Avi Blizovsky
Direct link to this page: https://www.hayadan.org.il/icecover.html
Last update – 11/12/02 03:49
1.2 million square kilometers of ice less than last summer
By Kenneth Chang
The surface of the earth / the frozen mantle of the Arctic Ocean melted a considerable amount last summer
Arctic Ocean. Less ice and thinner ice
The melting of the glaciers in Greenland and the ice sheet in the Arctic Ocean last summer reached levels not seen in decades, scientists reported this week. According to the researchers, this is further evidence of the rapid warming that has recently occurred in the Arctic Ocean, partly due to natural fluctuations in the climate. But the researchers added that it is possible that environmental changes that occurred as a result of human activity, such as the destruction of the ozone layer and the emission of carbon dioxide, accelerated and worsened the phenomenon.
At the end of summer, the ice cover of the Arctic Ocean was reduced to 5 million square kilometers. It then returned and expanded. Since 1978, when the direct satellite measurements of sea ice began, the average minimum in summer was 6.2 million square kilometers. Of the remaining sea ice, the majority was thinner than usual.
"This was probably the craziest summer I've ever seen here," said Dr. Mark Sarza, a researcher at the National Snow and Ice Information Center in Boulder, Colorado, and one of the scientists who presented the findings at a press conference at the American Geophysical Union conference in San Francisco.
The weather in the Arctic Ocean has been unusually warm and stormy this year, causing the ice to break up and melt more easily. The shrinking of the glaciers coincides with a trend observed since the late 70s and with the predictions of global warming. "This is the kind of change we were expecting," said Dr. James Morrison of the University of Washington in Seattle.
Other information, including data collected during flights, reveals that at least since the 50s there has not been such a small amount of ice in the ocean. If the shrinkage continues at the current rate, the annual average ice sheet may decrease by 20% by 2050, and according to Sarza, in this situation there may be almost no ice in the ocean during the summer months. "I believe we will continue to see a reduction in sea ice coverage, because I think human activity has an impact on the climate," he said. "The rate of change is unknown."
Other evidence, pointing to the mass of the frozen ground layer and the northward spread of trees, also raises the hypothesis that the warming in recent times is rapid and unusual.
The reduction of sea ice is expected to affect global ocean currents. Freshwater from melting ice is less dense than salty seawater, and may prevent the rise of water from the ocean depths. In addition, the extensive melting will contribute to warming because water absorbs more than 80% of the sunlight that hits it, while ice reflects about 80% of the light.
Satellite measuring devices have shown that in the Greenland ice shelf, the area of the area where the ice is melting is more than 690,000 square kilometers. This area is 9% larger than the area where the mass of ice was previously observed. The ice is melting in areas up to 2,000 meters high, where the melting has never been observed. Meltwater flows to the base of the glaciers and serves as a lubricant, accelerating the gliding of the glaciers into the ocean.
In the latest issue of the journal Science, scientists at NASA's Jet Propulsion Laboratory in Pasadena, California, and the Royal Observatory of Belgium, reported that the melting glaciers are causing a change in the shape of the Earth. Since 1997 the ball has become slightly flatter at the poles, like a pumpkin. The find indicates a reversal of a trend that began at the end of the last ice age, when the Earth was freed from the heavy ice shelves at the poles and became more spherical. The article in "Science" states that the addition of the melting water of the glaciers, moving towards the equator, causes the Earth to become flatter.
Update 9/12/2002: Glacier melting has reached an unprecedented high
Since the 50s, such a small amount of ice has not been measured in the Arctic region
Scientists report today (Monday) that the melting of the glaciers in Greenland and the ice sheet in the Arctic Ocean reached unprecedented proportions this summer. The melting, which provides evidence of the extreme warming of the Arctic Ocean, is partly related to natural factors and climate change and partly to environmental changes caused by humans, such as the destruction of the ozone layer.
In September of this year, at the end of the summer, the ice mass in the Arctic Ocean shrank to two million square miles, before the mass of ice began to grow again. Accurate satellite measurements of the Arctic Ocean have been conducted since 1978 and since that year the minimum size of the ice mass has not been below 2.4 million square miles. Most of the remaining ice is thinner than normal.
The weather in the arctic region this summer was hotter and windier than usual and this caused the breaking of glaciers. "It was the craziest summer I've ever seen there," said Dr. Mark Cesar, who studies the phenomenon. Cesar even published the data at a conference of the Geographical Union in the USA.
Additional data indicate that such a small amount of ice has not been measured in the Arctic region since the 50s. If the reduction of ice mass continues at the current rate, the amount of ice will decrease by 20% by 2050 and the Arctic Ocean will be left with almost no ice cover during the summer months. Dr. Cesar predicts that the thaw will continue and attributes the reason to the influence of humans on the climate.
The melting of the ice sheet is expected to affect currents in the oceans, as well as the temperature of the water. Without the ice layer, which reflects 80% of the sun's radiation, the sun will heat the water directly. Also, satellite data indicates the melting of over 265 thousand square miles of the Greenland ice sheet - the melting is 9% higher than the maximum melting measured there so far. Melted glacial water flows around the bases of the glaciers and serves as a lubricant that accelerates the separation of ice blocks and their drift into the ocean.
