Rapid Loss of Sunlight Could Have Unleashed Snowball Earth Events in The Past - Latest Govt Exam
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Rapid Loss of Sunlight Could Have Unleashed Snowball Earth Events in The Past

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Not all ice ages are equally brutal. In the most extreme glaciation events known to science, ice stretches out from Earth’s polar regions and extends all the way into lower latitudes, literally reshaping the face of the planet.

Evidence for such epic transitions can be found in the geologic record, most recently in formidable glaciations during the Cryogenian period. Scientists think these extreme cooling events had potentially global reach and ramifications: a phenomenon called ‘Snowball Earth’.

But what on Earth could unleash such devastating, unrelenting cold that most – or all – of our planet would end up sheathed in a frozen sphere of ice and snow? While the exact triggers remain unknown, researchers have now unearthed a new theoretical explanation for how such a thing could happen.

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“There are lots of ideas for what caused these global glaciations, but they all really boil down to some implicit modification of solar radiation coming in,” says planetary science researcher Constantin Arnscheidt from MIT.

“But generally it’s been studied in the context of crossing a threshold.”

In other words, the conventional explanation for how a Snowball Earth could transpire is that, in some kind of cataclysmic throwing of shade, a reduced amount of sunlight would reach the surface of the planet, resulting in a cooler Earth that proceeds to freeze over.

Another hypothetical explanation, to do with the carbon cycle, would be the opposite of the global warming crisis facing Earth now: what if our planet had so little heat-trapping carbon dioxide in the atmosphere that we lost Earth’s temperate climate altogether, with its warmth drifting off into space?

“Although there remains debate about the specific triggers of the low-latitude glaciations in Earth’s geologic past, there is a general understanding that glaciation is initiated when changes in radiative fluxes or in CO2 fluxes exceed a critical threshold,” Arnscheidt and his co-author, MIT geophysicist Daniel Rothman, explain in a new paper.

While the theory has focused on such critical thresholds before, the researchers have struck upon a new avenue for thinking about Snowball Earth precursors: what if it wasn’t a critical threshold that was met (in terms of solar radiation plunging, for example), but a critical rate of change that was reached?

In new modelling, the researchers simulated Earth’s dynamic systems in glaciation scenarios – chiefly the interplay of ice-albedo feedback and the carbonate-silicate cycle.

The former is an example of positive feedback. As Earth gets icier and approaches Snowball Earth, it’s frosty coat of ice and snow end up reflecting more sunlight away from the planet, which in turn accelerates the cooling effects already in process.

However, as Earth becomes icier, our usual carbonate–silicate cycle becomes disrupted. With Earth’s rocks sealed under ice, they’re less able to absorb atmospheric carbon, so it sticks around in the air trapping heat. That’s why – at Earth’s distance from the Sun, anyhow – our planet theoretically wouldn’t get stuck in a permanent Snowball Earth state, despite the perpetuation of ice–albedo feedback.

With these kinds of factors built into their models, the researchers examined whether rate-induced tipping might induce a Snowball Earth event. In the right circumstances, it did.

 

In the simulations, Arnscheidt and Rothman found that if solar radiation dropped quickly enough for long enough, that in itself could be enough to unleash a Snowball Earth – and all it might take would be about a 2 percent drop in sunlight reaching the surface for 10,000 years, the researchers estimate.

In the grand scheme of things (read: Earth’s approximate 4.5 billion years of age), that’s not very long. But what could hide Earth from the Sun like that, for 10,000 years at a stretch?

Nobody really knows for sure, but it’s plausible that something like a planetary-scale volcanic winter unleashed by volcanic eruptions might sufficiently cloud our atmosphere. Alternatively, some kind of biological phenomenon in Earth’s ancient past, like a surge in moisture-producing algae, could generate clouds of condensation that might ultimately freeze them and everything else into oblivion.

Of course, all these ideas are pretty out there. But that doesn’t mean we shouldn’t go looking for what might have made Snowball Earth eventuate, or exploring how quickly this ancient, icy history may have unfolded.

