Advertisements

A Trillion Tonnes of Antarctica Fell into the Sea

In late August 2016, sunlight returned to the Antarctic Peninsula and unveiled a rift across the Larsen C Ice Shelf that had grown longer and deeper over the austral winterNASA/John Sonntag

Antarctica, Earth’s coldest continent, is known for its remoteness, its unique fauna, and its frigid surface of ice. Around Antarctica’s periphery, dozens of ice shelves (that is, masses of glacier-fed floating ice that are attached to land) project outward into the Southern Ocean. The two largest ice shelves, the Ross Ice Shelfand the Ronne Ice Shelf, span a combined area of nearly 350,000 square km (about 135,000 square miles)—an area roughly equivalent to Venezuela—but Antarctica’s Larsen Ice Shelf, the continent’s fourth largest, has received the bulk of the attention over the last 25 years because it is slowly coming apart. The latest episode in this saga occurred between July 10 and July 12, 2017, when a one-trillion-metric-ton chunk of ice—possibly critical to holding back a large section of the remaining shelf—calved (that is, broke away).

The Larsen Ice Shelf is located on the eastern side of the Antarctic Peninsula and juts out into the Weddell Sea. It originally covered an area of 86,000 square km (33,000 square miles), but its footprint has declined dramatically, possibly as a result of warming air temperatures over the Antarctic Peninsula during the second half of the 20th century. In January 1995 the northern portion (known as Larsen A) disintegrated, and a giant iceberg calved from the middle section (Larsen B). Larsen B steadily retreated until February–March 2002, when it too collapsed and disintegrated. The southern portion (Larsen C) made up two-thirds of the ice shelf’s original extent, covering an area of about 50,000 square km (19,300 square miles) alone. Its thickness ranges from 200 to 600 meters (about 660 to 1,970 feet). Sometime between July 10 and July 12, 2017, a 5,800-square-km- (~2,240-square-mile-) section—some 12% of the Larsen C—broke away. Signs of Larsen C’s impending fracture date back to 2012, when satellite monitoring detected a steadily growing crack near the Joerg Peninsula at the southern end of the shelf. NASA and ESA satellites tracked the rift as it grew to more than 200 km (124 miles) in length and the huge iceberg separated from the continent.

Although some 88% of Larsen C remains, many scientists worry that it will fall apart like Larsen A and Larsen B, because the loss of such a huge area of the shelf’s ice front may make the remainder of the ice shelf less stable. The shelf’s mass, along with the fact that it is pinned behind shallow undersea outcrops of rock below, creates a natural dam that significantly slows the flow of the ice into the Weddell Sea. Scientists note that the section that calved was not held back by rock, so they are less worried that the loss of the calved section will result in the shelf’s wholesale disintegration in the near term. Some scientists even concede that the calved area could regrow to form a new ice dam that reinforces the shelf. However, the results of ice-calving and glacier-flow models predict that the shelf will continue to break apart over the course of years and decades.

Calving is a natural process driven, in part, by seasonal changes in temperature and the pressures associated with the build-up of compressional stress on the ice. Some studies argue that spring and summer foehns (warm dry gusty winds that periodically descend the leeward slopes of mountain ranges) have also contributed to the weakening of the ice. As investigations into ice shelf dynamics continue, such large iceberg calving events are often regarded as symptoms of climate changeassociated with global warming. While global warming may turn out to play a part in ice shelf calving events, scientists disagree on the role, if any, the phenomenon has played in recent developments on Larsen C.

Disintegration of Larsen Ice ShelfThe map shows the section of Larsen C that calved in July 2017.Encyclopædia Britannica, Inc.

Lake Chad: Can the vanishing lake be saved?

Lake ChadImage copyrightGETTY IMAGES

Lake Chad – a source of water to millions of people in West Africa – has shrunk by nine-tenths due to climate change, population growth and irrigation. But can a scheme dating back to the 1980s save it?

