Melting ice in Antarctica could bring monsoon rains to the ice cap

In an ever-warming climate, ripple effects or chain reactions could lead to altered weather patterns across the globe thanks to a melting Antarctic ice sheet, a new study says.

Melting ice in Antarctica could bring monsoon rains to the ice cap

In an ever-warming climate, ripple effects or chain reactions could lead to altered weather patterns across the globe thanks to a melting Antarctic ice sheet, a new study says.

The study, published in the journal Nature Geoscience, found that as Earth continues to heat up, the land underneath the Antarctic ice sheet will become more exposed.

As a result of that process, wind patterns will shift, and rainfall will increase over Antarctica, which could trigger processes that speed up ice loss.

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"We found that ice sheet retreat exposing previously ice-covered land led to big increases in rainfall, which through a feedback mechanism dramatically warms the ocean," Catherine Bradshaw, senior scientist at the UK Met Office and lecturer at the University of Exeter, told CNN.

"This feedback mechanism could potentially trigger additional processes that accelerate ice loss."

The joint study is based on combining climate modelling and data comparisons from the Middle Miocene epoch (13-17 million years ago).

Why do we care about something that happened more than 13 million years ago?

Because carbon dioxide levels and global temperatures during the Middle Miocene were similar to those Earth is forecast to reach by the end of this century.

When it rains it pours

"With the big ice sheet on Antarctica like we have today, the predominant winds are known as katabatic winds, and these go from the land to the sea," Dr Bradshaw said.

"They originate from the ice sheet where it is very high, very cold and very dry - in fact, Antarctica receives only a few inches of snowfall a year and is so dry it is classified as a desert."

https://twitter.com/ClimateCb/status/1392936730270052354?ref_src=twsrc%5Etfw

Dr Bradshaw cautions that those winds could actually reverse - blowing instead from the cooler sea to the warmer, drier land - if Antarctica continues to warm.

That would generate the same results we see from daily sea breezes as well as seasonal monsoon winds that occur around the world.

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A monsoon is simply a seasonal reversal of wind direction which results in changes in precipitation for a specific region of the globe.

For Antarctica, this means an increase in rain.

"The surface of the Antarctic ice sheet is very bright, and it reflects some 50-80 per cent of the sunlight that hits it. Where the ice sheet retreats and exposes the darker land surface underneath, this ground is much less reflective and so absorbs more sunlight, which warms it up," Dr Bradshaw said.

Antarctic

Dr Bradshaw explained that ice-free ground at the coast warms up more than the surrounding sea surface which in turn causes the change in wind direction.

Similar to the seas breezes Florida experiences, these winds can bring in moisture from the surrounding ocean that can dramatically increase rainfall.

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"What happens to an ice sheet when rainfall increases depends on where the rain falls and whether it is cold enough to fall as snow instead of rain," Dr Bradshaw said.

"If the temperatures are warm enough for the moisture to fall as rain over the ice-free area, this could trigger processes that can accelerate ice loss.

"Conversely, if the temperatures are cold enough for the moisture to fall as snow over the ice sheet, this can cause ice growth."

As the Earth continues to warm, scientists may be able to learn from monsoonal regions of the world about how to prevent a collapse of the Antarctic ice sheet.

While that may sound a little far-fetched, this new research shows it may have actually happened in the past when the Antarctic ice sheet was even more unstable.

"Essentially, if more land is exposed in Antarctica, it becomes harder for a large ice sheet to reform, and without (favourable) orbital positions in the Middle Miocene playing a role, perhaps the ice sheet would have collapsed at that time," Dr Bradshaw said in a news release.

While the study suggests the Antarctic ice sheet was capable of major advance and retreat across the continent during the Middle Miocene, Dr Bradshaw emphasises that conditions now are not identical to those millions of years ago.

"It is important to stress that there were many important processes not included in our study, which, considering our findings, require additional research to establish exactly what the implications are for the future," Dr Bradshaw told CNN.

"This is the work that I intend to do next, but have not yet started."

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Walking on thin ice

Additional rainfall on the Antarctic continent isn't just about the local impacts, but also global ones - since that new rainfall would eventually cause more freshwater to end up in the surrounding oceans in turn causing sea levels to rise.

A fragment which had broken off from one of the largest recorded icebergs, called the A68a, floating near the island of South Georgia in the South Atlantic in December 2020.

"Rain ultimately flows back to sea, and because it is freshwater rather than saltwater, it is less dense than the seawater it is draining into," Dr Bradshaw told CNN.

