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Ozone layer collapse preceded mass extinction event 360 million years ago

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May 27 (UPI) — Until now, scientists weren’t sure caused the Late Devonian extinction, one of five major extinction events in Earth’s history.

But new research — published Wednesday in the journal Science Advances — suggests a combination of global warming and the collapse of the ozone layer preceded the mass terrestrial die-off that occurred 360 million years ago.

The extinction event that killed the dinosaurs is the only die-off caused by an asteroid. At least two were caused by some combination of volcanic activity and ozone destruction. But the cause of the Devonian-Carboniferous extinction remained a mystery.

“There has always been the view that continental scale volcanic eruptions at the End Permian Great Dying and the Triassic/Jurassic mass extinction caused ozone damage,” John Marshall, professor of earth sciences at the University of Southampton in Britain, told UPI in an email. “There are malformed pollen/spores through both these extinctions.”

“What is different here is that there is no vast eruption at the D-C boundary,” Marshall said. “We have shown this by the absence of mercury.”

When Marshall and his research partners conducted a survey of ancient plant spores trapped in the sediment layers of lakes in Greenland and Bolivia, they found evidence of genetic damage caused by ultraviolet radiation.

“In the rocks in Greenland nearly all of the spores with spines are malformed,” Marshall said. “The [percentage] of this malformation increases progressively into the center of the lake bed. As it gets warmer there is more malformation.”

“Experimental work has been done that shows modern pollen malform if you subject them to UV light,” Marshall said.

Researchers already knew that the Late Devonian extinction event was preceded by a period of warming, which followed a prolonged ice age. They were surprised to find that the global warming corresponded with a breakdown of the ozone layer and an increase in UV radiation.

The ozone layer exists in a constant state of flux. The latest findings confirm that large volcanic eruptions aren’t needed to trigger the momentary but compete depletion of the layer.

Scientists suspect the period of global warming at the end of the Devonian period pushed ozone-eating chemicals higher into the atmosphere, depleting the layer that normally protects Earth’s surface and its living residents from the sun’s most damaging rays.

The disruptive effects of global warming and ozone depletion created a negative feedback loop that spelled doom for many of the planet’s terrestrial species.

“Ozone eating chemicals are a metabolic byproduct of many living algae, fungi and land plants,” Marshall said. “Start the process, strip off the forests and the nutrients flush to the sea. This will produce more ozone eating chemicals. Positive feedback.”

Marshall and his colleagues suggest a similar breakdown could result from human-caused global warming. As the atmosphere gets warmer, ozone-eating chemicals could once again get pushed into the upper layers of the atmosphere.

“As our climate warms rapidly, the same process may happen,” Marshall said. “We are not in a Devonian world but the key is rapid warming. It’s a warning from Deep Time.”



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Citizen scientists help improve space weather forecasts

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Sept. 18 (UPI) — Data collected by citizen scientists have helped space weather forecasters more accurately predict when Earth will get hit by solar storms, according to a study published Friday in the journal AGU Advances.

When researchers supplement computer models with citizen scientist-collected data on the size and shape of coronal mass ejections, or CMEs, forecasts were 20 more accurate.

The supplemental data, collected by volunteers through the Solar Stormwatch citizen science project, also reduced forecasting uncertainty by 15 percent.

“CMEs are sausage-shaped blobs made up of billions of tonnes of magnetized plasma that erupt from the sun’s atmosphere at a million miles an hour,” lead researcher Luke Barnard said in a news release.

“They are capable of damaging satellites, overloading power grids and exposing astronauts to harmful radiation,” said Barnard, space weather scientist at the University of Reading in Britain. “Predicting when they are on a collision course with Earth is therefore extremely important.”

Because the speed and trajectory of coronal mass ejections vary dramatically, scientists have struggled to accurately predict when and where solar storms will hit Earth.

“Solar storm forecasts are currently based on observations of CMEs as soon as they leave the Sun’s surface, meaning they come with a large degree of uncertainty,” Barnard said. “The volunteer data offered a second stage of observations at a point when the CME was more established, which gave a better idea of its shape and trajectory.”

Researchers say the study supports the deployment of wide-field CME imaging cameras on space weather monitoring missions.

Real-time analysis of the images provided by the spacecraft cameras could help forecasters pinpoint solar storm threats days in advance, they said.



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Ancient footprints in Saudi Arabia help researchers track human migrations out of Africa

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Sept. 18 (UPI) — Paleontologists have discovered a diverse assemblage of 120,000-year-old human and animal footprints in an ancient lake deposit in Saudi Arabia’s Nefud Desert, offering new insights into the trajectories of human migrations out of Africa, according to a study published Friday in the journal Science Advances.

A mounting body of evidence, compiled and published over the last two decades, has upended early theories that humans migrated out of Africa in one or two giant waves.

“As more and more fossils are discovered, it seems that humans repeatedly dispersed out of Africa and did so much earlier than previously thought,” study co-author Mathew John Stewart told UPI in an email.

“Precisely when, how often and under what conditions remain open questions,” said Stewart, a researcher at the Max Planck Institute for Chemical Ecology in Germany.

