Connect with us

affilate software business

Tech

How Life on Our Planet Made It Through Snowball Earth

Published

on


Today, the world is warming. But from about 720 to 635 million years ago, temperatures swerved the other way as the planet became encased in ice during the two ice ages known as Snowball Earth.

It happened fast, and within just a few thousand years or so, ice stretched over both land and sea, from the poles to the tropics. Life lived in the oceans at the time, and the encroaching ice entombed that life, cutting it off from both the sun and the atmosphere.

“This is the one time when Earth’s natural thermostat broke,” said Noah Planavsky, a biogeochemist at Yale University. “The question on everyone’s minds was: How did life actually make it through this?”

Glaciations can drive mass extinctions of life. Yet life, including perhaps our distant animal ancestors, somehow survived these deep freezes. In research published Monday in Proceedings of the National Academy of Sciences, Dr. Planavsky and his colleagues report the discovery of oases just beneath the ancient ice sheets that likely helped life persevere.

Snowball Earth came to an abrupt end over a half-billion years ago, but its marks still exist in remote corners of the planet. In 2015, to reach one of those corners, Max Lechte and his graduate adviser at the time, Malcolm Wallace, both sedimentologists at the University of Melbourne, drove 15 hours into the South Australian outback.

They trekked over hills made of red-colored rock, and it was so hot out — about 122 degrees Fahrenheit — that the soles of Dr. Wallace’s boots melted.

“A bit of duct tape fixed that up,” said Dr. Lechte, who led the new research.

These red-hot rocks formed in the oceans during the snowball glaciations, and their color caught Dr. Lechte’s eye, so he took a few samples. Then, in 2015 and 2016, he traveled to Namibia and Death Valley in California and found more rocks — also red — that formed at the same time.

The rocks’ color signaled to Dr. Lechte that they are rich in iron, which means they turned red for the same reason that old cars with iron exteriors turn red: They rusted.

Oxygen needs to be present for iron to rust. It also needs to be present for animals and many other organisms to survive. If the iron rocks below the ancient oceans rusted, then there was also oxygen in those oceans. And if there was oxygen, then oxygen-breathing life-forms had a lifeline they could cling to.

“This is the first direct evidence for oxygen-rich marine environments during Snowball Earth,” said Dr. Lechte, now a postdoctoral researcher at McGill University in Canada.

But how that oxygen got into the oceans in the first place was a mystery. The atmosphere is a major source of oxygen for the oceans, and with the ice sheets of Snowball Earth acting as giant air-blocking shields, oxygen in seawater should’ve been nonexistent.

“This could’ve led to anoxic oceans, which could’ve killed off life-forms that need oxygen to survive.” Dr. Lechte said. “It presents a bit of an unsolved problem.”

In labs at Yale as well as Nanjing University in China, Dr. Lechte and his team crushed the iron-rich rocks, dissolved them in acid and measured the abundances of different iron isotopes. They found that the iron in rocks that formed far out in the open oceans rusted much less than the iron in rocks that formed closer to land, right where ice sheets dove from continents and into the oceans.

Today, beneath ice sheets in Antarctica, glacial meltwater streams flow into the Southern Ocean. That water melts from ice that can have air bubbles trapped inside it, and those bubbles can seed the meltwater streams with oxygen. On Snowball Earth, Dr. Planavsky explained, such oxygen-laden streams flowed into the oceans around the edges of continents and sustained life.

Paul Hoffman, a geologist at Harvard University who pioneered the Snowball Earth hypothesis, thinks this idea for how oxygen made it into the oceans is solid. “I’m attracted to the idea, and I think it’s consistent with my own observations,” he said.

But, Dr. Hoffman added, whether or not this oxygen pump was the main thing that helped many living things survive those ice ages is still an open question.

“We just don’t know enough from a theoretical standpoint about how life would have responded to the challenge of a Snowball Earth,” he said.



Source

Continue Reading
Partners
Click to comment

Leave a Reply

Your email address will not be published. Required fields are marked *

Tech

HiTech Group Australia (ASX:HIT) Trading Up 0.8%

Published

on

By


HiTech Group Australia Limited (ASX:HIT)’s stock price traded up 0.8% during trading on Thursday . The stock traded as high as A$1.19 ($0.84) and last traded at A$1.19 ($0.84), 4,900 shares changed hands during mid-day trading. The stock had previously closed at A$1.18 ($0.84).