"This means it can form a cap at the surface rather than sinking and circulating."

This is important because you have now essentially created a separation point between the deep ocean and the surface of the ocean which leads the deep waters to warm up.

"Since much of the West Antarctic ice sheet in particular is grounded beneath the sea surface, warmer waters can interact with the ice sheet from beneath," Dr Bradshaw said.

"If the surface of the ice sheet is melting it can form meltwater lakes that rainfall can add to.

"Meltwater lakes tend to be blue rather than white, making them darker than the ice underneath and therefore they absorb more sunlight, which makes them warmer."

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This can create a domino effect in which these darker, warmer waters could cause the ice sheet to melt from the inside out.

So the worst-case scenario now is the ice sheet not only melting from within - but also shrinking at the coastline.

"Near the coast, the ice flows faster in ice streams, glaciers and ice shelves and is lost to the ocean as either meltwater or icebergs," Dr Bradshaw said.

"Without new snowfall to replace the ice that is constantly being lost, the ice sheet will lose mass."

Even though this study focused mainly on Antarctica there have also been noticeable changes in ocean temperatures and salinity not only in the Southern Hemisphere but also in the Northern Hemisphere due to melting from Greenland's ice sheet.

This dramatic melting of the world's ice sheets could lead to dramatic changes in weather patterns.

Exactly how stable or unstable the Antarctic ice sheet is, is still not fully determined.

However, one thing is certain and that is that the ice is constantly moving.

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Asia's most notorious serial killer was charming and 'emanated power'

Two Australian journalists spent weeks interviewing Asia's most notorious killer; Charles Sobhraj after his arrest. One said it was impossible not to fall under his spell.

Asia's most notorious serial killer was charming and 'emanated power'

Serial killer Charles Sobhraj would use his charm to lure in unsuspecting victims, a true crime author says.

Then "The Serpent" would strike.

He would drug them, kill them — often by stabbing or strangulation — then he would steal their identity and use it to travel through the well-worn backpacker routes of Asia searching for more victims.

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Sobhraj, a French national of Indian and Vietnamese descent, preyed on Western tourists looking to get lost along the "hippie trail" in South Asia during the 1970s.

Also known as the "Bikini Killer", he is suspected of murdering anywhere between 12 to 24 people.

As the bodies piled up, Sobhraj and his accomplices Marie-Andree Leclerc and Ajay Chowdhur managed to escape incarceration three times.

But his murder spree caught up to him in 1976.

Teresa Knowlton, 21, was Sobhraj's first known victim.

He was imprisoned in New Delhi after drugging 60 French engineering students at a banquet in the Hotel Vikram.

A year later, journalists Julie Clark and Richard Neville flew to the Indian capital to meet Sobhraj.

The couple spent weeks interviewing the then 33-year-old for a book titled The Life and Crimes of Charles Sobhraj.

Speaking to Today Extra, Ms Clark said Sobhraj "emanated power", even while awaiting trail.

"Charles was just so charming," she said.

"We knew what he'd done, but he hadn't been convicted, so we had a kind of an open mind, but I - I mean, I'm really embarrassed to say I really wanted him to like me.

Julie Clarke first met Sobhraj with her partner Richard Neville at a New Delhi courthouse. She said it was impossible not to be drawn in by the killer.

"He sort of emanated a power, like you know very major movie stars have. They have a kind of a power field around them.

"And he had a gravitas as though he was some sort of important scholar, and he was a really impressive person.

"I hate to say that."

Charles Sobhraj was arrested in New Dehli in 1976 after drugging dozens of students in a hotel lobby.

Ms Clarke, who travelled the hippie trail herself in 1976, said it was hard not fall under Sobhraj's spell.

"Richard used to visit him every day at the courthouse," she said.

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"They had a little private shed where they were allowed to talk and Richard would tape the interviews, then I would listen to them at night and we'd both type them out.

"I could see Richard was getting to like Charles.

"We thought, we're meant to do this book, and we did become very obsessed with the case."

'The Serpent' is an eight-part limited series.

Sobhraj was sentenced to 20 years behind bars in New Dehli.

When he was released in 1997, he headed back to France after a warrant for his extradition to Thailand had expired.

Sobhraj walked free and returned to France in 1997 after serving 20 years.

In 2003, for reasons that still remain a mystery, Sobhraj returned to Nepal; the only country that had a warrant out for his arrest.

There he was imprisoned to a life sentence for killing American Connie Jo Bronzich and her partner Canadian Laurent Carriere.

Source : 9 News More   

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