“It’s a ridiculous plan and it will never happen.” That’s the reaction many people have to the idea of trying to fill up Lake Chad and restore it to its former ocean-like glory by diverting water from the Congo river system 2,400km (1,500 miles) away.

Sceptics in Nigeria, who have seen successive governments fail even to make the lights work, wonder if the region’s politicians have nodded off and have been dreaming a little too hard.

But the government ministers and engineers who were recently sipping mineral water in the capital, Abuja, at the International Conference on Lake Chad had good reason to be thinking outside the box.

Lake Chad

Lake Chad has shrunk by 90% since the 1960s, due to climate change, an increase in the population and unplanned irrigation. Its basin covers parts of Nigeria, Niger, Chad and Cameroon, and has been a water source for between 20 million and 30 million people.

But with the desert encroaching further every year, it is getting increasingly difficult for families to make a living through agriculture, fishing and livestock farming. The UN says 10.7 million people in the Lake Chad basin need humanitarian relief to survive.

“We used to pass fields of maize on our way to the lake and there were vast numbers of boats bobbing up and down on the water back then, and huge fish markets,” says Bale Bura, who grew up by the lake in the 1970s and now works for the Lake Chad Fishermen’s Association.

Drawing of Transaqua planImage copyrightGROUP BONIFICA
Image captionTransaqua would cost tens of billions of dollars to build

Now far fewer farmers are able to earn a living on the mineral-rich but bone-dry shores.

This is one reason why the delegates in Abuja decided to dust off a scheme first mooted back in 1982 by the Italian engineering company Bonifica Spa.

It came up with Transaqua – a plan to construct a 2,400km (1,500 mile) canal to transfer water from the upstream tributaries of the mighty Congo River all the way to the Chari River basin, which feeds Lake Chad.

‘Deafening silence’

It proposed the transfer of up to 100 billion cubic metres (3.5 trillion cubic feet) of water a year and featured a series of dams along the route to generate electricity.

“I sent one of our engineers to the USA, to purchase the only reliable maps of Africa, which were made by the US Air Force and were the only maps with contour lines,” says Marcello Vichi, the Italian engineer who was asked to look into the idea during the early 1980s.

“After a couple of months of solitary study, I announced to the then chief executive that this thing could be done.”

He says 500 copies of the plans were sent out in 1985 to government representatives of every African country, as well as international financial agencies.

“The response was a deafening silence,” he adds.

But more than three decades later, minds are finally focusing on the lake’s shrinkage, prompted by its link to the deadly geopolitical crises of Islamist militancy and migration.

Freed schoolgirls in NigeriaImage copyrightEPA
Image captionBoko Haram recently seized more than 100 schoolgirls, before releasing most of them a month later

In 2014, I headed out of the north-east Nigerian city of Maiduguri towards Lake Chad in a new minibus. There were armoured vehicles in front as well as behind, and right next to me was a Nigerian soldier – fast asleep. Our destination was Kirenawa, the latest village that the marauding Boko Haram jihadists had terrorised.

As the road became steadily sandier, we entered a long-neglected area, passing the faded signs of abandoned government projects in ever hotter and sleepier villages.

Buildings had been torched and people had been left terrified, watching as others were killed in front of them.

In all the villages, people complained there was nothing for young people to do, nothing to dream of except getting out.

‘Ugly kinds of jobs’

It had become a perfect recruiting ground for the Islamist militants. The offer of a little cash and the promise of some training and a gun persuaded many to join.

Of course, Lake Chad’s decline is not the sole reason for the rise of violent extremism – a number of factors including poor governance have also played a role – but there is clearly a link.

“I know many young people from my own village who got into these ugly kinds of jobs,” Mr Bura says.

As if the delegates gathering in Abuja last month needed reminding of how dire the security situation had become, more than 100 schoolgirls had just been seized from Dapchi, Nigeria.

At the meeting, it was agreed that Bonifica and PowerChina, the company that helped build the Three Gorges dam spanning the Yangtze River, would complete a feasibility study. They announced that the effort to raise $50bn (£35bn) for the Lake Chad Fund should begin immediately.

