Older Neanderthal survived with a little help from his friends

The skull of a Neanderthal known as Shanidar 1 shows signs of a blow to the head received at an early age.

An older Neanderthal from about 50,000 years ago, who had suffered multiple injuries and other degenerations, became deaf and must have relied on the help of others to avoid prey and survive well into his 40s, indicates a new analysis published Oct. 20 in the online journal PLoS ONE.

"More than his loss of a forearm, bad limp and other injuries, his deafness would have made him easy prey for the ubiquitous carnivores in his environment and dependent on other members of his social group for survival," said Erik Trinkaus, study co-author and professor of anthropology in Arts & Sciences at Washington University in St. Louis.

Known as Shanidar 1, the Neanderthal remains were discovered in 1957 during excavations at Shanidar Cave in Iraqi Kurdistan by Ralph Solecki, an American archeologist and professor emeritus at Columbia University.

Previous studies of the Shanidar 1 skull and other skeletal remains had noted his multiple injuries. He sustained a serious blow to the side of the face, fractures and the eventual amputation of the right arm at the elbow, and injuries to the right leg, as well as a systematic degenerative condition.

In a new analysis of the remains, Trinkaus and Sébastien Villotte of the French National Centre for Scientific Research confirm that bony growths in Shanidar 1's ear canals would have produced profound hearing loss. In addition to his other debilitations, this sensory deprivation would have made him highly vulnerable in his Pleistocene context.

As the co-authors note, survival as a hunter-gatherer in the Pleistocene presented numerous challenges, and all of those difficulties would have been markedly pronounced with sensory impairment. Like other Neanderthals who have been noted for surviving with various injuries and limited arm use, Shanidar 1 most likely required significant social support to reach old age.

"The debilities of Shanidar 1, and especially his hearing loss, thereby reinforce the basic humanity of these much maligned archaic humans, the Neanderthals," said Trinkaus, the Mary Tileston Hemenway Professor.

From Science Daily

Ancient Icelandic Volcanoes May Have Hastened Ice Age Melting

View of the Svinafell glacier with a glacial lagoon, part of Vatnajökull National Park, in eastern Iceland

A surge of volcanic eruptions from Iceland may have sped up the melting of the ice sheets that covered Scandinavia thousands of years ago as tons of soot fell from the sky.

That thaw would have taken place even as the cloud of ash released from the volcanoes was cooling northern Europe, paleoclimatologist Francesco Muschitiello told Seeker. And it’s a story that has some relevance to current climate concerns.

“You have his cooling effect of volcanic eruptions,” said Muschitiello of Columbia University’s Lamont-Doherty Earth Institute in New York and the Uni Research Climate center at Norway’s University of Bergen. “But at the same time, as you increase the deposition of dust and ash on the ice sheets, you increase the runoff. You increase the melting of the ice. You have these two counteracting effects.”

The story Muschitiello and his colleagues tell in the Oct. 24 issue of Nature Communications unfolded in the waning days of the last ice age, about 13,000 years ago. It’s a tale teased out of layers of sulfur compounds in the clay of what’s now southeastern Sweden.

James Lea (left) and Francesco Muschitiello drill into the ground to sample the sedimentary deposits of an ancient glacial lake in Sweden.

At that time, Scandinavia was buried under an ice sheet that stretched from the British Isles to the Ural Mountains of present-day Russia. But as the glaciers began to recede, the volcanoes beneath them began to stir.

“The ice sheets are getting lighter and lighter, they relieve pressure on top of the Earth’s crust,” Muschitiello said. “And this lightening basically in turn triggers volcanic eruptions, especially in Iceland and North America, in Alaska and Kamchatka.”

Iceland is a volcanic hot spot even today. And at that time, its volcanoes belched sulfuric smoke, soot and ash across the Northern Hemisphere. The sulfur compounds Muschitiello recorded in core samples of Swedish clay match those found in ice cylinders extracted from Greenland’s ice sheets from the same era.