Especially given we’re right now rushing so fast in the opposite direction, the researchers say.

“It teaches us that we should be wary of the speed at which we are modifying Earth’s climate, not just the magnitude of the change,” Arnscheidt says.

“There could be other such rate-induced tipping points that might be triggered by anthropogenic warming.”

The findings are reported in Proceedings of the Royal Society A.

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Women in the newsroom: Why South Africa leads the way

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Mahlatse Mahlase is group editor-in-chief of Eyewitness News, a major broadcaster in South Africa. It’s a role she would have been unlikely to fill 30 years ago, under the apartheid regime, whose hierarchy put Black women on a bottom tier.

But no matter where you look in the world, women’s leadership in the news media has lagged – and still does. South Africa, in fact, is a relative success story. Today, women lead nearly half of the country’s major publications and broadcasters, according to a recent analysis by Oxford University. That puts it ahead of the United States, the United Kingdom, and even countries held up as models of gender parity, like Finland.

Yet South African women’s gains have been especially hard-won, and incomplete. Women hold few of journalism’s purse strings, for instance. 

Ms. Mahlase says she has reflected on representation through a new prism since she gave birth seven months ago to her first child, a boy. 

“I want my son to grow up in a world where he has female bosses,” she says. “I want him to grow up listening to women experts on the radio, hearing them as contributors to changing the world and not just as victims of an unfair system.”

Johannesburg

Nwabisa Makunga can point to the exact moment she knew she would become a journalist.

It was April 1993 and she was 11 years old, watching the TV broadcast of the funeral of assassinated anti-apartheid leader Chris Hani with her family in their living room. The presenter was a Black reporter named Noxolo Grootboom, and her powerful tribute to Mr. Hani brought Ms. Makunga’s parents to tears.

“She was a woman who looked like me, who spoke like me, telling the story of a man who had been so important to people from my community,” she recalls. “I said to myself – this is what I’m going to do. I’m going to be like Noxolo, and I’m going to tell stories.”

Three decades later, Ms. Makunga is the editor-in-chief of the Sowetan, one of South Africa’s most-circulated daily newspapers. She is part of a generation of women who have risen through the ranks to take leadership of many of the country’s most important news outlets. Today, these women – most of them Black, Asian, and multiracial – lead nearly half the country’s major publications and broadcasters, according to a recent analysis by Oxford University. That makes the country a global leader for women’s leadership in the media, putting it ahead of the United States, the United Kingdom, and even countries held up as models of gender parity, like Finland.

And the achievement is doubly remarkable in South Africa, where only a generation ago the entire country was run largely by white men. Editors like Ms. Makunga grew up not only with few role models who looked like them, but also in a world where the media was used as a weapon of the apartheid regime, premised on white supremacy – enforcing a hierarchy in which they were the bottom tier.

Alexander Joe/AFP/Getty Images/File

A vendor sells a Daily Sun edition honoring former South African President Nelson Mandela’s birthday on July 18, 2013. The country’s transition to democracy opened up opportunities for many of today’s journalists.

Hard-won gains

Even after apartheid formally ended, these editors came up in newsrooms where its effects lingered. They were told their accents were “too African,” or their looks “too tempting.” Even as the newsrooms around them began to change from mostly white to mostly not, they still found themselves edged out of the pub trips and golf games where their male colleagues networked their way to the top.

“Make no mistake: Those statistics changing are the result of a fight,” says Mahlatse Mahlase, group editor-in-chief of Eyewitness News, a major breaking-news broadcaster. Women in South Africa’s newsrooms “have fought racism and they’ve also fought the patriarchy. The discrimination came from every side.”

Although they’ve now arrived, many of these same leaders note that South Africa’s media transformation remains incomplete. Women hold few of journalism’s purse strings, for instance. Just 19% of the board members at media companies here are female, according to a 2018 academic study of women in the media called “Glass Ceilings.” The vast majority of the country’s major media houses have a male CEO.

