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6 mysterious structures hidden beneath the Greenland ice sheet – Space.com

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Fridtjof Nansen, the leader of the first expedition to cross Greenland, once described what he found in the Arctic as “the great adventure of the ice, deep and pure as infinity.” Nansen, who made his journey in 1888, could not have known of the wonders hidden below the icy landscape beneath his skis. 

Today, thanks to radar and other technologies, the part of Greenland that sits below its 9,800-foot-thick(3,000 meters) ice sheet is coming into focus. These new tools reveal a complex, invisible landscape that holds clues to the past and future of the Arctic.

The world’s longest canyon

3D view of the subglacial canyon, looking northwest from central Greenland. (Image credit: J. Bamber, University Bristol)

The Greenland ice sheet hides the longest canyon in the world. 

Discovered in 2013, the canyon stretches 460 miles (740 kilometers) from the highest point in central Greenland to Petermann Glacier on the northwest coast. That’s significantly longer than China’s 308-mile-long (496 km) Yarlung Tsangpo Grand Canyon, the longest canyon on the planet that you can actually see. 

The canyon plunges up to 2,600 feet (800 m) deep in places and is 6 miles (10 km) wide. For comparison, the Grand Canyon in Arizona averages about 1 mile (1.6 km) deep and 10 miles (16 km) across. 

Parts of the canyon may route meltwater from beneath the ice sheet to the sea. It probably formed before the ice sheet and was once the channel for a mighty river. 

Invisible mountains

As ice in Greenland melts at the surface, water carves fissures and reaches the base, where ice meets land. This sub-glacial ice can lubricate a glacier, causing it to flow to the ocean faster and be depleted more quickly. (Image credit: Ashley Cooper via Getty Images)

The canyon isn’t the only rugged part of Greenland’s under-ice landscape. Decades of mapping the island by ice-penetrating radar (which is usually mounted on airplanes) have revealed rugged mountain ranges and plunging fjords beneath the ice sheet. 

A 2017 map of Greenland stripped of its ice shows a bowl-like depression in the center of the island. A circle of coastal mountain ranges rings this depression. The map revealed the topography underlying Greenland’s flowing glaciers, which can help scientists predict how fast the glaciers will move in warming conditions and how quickly they will calve icebergs into the ocean. 

A primeval lake

Ice seems to go on forever at Humboldt Glacier in northwest Greenland. (Image credit: VWPics/Universal Images Group via Getty Images)

Hundreds of thousands or millions of years ago, before Greenland was covered with ice, it was home to a lake the size of Rhode Island and Delaware combined

Today, the lake is a depression filled with sediment. But it was once filled with water 800 feet (250 m) deep in some places. The lake basin covers 2,700 square miles (7,100 square km) and was fed by at least 18 different streams. 

The lake bed could hold valuable clues to the climate of the Arctic in the distant past, though discovering these secrets would require drilling through the 1.1 miles (1.8 km) of ice that now caps the ancient site.

Hidden gems

The blue rivers and splotches are Greenland’s surface meltwaters. (Image credit: Andrew Sole/University of Sheffield)

Greenland’s ice sheet also hides a landscape of jewel-like lakes filled with crystalline meltwater. There are at least 60 of these small lakes, mostly clustered in northern and eastern Greenland, Stephen Livingstone, a senior lecturer in physical geography at the University of Sheffield in the United Kingdom and co-researcher of a study into the lakes, Live Science previously reported.

The lakes range in size from 656 feet (200 m) across to 3.7 miles (5.9 km) across. The meltwater in these lakes may flow from the surface of the ice sheet, or it may melt because of friction from the movement of ice or geothermal energy from below. 

Evidence of meteor impacts

Crater in Greenland below the ice sheet. (Image credit: NASA’s Goddard Space Flight Center/ Cynthia Starr)

Not all the topography below the ice sheet is of Earthly origin. Scientists have found at least two likely meteor craters buried beneath the ice. Both are in northwest Greenland: One sits below Hiawatha Glacier, while the other is 114 miles (183 km) away from the first. The Hiawatha crater sits under about a half-mile (930 m) of ice, while the second crater is buried under 1.2 miles (2 km) of ice. The second crater is 22 miles (36 km) across, making it the 22nd-largest impact crater ever found on Earth. The first is a bit smaller at 19 miles (31 km) across. 