That cloud gradually would have driven temperatures down as they hung in the atmosphere, blocking more sunlight. But the portion that fell onto the ice sheets would have led to a faster melt, as the spots of dark carbon meant the ice absorbed solar radiation it otherwise would have reflected back into space.

Sediments deposited by ice sheet meltwater provide clues about ancient climates, as well as the future effects of global warming.

Using computer models of the climate, Muschitiello’s team tried to reproduce the effects of those eruptions. They found an eruption in the summer would have cooled northern Europe by as much as 3.5 degrees Celsius (6.3 degrees Fahrenheit). Meanwhile, even small changes in the amount of sunlight could have sped up dramatically the amount of water they shed.

“Even though you have sort of a long-term cooling, you have an immediate response of the ice sheet, which increases melting,” he said.

That process may be relevant today, as researchers attempt to project the effects of climate change and its impact on future sea levels.

Read more at Seeker

The World’s First Trees Were More Structurally Complex Than Trees Today

An illustrative transverse plane through a small cladoxylopsid trunk, showing the three naturally-fractured parts.

Life that arose from Earth’s primordial soup hundreds of millions of years ago was usually simple compared to the highly evolved creatures that exist today.

But new research has found that the world’s first trees – the cladoxylopsids – were more complex than their successors, creating a new mystery about the origins of plants that once dominated the globe.

Writing in the journal Proceedings of the National Academy of Sciences, a team of researchers identified never-before-seen growth patterns in a 374 million-year-old cladoxylopsid trunk discovered in China.

“It’s a new way of being a plant and particularly a new way of being a tree,” Cardiff University paleobotanist and study co-author Chris Berry told Seeker. “That just in and of itself is extremely interesting.”

Rather than growing in the familiar ring pattern that lets schoolchildren determine the age of most felled trees today, cladoxylopsid trunks were hollow. Around the empty core of the trees were 2-inch-thick strands of xylem, or the material that carries water from tree roots to their branches and leaves.

The strands didn’t behave like ordinary xylem, however. Instead, they bore rings like the cores of modern-day trees, as if the cladoxylopsid was a collection of saplings. What’s more, the tree-like strands connected to each other in an extremely sturdy manner that resembled a network of interconnected water pipes, the researchers wrote. While palm trees and other plants also don’t grow rings, their xylem don’t interconnect, Berry said.

Cladoxylopsids grew weirdly, too. The strands developed vertically and thickened. But more didn’t appear once the tree was growing. Instead, the soft wooden tissues between the strands would split apart and heal as the tree’s diameter expanded.

“It builds a skeleton at that point, and it’s sort of fixed,” said Berry. “This skeleton is gradually ripping itself apart to accommodate the expansion. As it does, it repairs itself.”

Capable of growing more than 30 feet tall with diameters of more than a foot, their appearance reflected their primordial environment. “These trees didn’t have leaves in a big, green flat sort of sense,” he said. “They were just twigs, little appendages, sticky things.”

Berry didn’t understand why or how cladoxylopsids grew in their unique way. But they were a monoculture, which could hold clues to their evolution.

“You’d think the oldest tree would be the most primitive and simple,” he said. “I have no explanation for that. The only thing you could argue is that there was no competition. There were no other trees around to complete with.”

Read more at Seeker

Drug can dramatically reduce weight of people with obesity

A new developed drug is highly promising for weight loss.

A drug that targets the appetite control system in the brain could bring about significant weight loss in people with clinical obesity, according to new research.

On average, people lost 5kg (11lbs) over a 12 week period after receiving weekly doses of semaglutide, a compound currently being developed as a treatment for Diabetes.

Most of the weight loss came from a reduction in body fat, researchers at the University of Leeds found after reviewing its effectiveness. The drug reduced food cravings, with people choosing to eat smaller meals and decreasing their preferences for foods with a higher fat content. The study also added to the scientific understanding of how drug therapy can be used to tackle obesity. For the first time, scientists saw the benefit of very specific targeting of receptors or sensors that could affect multiple components of the brain's appetite control system.