And while the proportion of Black, Asian, and multiracial women in the top echelons of South African media companies has grown from 6% in 2006 to 30% in 2018, that number still lags, in a country where they represent 46% of the population, according to the Glass Ceilings survey. Once they get there, meanwhile, they’re often placed under intense scrutiny and pressure.

“When men get to the top of their profession, they’re celebrated. When women get there, particularly Black women, there’s backlash, there’s trolling, there’s bullying,” says Glenda Daniels, an associate professor of media studies at the University of the Witwatersrand in Johannesburg and the co-author of the Glass Ceilings study. She uses the term “Black” as it is frequently applied in South Africa, to describe anyone who is not white. “Women at the top find they’re often exhausted just proving over and over that they deserve to be in the room.”

“Newsrooms figured out they needed to mimic what was happening in society so they wouldn’t end up on the wrong side of history.” – Mapula Nkosi, editor of the Daily Sun

Coming up the ladder

In 1994, the same year Nelson Mandela took the oath as South Africa’s first Black president, an ambitious young reporter named Mapula Nkosi walked into the Johannesburg newsroom of the Weekly Mail, which made its name opposing apartheid, to begin her career as a cadet reporter.

When she looked up the ranks, she says, she saw only men. But all around her, the country had a new buzzword: transformation. The process was often fuzzy, but the objective was clear: The structures that ruled the country should look more like the people who lived in it.

“Those newsrooms figured out they needed to mimic what was happening in society so they wouldn’t end up on the wrong side of history,” says Ms. Nkosi, now the editor of the Daily Sun, the country’s most-circulated daily newspaper. “The whole time I was coming up I had people on one side of me saying, ‘We don’t understand why you’re in this position,’ and people on the other side saying, ‘We are so excited to see where you go.’”

Those competing forces followed many of South Africa’s women journalists through their rise. Each time they pulled themselves up another rung on the ladder, they heard whispers – that they only got this job because leadership wanted a woman, that they’d never make it.

But when they did, the conversation changed.

“When you do well, you become almost genderless,” says Paula Fray, a media consultant and the first woman to edit the Saturday Star, a major South African newspaper. “But if you don’t do well, then your failings represent your whole gender.”

Meanwhile, women leaders in the newsroom “carry the added responsibility of making these environments more welcoming for women,” says Mary Papayya, a veteran journalist and editor who now sits on the board of the South African Broadcasting Corp. That, she notes, is a particularly difficult task at a time when many outlets have seen their budgets slashed and are now contending with a pandemic that has made news reporting both more dangerous and less lucrative.

And the fight for change goes beyond who sits in the corner office. In South Africa, like many countries, men are disproportionately both the experts and subjects of news stories. A recent analysis of the South African media’s coverage of the COVID-19 pandemic by the organization Media Monitoring Africa, for instance, found that 80% of those quoted in stories about the virus were men.

Ms. Mahlase, the radio news editor, says she sees these kinds of statistics through a new prism since she gave birth seven months ago to her first child, a boy. 

“I want my son to grow up in a world where he has female bosses,” she says. “I want him to grow up listening to women experts on the radio, hearing them as contributors to changing the world and not just as victims of an unfair system.”

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Environment

Women in the newsroom: Why South Africa leads the way

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Mahlatse Mahlase is group editor-in-chief of Eyewitness News, a major broadcaster in South Africa. It’s a role she would have been unlikely to fill 30 years ago, under the apartheid regime, whose hierarchy put Black women on a bottom tier.

But no matter where you look in the world, women’s leadership in the news media has lagged – and still does. South Africa, in fact, is a relative success story. Today, women lead nearly half of the country’s major publications and broadcasters, according to a recent analysis by Oxford University. That puts it ahead of the United States, the United Kingdom, and even countries held up as models of gender parity, like Finland.

Yet South African women’s gains have been especially hard-won, and incomplete. Women hold few of journalism’s purse strings, for instance. 

Ms. Mahlase says she has reflected on representation through a new prism since she gave birth seven months ago to her first child, a boy. 