For answers to these questions, researchers have mostly looked to Africa and Eurasia, ignoring the Arabian Peninsula. Though it neighbors both Africa and Asia, evidence of human occupation in the region is scant.

“The area today is a hyper-arid desert, characterized by very little rainfall and large, expansive sand dunes,” Stewart said. “The conditions are not very amenable to the preservation of material and sediments. Significant erosion of sediments and the subsequent destruction of material, such as fossil remains, is unfortunately common.”

Paleoclimate data suggests that Arabia wasn’t always as dry as it was today, and a scattering of fossil discoveries has confirmed that humans were able to make forays into the Arabian interior when shifts in climate turned the peninsula’s deserts into grassland.

The ancient footprints found in the Nefud Desert, fossilized in an ancient lake deposit known as ‘Alathar’ — Arabic for “the trace” — suggests humans made one of those forays roughly 120,000 years ago.

“The age of the footprints are consistent with Homo sapiens fossils in the Levant, and suggests that there were multiple routes that humans took upon expanding beyond Africa,” study co-author Richard Clark-Wilson told UPI in an email.

“There is earlier evidence for our species moving into the Mediterranean environment of the Levant and southern Greece, but this is the earliest evidence of our species moving into a semi-arid grassland as Arabia would have been,” said Clark-Wilson, a postgraduate research student at Royal Holloway in Britain.

In addition to human footprints, researchers uncovered footprints left by elephants, horses and hippos, suggesting Homo sapiens weren’t the only species drawn to the open grasslands and water resources of northern Arabia. Research suggests it’s possible humans were following animals when they first moved into the region.

“Whats exciting about the animal footprints is that it closely ties human and animal movements around lakes in northern Arabia,” Stewart said. “Unlike most other records, footprints provide very high-resolution information, on the order of hours or days. Also, the animal footprints provide information on what the environment and ecology was like when these people were moving through the landscape.”

While the discovery of ancient footprints in Arabia suggests human movements out of Africa extended eastward into northern Arabia, Stewart said plenty of questions remain unanswered.

“Precisely what happened to these people during the more arid periods? How long did they occupy the Arabian interior? Where did they go?”



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Study: Commercial fisheries regularly catch threatened, endangered fish species

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Sept. 21 (UPI) — Despite Australia’s international reputation for high quality marine conservation programming, new research out of the University of Queensland suggests Australia’s seafood eaters are regularly consuming engendered species.

The findings, published Monday in the journal Nature Communications, suggest the consumption of endangered fish species isn’t just a problem Down Under — it is a global crisis.

When researchers surveyed commercial catch and seafood import data, they found 92 endangered and 11 critically endangered species of seafood are being caught elsewhere before being imported and sold at grocery stores, fish markets and restaurants in Australia, Europe and elsewhere.

That’s because it’s perfectly legal for commercial fishers to catch species threatened with extinction. Additionally, seafood is not required to be labeled according to its species.

“This means that the ‘fish’, ‘flake’ or ‘cod’ that Australians typically order at the fish and chip shop could be critically endangered,” lead researcher Leslie Roberson said in a news release.

“Australian seafood is not as sustainable as consumers would like to think, and it’s definitely not in line with many of the large international conservation agreements that Australia has signed to protect threatened species and ecosystems,” said Roberson, a doctoral candidate at the University of Queensland.

Home to the Great Barrier Reef and tremendous marine biodiversity, Australia has earned a reputation for progressive marine conservation programming.

But according to the latest study, unsustainable seafood importation and consumption patterns can undermine conservation efforts at home.

“Australia imports around 75 per cent of the seafood we consume and is internationally regarded as having effective conservation and fisheries management policies,” said study co-author Carissa Klein.

“When importing seafood from other places, we are displacing any social or environmental problems associated with fishing to that place, which is likely to have less capacity to sustainably manage its ocean,” Klein, senior research fellow at the University of Queensland.

According to Roberson, Klein and their colleagues, the estimates for the number of threatened species currently being caught by commercial fisheries are quite conservative.

The study authors suggest that part of the problem is that the international seafood trade is highly complex, making it difficult to track and regulate. One part of a fish may be processed in China, but the rest may go to Europe, they said.

“A typical situation might look something like — a fishing boat operating in Australian waters, owned by a Chinese company, with a crew of fishermen from the Philippines,” Roberson said. “We don’t know what we’re eating — it’s really hard to trace seafood back to its origin and species because the industry is such a mess.”

Researchers suggest trade and importation rules can be put in place to encourage Australians to eat more local seafood, which can be more easily regulated for sustainability. Australian-farmed abalone and wild-caught sardines are two seafood sources that could ease pressures on threatened fish species.

“Improving the sustainability of Australia’s seafood trade policies could significantly benefit the ocean worldwide, as well as the billions of people that depend on a healthy ocean for their health and livelihoods,” Klein said.

“It should be illegal to eat something that is threatened by extinction, especially species that are critically endangered — if we can better coordinate fisheries and conservation policies, we can prevent it from happening,” she said.



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