John Blundell, Professor of Psycho-Biology at the University of Leeds and lead researcher, said: "What was striking was the potency of the drug's action. We saw results in 12 weeks which may take as long as six months with other anti-obesity medication.

"The drug reduced hunger but also cravings for food and the sensation of wanting to eat -- and these had previously been thought to stem from different parts of the brain."

The research has been published in the journal Diabetes, Obesity and Metabolism.

Semaglutide is a new drug being developed by the Danish pharmaceutical company Novo Nordisk as a treatment for diabetes.

Its chemical structure is very similar to the naturally-occurring hormone GLP-1 which is believed to act on the appetite control centre in the hypothalamus in the brain to reduce feelings of hunger.

Given the close similarity between semaglutide and the body's own appetite-control chemical, the study set out to examine whether the drug could also be used to tackle obesity by acting on the brain's appetite control receptors.

Professor Blundell said: "The potency of the drug is probably due to the action of the GLP-1 protein receptors on broad aspects of the appetite control system including hunger, craving and rewarding aspects of food."

In the study, the drug was given to 28 people with a body mass index (BMI) range of 30 to 45 kg/m2 -- meaning they were very overweight with a lot of body fat.

The participants were split in two groups -- half got semaglutide and the other half a placebo (dummy) substance for 12 weeks. They did not know what they were getting.

At the end of the 12 weeks, they were invited into a testing centre and offered a lunch and evening meal and told to consume as much as they needed to feel 'pleasantly full'. What they were eating was recorded, along with food preferences and their sensations of liking and wanting food. Body weight and body composition -- the percentage of body fat -- were also recorded.

They then repeated the process, with participants who got semaglutide this time getting the placebo and vice versa.

The results were then compared. The research team found that on average the daily energy intake, a measure of the amount of food consumed, was 24 per cent lower with semaglutide.

A further feature of the study was that measured energy expenditure from metabolic processes (the Resting Metabolic Rate) remained roughly the same throughout the experiment suggesting the weight loss could not be due to metabolism becoming more active. Consequently the fat loss produced by the drug could be attributed to better control over appetite.

Professor Blundell added: "A drug that reduces daily food intake by about a quarter with a substantial reduction in body fat will help some people to feel more in control of their lives and will help to prevent the onset of poor health that often arises from obesity" Semaglutide is in the advanced stages of development but is not yet on the market.

Read more at Science Daily

Mongolian microfossils point to the rise of animals on Earth

This is an image of assorted microfossils from the Ediacaran Khesen Formation, Mongolia. Each fossil is on the order of 200 microns maximum dimension.

A Yale-led research team has discovered a cache of embryo-like microfossils in northern Mongolia that may shed light on questions about the long-ago shift from microbes to animals on Earth.

Called the Khesen Formation, the site is one of the most significant for early Earth fossils since the discovery of the Doushantuo Formation in southern China nearly 20 years ago. The Dousantuo Formation is 600 million years old; the Khesen Formation is younger, at about 540 million years old.

"Understanding how and when animals evolved has proved very difficult for paleontologists. The discovery of an exceptionally well-preserved fossil assemblage with animal embryo-like fossils gives us a new window onto a critical transition in life's history," said Yale graduate student Ross Anderson, first author of a study in the journal Geology.

The new cache of fossils represents eight genera and about 17 species, comprising tens to hundreds of individuals. Many of them are spiny microfossils called acritarchs, which are roughly 100 microns in size -- about one-third the thickness of a fingernail.

The Khesen Formation is located to the west of Lake Khuvsgul in northern Mongolia. "This site was of particular interest to us because it had the right type of rocks -- phosphorites -- that had preserved similar organisms in China," Anderson said.

The discovery may help scientists confirm a much earlier date for the existence of Earth ecosystems with animals, rather than just microbes. For two decades, researchers have debated the findings at the Doushantuo Formation, with no resolution. If confirmed as animals, these microfossils would represent the oldest animals to be preserved in the geological record.

