximate extent of the lake at the end of summer in 2009.

At one time this channel was substantially deeper, but it has since filled with snow.

At one time this channel was substantially deeper, but it has since filled with snow.

Although snow has dammed outflow from the lake, nearby melt streams continue to fill sections of the canyon where snow has not accumulated (see http://bigice.apl.washington.edu/photos/Greenland07-15.jpg).

Although snow has dammed outflow from the lake, nearby melt streams continue to fill sections of the canyon where snow has not accumulated (see http://bigice.apl.washington.edu/photos/Greenland07-15.jpg).

lednik_15 lednik_16

Water flowing into a small "moulin" roughly 3 feet wide. This feature probably does not extend directly to the ice-sheet base. Instead, it like flows laterally through a crack at some depth to connect with a large moulin that does reach the bed.

Water flowing into a small «moulin» roughly 3 feet wide. This feature probably does not extend directly to the ice-sheet base. Instead, it like flows laterally through a crack at some depth to connect with a large moulin that does reach the bed.

lednik_18

Summer meltwater has drained through a snow-covered channel.

Summer meltwater has drained through a snow-covered channel.

Some years south lake drains out the bottom (2009 http://bigice.apl.washington.edu/photos/Greenland09A-1.jpg) and other years it overflows to a nearby moulin. Unlike the north-north lake channel, which appears to have been active for many years, the south lake channels are only active for a couple of years before ice flow moves them to higher ground. Several extinct drainage channels formed over the last couple of decades are visible in satellite imagery.

Some years south lake drains out the bottom (2009 http://bigice.apl.washington.edu/photos/Greenland09A-1.jpg) and other years it overflows to a nearby moulin. Unlike the north-north lake channel, which appears to have been active for many years, the south lake channels are only active for a couple of years before ice flow moves them to higher ground. Several extinct drainage channels formed over the last couple of decades are visible in satellite imagery.

lednik_21

This deep pool through which a substantal volume of water appears to have flowed is likely the site of the moulin that formed in 2006 (see same pool in 2007 http://bigice.apl.washington.edu/photos/Greenland07-6.jpg).

This deep pool through which a substantal volume of water appears to have flowed is likely the site of the moulin that formed in 2006 (see same pool in 2007 http://bigice.apl.washington.edu/photos/Greenland07-6.jpg).

A large meandering melt stream feeding the north lake eroded this feature.

A large meandering melt stream feeding the north lake eroded this feature.

lednik_24

This lake is high on the ice sheet near the upper limit of where lakes form. Unlike lakes at lower elevations, much of its surface remains ice-covered throughout the summer.

This lake is high on the ice sheet near the upper limit of where lakes form. Unlike lakes at lower elevations, much of its surface remains ice-covered throughout the summer.

lednik_26 lednik_27

This view shows the transition to smaller crevasses in the region of the ice sheet feeding into Jakobshavn Isbrae.

This view shows the transition to smaller crevasses in the region of the ice sheet feeding into Jakobshavn Isbrae.

This photo was taken near the grounding line of Pine Island Glacier, looking seaward down the floating shelf center.

This photo was taken near the grounding line of Pine Island Glacier, looking seaward down the floating shelf center.

Closeup of crevasses near the Pine Island Glacier grounding line, near the western margin.

Closeup of crevasses near the Pine Island Glacier grounding line, near the western margin.

These crevases are located near the western margin and their shape likely was deformed by shear after they first opened.

These crevases are located near the western margin and their shape likely was deformed by shear after they first opened.

Crevase field near the western shear margin, taken from the east side of the flight path (see location map)

Crevase field near the western shear margin, taken from the east side of the flight path (see location map)

Crevase field near the western shear margin, taken from the east side of the flight path (see location map).

Crevase field near the western shear margin, taken from the east side of the flight path (see location map).

lednik_34 lednik_35 lednik_36 lednik_37 lednik_38 lednik_39

 

Если вы нашли ошибку, пожалуйста, выделите фрагмент текста и нажмите Ctrl+Enter.

Июн 9, 2015 / в мире, природа / Теги: , , , / Комментарии: 0

Добавить комментарий

:good: 
:negative: 
:scratch: 
:wacko: 
:yahoo: 
B-) 
:heart: 
больше...
 

Сообщить об опечатке

Текст, который будет отправлен нашим редакторам: