Glaciers and Icebergs


Planet Earth is rapidly changing - icebergs in the Arctic and Antarctic regions
along other areas - breaking away every day resulting in a rise in sea levels.




Glaciers


A glacier is a large mass of ice moving slowly over some land surface or down a valley, formed over long periods from the accumulation of snow in areas where the amount of snow that falls exceeds the amount that melts. The word glacier comes from French via the Vulgar Latin glacier, and ultimately from Latin glacies meaning ice.

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 the polar regions and are found in mountain ranges of every continent except Australia, although there are glaciers on New Zealand. In the tropics glaciers are restricted to the highest mountains. The processes and landforms caused by glaciers and related to them are referred to as glacial. The process of glacier growth and establishment is called glaciation. Glaciers are sensitive monitors of climate conditions and are crucial to both world water resources and sea level variation.

Glaciers slowly deform and flow due to stresses induced by their weight, creating crevasses, seracs, and other distinguishing features. They also abrade rock and debris from their substrate to create landforms such as cirques and moraines. Glaciers form only on land and are distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water.

On Earth, 99% of glacial ice is contained within vast ice sheets in the polar regions, but glaciers may be found in mountain ranges on every continent, and on a few high-latitude oceanic islands. Between 35°N and 35°S, glaciers occur only in the Himalayas, Andes, a few high mountains in East Africa, Mexico, New Guinea and on Zard Kuh in Iran.

Glacial ice is the largest reservoir of freshwater on Earth. Many glaciers from temperate, alpine and seasonal polar climates store water as ice during the colder seasons and release it later in the form of meltwater as warmer summer temperatures cause the glacier to melt, creating a water source that is especially important for plants, animals and human uses when other sources may be scant. Within high altitude and Antarctic environments, the seasonal temperature difference is often not sufficient to release meltwater.

Because glacial mass is affected by long-term climate changes, e.g., precipitation, mean temperature, and cloud cover, glacial mass changes are considered among the most sensitive indicators of climate change and are a major source of variations in sea level. Read more ...




Icebergs


The first to explain the formation of icebergs was the Russian peasant prodigy Mikhail Lomonosov. In the 20th century, several scientific bodies were established to study and monitor the icebergs. The International Ice Patrol, formed in 1914 in response to the Titanic disaster, monitors iceberg dangers near the Grand Banks of Newfoundland and provide the "limits of all known ice" in that vicinity to the maritime community.

Icebergs are a mass of ice that has become detached, or calved, from the edge of an ice sheet or glacier and is floating on the ocean. Because ice is slightly less dense than water about one ninth of the total mass of a berg projects above the water.

Icebergs differ from other ocean ices: sea ice is formed directly from the freezing of ocean water; pack ice is tightly packed fragments of sea ice; ice floes are small, floating ice fragments that separate from pack ice. Fast ice - is ice attached to a shore.

Icebergs are mostly white because the ice is full of tiny air bubbles. The bubble surfaces reflect white light giving the iceberg an overall white appearance. Ice that is bubble free has a blue tint which is due to the same light phenomenon that tints the sky.

The bluish streaks of clear, bubble free ice often seen in icebergs results from the refreezing of meltwater which fills crevasses formed in the glacier as it creeps over land. The ice is blue because of the natural light scattering characteristics of pure ice. Occasionally airborne dust or dirt eroded from land ends up on the glacier surface eventually forming a noticeably darkened brown or black layer (in any orientation) within the ice of a floating iceberg.

Greenland is the source of most of the icebergs in the N Atlantic, where the iceberg season lasts roughly from February to October. Greenland and other N Atlantic icebergs are usually peaked and irregular in shape; Antarctic icebergs are tabular, with flat tops and steep sides.

Before the development of radar, sonar, and the Global Positioning System, sailors on watch in the Arctic region would listen for distinctive sounds to help them determine whether icebergs were close or far away.