The other authors of the study are Derek Briggs, Yale's G. Evelyn Hutchinson Professor of Geology and Geophysics and curator at the Yale Peabody Museum of Natural History; Sean McMahon, a postdoctoral fellow in the Briggs lab; Francis Macdonald of Harvard; and David Jones of Amherst College.

The researchers said the Khesen Formation should provide scientists with additional information for years to come.

"This study is only the tip of the iceberg, as most of the fossils derive from only two samples," Anderson said. Since the original discovery, the Yale team has worked with Harvard and the Mongolian University of Science and Technology to sample several additional sites within the formation.

From Science Daily

9 Million People Die Prematurely Each Year From Pollution

A tourist wearing a mask visits the Tiananmen Square amid dangerous levels of air pollution on January 23, 2013 in Beijing, China.

Pollution is responsible for more than nine million premature deaths worldwide each year, killing 15 times more people than war and violence, according to a new study published in The Lancet.

Researchers, using World Health Organization (WHO) data from 130 countries, examined ambient air pollution, household air pollution from solid fuels, unsafe drinking water, unsafe sanitation, and lead exposure. Their results show that pollution is responsible for three times more deaths each year than tuberculosis, malaria, and AIDS combined.

“My colleagues and I were stunned by the sheer magnitude of the total numbers of death caused by pollution and by the massive economic costs associated with pollution-related disease,” Philip Landrigan, dean of global health at the Mount Sinai School of Medicine and co-chair of the commission that authored the report, told Seeker. “We knew going in that these numbers would be large, but we had no idea how large they would turn out to be.”

Most of the nine million deaths each year occur in developing nations where there are fewer regulations for industries that pollute the environment. Pollution also kills people in developed countries like the US and Japan, however these deaths tend to be concentrated in poor areas.

“Pollution is highly unjust,” Landrigan said. “Ninety-two percent of all pollution-related deaths occur in low and middle-income countries. And in the United States and other high-income countries, pollution-related disease and death are concentrated among minorities and the poor. Think Flint, [Michigan].”

The data shows that air-pollution is the biggest culprit in pollution-related deaths. In 2015, 6.5 million people died from illnesses related to breathing in harmful chemicals like mercury and arsenic, as well as smoke from wood-burning stoves.

Some of the world’s poorest laborers suffer from workplace exposure to carcinogens, like dye factory workers who develop bladder cancer or coal miners who contract lung disease, which account for 800,000 deaths each year. Nearly two million people die annually from contaminated drinking water and unsafe sanitation, which can cause parasitic infections and cholera.

India had the highest umber of deaths from pollution each year at 2.5 million, followed by China with 1.8 million.

“High-income countries need to share the lessons we have learned in pollution control with low-and middle-income countries to help them avoid the mistakes of the past,” Landrigan said.

The report also zeroed in on the monetary consequences of pollution, which is responsible for 1.7 percent of annual health spending in high-income countries like the US and up to 7 percent of health spending in heavily polluted and rapidly developing low-and middle-income countries. The authors estimate that the cost globally of pollutants adds up to approximately $4.6 trillion per year, which is about 6 percent of the global gross domestic product.

While certain types of pollution like contaminated water have decreased in recent years, pollution from some sources, like industry, has increased. This data comes at a time when the Trump administration considers rolling back regulations on industry, vehicles, and power plants.

American views on environmental regulation are deeply partisan, according to a 2017 Pew survey, which found 58 percent of Republicans though they cost too many jobs and hurt the economy. But Landrigan said it’s simply not the case. “The claim that pollution control stifles economic growth, kills jobs, and drags down the economy is false and has repeatedly been proven to be untrue,” he said.

Read more at Seeker

London Pollution Tax Aims to Improve the Air in One of Europe’s Dirtiest Cities

The capital's poor air quality, caused largely by traffic, has seen the UK facing 300m euros in fines for breaching EU targets.

