Antarctica’s melting ice shelves have unleashed 7.5 TRILLION tonnes of water into the oceans since 1997, study finds

By William On Oct 12, 2023

A study revealed that the melting of Antarctica’s ice sheets over the past 25 years has released 7.5 trillion tons of water into the ocean.

By analyzing more than 100,000 satellite radar images, researchers from the University of Leeds discovered a steady erosion of the continent’s ice sheets, with more than 40 percent shrinking between 1997 and 2021.

While some ice sheets increased in size during this period, the data revealed that a third have now lost more than 30% of their initial mass, releasing massive amounts of fresh water in the process.

Worryingly, scientists say this massive release of fresh water could threaten to destabilize ocean currents and contribute to global sea level rise.

Moreover, climate change caused by human activity means that the ice will continue to melt faster in the future, experts warn.

A study revealed that the melting of Antarctica’s ice sheets over the past 25 years has released 7.5 trillion tons of water into the ocean.

Warm waters off the west coast of Antarctica have caused the ice sheets to melt at a much faster rate than in the east where they are protected by a layer of cold water.

What is sea ice?

Sea ice is simply frozen ocean water. It forms, grows, and dissolves in the ocean.

It floats on the surface of the sea because it is less dense than liquid water.

In contrast, icebergs, glaciers, ice sheets, and ice shelves arise on Earth.

It is estimated that sea ice covers about 7 percent of the Earth’s surface and about 12 percent of the world’s oceans.

The lion’s share of sea ice is contained within the polar ice masses in the Arctic Ocean and the Southern Ocean.

These ice masses undergo seasonal changes and are also affected locally on smaller timescales by fluctuations in winds, currents and temperatures.

Sea ice is a vital habitat for the penguins and seals that call Antarctica home

Scientists found that while almost all of the ice sheets on the East Coast were melting, many of the ice sheets on the West Coast remained the same size or grew.

This is due to the patterns of ocean currents that surround Antarctica, which carry water at different temperatures.

While the western side is exposed to warm waters that erode ice shelves from below, East Antarctica is protected by a strip of cold water near the shore.

Overall, 59 trillion tons of water have been added to the continent’s ice shelves since 1975.

However, this was offset by a loss of 67 trillion tons.

The largest losses occurred in the Getz Glacier, where 1.9 trillion tons of water were lost.

For perspective, a trillion tons of ice would make a cube more than six miles (10 kilometers) long in each direction — more than half a mile longer than Mount Everest!

Of this loss, 95 percent was due to melting, and 5 percent was due to “break-off,” where large chunks of ice break off into the ocean.

Meanwhile, on the other side of Antarctica, the Ameri Ice Shelf has gained 1.2 trillion tons of ice due to the cold waters surrounding it.

Dr. Benjamin Davison, who led the study, says that this evidence indicates a clear change in Antarctic ice.

“We would expect most ice shelves to go through cycles of rapid, but short-lived, shrinkage and then grow back slowly,” Dr Davidson said.

“Instead, we see about half of them shrinking with no sign of recovery.”

Dr. Davidson and his colleagues believe this change has been caused by human-caused global warming.

If the increased rate of melting was the result of natural factors such as a change in climate patterns, there would also have been evidence of ice regrowth in the typically warmer west.

The Getz Ice Shelf, where the worst of the ice melt occurred, dumped 1.9 trillion tons of water into the Southern Ocean over 25 years

The team behind this latest study is now concerned that the continued erosion of the ice sheet could have huge impacts on the wider climate.

Ice sheets floating on the sea act like giant “plugs” at the end of glaciers.

As they thin out or decrease in size, glaciers make their way to the sea faster, increasing the rate of ice loss to the ocean.

If ice shelves are removed or reduced, it could disrupt the Antarctic ice system as well as global ocean circulation.

In the Southern Ocean around Antarctica, dense, cold, salty water sinks to the ocean floor.

When water sinks, it forms the engine that drives the ocean’s giant “conveyor belt” or currents that transport nutrients and heat away from the delicate polar ecosystem.

Since the vast majority of water coming from melting ice sheets is fresh, this dilutes the ocean’s salinity, making it less dense and taking longer to sink, impairing ocean circulation.

Studies already show that this process may be beginning to weaken the delicate balance in Antarctica.

Scientists at the National Snow and Ice Data Center have revealed that Antarctica’s sea ice levels reached a “staggering” historic low during the winter. The graph shows the current extent of sea ice compared to the average for this time of year

Recent research has revealed that the ice surrounding Antarctica, known as the sea ice extent, was at a historic low in September It has an area of less than 6.5 million square miles (17 million square kilometers), according to the U.S. National Snow and Ice Data Center.

While this may sound like a lot, it is actually 580,000 square miles (1.5 million square kilometres) less than the September average – an area five times the size of the British Isles.

This comes after scientists revealed that the winter heatwave in March 2022 saw temperatures rise by 40 degrees Celsius above normal levels.

If this happened in the summer, scientists say it would be hot enough to melt the surface of the ice sheets; Something never seen before.

Activists said rapid warming has already caused a major southward shift and a contraction in the distribution of Antarctic krill – a keystone species.

A recent Greenpeace expedition to Antarctica also confirmed that gentoo penguins are breeding south as a result of the climate crisis.

Sea levels could rise by up to 4 feet by 2300

Scientists have warned that global sea levels could rise by up to 1.2 meters (4 feet) by 2300 even if we meet the 2015 Paris climate goals.

Long-term change will be driven by melting ice from Greenland to Antarctica, which is set to redraw global coastlines.

Sea level rise threatens cities from Shanghai to London, to low-lying areas of Florida or Bangladesh, and to entire countries such as the Maldives.

It is essential that we reduce emissions as quickly as possible to avoid a further rise, a German-led team of researchers said in a new report.

By 2300, the report forecasts sea levels will rise by 0.7 to 1.2 metres, even if nearly 200 countries meet targets set in the 2015 Paris Agreement.

The goals set by the agreements include reducing greenhouse gas emissions to net zero in the second half of this century.

She added that ocean levels will inevitably rise because heat-trapping industrial gases already emitted will remain in the atmosphere, causing more ice to melt.

In addition, water naturally expands when its temperature rises above four degrees Celsius (39.2 degrees Fahrenheit).

Every five years of delay after 2020 in reaching peak global emissions would mean an additional 8 inches (20 cm) of sea level rise by 2300.

“Sea level is often talked about as a really slow process and you can’t do much about it, but the next 30 years are really important,” said lead author Dr. Matthias Mengele, from the Potsdam Institute for Climate Impact Research in Potsdam. Germany.

None of the 200 governments that signed the Paris Agreement are on track to fulfill their pledges.

(tags for translation)dailymail