New York Times Update
NASA: The ice in the Arctic Ocean may disappear by the end of the 21st century
A NASA study shows that the sea ice in the Arctic Ocean is melting much more than they thought - up to nine percent per decade. If the rate of melting continues for a few more decades, the sea ice will disappear completely in the 21st century due to the rise in temperatures and the interaction between the sea, ocean and atmosphere, a process that accelerates the melting.
The Arctic sea ice floats in the polar oceans and remains frozen even at the end of summer, when part of it melts every summer. This year the depth of the ice layer reached about 3 meters and in some places even seven meters. The study also shows that the temperature in the Arctic region increases by 1.2 degrees Celsius per decade.
Unlike the Antarctic, where the ice layer is several kilometers thick, and where most of the planet's fresh water is found, the melting of the ice at the North Pole will not significantly change the sea level, but it could affect shipping lines in the summer, the plankton bloom, the circulation of water in the oceans and the global climate .
If the perennial ice sheet were to disappear, the entire Arctic Ocean's climate and ecology could be completely different, says Giospino Commisso, a researcher at NASA's Goddard Space Flight Center in Greenblad, Maryland, who is leading the study. Commisso used satellite data to track the minimum size of the ice sheet and its cover, as well as temperatures in the Arctic between 1978 and 2000. Because the ice cover does not vary uniformly in terms of space or time, Commisso looked at parts of this data and analyzed these areas carefully to see if the ice reached the minimum cover each year. These results were processed to obtain annual data on the ice cover.
Before 1978, most data came randomly from ships, weather stations and research mobiles.
It seems that the rate of decline is accelerating thanks to a positive feedback in the system of connections between the ice, the ocean and the atmosphere. As the temperature in the Arctic increases, the summer ice cover retreats, more heat is absorbed by the oceans and more ice melts due to the warmer upper water layer. Warmer winters can delay freezing in the fall and lead to a thinner layer of ice in the winter and spring, which in turn makes the sea more susceptible to melting the following summer.
Also, an increase in the ice temperature in the summer at a rate of 1.2 degrees per decade may extend the summer, and allow an earlier spring, and a later fall freeze, which will further reduce the thickness of the layer and the ice cover.
When he compares the change from 1979 to 1989 with the data from 1990-2000, Commisso found that the greatest melting is in the western region (Beauport and Chuki seas). A large ice loss is also found in the eastern seas (Siberian Sea, Laptev and Kara). Also, the ice cover expanded somewhat in relatively small areas near Greenland.
In the short term, reducing the amount of ice can bring shipping lines to the Arctic Ocean, also the massive mass can increase biological fertility, since melted water floats and creates a stable layer for plankton blooms. Also, the regional and global climate will be affected. Since the summer sea ice reflects sunlight into space, it cools the surface of the planets and warms the atmosphere.
While the data for the last two years came too late to be included in the paper, Commisso recently looked at ice cover data up to the present and found that this year was the least massive ice cover observed since the satellite era began.
The study appeared in the late October issue of Geophysical Research Letters, and was funded by the Earth Science Initiative Cryosphere Science Program and the Earth Observation Project.
The mission of NASA's Earth Science Initiative is to develop a scientific understanding of the Earth system and its response to natural or human-made changes to improve climate forecasting, weather forecasting, and natural disaster capability.
Another huge glacier broke off from the Antarctic continent
16/05/2002
The C-19 iceberg, which is about a third of Israel's territory, is sailing in the sea to the north; A week
that passed separated another glacier from the same ice surface; The breakup of the glaciers constitutes
An early sign of global warming and expected climate change
By: Haaretz Service, Haaretz
A glacier broke off at the South Pole. Danger to shipping lanes (Reuters)
Satellite images have located another huge glacier that broke off from the Antarctic continent - like this
It was reported yesterday on the website of the CNN network. The area of the ice block
The rectangle, known as C-19, is about 6,336 square kilometers. although he is not
The largest glacier that broke off from Antarctica in recent years, the size of
C-19 is about a third the size of Israel.
Last week, another glacier broke off, C-18, which is 75 km long and 7 km wide
– a little less than 10 times the area of Manhattan. C-18 and C-19 are next to each other
On the edge of the "Ross" ice shelf - a huge area of ice stretching from the continent into the sea
Ross, in the part of the continent closest to New Zealand.
The new glaciers were located by the National Oceanic Administration
and Atmosphere, which tracks satellite images of the satellite program
The meteorologist of the US Department of Defense.
A series of glaciers that are increasing in size have been cut off from the continent in recent years
Antarctica, and raised concerns that temperatures are on a constant upward trend
in the arctic region. For such a trend, which in the estimation of many scientists is a sign
Early for global warming, there may be consequences for climate change
in many regions on earth.
Concerns were also raised that these giant glaciers - some of them the size of more
From 10,000 square kilometers - may endanger shipping routes, as much as they are
Moving north and breaking. Oceanic Administration Ice Center
And Atmosphere tracks the location of the glaciers, and in recent years
Scientists have located glaciers within a range of 1,600 km from the city of Cape Town
in South Africa and Christchurch in New Zealand.
A compilation of news and articles about global warming between the years 1999-2001
Scientist of the Earth
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