Drivers of the most polluting vehicles face an extra daily charge for driving into central London under a scheme introduced Monday that aims to improve air quality in one of Europe's most polluted cities.

London Mayor Sadiq Khan claimed that with the rollout of the new weekday "toxicity charge" — dubbed the "T-charge" — London had "the world's toughest emission standard."

The £10 (11.20 euro, $13.20) levy is in addition to a daily £11.50 congestion fee and follows an order by the European Union for Britain to cut air pollution.

Khan, who announced the charge in February, said he was "determined to take urgent action to help clean up London's lethal air."

"The shameful scale of the public health crisis London faces, with thousands of premature deaths caused by air pollution, must be addressed," he said.

The levy applies to all petrol and diesel cars registered before the introduction of environmentally friendly Euro 4 emissions standards in 2005.

But Transport for London, which runs the scheme, has said any vehicle registered before 2008 may be liable.

It estimates 6,500 vehicles per day will be covered, about 6.3 percent of around 103,000 that enter the congestion zone.

Even before it came into force, the charge has had a deterrent effect — Khan said there has been a 15 percent reduction in eligible vehicles entering the area since the scheme was announced.

The European Commission in February issued a warning to five member states including Britain, urging them to take action on car pollution or risk being sent to the European Court of Justice.

It said that "persistently high" levels of nitrogen dioxide caused 70,000 premature deaths in Europe in 2013.

The mayor's office said 7.9 million Londoners lived in areas that exceeded World Health Organization guidelines on toxic air quality.

'Easy targets'

The RAC, a British motoring group, said the mayor was right to take action over the oldest vehicles, "because these are more likely to be the most polluting."

But roads policy spokesman Nick Lyes warned that "drivers may also see themselves as an easy target."

London drivers appeared divided by the plans.

"I think it's a good thing (to) keep the air pollution down," said Tony Smith, 53, a waste removal driver whose modern vehicle is unaffected by the new charge.

But George Tamale, 36, a parcel delivery driver also not impacted by the T-charge, said he questioned the motives behind it.

"They just want people to buy new cars. It's not about the environment, it's about economics," he said.

London is the largest city around the world to use congestion charging, alongside Stockholm, Milan, and Gothenburg.

Singapore was the first and now has the most comprehensive road-pricing system, which it plans to upgrade in 2020 by incorporating GPS technology.

Long-stymied plans for congestion charging in New York saw fresh impetus in August after state governor Andrew Cuomo came out in support of the idea for parts of Manhattan.

Studies of the London scheme indicate the number of cars entering the city center has fallen by nearly a quarter since 2000.

Read more at Seeker

Ominous Climate Change Warning Seen in Caribbean Storms 100K Years Ago

In this NOAA handout image, taken by the GOES satellite at 1620 UTC, Hurricane Matthew is seen in the Caribbean Sea heading towards Jamaica, Haiti, and Cuba on October 3, 2016.

Scientists from North Carolina are bearing a probably unwelcome but unquestionably vital message for those rebuilding after the recent deadly hurricanes in the Caribbean: You ain’t seen nothing yet.

According to study of rock strata on the Bahamas and Bermuda, as well as a review of other studies on the topic, the Caribbean Islands endured far worse storms when the planet’s climate more closely resembled the conditions that scientists foresee if global warming continues, according to a paper published recently in the journal Marine Geology.

“In the interest of our future world, we must seek to understand the complex set of linked natural events and field observations that are revealed in the geology of past warmer climates,” wrote Retired University of North Carolina at Wilmington environmental scientist Paul Hearty and Coastal Research Scientist Blair Tormey of Western Carolina University in the study.

In other words, if humankind continues to dumping carbon into the atmosphere, Hurricanes Harvey, Irma, and Maria might become not only commonplace but might someday be fondly remembered as mild disasters compared to things to come, the researchers concludes.

