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Antarctic ice sheets can retreat as fast 165 feet per day

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May 28 (UPI) — Antarctic ice sheets can retreat much faster than modern satellite measurements suggest, new research shows.

According to a survey of ridge patterns along the Antarctica seafloor — published Thursday in the journal Science — the continent’s ice sheets can retreat upwards of 165 feet per day.

“By examining the past footprint of the ice sheet and looking at sets of ridges on the seafloor, we were able to obtain new evidence on maximum past ice retreat rates, which are very much faster than those observed in even the most sensitive parts of Antarctica today,” Julian Dowdeswell, director of the Scott Polar Research Institute at the University of Cambridge, said in a news release.

In 2019, researchers on the Weddell Sea Expedition set out to find Sir Ernest Shackleton’s sunken ship Endurance. Sea ice conditions prevented the team from locating the shipwreck, but scientists successfully mapped the seafloor surrounding the Larsen Ice Shelf, which extends off the east coast of the Antarctic Peninsula.

Because ice shelves like Larsen C act like dams, slowing the flow of inland ice toward the coast, understanding their structural integrity is essential to forecasting the loss of Antarctic ice.

As previous studies have demonstrated, currents have pushed warm water beneath several of Antarctica’s ice sheets, accelerating melt rates and threatening their stability. At the same time, warmer air temperatures are accelerating melt rates from the top.

To better understand what glacial flow rates might look like should Antarctica’s dam-like ice sheets collapse, scientists turned the seafloor signatures left by retreating ice sheets 12,000 years ago.

“By examining landforms on the seafloor, we were able to make determinations about how the ice behaved in the past,” said Dowdeswell, who served as chief scientist on the Weddell Sea Expedition. “We knew these features were there, but we’ve never been able to examine them in such great detail before.”

Researchers detected delicate wave-like ridges on the seafloor, marks they determined were left by the influence of the tides on the grounding lines of ancient ice sheets — the area where the ice sheet begins to float.

By measuring the distance between ridges, formed over the course of a 12-hour tidal cycle, scientists were able to calculate the daily retreat of Antarctica’s ice sheets at the end of the Paleolithic ice age.

As Earth’s atmosphere rapidly warmed some 12,000 years ago, Antarctica’s ice sheet retreated between 40 and 50 meters, or as much as 165 feet, per day — more than six miles a year. Today, even Antarctica’s fastest glaciers, like those found on Pine Island, are retreating less than a mile per year.

“The deep marine environment is actually quite quiet offshore of Antarctica, allowing features such as these to be well-preserved through time on the seafloor,” said Dowdeswell. “We now know that the ice is capable of retreating at speeds far higher than what we see today. Should climate change continue to weaken the ice shelves in the coming decades, we could see similar rates of retreat, with profound implications for global sea level rise.”



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Scientists turn seawater into drinkable freshwater with metal compounds, sunlight

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Aug. 10 (UPI) — Researchers have successfully turned brackish water and seawater into clean, potable freshwater using metal-organic frameworks, MOFs, and sunlight.

The process, which takes just 30 minutes, was not only able to remove salt ions, but also filter out a range of contaminants.

The breakthrough technology, described Monday in the journal Nature Sustainability, could help millions gain access to clean drinking water.

Metal-organic frameworks are a class of compounds composed of intricate clusters of metal ions. MOFs boast the largest surface area of any known material.

To create a new water-cleaning compound, researchers introduced a metal compound called poly(spiropyran acrylate), or PSP, into the pores of MIL-53, a well-studied MOF, frequently utilized for its ability to efficiently absorb water and carbon dioxide.

In tests, the new MOF, called PSP-MIL-53, was able to produce 139.5 liters of clean freshwater per kilogram of MOF per day.

PSP-MIL-53 successfully filtered salt ions and other solids from brackish and saltwater sources. Sunlight helped the material periodically clean and regenerate its porous, crystalline structure.

“Desalination has been used to address escalating water shortages globally,” lead study author Huanting Wang said in a news release.

“Due to the availability of brackish water and seawater, and because desalination processes are reliable, treated water can be integrated within existing aquatic systems with minimal health risks,” said Wang, a professor of chemical engineering at Monash University in Australia.

The new technology is attractive, he said, because other desalination processes — such as thermal desalination and reverse osmosis — are energy intensive and potentially bad for the environment.

The World Health Organization recommends potable water feature fewer than 600 total dissolved solid parts per million. The new technology was able to produce freshwater with fewer than 500 TDS pars per million.

“This study has successfully demonstrated that the photoresponsive MOFs are a promising, energy-efficient, and sustainable adsorbent for desalination,” Wang said. “Our work provides an exciting new route for the design of functional materials for using solar energy to reduce the energy demand and improve the sustainability of water desalination.”

Researchers suggest the energy-efficient technology could be adapted for mineral extraction and other kinds of mining activities.



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World’s most pristine tropical forests remain vulnerable to deforestation

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Aug. 10 (UPI) — An analysis of the planet’s healthiest, most-intact tropical forests suggests an overwhelming majority remain vulnerable to deforestation.

