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Satellite imagery shows Antarctic ice shelf crumbling faster than thought

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(Last Updated On: August 11, 2022)

Antarctica’s coastal glaciers are shedding icebergs more rapidly than nature can replenish the crumbling ice, doubling previous estimates of losses from the world’s largest ice sheet over the past 25 years, a satellite analysis showed on Wednesday.

The first-of-its-kind study, led by researchers at NASA’s Jet Propulsion Laboratory (JPL) near Los Angeles and published in the journal Nature, raises new concern about how fast climate change is weakening Antarctica’s floating ice shelves and accelerating the rise of global sea levels, Reuters reported.

The study’s key finding was that the net loss of Antarctic ice from coastal glacier chunks “calving” off into the ocean is nearly as great as the net amount of ice that scientists already knew was being lost due to thinning caused by the melting of ice shelves from below by warming seas.

Taken together, thinning and calving have reduced the mass of Antarctica’s ice shelves by 12 trillion tons since 1997, double the previous estimate, the analysis concluded.

The net loss of the continent’s ice sheet from calving alone in the past quarter-century spans nearly 37,000 sq km, an area almost the size of Switzerland, according to JPL scientist Chad Greene, the study’s lead author.

“Antarctica is crumbling at its edges,” Greene said in a NASA announcement of the findings. “And when ice shelves dwindle and weaken, the continent’s massive glaciers tend to speed up and increase the rate of global sea level rise.”

The consequences could be enormous. Antarctica holds 88% of the sea level potential of all the world’s ice, he said.

Ice shelves, permanent floating sheets of frozen freshwater attached to land, take thousands of years to form and act like buttresses holding back glaciers that would otherwise easily slide off into the ocean, causing seas to rise.

When ice shelves are stable, the long-term natural cycle of calving and re-growth keeps their size fairly constant.

In recent decades, though, warming oceans have weakened the shelves from underneath, a phenomenon previously documented by satellite altimeters measuring the changing height of the ice and showing losses averaging 149 million tons a year from 2002 to 2020, according to NASA.

The losses measured from calving outpaced natural ice shelf replenishment so greatly that researchers found it unlikely Antarctica can return to pre-2000 glacier levels by the end of this century.

The accelerated glacial calving, like ice thinning, was most pronounced in West Antarctica, an area hit harder by warming ocean currents. But even in East Antarctica, a region whose ice shelves were long considered less vulnerable, “we’re seeing more losses than gains,” Greene said.

One East Antarctic calving event that took the world by surprise was the collapse and disintegration of the massive Conger-Glenzer ice shelf in March, possibly a sign of greater weakening to come, Greene said.

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Turkey moves against Meta over Threads-Instagram data sharing

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(Last Updated On: March 18, 2024)

Turkey’s competition authority on Monday imposed an interim measure on Meta Platforms Inc meant to hinder data sharing between the Instagram and Threads platforms as it investigates possible abuse of the company’s dominant market position.

In December the authority launched an investigation into Facebook parent Meta (META.O), opens new tab over a possible violation of competition law by linking its social media platforms Instagram and the newer Threads.

The authority said the interim measure would remain in place until a final decision is made, since the data obtained and merged through these two apps could “violate competition law and cause irreparable damage” in the market.

Separately, the Turkish authority fined Meta 4.8 million lira ($148,000) daily as part of a separate investigation over a notification message that the company sends users about the sharing of data.

The notification about data sharing between the company’s Facebook, Instagram and WhatsApp services did not provide sufficient information and was not sufficiently transparent, it said.

The notification was also designed to guide users to approve data sharing, which was not deemed sufficient to address anti-competition concerns, it added.

A Meta spokesperson said that the company is considering the decision and will have more to say in due course. – Reuters

 

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Musk’s SpaceX building spy satellite network for US intelligence agency

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(Last Updated On: March 17, 2024)

SpaceX is building a network of hundreds of spy satellites under a classified contract with a U.S. intelligence agency, five sources familiar with the program said, demonstrating deepening ties between billionaire entrepreneur Elon Musk’s space company and national security agencies.