Perfectly preserved fossil plants

Greenland’s ice sheet may have disappeared far more recently than once thought, enabling plants and trees to thrive. (Image credit: Joshua Brown/UVM)

An ice core dug up during a Cold War-era attempt at building a nuclear weapons base was rediscovered in a freezer in 2017 and found to hold the perfectly preserved fossils of plants dating to a million years ago. 

“The best way to describe them is freeze-dried,” Andrew Christ, lead author of a study into the core and a postdoctoral fellow and lecturer in the Department of Geology at The University of Vermont in Burlington, told Live Science at the time. “When we pulled these out and put a little water on them, they kind of unfurled, so they looked like they died yesterday.”

The core came from northwestern Greenland, and the plants held within may have grown in a boreal forest. Such a forest could only grow in largely ice-free conditions, suggesting that parts of Greenland’s ice sheet may be younger than researchers previously believed.

Originally published on Live Science

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Bird reports rose during lockdowns | Cornell Chronicle – Cornell Chronicle

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Around 80% of bird species examined in a new study were reported in greater numbers in human-altered habitats during pandemic lockdowns, according to new research based on data from the eBird program at the Cornell Lab of Ornithology.

In the paper, “Reduced Human Activity During COVID-19 Alters Avian Land Use Across North America,” published Sept. 22 in Science Advances, researchers compared online eBird observations from the United States and Canada from before and during the pandemic. They focused on areas within about 100 km of urban areas, major roads, and airports.

Vast amounts of data from a likewise vast geographic area were vital for this study. The researchers used more than 4 million eBird observations of 82 bird species from across Canada and the U.S.

“A lot of species we really care about became more abundant in human landscapes during the pandemic,” said study senior author Nicola Koper of the University of Manitoba, which led the research. “I was blown away by how many species were affected by decreased traffic and activity during lockdowns.”

Reports of bald eagles increased in cities with the strongest lockdowns. Ruby-throated hummingbirds were three times more likely to be reported within a kilometer of airports than before the pandemic. Barn swallows, a threatened species in Canada, were reported more often within a kilometer of roads than before the pandemic.

A few species decreased their use of human-altered habitat during the pandemic. Red-tailed hawk reports decreased near roads, perhaps because there was less roadkill when traffic declined. But far more species had increased counts in these human-dominated landscapes.

The authors filtered pandemic and pre-pandemic eBird reports so that the final data sets had the same characteristics, such as location, number of lists, and level of birdwatcher effort.

“We also needed to be aware of the detectability issue,” said co-author Alison Johnston, assistant director of the Center for Avian Population Studies and Ecological Data in the Lab of Ornithology. “Were species being reported in higher numbers because people could finally hear the birds without all the traffic noise, or was there a real ecological change in the numbers of birds present?”

The study tested whether better detectability might be a factor in the larger bird numbers reported. If it was, the scientists expected that to be more noticeable for smaller birds, which are harder to detect beneath traffic noise. However, effects were noticed across many species, from hawks to hummingbirds, suggesting that the increased numbers were not only caused by increased detectability in the quieter environments.

“Having so many people in North America and around the world paying attention to nature has been crucial to understanding how wildlife react to our presence,” says lead author Michael Schrimpf, a postdoctoral fellow at the University of Manitoba. “Studies such as this one rely on volunteer birdwatchers, so if you enjoy watching wildlife, there are many projects out there, like eBird and iNaturalist, that can use your help.”

The study was funded by Natural Sciences and Engineering Research Council of Canada with in-kind support provided by Environment and Climate Change Canada and the Cornell Lab of Ornithology.

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SpaceX Crew Dragon cupola provides awe-inspiring view of the Earth from space – Californianewstimes.com

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Holy Molly.

