Researchers use 1,000 historical photos to reconstruct Antarctic glaciers before a dramatic collapse
In March 2002, the Larsen B Ice Shelf collapsed catastrophically, breaking up an area about one-sixth the size of Tasmania.
In March 2002, the Larsen B Ice Shelf collapsed catastrophically, breaking up an area about one-sixth the size of Tasmania.
Earth Sciences
Jul 8, 2024
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In recent years, global warming has left its mark on the Antarctic ice sheets. The "eternal" ice in Antarctica is melting faster than previously assumed, particularly in West Antarctica more than East Antarctica. The root ...
Earth Sciences
Jul 4, 2024
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920
Slush—water-soaked snow—makes up more than half of all meltwater on the Antarctic ice shelves during the height of summer, yet is poorly accounted for in regional climate models.
Earth Sciences
Jun 27, 2024
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A new and worrying way that large ice sheets can melt has been characterized by scientists for the first time. The research focuses on how relatively warm seawater can lap at the underside of ground-based ice, which can accelerate ...
Earth Sciences
Jun 25, 2024
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870
Ice shelves surrounding Antarctica have been melting with increasing speed in recent years. Much of this melting happens from below, as warm water eats away at their bases. This warm water is moved around Antarctica by currents ...
Earth Sciences
Jun 5, 2024
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197
A great armada entered the North Atlantic, launched from the cold shores of North America. But rather than ships off to war, this force was a fleet of icebergs, and the havoc it wrought was on the ocean current itself.
Earth Sciences
May 30, 2024
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793
As they seep and calve into the sea, melting glaciers and ice sheets are raising global water levels at unprecedented rates. To predict and prepare for future sea-level rise, scientists need a better understanding of how ...
Earth Sciences
May 30, 2024
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When Tasmanian astronomer Louis Bernacchi set foot on Antarctica in 1898, he declared, "Antarctic exploration is of capital importance to science." While his statement remains as true as ever, scientific exploration has faced ...
Environment
May 29, 2024
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20
A large iceberg (380 km2), about the size of the Isle of Wight, has broken off the 150m-thick Brunt Ice Shelf. It broke off after a crack suddenly appeared in the ice shelf a few weeks ago. The final break happened in the ...
Earth Sciences
May 23, 2024
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Scientists at the British Antarctic Survey (BAS) have found that the record-low levels of sea ice around Antarctica in 2023 were extremely unlikely to happen without the influence of climate change. This low was a one-in-a-2000-year ...
Earth Sciences
May 20, 2024
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407
The Antarctic ice sheet is one of the two polar ice caps of the Earth. It covers about 98% of the Antarctic continent and is the largest single mass of ice on Earth. It covers an area of almost 14 million square km and contains 30 million cubic km of ice. That is, approximately 61 percent of all fresh water on the Earth is held in the Antarctic ice sheet, an amount equivalent to 70 m of water in the world's oceans. In East Antarctica, the ice sheet rests on a major land mass, but in West Antarctica the bed can extend to more than 2,500 m below sea level. The land in this area would be seabed if the ice sheet were not there.
Ice enters the sheet through precipitation as snow. This snow is then compacted to form glacier ice which moves under gravity towards the coast. Most of it is carried to the coast by fast moving ice streams. The ice then passes into the ocean, often forming vast floating ice shelves. These shelves then melt or calve off to give icebergs that eventually melt.
If the transfer of the ice from the land to the sea is balanced by snow falling back on the land then there will be no net contribution to global sea levels. A 2002 analysis of NASA satellite data from 1979-1999 showed that areas of Antarctica where ice was increasing outnumbered areas of decreasing ice roughly 2:1. The general trend shows that a warming climate in the southern hemisphere would transport more moisture to Antarctica, causing the interior ice sheets to grow, while calving events along the coast will increase, causing these areas to shrink. However more recent satellite data, which measures changes in the gravity of the ice mass, suggests that the total amount of ice in Antarctica has begun decreasing in the past few years. Another recent study compared the ice leaving the ice sheet, by measuring the ice velocity and thickness along the coast, to the amount of snow accumulation over the continent. This found that the East Antarctic Ice Sheet was in balance but the West Antarctic Ice Sheet was losing mass. This was largely due to acceleration of ice streams such as Pine Island Glacier. These results agree closely with the gravity changes.
The continent-wide average surface temperature trend of Antarctica is positive and significant at >0.05°C/decade since 1957. West Antarctica has warmed by more than 0.1°C/decade in the last 50 years, and this warming is strongest in winter and spring. Although this is partly offset by fall cooling in East Antarctica, this effect is restricted to the 1980s and 1990s.
Despite this warming total Antarctic sea ice anomalies have been steadily increasing since 1978 (NSIDC (2006)). 2007 showed the largest positive anomaly of sea ice in the southern hemisphere since records have been kept starting in 1979 and 2008 is currently on pace to surpass last years record. The atmospheric warming cannot be directly linked to the recent mass losses in West Antarctica. This mass loss is more likely to be due to increased melting of the ice shelves because of changes in ocean circulation patterns. This in turn causes the ice streams to speed up. The melting and disappearance of the floating ice shelves will only have a small effect on sea level, which is due to salinity differences. The most important consequence of their increased melting is the speed up of the ice streams on land which are buttressed by these ice shelves.
This text uses material from Wikipedia, licensed under CC BY-SA