The stock has a market cap of $45.28 million and a price-to-earnings ratio of 15.66. The business’s 50 day moving average is A$1.12 and its 200 day moving average is A$1.07.

About HiTech Group Australia (ASX:HIT)

HiTech Group Australia Limited provides recruitment services for permanent and contract staff to the information and communications technology (ICT) industry in public and private sectors in Australia. Its permanent recruitment services comprise the search and selection of candidates for full time employment; and ICT contracting services include the provision of ICT professionals for temporary and other non-permanent staffing needs of clients for specific projects in system development, infrastructure support and cloud integration, operation, and other skill sets.

Featured Story: Are sell-side analysts objective?

Receive News & Ratings for HiTech Group Australia Daily – Enter your email address below to receive a concise daily summary of the latest news and analysts’ ratings for HiTech Group Australia and related companies with MarketBeat.com’s FREE daily email newsletter.



Source

Continue Reading

Tech

New NASA mission will allow scientists to track rising seas from space

Published

on

By


Scientists at NASA’s Jet Propulsion Laboratory are teaming up with European researchers to launch a mission that will probe the oceans’ depths over the next decade — and chart their inexorable rise.

The Sentinel-6/Jason-CS mission builds on four previous satellites that have circled the globe along the same path since 1992, carefully documenting the millimeter-by-millimeter changes in sea level fueled by greenhouse gas emissions. Over that time, they have found that the world’s oceans are rising at an increasingly rapid rate.

The rising waters have had some disastrous consequences, including the erosion of precious coastlines, contamination of agricultural land, more frequent and destructive high tides, and lost habitat for both humans and wildlife.

The Jason satellites, coupled with complementary readings from other NASA Earth-facing missions, have been essential to tracking these changes and dealing with their consequences, said R. Steven Nerem, a professor of aerospace engineering sciences at the University of Colorado Boulder and member of NASA’s Ocean Surface Topography Science Team.

“Without the satellites we’d be blind,” said Nerem, who has tracked sea level rise and its causes for decades. “It’s just very critical that we continue these missions because it’s the way we understand what’s going on.”

Earth’s oceans have swelled and shrunk for eons, but they’ve typically done so very gradually, rather than at the breakneck pace being recorded today.

Recent readings put the rate at roughly 4.5 millimeters per year, up from about 3 millimeters per year in 2005 and around 2 millimeters per year in 1993. Add it all up and the seas are now about 3 inches higher, on average, than they were a quarter-century ago.

The question the new Sentinel-6/Jason-CS mission will seek to answer is this: How much faster will the seas rise in the coming decade? And what will happen to Earth beyond then?

“Hundreds of millions of people around the Earth will be affected by sea level rise in the next 50 to 100 years, and our ability to measure how much of that is human-caused is really rooted in these satellites,” said JPL climate scientist Josh Willis, NASA’s project scientist for Jason-CS.

Since the dawn of the industrial age, humans have been emitting excess amounts of carbon dioxide and other heat-trapping gases, causing Earth’s temperature to rise. Melting glaciers have added water to the oceans. The additional heat also causes water to expand, pushing sea levels up even higher.

Altogether, the oceans have absorbed more than 90% of the extra heat trapped by greenhouse gases, Willis said.

And since they cover more than two-thirds of Earth’s surface, the oceans are reshaping the planet.

“The oceans, in a really big way, are kind of our most important indicator of just how much humans have changed the climate since the start of the industrial revolution,” Willis said.

From an orbit 830 miles above Earth, Sentinel-6/Jason-CS will scan 95% of the planet’s ice-free oceans, gathering a new set of global data every 10 days. Its altimeter will bounce a radar signal off the water’s surface, measuring the time it takes for the signal to return and using that information to calculate the ocean’s height.

Other instruments will hone those readings by compensating for the atmosphere’s effect on the timing of these radar signals, and by helping keep track of the spacecraft’s precise position.

The first Sentinel spacecraft in a clean room in Germany. The satellite is scheduled to launch in November.

(IABG)

Beyond average sea level, the radar readings will provide a wealth of additional information for researchers, who can use them to determine heat changes in the upper ocean, the flow of ocean currents, wave heights and the speed of wind over the water.