As a consequence of the loss of the Titanic through collision with an iceberg in 1912, a patrol of N Atlantic shipping channels was initiated in 1914 by the international agreement of 16 nations.

Patrols use planes and surface vessels equipped with radar, loran, and underwater sound equipment. A constant census of bergs is maintained, and the location of an iceberg is reported to any ship in its vicinity.

A fantastic variety of shapes result from the deterioration process of icebergs. Despite the fact that no two icebergs are the same, there are certain categories of shapes that are used for iceberg observation. Often the terms; tabular, blocky, wedge, dome, pinnacle, and drydock are used.

For those who wish to look beyond the beauty of icebergs there are many things to look for which can make iceberg watching more interesting. Besides estimating the iceberg's size and shape there are many features which may be noted. Colored streaks, caves and tunnels, old and new waterline notches, even objects such as boulders or birds are seen on icebergs. Even more spectacular is the occasion of an iceberg calving and rolling which can often be heard from a good distance.

Icebergs Wikipedia




In the News ...


Scotland had a glacier up to 1700s, say scientists   BBC - January 21, 2014

A glacier was still in place in Scotland within the past 400 years - 11,000 years less than previously thought - it has been suggested. The moraines were formed within the last couple of thousand years, which shows that a Scottish glacier existed more recently than we had previously thought.


Underwater Sounds of Shattering Icebergs Revealed   Live Science - July 12, 2013
What does a splintering iceberg sound like underwater? Imagine the cracks and pops of an ice cube melting in a glass of lemonade multiplied on a colossal scale, say researchers from Oregon State University, who recorded a thawing berg near Antarctica.


Massive Ice Balls Along Lake Michigan   Live Science - March 12, 2013

Floating boulders of ice the size of basketballs lined the shores of Lake Michigan last month, and were captured in a photo. Weighing in at up to 50 pounds (22 kilograms) each, the ice spheres are a winter weather phenomenon resulting from wind and wave action along the shore, according to reporting by NASA's Earth Science Picture of the Day. Small fragments of floating ice act like seeds, with layers upon layers of supercooled lake water freezing around them as the balls churn in the waves. Wind then pushes the ice concretions onshore.


Antarctic: Grand Canyon-sized rift 'speeding ice melt'   BBC - July 26, 2012
A rift in the Antarctic rock as deep as the Grand Canyon is increasing ice melt from the continent, researchers say. A UK team found the Ferrigno rift using ice-penetrating radar, and showed it to be about 1.5km (1 mile) deep. Antarctica is home to a geological rift system where new crust is being formed, meaning the eastern and western halves of the continent are slowly separating.


Satellites reveal sudden Greenland ice melt   BBC - July 25, 2012
The surface of Greenland's massive ice sheet has melted this month over an unusually large area, Nasa has said. Scientists said the "unprecedented" melting took place over a larger area than has been detected in three decades of satellite observation.


Lost Photographs Reveal History of Greenland's Glaciers   Live Science - May 30, 2012

A set of 80-year-old photographs discovered in a basement archive reveals the remarkable sensitivity of Greenland's glaciers to climate change, according to a new study that one scientist called "glaciological research with a splash of Indiana Jones." A set of 80-year-old photographs discovered in a basement archive reveals the remarkable sensitivity of Greenland's glaciers to climate change, according to a new study that one scientist called "glaciological research with a splash of Indiana Jones."


Sentinels of the Arctic   NASA - May 29, 2012

Who guards the north? Judging from the above photograph, possibly giant trees covered in snow and ice. The picture was taken last winter in Finnish Lapland where weather can include sub-freezing temperatures and driving snow. Surreal landscapes sometimes result, where common trees become cloaked in white and so appear, to some, as watchful aliens. Far in the distance, behind this uncommon Earthly vista, is a more common sight -- a Belt of Venus that divided a darkened from sunlit sky as the Sun rose behind the photographer. Of course, in the spring, the trees have thawed and Lapland looks much different.


The lake that time forgot   Telegraph.co.uk - May 30, 2012

After 20 million years below the Antarctic ice, Lake Vostok will finally reveal its secrets At the bottom of the Earth, two miles below Antarctica’s ice sheet, scientists have broken a 20-million-year silence. A Russian team has drilled 3,770 metres (2.3 miles) through the polar ice to a vast freshwater lake, called Lake Vostok. It has lain undisturbed for four times as long as human beings have been separate from apes.


Melting Glaciers Alter Earth's Gravity   Live Science - August 17, 2011
Melting glaciers can alter Earth's gravity field, scientists have found, a discovery that is shedding light on when Greenland and Antarctica began heavily melting. Knowing the timing of this melting could help climate scientists make better estimates of the potential sea level rise resulting from melting ice pouring off these two massive ice sheets. Anything that has mass has a gravity field that attracts objects toward it. The strength of this field depends on a body's mass. Since the Earth's mass is not spread out perfectly evenly, this means its gravity field is stronger at some places and weaker in others.

Icebergs Feed Ocean Life   Live Science - May 14, 2011
Rivers carry important nutrients to oceans, but no rivers pour from the frozen continent Antarctica into the Southern Ocean that surrounds it. But now scientists say they have found an icy equivalent to a nutrient-bearing river - an area they have dubbed "Iceberg Alley," where 90 percent of the icebergs that break off from the continent's ice shelves congregate east of the Antarctic Peninsula in the Weddell Sea.


Ice Island Breaks off Greenland; Bigger Than Manhattan   National Geographic - August 6, 2010

Satellite Imagery

New Petermann glacier collapse may be biggest in recorded history.


Huge ice sheet breaks from Greenland glacier   BBC - August 6, 2010

It is the largest Arctic iceberg to calve since 1962.


Studying Greenland's Glaciers - Scientists Get To The Bottom Of Vanishing Ice   National Geographic - May 28, 2010

At first glance Greenland is an expanse of blinding white. But as my chopper swings low over the island, color catches my eye. For miles on end, bands of blue meltwater fringe the ice sheet. Fields of white are threaded with rivers, etched with crevasses, and blotched with lakes. There is also ice that appears neither white nor blue but rather brown and even black - darkened by a substance called cryoconite.


Ancient Tools Revealed by Melting Arctic Ice   Live Science - April 27, 2010
Ice Patch Archaeology is a recent phenomenon that began in Yukon. In 1997, sheep hunters discovered a 4,300-year-old dart shaft in caribou dung that had become exposed as the ice receded. Scientists who investigated the site found layers of caribou dung buried between annual deposits of ice. They also discovered a repository of well-preserved artifacts.


2 more glaciers gone from Glacier National Park   PhysOrg - April 8, 2010
Glacier National Park has lost two more of its namesake moving icefields to climate change, which is shrinking the rivers of ice until they grind to a halt, a government researcher said Wednesday.


Thousands of Quakes Strike Glaciers Every Day   Live Science - April 3, 2010
Up to thousands of "icequakes" may shake a glacier a day, rumblings that could shed light on how climate is changing. Just as volcanoes involve magma interacting with rock, so too do glaciers often involve interplays between water and ice. As such, giant events within glaciers can occur, with icequakes in Antarctica known to reach the force of a magnitude 7 earthquake


When Glaciers Melt, What's in the Water?   Live Science - March 5, 2010

Environmental engineer Michael Nassry studies glacial streams from melting glaciers in Alaska. This shot shows new forests above the shrinking Mendenhall Glacier. It's rare to see a developing forest above a glacier.


Ice Once Covered the Equator   Live Science - March 5, 2010
Sea ice may have covered the Earth's surface all the way to the equator hundreds of millions of years ago, a new study finds, adding more evidence to the theory that a "snowball Earth" once existed. The finding, detailed in the March 5 issue of the journal Science, also has implications for the survival and evolution of life on Earth through this bitter ice age.


"Snowball Earth" Confirmed: Ice Covered Equator   National Geographic - March 5, 2010 But volcanoes would've made Earth more mud ball than snowball, scientists say.
Earth's now steamy Equator was covered with ice 716 million years ago.


Were short warm periods typical for transitions between interglacial and glacial epochs?   PhysOrg - March 2, 2010
At the end of the last interglacial epoch, around 115,000 years ago, there were significant climate fluctuations. In Central and Eastern Europe, the slow transition from the Eemian Interglacial to the Weichselian Glacial was marked by a growing instability in vegetation trends with possibly at least two warming events.


Research team breaks the ice with new estimate of glacier melt   PhysOrg - March 2, 2010
The melting of glaciers is well documented, but when looking at the rate at which they have been retreating, a team of international researchers steps back and says not so fast.


Glaciers discovered in 'cursed' mountains of Albania   PhysOrg - January 28, 2010
The glaciers are at the relatively low level of 2,000 metres - almost unique for such a southerly latitude. Most glaciers at this latitude are usually much higher, and many only survive on higher mountains further north, such as the Alps. The Prokletije mountains - known as the 'cursed' mountains in Albanian - extend from northern Albania and Kosovo to eastern Montenegro in the Western Balkans.


Cave reveals Southwest's abrupt climate swings during Ice Age   PhysOrg - January 20, 2010
Ice Age climate records from an Arizona stalagmite link the Southwest's winter precipitation to temperatures in the North Atlantic, according to new research.


Earth's Polar Ice Sheets Vulnerable to Even Moderate Global Warming; New Orleans, Much of Southern Florida, Expected to Be Permanently Submerged   Science Daily - December 17, 2009
A new analysis of the geological record of the Earth's sea level, carried out by scientists at Princeton and Harvard universities and published in the Dec. 16 issue of Nature, employs a novel statistical approach that reveals the planet's polar ice sheets are vulnerable to large-scale melting even under moderate global warming scenarios. Such melting would lead to a large and relatively rapid rise in global sea level


Greenland Glaciers: Water Flowing Beneath Ice Plays More Complex Role   Science Daily - December 16, 2009
Scientists who study the melting of Greenland's glaciers are discovering that water flowing beneath the ice plays a much more complex role than they previously imagined.


Life's Ancient Island in the Ice   PhysOrg - October 29, 2009
During the last ice age, massive glaciers covered much of our planet. However, a region of Alaska, Siberia and the Canadian Yukon remained ice-free. This region, known as Beringia, supported unique organisms and was an important haven for evolution. Now, scientists may have uncovered how Beringia supported such diversity at a time when conditions for life were harsh.


Melting Kyrgyz glaciers pose threat   BBC - October 28, 2009
Geologist Bakutbek Ermenbaev points up through the pine trees at the glacier above us in Kyrgyzstan's Alatau mountains. "That one - called Adigene - has decreased in size by about 20% over the last 50 years," he says.


Melting Glaciers Behind Mysterious Increase in Pollution   Live Science - October 21, 2009

A mysterious increase in pollution deposits in recent years, despite reductions in the production of the pollutants, may have a solution. Alpine glaciers have been melting rapidly since the 1990s, and now scientists think pollution collected in the ice in decades past is flowing at an increased pace into lakes and rivers today. Previous research had documented increases in organic pollutants in sediment from certain lakes since the 1990s, despite decreased use of those compounds in pesticides, electric equipment, paints and other products.


Melting of the Greenland ice sheet mapped   PhysOrg - September 16, 2009
Will all of the ice on Greenland melt and flow out into the sea, bringing about a colossal rise in ocean levels on Earth, as the global temperature rises? The key concern is how stable the ice cap actually is and new Danish research from the Niels Bohr Institute at the University of Copenhagen can now show the evolution of the ice sheet 11,700 years back in time - all the way back to the start of our current warm period.


The mysterious glaciers that grew when Asia heated up   PhysOrg - August 27, 2009
Long ago a group of Himalayan glaciers grew by several kilometers even while Central Asia's climate warmed up to six degrees Celsius. BYU professor Summer Rupper's analysis attributes much of the glacial growth to increased cloudiness and wind. Rupper is lending her glacier expertise to a project that will forecast the Indus River system's water supply for the coming decades.


Mystery Glaciers Growing As Most Others Retreat   National Geographic - June 23, 2009
Two South American glaciers are displaying strange behavior for the times: They're growing. Most of the 50 massive glaciers draped over the spine of the Patagonian Andes are shrinking in response to a global warming, said Andres Rivera, a glaciologist at the Center for Scientific Studies in Valdivia, Chile.


Himalayan glacier studies commence   BBC - June 23, 2009
After a long gap, scientists in Nepal have embarked on the first field studies of Himalayan glacial lakes, some of which are feared to be swelling dangerously due to global warming. In May, they completed the field visit to the first location, a lake in the Everest region, in a series of studies. They plan to conduct similar surveys of two other glacial lakes in the central and western part of the Nepalese Himalayas later in the year.


Ice Sheets Can Retreat 'In a Geologic Instant,' Study of Prehistoric Glacier Shows   PhysOrg - June 21, 2009
Modern glaciers, such as those making up the Greenland and Antarctic ice sheets, are capable of undergoing periods of rapid shrinkage or retreat, according to new findings by paleoclimatologists at the University at Buffalo.


Silk Road threatened by melting glaciers   New Scientist - June 15, 2009
The Chinese gateway to the ancient Silk Road is being flooded - and the culprit, researchers say, is climate change. Melting glaciers sitting above the Hexi corridor in Gansu province, once an important trading and military route into Central Asia, are fueling dramatic regional floods. The finding illustrates a major problem for the coming century: around the world, arid regions that sit next to glaciers will suffer a spate of floods, then dry up completely when the glaciers melt away. Once the eastern gateway to the Silk road, the Hexi corridor is sandwiched between the Qilian mountains to the southwest, and lower mountains bordering the Gobi desert to the northeast.


Major ice-shelf loss for Canada BBC - September 3, 2008 The ice shelves in Canada's High Arctic have lost a colossal area this year, scientists report. The floating tongues of ice attached to Ellesmere Island, which have lasted for thousands of years, have seen almost a quarter of their cover break away. One of them, the 50 sq km (20 sq miles) Markham shelf, has completely broken off to become floating sea-ice. Researchers say warm air temperatures and reduced sea-ice conditions in the region have assisted the break-up.


Canadian Arctic sheds ice chunk BBC - July 30, 2008

A large chunk of an Arctic ice shelf has broken free of the northern Canadian coast, scientists say.


Ice Remained Even When Earth Was Hot Live Science - July 29, 2008
Ice is in retreat worldwide as glaciers melt, Arctic ice floes vanish, and Antarctic ice shelves break apart. Will all of it eventually disappear as the globe warms? Not necessarily, say Andre Bornemann of the University of Leipzig in Germany and several colleagues. From sediment cores drilled out of the Atlantic seafloor, they retrieved fossils of tiny, shell-encased marine organisms called foraminifers that lived 91 million years ago during the Cretaceous Thermal Maximum, when tropical seas were about 12 Fahrenheit degrees warmer than they are today. The fossils' shells contained a high proportion of oxygen-18, an isotope that increases in the ocean relative to oxygen-16 when water evaporates from the sea and gets trapped on land as ice. The isotope data suggest that even during the hot spell, an ice sheet half the size of the current Antarctic ice cap existed - but where?


Ice Adrift From Warming Scrapes Antarctic Seabed Bare National Geographic - July 18, 2008
Rapid warming along the Antarctic Peninsula is causing more skyscraper-sized icebergs to break free, drift, and scour away practically all life along swaths of the seafloor, according to a new study. Ocean-bottom scrubbings along the West Antarctic Peninsula will increase as temperatures rise, annihilating some animal and plant populations but helping others by clearing the habitat, the study said.


"Mountains of the Moon" Glaciers Melting in Africa National Geographic - March 26, 2008

The Mountains of the Moon are melting. The iconic glaciers of the Ruwenzori Mountains, which cast a thick and icy mist more than 16,000 feet (4,900 meters) above the Equator in central Africa, have shrunk by 50 percent over the past 50 years, says the conservation group WWF


Giant Antarctic Ice Shelf Collapses National Geographic - March 26, 2008

A chunk of Antarctic ice about seven times the size of Manhattan suddenly collapsed, putting an even greater portion of glacial ice at risk.


Video: Antarctica Ice Collapses National Geographic - March 27, 2008


Huge Iceberg Splits In Southern Atlantic Ocean Science Daily - March 17, 2008

A huge fissure was spotted running south to north through the berg on 1 March by C-CORE, the Canadian ice-tracking service, while studying satellite images collected from Envisat's Advanced Synthetic Aperture Radar (ASAR) instrument using the Polar View monitoring programme. The radar image indicated the berg was unstable and likely to split. Just days afterwards on 4 March, Envisat's Medium Resolution Imaging Spectrometer (MERIS) sensor captured the break. Both bergs are estimated to measure around 30 km in length. As a reference, South Georgia Island is approximately 180-km long.


Antarctic Icebergs Teeming With Life, Study Says National Geographic - June 22, 2007
Anecdotal scientific observations suggest marine plants, shrimplike crustaceans, and seabirds - big players in the ocean food chain - congregate on and around the chunks of ice. Icebergs are proliferating in the Antarctic as rising temperatures shrink and split the continent's ice shelves, leading scientists to wonder what effect this has on the marine environment.


Icebergs are 'ecological hotspot' BBC - June 22, 2007
Drifting icebergs are "ecological hotspots" that enable the surrounding waters to absorb an increased volume of carbon dioxide, a study suggests


Pile-up as berg hits Antarctica BBC - April 2005

An iceberg the size of Luxembourg has smashed into another vast slab of ice that juts out from Antarctica. The 115km-long B-15A iceberg broke off a 5km-long section of the Drygalski ice tongue when it collided with the prominence in the Ross Sea. The iceberg itself so far appears unaffected by the smash-up. More of the B-15A iceberg still has to pass by Drygalski, so the ice tongue may be in for even more punishment in the coming days, experts have said. The European Space Agency's Earth-observation platform Envisat has returned some remember...


Scientists Discover Why The North Pole Is Frozen Science Daily - March 2005
Ice has been building up in the Arctic for 2.7 million years. Until now, no one has been able to prove what mechanism brought about this accumulation of ice. However, a team of international scientists led by Antoni Rosell, a researcher for the Universitat Autonoma de Barcelona, and Gerald H. Haug of the Potsdam Institute for Climate Impact Research (Germany) has discovered the mechanism that set off the accumulation of ice.


Giant ice slabs set for collision BBC - January 2005
Two giant slabs of ice are about to hit each other in Antarctica, possibly with spectacular results, say Nasa experts. A 160km-long iceberg is heading on a collision course with a huge floating glacier in the sea near the US McMurdo Research Station. The B-15A iceberg should collide with the Drygalski Ice Tongue no later than 15 January 2005, though it is slowing. US space agency scientists are studying the iceberg's progress by monitoring satellite images of the region.


NASA looks at the current meltdown - Antarctica NASA - January 2005
In early January 2005, it appeared that the B-15A iceberg was on a collision course with the Drygalski Ice Tongue, the floating portion of a glacier flowing off the Scott Coast of Antarctica and into the Ross Sea. Scientists and amateur Earth-observers checked satellite images of the region each day to monitor the northward march of the berg and to witness the impacts. Would it be just a fender bender, or would the ice tongue shatter under the impact of the oncoming berg?




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