According to the new study, published Monday in the journal Nature Ecology and Evolution, just 6.5 percent of the “best of the last” tropical forests enjoy formal protections.

For the study, an international team of researchers, including scientists with NASA and the United Nations, used high-resolution satellite images to map the presence of high-quality forests across the tropics. Researchers focused on finding the most intact forests, and those with the high ecological value, not necessarily the largest.

“Every year, research reveals new ways that old, structurally complex forests contribute to biodiversity, carbon storage, water resources, and many other ecosystem services,” study author Patrick Jantz said in a news release.

“That we can now map such forests in great detail is an important step forward in efforts to conserve them,” said Jantz, a research professor at Northern Arizona University.

When researchers compared maps of currently protected tropical forests with their maps of intact, high quality forests, they found very little overlap. Historically, protection efforts have favored quantity over quality, according to the authors of the new paper.

The study determined just half of the Earth’s humid tropical forests boast high ecological integrity, the majority of which are located within the the Amazon and Congo basins.

Researchers also looked at deforestation rates and the human pressures currently threatening the tropic’s healthiest forests. Their findings suggest the best of the last tropical forests are exceedingly vulnerable.

Scientists say they hope their findings will help policy makers and forest managers better prioritize forest protection and restoration efforts. Of the 4.6 million acres of the humid tropical forests found around the globe, the authors of the new study suggest 41 percent be granted new protections.

The researchers suggest forest managers work reduce human pressures across another 19 percent. The study calls also calls for active restoration efforts in 7 percent of tropical forests.



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Peak viewing Tuesday night for Perseid meteor shower

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The wait is over. For stargazers in North America, one of the most highly anticipated and reliable meteor showers will peak this week.

The Perseid meteor shower will peak on Tuesday night into early Wednesday morning, a reliable meteor shower that puts on a show year in and year out.

The Perseids are the most popular meteor shower as they peak on warm August nights as seen from the northern hemisphere,” the American Meteor Society said on its website.

This year, spectators across the Northern Hemisphere can expect to see between 50 and 75 meteors an hour under dark skies, which averages about one meteor every minute. Areas south of the equator will still be able to see some of the Perseids, but the hourly rates will be lower.

“The Geminid meteor shower in December produces about the same number of meteors. Both showers produce about four times more than any other shower during the year typically does,” AccuWeather astronomy blogger Dave Samuhel said.

One big difference between the Perseids and the Geminids is the weather.

August typically features more comfortable stargazing weather for the Perseids compared to December’s cold and often cloudy conditions around the peak of the Geminids.

As with every meteor shower, the best time to look is when the shower’s radiant point is highest in the sky. The number of meteors able to be seen will gradually increase as the radiant point moves higher in the sky.

“They are called Perseids since the radiant (the area of the sky where the meteors seem to originate) is located near the prominent constellation of Perseus,” the AMS explained.

Contrary to popular belief, sky watchers do not need to look at radiant point to see the meteor shower — shooting stars will be visible streaking across all areas of the sky.

The radiant point for the Perseids will rise above the horizon by around 11 p.m. local time and will continue to climb higher in the sky as the night progresses. However, the moon is set to rise by around 1 a.m. local time and will bring with it natural light pollution, making it more difficult to see some of the fainter meteors.

Because of this, the best window for viewing this year’s Perseid meteor shower will occur between 11 p.m. and 1 a.m. local time.

“Even though the Perseids will be most active after midnight, I encourage people to start looking once it gets dark in the evening,” Samuhel said.

“You will be more likely to see a long-lived, bright meteor fly across a large portion of the sky during the evening.”

Onlookers staying out after 1 a.m. to watch the celestial light show should look to the darkest part of the sky away from the moon.

This year, most of the western and central United States will have cloud-free conditions for the peak of the Perseids. Favorable weather is also in the forecast for much of western Canada and the Canadian Prairies.

Folks east of the Mississippi River may have some clouds to contend with, especially across the Ohio Valley to the coast of the mid-Atlantic.

Other areas, such as the Deep South, northern New England and into the St. Lawrence River Valley will have some breaks in the clouds, which could provide opportunities to spot a few shooting stars throughout the night.

Meteors will continue to be visible in the nights following the peak, so those that find themselves under clouds on Tuesday night should plan for a night under the stars later in the week when weather conditions improve. However, the number of meteors visible will gradually decrease each night.

In addition to needing clear weather, a little patience is also required for watching the Perseids.

Dedicate a solid hour to doing nothing but looking for meteors,” Samuhel said. “If you look for only a few minutes, you might not see any.”

It is important not to look at any source of light while out looking for shooting stars this includes cellphone screens.

“Make yourself comfortable. Lay back on a lounge chair or a blanket on the grass. Don’t sit in a normal chair and look up, your neck will quickly get tired,” Samuhel said.

After the Perseids pass, the next moderate meteor shower will not occur until mid-October with the peak of the Orionids.



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