The data may even shed light on much of the still-mysterious topography of the sea floor, said Eric Leuliette, the Jason program and project scientist for the National Oceanic and Atmospheric Administration.

“As my colleagues here often point out, we’ve mapped Venus, the moon and Mars better than we’ve mapped the bottom of the ocean,” he said.

Jason data hits the ground running, Leuliette said. Within hours, it’s sent out to National Weather Service forecasters, whose predictions are used by ships for navigation and other maritime purposes. Within a day, it goes into models that help meteorologists make better predictions about large weather events. For example, the information Jason gathers on how much heat is stored beneath the ocean surface can help in forecasting the intensity of a hurricane, or the strength of an El Niño event.

Sentinel-6/Jason-CS is part of an international collaboration involving NASA, NOAA, the European Space Agency, the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) and France’s National Center for Space Studies (CNES).

The spacecraft will fly in the same orbit as its predecessors, to ensure an unbroken line of sea level readings. That consistency is key for predicting future sea level rise — and preparing for its consequences, Willis said.

Unlike prior missions, which involved only a single spacecraft, this one will employ two satellites, each with a primary mission of five years, said Parag Vaze, Jason’s project manager at JPL. The first is scheduled to launch from Vandenberg Air Force Base in California in November, and the second will follow in 2025, making it the most long-lived of the Jason missions to date.

Sentinel-6/Jason-CS will also meet a different end than its forebears, Vaze said.

In an effort to reduce the accumulation of space junk, the two satellites will be the first in the Jason line to execute a planned de-orbit once they complete their final tasks. Even as the older satellites continue to circle the globe, their younger brethren will burn up in the atmosphere as they plunge back toward Earth.





Source

Continue Reading

Tech

Students should use technology constructively: Seer

Published

on

By


At a time when technology has become an integral part of human life, students should make conscious efforts to make use of it for postive and constructive works, Shivamurthy Murugha Sharanaru of Brihan Mutt, Chitradurga, has said.

He was interacting with students of G.H. College at Hosa Mutt in Haveri on Saturday, in a personality development programme, organised as part of the ‘Sharana Samskruti Utsava’, to commemorate Nighantina Siddhabasava Murugharajendra Swami, and Murughendra Mahashivayogi.

The seer said that it was natural that young minds get easily attracted towards technology. “However what is important is how one uses it. You should make use of technology for constructive works, for developing your personality, rather than for negative works. Constructive use will always lead to a better life,” he told the students.

Emphasising on the need for imbibing values in one’s life, the seer said that good thoughts will help in building one’s life, while bad thoughts would destroy it.

Pointing out that several students suffered from a lack of concentration, the seer said that educational institutions should help such students through confidence-building measures, and encouragement.

Several students sought to know the methods to avoid the fear of examinations.

They also sought to know ways to develop concerntration and raised queries about their dilemma and how to build their lives.

The seer answered their queries and gave them tips on building a better life.

Basava Shanthalinga Swami of Hosa Mutt said that the utsav was not just limited to religious activities and fairs but also focussed on efforts towards dissemination of knowledge and making people think.

Principal of the College M.S. Yaragoppa, president of the utsav samiti Basavaraj Veerapur, vice-president Shridhar Doddamani, and others were present.

You have reached your limit for free articles this month.

Register to The Hindu for free and get unlimited access for 30 days.

Subscription Benefits Include

Today’s Paper

Find mobile-friendly version of articles from the day’s newspaper in one easy-to-read list.

Unlimited Access

Enjoy reading as many articles as you wish without any limitations.

Personalised recommendations

A select list of articles that match your interests and tastes.

Faster pages

Move smoothly between articles as our pages load instantly.

Dashboard

A one-stop-shop for seeing the latest updates, and managing your preferences.

Briefing

We brief you on the latest and most important developments, three times a day.

Not convinced? Know why you should pay for news.

*Our Digital Subscription plans do not currently include the e-paper ,crossword, iPhone, iPad mobile applications and print. Our plans enhance your reading experience.



Source

Continue Reading

Trending

//onvictinitor.com/afu.php?zoneid=2954224
We use cookies to best represent our site. By continuing to use this site, you agree to the use of cookies.
Yes