“Our global society is producing a climate system that is racing forward out of humanity's control into an uncertain future,” they wrote.

The image on the left shows eolian (lower) and runup bedding (upper) exposed in a roadcut on Old Land Road on Great Exuma Island (road elevation +23 meters). On the right are thick beds with fenestral porosity, or "beach bubbles," showing that massive waves ran up over older dunes exposed in a roadcut on Suzy Turn Road along the Atlantic Ocean east side of Providenciales, Turks and Caicos Islands, BWI.

With the help from the National Science Foundation, the University of North Carolina at Wilmington, and others, the researchers reviewed a millennium approximately 120,000 years ago when temperatures were slightly warmer than today, Earth’s glaciers had melted, and the world’s sea levels were almost 30 feet higher. The scope of the period of the study ruled out tsunamis, said Hearty.

The researchers concluded big waves and wind pushed boulders, rocks, sediment, and other materials from the ocean almost six miles inland on the islands in what were probably epically violent storms.

They looked at boulders as heavy as 1,000 tons that were once underwater but now sit on land that was dry before they arrived, so-called “chevron storm ridges,” or V-spaced lines of sediment pushed inland by rushing water and deposits of beach sedimentation almost 100 feet above sea level.

“Super perfect storms,” said Hearty.

Especially helpful for the research were ooids – or tiny grains of calcium carbonate and other materials plentiful off the islands that quickly harden like cement when out of the water. Layers of cemented ooids are called oolite. One can see oolite layers at many road cuts in the Bahamas and Bermuda, with each one providing a perfectly preserved record of the conditions that created it.

“Every steep road cut that would go over the top of the island, we would look closely and essentially see beach bedding,” said Hearty.

Read more at Seeker

More teens than ever aren't getting enough sleep

The more time young people reported spending online, the less sleep they got, according to researchers.

If you're a young person who can't seem to get enough sleep, you're not alone: A new study led by San Diego State University Professor of Psychology Jean Twenge finds that adolescents today are sleeping fewer hours per night than older generations. One possible reason? Young people are trading their sleep for smartphone time.

Most sleep experts agree that adolescents need 9 hours of sleep each night to be engaged and productive students; less than 7 hours is considered to be insufficient sleep. A peek into any bleary-eyed classroom in the country will tell you that many youths are sleep-deprived, but it's unclear whether young people today are in fact sleeping less.

To find out, Twenge, along with psychologist Zlatan Krizan and graduate student Garrett Hisler -- both at Iowa State University in Ames -- examined data from two long-running, nationally representative, government-funded surveys of more than 360,000 teenagers. The Monitoring the Future survey asked U.S. students in the 8th, 10th and 12th grades how frequently they got at least 7 hours of sleep, while the Youth Risk Behavior Surveillance System survey asked 9th-12th-grade students how many hours of sleep they got on an average school night.

Combining and analyzing data from both surveys, the researchers found that about 40% of adolescents in 2015 slept less than 7 hours a night, which is 58% more than in 1991 and 17% more than in 2009.

Delving further into the data, the researchers learned that the more time young people reported spending online, the less sleep they got. Teens who spent 5 hours a day online were 50% more likely to not sleep enough than their peers who only spent an hour online each day.

Beginning around 2009, smartphone use skyrocketed, which Twenge believes might be responsible for the 17% bump between 2009 and 2015 in the number of students sleeping 7 hours or less. Not only might teens be using their phones when they would otherwise be sleeping, the authors note, but previous research suggests the light wavelengths emitted by smartphones and tablets can interfere with the body's natural sleep-wake rhythm. The researchers reported their findings in the journal Sleep Medicine.

"Teens' sleep began to shorten just as the majority started using smartphones," said Twenge, author of iGen: Why Today's Super-Connected Kids Are Growing Up Less Rebellious, More Tolerant, Less Happy -- And Completely Unprepared for Adulthood. "It's a very suspicious pattern."

Students might compensate for that lack of sleep by dozing off during daytime hours, adds Krizan.