“I want my son to grow up in a world where he has female bosses,” she says. “I want him to grow up listening to women experts on the radio, hearing them as contributors to changing the world and not just as victims of an unfair system.”

Johannesburg

Nwabisa Makunga can point to the exact moment she knew she would become a journalist.

It was April 1993 and she was 11 years old, watching the TV broadcast of the funeral of assassinated anti-apartheid leader Chris Hani with her family in their living room. The presenter was a Black reporter named Noxolo Grootboom, and her powerful tribute to Mr. Hani brought Ms. Makunga’s parents to tears.

“She was a woman who looked like me, who spoke like me, telling the story of a man who had been so important to people from my community,” she recalls. “I said to myself – this is what I’m going to do. I’m going to be like Noxolo, and I’m going to tell stories.”

Three decades later, Ms. Makunga is the editor-in-chief of the Sowetan, one of South Africa’s most-circulated daily newspapers. She is part of a generation of women who have risen through the ranks to take leadership of many of the country’s most important news outlets. Today, these women – most of them Black, Asian, and multiracial – lead nearly half the country’s major publications and broadcasters, according to a recent analysis by Oxford University. That makes the country a global leader for women’s leadership in the media, putting it ahead of the United States, the United Kingdom, and even countries held up as models of gender parity, like Finland.

And the achievement is doubly remarkable in South Africa, where only a generation ago the entire country was run largely by white men. Editors like Ms. Makunga grew up not only with few role models who looked like them, but also in a world where the media was used as a weapon of the apartheid regime, premised on white supremacy – enforcing a hierarchy in which they were the bottom tier.

Alexander Joe/AFP/Getty Images/File

A vendor sells a Daily Sun edition honoring former South African President Nelson Mandela’s birthday on July 18, 2013. The country’s transition to democracy opened up opportunities for many of today’s journalists.

Hard-won gains

Even after apartheid formally ended, these editors came up in newsrooms where its effects lingered. They were told their accents were “too African,” or their looks “too tempting.” Even as the newsrooms around them began to change from mostly white to mostly not, they still found themselves edged out of the pub trips and golf games where their male colleagues networked their way to the top.

“Make no mistake: Those statistics changing are the result of a fight,” says Mahlatse Mahlase, group editor-in-chief of Eyewitness News, a major breaking-news broadcaster. Women in South Africa’s newsrooms “have fought racism and they’ve also fought the patriarchy. The discrimination came from every side.”

Although they’ve now arrived, many of these same leaders note that South Africa’s media transformation remains incomplete. Women hold few of journalism’s purse strings, for instance. Just 19% of the board members at media companies here are female, according to a 2018 academic study of women in the media called “Glass Ceilings.” The vast majority of the country’s major media houses have a male CEO.

And while the proportion of Black, Asian, and multiracial women in the top echelons of South African media companies has grown from 6% in 2006 to 30% in 2018, that number still lags, in a country where they represent 46% of the population, according to the Glass Ceilings survey. Once they get there, meanwhile, they’re often placed under intense scrutiny and pressure.

“When men get to the top of their profession, they’re celebrated. When women get there, particularly Black women, there’s backlash, there’s trolling, there’s bullying,” says Glenda Daniels, an associate professor of media studies at the University of the Witwatersrand in Johannesburg and the co-author of the Glass Ceilings study. She uses the term “Black” as it is frequently applied in South Africa, to describe anyone who is not white. “Women at the top find they’re often exhausted just proving over and over that they deserve to be in the room.”

“Newsrooms figured out they needed to mimic what was happening in society so they wouldn’t end up on the wrong side of history.” – Mapula Nkosi, editor of the Daily Sun

Coming up the ladder

In 1994, the same year Nelson Mandela took the oath as South Africa’s first Black president, an ambitious young reporter named Mapula Nkosi walked into the Johannesburg newsroom of the Weekly Mail, which made its name opposing apartheid, to begin her career as a cadet reporter.

When she looked up the ranks, she says, she saw only men. But all around her, the country had a new buzzword: transformation. The process was often fuzzy, but the objective was clear: The structures that ruled the country should look more like the people who lived in it.

“Those newsrooms figured out they needed to mimic what was happening in society so they wouldn’t end up on the wrong side of history,” says Ms. Nkosi, now the editor of the Daily Sun, the country’s most-circulated daily newspaper. “The whole time I was coming up I had people on one side of me saying, ‘We don’t understand why you’re in this position,’ and people on the other side saying, ‘We are so excited to see where you go.’”

Those competing forces followed many of South Africa’s women journalists through their rise. Each time they pulled themselves up another rung on the ladder, they heard whispers – that they only got this job because leadership wanted a woman, that they’d never make it.

But when they did, the conversation changed.

“When you do well, you become almost genderless,” says Paula Fray, a media consultant and the first woman to edit the Saturday Star, a major South African newspaper. “But if you don’t do well, then your failings represent your whole gender.”

Meanwhile, women leaders in the newsroom “carry the added responsibility of making these environments more welcoming for women,” says Mary Papayya, a veteran journalist and editor who now sits on the board of the South African Broadcasting Corp. That, she notes, is a particularly difficult task at a time when many outlets have seen their budgets slashed and are now contending with a pandemic that has made news reporting both more dangerous and less lucrative.

And the fight for change goes beyond who sits in the corner office. In South Africa, like many countries, men are disproportionately both the experts and subjects of news stories. A recent analysis of the South African media’s coverage of the COVID-19 pandemic by the organization Media Monitoring Africa, for instance, found that 80% of those quoted in stories about the virus were men.

Ms. Mahlase, the radio news editor, says she sees these kinds of statistics through a new prism since she gave birth seven months ago to her first child, a boy. 

“I want my son to grow up in a world where he has female bosses,” she says. “I want him to grow up listening to women experts on the radio, hearing them as contributors to changing the world and not just as victims of an unfair system.”

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Trump Administration Penalizes Chinese Officials for Hong Kong Crackdown

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WASHINGTON — The Trump administration on Friday imposed sanctions on 11 senior Chinese Communist Party officials and their Hong Kong allies, including chief executive Carrie Lam, over their role in cracking down on political dissent in the southern Chinese territory.

These are the first sanctions against officials from China and Hong Kong over suppression of pro-democracy protests and dissent in the territory. They are being imposed as actions following an executive order President Trump signed last month seeking to punish China for its repression in Hong Kong.

“The United States stands with the people of Hong Kong and we will use our tools and authorities to target those undermining their autonomy,” Steven T. Mnuchin, the Treasury secretary, said in a statement.

The action is another in a series of measures the Trump administration has taken in recent months to ratchet up pressure on Beijing. Last month, the administration imposed sanctions on the Chinese government, including a senior member of the Communist Party, over human rights abuses against the largely Muslim Uighur minority.

Beijing announced in June that it was imposing a new national security law in Hong Kong to grant security agencies expansive powers to crack down on dissent.

Since then, American officials have debated how to get Beijing to roll back the law or how to penalize the action.

Last month, Mr. Trump signed an executive order ending the special status that the United States grants Hong Kong in diplomatic and trade relations, saying Hong Kong was no longer an autonomous entity, and officials are now beginning to treat the territory like mainland China.

Some administration officials had wanted Mr. Trump to announce during the signing that his government was imposing sanctions on Ms. Lam and other officials in China and Hong Kong. The president declined to do so then.

The current flurry of actions against China dovetails with a core part of Mr. Trump’s campaign strategy. His campaign aides are trying to show Mr. Trump is hitting China hard in order to shift the national conversation from his failures on managing the coronavirus pandemic and the economy.

The initial virus outbreak began in central China, and Mr. Trump has blamed Chinese officials for failing to contain it, though he also praised China’s leader, Xi Jinping, for efforts this winter.

Some of the administration’s China hawks are trying to set the two nations on a course for long-term confrontation and ensure that relations remain in a state of open rivalry even if Democratic candidate Joseph R. Biden Jr. wins the November election.

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