SpaceX

Give a few seconds (or a minute or two if needed) to startle and gaze at the Earth’s scenery from the recently launched SpaceX Crew Dragon above.

on Wednesday, As part of the Inspiration4 mission, four civilians were blown up in a three-day orbital stay.Tied to the SpaceX Crew Dragon with one of the upgrades: Cupola. The transparent dome at the top of the Dragon Capsule provides the Inspiration 4 crew with the best views of the Earth that up-and-coming astronauts can dream of. This is the first time a cupola has been installed on a dragon. Dragons typically carry astronauts and cargo to the ISS, with docking ports at the top instead of windows.

A short video posted to the SpaceX Twitter account hours after the launch shows the cupola’s transparent dome against the Earth, which is a pale blue marble.

As the Crew Dragon orbits from a height of 585 kilometers (more than 360 miles), our planet is exposed to the sun and slowly roams around the orbs.

Inspiration 4’s crew (commander Jared Isaacman, doctor’s assistant, childhood cancer survivor Haley Arseno, aerospace engineer Chris Sembroski, African-American geology professor Sian Proctor) are in orbit for three days. Ride and stare at the cupola and the earth.

And did you say that the cupola is right next to the dragon’s toilet? Yeah, the view of the earth should be visible from the crew dragon’s bathroom. Isaacman told insiders Toilets are one of the few places where you can separate yourself from others with privacy curtains and have the best toilet windows of mankind. “When people inevitably have to use the bathroom, they will see one view of hell,” he said.

Astronauts who have been to space often talk about a phenomenon called the “overview effect.” Looking at the planet from above, the idea is that the way we think about the planet and the mass of humankind that depends on it will change. There may be a lot of revelation at the end of the Inspiration 4 journey, as I don’t know if they thought of it while sitting in the can.

The mission is the first mission to take off from the Florida coast on Wednesday night and be launched with four civilians. It is expected to return to Earth on Saturday and land in the Atlantic Ocean.

SpaceX Crew Dragon cupola provides awe-inspiring view of the Earth from space Source link SpaceX Crew Dragon cupola provides awe-inspiring view of the Earth from space

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Oldest human footprints in North America found in New Mexico – Al Jazeera English

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Fossilised footprints dating 23,000 years push back the known date the continent was colonised by thousands of years.

Footprints dating back 23,000 years have been discovered in the United States, suggesting humans settled North America long before the end of the last Ice Age, according to researchers.

The findings announced on Thursday push back the date at which the continent was colonised by its first inhabitants by thousands of years.

The footprints were left in mud on the banks of a long-since dried up lake, which is now part of a New Mexico desert.

Sediment filled the indentations and hardened into rock, protecting evidence of our ancient relatives, and giving scientists a detailed insight into their lives.

The first footprints were found in a dry lake bed in White Sands National Park in 2009. Scientists at the United States Geological Survey recently analysed seeds stuck in the footprints to determine their approximate age, ranging from 22,800 to 21,130 years ago.

“Many tracks appear to be those of teenagers and children; large adult footprints are less frequent,” write the authors of the study published in the American journal Science.

“One hypothesis for this is the division of labour, in which adults are involved in skilled tasks whereas ‘fetching and carrying’ are delegated to teenagers.

“Children accompany the teenagers, and collectively they leave a higher number of footprints.”

Researchers also found tracks left by mammoths, prehistoric wolves, and even giant sloths, which appear to have been approximately at the same time as the humans visited the lake.

Historic findings

The Americas were the last continent to be reached by humanity.

For decades, the most commonly accepted theory has been that settlers came to North America from eastern Siberia across a land bridge – the present-day Bering Strait.

From Alaska, they headed south to kinder climes.

Archaeological evidence, including spearheads used to kill mammoths, has long suggested a 13,500-year-old settlement associated with so-called Clovis culture – named after a town in New Mexico.

This was considered the continent’s first civilisation, and the forerunner of groups that became known as Native Americans.

However, the notion of Clovis culture has been challenged over the past 20 years, with new discoveries that have pushed back the age of the first settlements.

Generally, even this pushed-back estimate of the age of the first settlements had not been more than 16,000 years, after the end of the so-called “last glacial maximum” – the period when ice sheets were at their most widespread.

This episode, which lasted until about 20,000 years ago, is crucial because it is believed that with ice covering much of the northern parts of the continent, human migration from Asia into North America and beyond would have been very difficult.

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