"Our body is going to try to meet its sleep needs, which means sleep is going to interfere or shove its nose in other spheres of our lives," he said. "Teens may catch up with naps on the weekend or they may start falling asleep at school."

For many, smartphones and tablets are an indispensable part of everyday life, so they key is moderation, Twenge stresses. Limiting usage to 2 hours a day should leave enough time for proper sleep, she says. And that's valuable advice for young and old alike.

Read more at Science Daily

Mountain glaciers shrinking across Western U.S.

This map shows the elevation change of Mount Rainier glaciers between 1970 and 2016. The earlier observations are from USGS maps, while the recent data use the satellite stereo imaging technique. Glacier surface elevations have dropped more than 40 meters (130 feet) in some places.

Until recently, glaciers in the United States have been measured in two ways: placing stakes in the snow, as federal scientists have done each year since 1957 at South Cascade Glacier in Washington state; or tracking glacier area using photographs from airplanes and satellites.

We now have a third, much more powerful tool. While he was a doctoral student in University of Washington's Department of Earth and Space Sciences, David Shean devised new ways to use high-resolution satellite images to track elevation changes for massive ice sheets in Antarctica and Greenland. Over the years he wondered: Why aren't we doing this for mountain glaciers in the United States, like the one visible from his department's office window?

He has now made that a reality. In 2012, he first asked for satellite time to turn digital eyes on glaciers in the continental U.S., and he has since collected enough data to analyze mass loss for Mount Rainier and almost all the glaciers in the lower 48 states. He will present results from these efforts Oct. 22 at the Geological Society of America's annual meeting in Seattle.

"I'm interested in the broad picture: What is the state of all of the glaciers, and how has that changed over the last 50 years? How has that changed over the last 10 years? And at this point, how are they changing every year?" said Shean, who is now a research associate with the UW's Applied Physics Laboratory.

The maps provide a twice-yearly tally of roughly 1,200 mountain glaciers in the lower 48 states, down to a resolution of about 1 foot. Most of those glaciers are in Washington state, with others clustered in the Rocky Mountains of Montana, Wyoming and Colorado, and in California's Sierra Nevada.

To create the maps, a satellite camera roughly half the size of the Hubble Space Telescope must take two images of a glacier from slightly different angles. As the satellite passes overhead, moving at about 4.6 miles per second, it takes images a few minutes apart. Each pixel of the image covers 30 to 50 centimeters (about 1 foot) and a single image can be tens of miles across.

Shean's technique uses automated software that matches millions of small features, such as rocks or crevasses, in the two images. It then uses the difference in perspective to create a 3-D model of the surface.

The first such map of a Mount St. Helens glacier was obtained in 2012, and the first for Mount Rainier in 2014. The project has grown steadily since then to include more glaciers every year.

The results confirm stake measurements at South Cascade Glacier, showing significant loss over the past 60 years. Results at Mount Rainier also reflect the broader shrinking trends, with the lower-elevation glaciers being particularly hard hit. Shean estimates cumulative ice loss of about 0.7 cubic kilometers (900 million cubic yards) at Mount Rainier since 1970. Distributed evenly across all of Mount Rainier's glaciers, that's equivalent to removing a layer of ice about 25 feet (7 to 8 meters) thick.

"There are some big changes that have happened, as anyone who's been hiking on Mount Rainier in the last 45 years can attest to," Shean said. "For the first time we're able to very precisely quantify exactly how much snow and ice has been lost."

The glacier loss at Rainier is consistent with trends for glaciers across the U.S. and worldwide. Tracking the status of so many glaciers will allow scientists to further explore patterns in the changes over time, which will help pinpoint the causes -- from changes in temperature and precipitation to slope angle and elevation.

"The next step is to integrate our observations with glacier and climate models and say: Based on what we know now, where are these systems headed?" Shean said.

Those predictions could be used to better manage water supplies and flood risks.

Read more at Science Daily