The network is being built by SpaceX’s Starshield business unit under a $1.8 billion contract signed in 2021 with the National Reconnaissance Office (NRO), an intelligence agency that manages spy satellites, sources told Reuters.

The plans show the extent of SpaceX’s involvement in U.S. intelligence and military projects and illustrate a deeper Pentagon investment into vast, low-Earth orbiting satellite systems aimed at supporting ground forces.

If successful, the sources said the program would significantly advance the ability of the U.S. government and military to quickly spot potential targets almost anywhere on the globe.

The contract signals growing trust by the intelligence establishment of a company whose owner has clashed with the Biden administration and sparked controversy.

The satellites can track targets on the ground and share that data with U.S. intelligence and military officials, the sources said.

In principle, that would enable the U.S. government to quickly capture continuous imagery of activities on the ground nearly anywhere on the globe, aiding intelligence and military operations, they added.

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Study documents headaches experienced by astronauts in space

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(Last Updated On: March 15, 2024)

Research in the expanding field of space medicine has identified many ways in which a microgravity environment and other factors can meddle with the human body during space missions. A new study has added to the field by showing that astronauts are more likely to experience headaches in space than previously known.

The study involved 24 astronauts from the U.S., European and Japanese space agencies who traveled aboard the International Space Station for up to 26 weeks. All but two of them reported experiencing headaches in space.

This was a larger proportion than the researchers had expected based on prior anecdotal evidence. The headaches – some resembling migraines and others resembling tension headaches – occurred not only during the first couple of weeks in space as the body goes through the process of adapting to microgravity, but also later.

The headaches occurring during the early period often present as migraine-like while those experienced later in space travel present more like a tension headache, the study found.

“We hypothesize that different mechanisms are involved for the early headache episodes – the first one to two weeks in space – versus later headache episodes,” said neurologist WPJ van Oosterhout of Zaans Medical Center and the Leiden University Medical Center in the Netherlands, lead author of the study published this week in the journal Neurology, opens new tab.

“In the first week, the body has to adapt to the lack of gravity, known as space adaptation syndrome. This phenomenon is similar to motion sickness, and can cause nausea, vomiting and dizziness, and headaches,” Van Oosterhout said. “The later headaches could result from an increase in intracranial pressure. Due to microgravity, there is more fluid accumulating in the upper part of the body and head, resulting in higher pressure in the skull.”

Migraines experienced on Earth are often throbbing and pulsating headaches lasting four to seven hours, accompanied by symptoms such as nausea, vomiting and hypersensitivity to light and sound, Van Oosterhout said. Tension-type headaches on Earth usually are a more dull pain felt over the entire head without those other symptoms, Van Oosterhout added.

The astronauts – 23 men and one woman, with an average age of about 47 – were aboard the International Space Station for missions that took place from November 2011 to June 2018, with a total of 378 headaches reported by 22 of the 24 astronauts during a total of 3,596 days in orbit. None of the 24 reported headaches in the three months after returning to Earth.

Thirteen of the astronauts were from NASA, six from the European Space Agency, two from Japan’s JAXA and one from the Canadian Space Agency. None had ever been diagnosed with migraines prior to their space missions and none had a history of recurrent headaches.

Various documented effects of space travel include bone and muscle atrophy, changes in the brain, cardiovascular system and immune system, issues with the balance system in the inner ear and a syndrome involving the eyes. Cancer risk from greater radiation exposure in space is another concern.

Experts are unsure of how much of a barrier these effects might be on human space travel over extended periods, for instance for journeys to our neighboring planet Mars or beyond.

“The honest answer is that we don’t know the effects of long-duration space travel – possibly years – on the human body,” Van Oosterhout said. “It is clear that even short-term – days or weeks – to medium-term – weeks or months – duration exposure to microgravity already has some effects, mostly reversible, on the human body. This is a clear task for the field of space medicine.” – Reuters

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