Camels crossing Lake ChadImage copyrightGETTY IMAGES

Bonifica says its plan will use less than 8% of the water the Congo River discharges into the Atlantic and would not be a threat to the Democratic Republic of Congo’s continuing Grand Inga Dam project, which would create the world’s largest hydropower generator if it is completed.

Further engineering work would be needed to enable the Chari River to handle the increased flow of water. The project can be done in a staggered way, with each completed stage immediately adding to the flow of water into the Lake Chad basin.

Other options that have been considered include one which involves pumping the water uphill from Palambo, in the Central African Republic.

As well as the funding challenge for Transaqua, there will be resistance from environmental campaigners to overcome. And even carrying out the feasibility study properly requires peace.

Chinese media has reported the transfer canal would be 100m (328ft) wide and 10m (33ft) deep and would be flanked by a service road and eventually a rail line.

“It is a project which responds to the never-tackled infrastructural needs of the African continent, which maybe will give birth to a real African renaissance,” says Mr Vichi, who sees all along the route of the canal vast potential for agro-processing and transforming agricultural products for African and foreign markets.

Ministers know life is likely to get ever tougher for the people who live around Lake Chad. That’s why they are paying attention to the plans to bring it back to life.

What is Mercury in Retrograde, and Why Do We Blame Things On It?

NASA

NASA

Crashed computers, missed flights, tensions in your workplace—a person who subscribes to astrology would tell you to expect all this chaos and more when Mercury starts retrograding for the first time this year on Friday, March 23. But according to an astronomer, this common celestial phenomenon is no reason to stay cooped up at home for weeks at a time.

“We don’t know of any physical mechanism that would cause things like power outages or personality changes in people,” Dr. Mark Hammergren, an astronomer at Chicago’s Adler Planetarium, tells Mental Floss. So if Mercury doesn’t throw business dealings and relationships out of whack when it appears to change direction in the sky, why are so many people convinced that it does?

THE HISTORY

Mercury retrograde—as it’s technically called—was being written about in astrology circles as far back as the mid-18th century. The event was noted in British agricultural almanacs of the time, which farmers would read to sync their planting schedules to the patterns of the stars. During the spiritualism craze of the Victorian era, interest in astrology boomed, with many believing that the stars affected the Earth in a variety of (often inconvenient) ways. Late 19th-century publications like The Astrologer’s Magazine and The Science of the Stars connected Mercury retrograde with heavy rainfall. Characterizations of the happening as an “ill omen” also appeared in a handful of articles during that period, but its association with outright disaster wasn’t as prevalent then as it is today.

While other spiritualist hobbies like séances and crystal gazing gradually faded, astrology grew even more popular. By the 1970s, horoscopes were a newspaper mainstay and Mercury retrograde was a recurring player. Because the Roman god Mercury was said to govern travel, commerce, financial wealth, and communication, in astrological circles, Mercury the planet became linked to those matters as well.

“Don’t start anything when Mercury is retrograde,” an April 1979 issue of The Baltimore Sun instructed its readers. “A large communications organization notes that magnetic storms, disrupting messages, are prolonged when Mercury appears to be going backwards. Mercury, of course, is the planet associated with communication.” The power attributed to the event has become so overblown that today it’s blamed for everything from digestive problems to broken washing machines.

WHAT IS IT ACTUALLY?

Though hysteria around Mercury retrograde is stronger than ever, there’s still zero evidence that it’s something we should worry about. Even the flimsiest explanations, like the idea that the gravitational pull from Mercury influences the water in our bodies in the same way that the moon controls the tides, are easily deflated by science. “A car 20 feet away from you will exert a stronger pull of gravity than the planet Mercury does,” Dr. Hammergren says.

To understand how little Mercury retrograde impacts life on Earth, it helps to learn the physical process behind the phenomenon. When the planet nearest to the Sun is retrograde, it appears to move “backwards” (east to west rather than west to east) across the sky. This apparent reversal in Mercury’s orbit is actually just an illusion to the people viewing it from Earth. Picture Mercury and Earth circling the Sun like cars on a racetrack. A year on Mercury is shorter than a year on Earth (88 Earth days compared to 365), which means Mercury experiences four years in the time it takes us to finish one solar loop.

When the planets are next to one another on the same side of the Sun, Mercury looks like it’s moving east to those of us on Earth. But when Mercury overtakes Earth and continues its orbit, its straight trajectory seems to change course. According to Dr. Hammergren, it’s just a trick of perspective. “Same thing if you were passing a car on a highway, maybe going a little bit faster than they are,” he says. “They’re not really going backwards, they just appear to be going backwards relative to your motion.”

https://giphy.com/embed/gidFS64MBFZNC

Embedded from GIFY

Earth’s orbit isn’t identical to that of any other planet in the solar system, which means that all the planets appear to move backwards at varying points in time. Planets farther from the Sun than Earth have even more noticeable retrograde patterns because they’re visible at night. But thanks to astrology, it’s Mercury’s retrograde motion that incites dread every few months.

Dr. Hammergren blames the superstition attached to Mercury, and astrology as a whole, on confirmation bias: “[Believers] will say, ‘Aha! See, there’s a shake-up in my workplace because Mercury’s retrograde.'” He urges people to review the past year and see if the periods of their lives when Mercury was retrograde were especially catastrophic. They’ll likely find that misinterpreted messages and technical problems are fairly common throughout the year. But as Dr. Hammergren says, when things go wrong and Mercury isn’t retrograde, “we don’t get that hashtag. It’s called Monday.”

(This story originally ran in 2017)  BY MICHELE DEBCZAK  MARCH 21, 2018

Why Do Radio Stations Begin With ‘K’ or ‘W’?

Hulton Archive/Getty Images

HULTON ARCHIVE/GETTY IMAGES

Radio might not be quite the media force it once was, but there are still thousands of stations around the country, and the call letters for almost every one of them begin with either “K” or “W.”

Why? Because the government said so.

In the days of the telegraph, operators started the practice of using short letter sequences as identifiers, referring to them as call letters or call signs. Early radio operators continued the practice, but without a central authority assigning call letters, radio operators often chose letters already in use, leading to confusion.

To alleviate the problem, the Bureau of Navigation (part of the Department of Commerce) began assigning three-letter call signs to American ships in the early 1910s. Ships in the Atlantic and Gulf of Mexico got a K prefix; in the Pacific and the Great Lakes, a W. The precise reasons for choosing these two letters, if there were any, are unknown (bureaucracy works in mysterious ways). At the 1912 London International Radiotelegraphic Convention, ranges of letters were assigned to each of the participating nations and the U.S. was told to keep using the W and most of the K range. (Military stations used N.)

When the federal government began licensing commercial radio stations soon after, it had planned to assign call letters to the land-based stations in the same way. Somehow, things got flipped during implementation, though, and Eastern stations got W call signs and the Western ones got Ks. Where exactly does the Bureau of Navigation draw the line between East and West? For a while it ran north along state borders from the Texas-New Mexico border, but shifted in 1923 to follow the Mississippi River.

Some areas, however, might have both a K and W station in the same vicinity. Why? When the dividing line switched, some stations were made to change their call signs, while others weren’t. For about a year in the 1920s, the Bureau of Navigation decided that all new stations were going to get a K call sign no matter where they were located. Still other exceptions were made by special request, station relocations, ownership changes, and even human error.

As for the rest of the call sign: That sometimes includes the station (ABC, NBC), but can also be an acronym. WGN stands for “World’s Greatest Newspaper” (as it was considered the Chicago Tribune‘s radio station) while Chicago’s WTTW is “Window to the World.” But nothing beats St. Louis sports station KRAP, which gave itself the very self-aware label in 2014. “Our signal is KRAP,” reads their website. “Our studios are KRAP. Even our staff is KRAP.”

BY MATT SONIAK   MARCH 12, 2018
%d bloggers like this: