Tag Archives: Ice

Possible Vast Global Ocean Discovered Beneath Ice on Saturn’s Moon Mimas

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Mimas photographed by NASA's Cassini spacecraft

NASA/JPL-California Institute of Technology/Space Science I

Saturn's moon Mimas appears to have a vast global ocean beneath its icy shell, according to detailed measurements of its orbit. If other icy worlds have similar oceans, the number of planets that can support life could increase.

Mimas is the smallest of Saturn's seven major moons. For a long time, it was thought that most of it was composed of solid ice and rock, but in 2014 astronomers observed that the orbit around Saturn was unexpectedly wobbling, suggesting that this could only be explained by either a rugby ball-shaped nucleus or a liquid ocean.

Many astronomers rejected the ocean explanation, as the friction required to melt the ice would have caused visible marks on Mimas's surface. However, recent simulations suggest that this ocean may exist even without such traces.

Looking for more clues? Valerie Rainey Researchers from France's Paris Observatory analyzed observations of Mimas' orbit by NASA's Cassini spacecraft. They found that the orbit around Saturn has shifted by about 10 kilometers over 13 years.

According to the team's calculations, this orbital drift could only have been caused by an ice shell sliding over the ocean, or by wobbles from the physically impossible pancake-shaped core.

The moon's elliptical orbit and lack of surface markings also suggest that the ocean is about 30 kilometers deep and formed less than 25 million years ago. “It was very recent,” Rainey says. “We are more or less witnessing the birth of this global ocean.”

This recent activity could help explain not only the lack of traces on the surface, but also why the moon is so different from its neighbors. Enceladus has a similar shape and orbit to Mimas, and has a global ocean, but it also has a very active surface and giant spout. Rainey said the difference is simply a difference in time, and in a few million years Mimas' ice could melt and it could look similar to Enceladus.

“It would be surprising if that were true,” he says. William McKinnon at Washington University in St. Louis, Missouri. But he says there are still things that aren't perfectly aligned, such as the vast 80-mile-wide Herschel crater, which was formed by a giant impact. If Mimas' ice shell was truly only tens of kilometers deep, McKinnon said, we would have seen evidence of a distorted crater floor in the impact and aftermath. It's also unlikely, he says, that you'll be able to get a front-row seat at such a short and unique time in Mimas' long history. “I remain a Mimas ocean skeptic,” McKinnon says.

However, if Mimas has a hidden ocean, it suggests that other icy planets and moons in the solar system and elsewhere may have the same, expanding the possibility of life. “It's expanding our vision of what is and isn't a habitable world,” Rainey says. “Mimas teaches us that even a corpse that seems to have no life in it may someday come to life.”

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Source: www.newscientist.com

Scientists Find Worsening Ice Melt in Greenland as Research Advances

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According to a new study, Greenland’s ice sheet has lost approximately 1,965 square miles to glacier retreat since 1985, which is about the same area as the state of Delaware. The study utilized satellite images to track the retreat and discovered that iceberg collapse is accelerating in Greenland, with previous analyses potentially underestimating its impact. The authors of the study noted that the current estimates of ice sheet mass balance may underestimate recent mass loss from Greenland by up to 20%. In recent decades, nearly all of Greenland’s glaciers have thinned or retreated.

The study, published in the journal Nature, is another indication that Greenland’s ice is melting at a rapid rate. There is growing concern among scientists that global warming could trigger a major ice sheet tipping point. If Greenland’s ice completely melts, sea levels could rise by almost 7 feet and change ocean circulation patterns. Additionally, the study suggests that the United Nations Intergovernmental Panel on Climate Change may be underestimating how much ice is being lost in Greenland.

Several studies published last year highlighted Greenland’s rapid changes, including one that found the rate of glacier retreat in the 21st century to be twice as fast as the 20th century. Another study showed that floating ice shelves in northern Greenland have lost over 35% of their total volume and are weakening, which could threaten ice sheet stability.

In November, a report by 60 leading snow and ice scientists raised concerns about the fate of the world’s ice sheets, warning that if global average temperatures rise to about 2 degrees Celsius above pre-industrial baselines, the planet could see sea level rise of more than 40 feet in the coming centuries. The report also indicates that by 2 degrees Celsius, most of Greenland, most of West Antarctica, and vulnerable parts of East Antarctica will have a very long-term chance of warming, leading to relentless sea level rise and decline.

Source: www.nbcnews.com

Rising Temperatures Lead to Minimal Ice on Great Lakes

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The Great Lakes, known for ice fishing and winter's frozen waves, rang out a nearly bare New Year's bell.

Less than 0.4% of ice covered the Great Lakes on New Year's Day, according to the Great Lakes Environmental Research Institute, which uses satellite data to measure ice concentrations.

“There's basically nothing,” said James Kessler, a physical scientist at the institute, part of the National Oceanic and Atmospheric Administration. “We have about 50 years of data. Today's average for January 1st is about 9%.”

Kessler said that although ice coverage is well below normal, it is not unheard of for ice concentrations to fall below 1% on January 1, still early in the season.

The amount of ice on the Great Lakes (Lake Superior, Lake Michigan, Lake Huron, Lake Erie, and Lake Ontario) determines when and how raw materials and cargo are shipped from ports in the Midwest. Fish species such as whitefish are covered in ice to protect their eggs for reproduction. Lower ice levels could increase erosion and contribute to changes in weather patterns in the region.

Kessler said temperatures have been unseasonably high this season, making it difficult for ice to form on the lake's surface. According to his research, the Great Lakes' annual ice area varies greatly from year to year, but tends to decline at a rate of about 5% every decade.

“This is certainly a sign of climate change,” he says.

Ice typically reaches its maximum extent from mid-February to early March. In a typical year, about 40% of the Great Lakes are covered in ice at peak times.

Last year, ice coverage reached about 23% and by mid-February the ice had diminished. just covered 7% of the lake.

In 2023, Earth experienced its hottest year on record, largely due to human-induced climate change. Researchers expect temperatures to rise further this year due to El Niño, a natural climate pattern that releases ocean heat into the atmosphere.El Niño winter Warmer trends across the Great Lakes region.

seasonal outlook Temperatures in the Great Lakes region are expected to be higher than normal this year. below average ice.

Forecasters expect little change this week.

Over the next five days, “temperatures are expected to remain near normal across the Great Lakes region, making the forecast less favorable for ice growth,” one report said. Ice outlook prepared by the National Weather Service in Cleveland.

Source: www.nbcnews.com

Is aerosol injection a solution to saving ice?

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A recent study from Indiana University’s Department of Earth and Atmospheric Sciences suggests that utilizing stratospheric aerosol injection to scatter sunlight-reflecting particles in the atmosphere could help slow the rapid melting of West Antarctica. This strategy aims to reduce the risk of catastrophic sea level rise due to climate change. The study shows that even with efforts to limit global warming to 1.5 degrees Celsius, significant sea level rise is still expected.

The study is one of the first to explore the effects of climate engineering on Antarctica, particularly focusing on the accelerating ice loss in West Antarctica. Researchers used high-performance computers and global climate models to simulate various stratospheric aerosol injection scenarios. The data analysis for the study was conducted on Carbonate, a large-memory computer cluster at IU University Information Technology Services.

The results of the study indicate that releasing stratospheric aerosols at multiple latitudes in the tropics and subtropics, with a larger proportion in the Southern Hemisphere, could be the best strategy for preserving Antarctic land ice. The researchers also emphasize the need for further research to quantify changes in melt rates and stress the importance of understanding the potential risks associated with stratospheric aerosol injection. These risks include changes in regional precipitation patterns and the potential for global temperatures to rapidly return to pre-injection levels if treatment is interrupted.

The study expands knowledge about the potential benefits and drawbacks of intentionally cooling the Earth and contributes to a growing conversation about geoengineering in response to the effects of climate change. While more research is needed, the findings highlight the importance of understanding how stratospheric aerosol injection affects the Antarctic region.

Source: scitechdaily.com

Tracing the Sea Ice Highway: The Arrival of North America’s First Immigrants

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New findings suggest that early humans arrived in North America earlier than 13,000 years ago, likely taking advantage of the “sea ice highway” along the Pacific coast. This theory is supported by paleoclimate data, challenges traditional migration theories, and emphasizes the adaptability of early humans. Credit: SciTechDaily.com

A new study suggests that some early Americans may have traveled down the coast from Beringia 24,000 years ago on winter sea ice.

One of the hottest debates in archeology is when and how humans first arrived in North America. Archaeologists have traditionally argued that people walked through temporary ice-free passages between ice sheets an estimated 13,000 years ago.

New evidence casts doubt on traditional theory

But a growing number of archaeological and genetic discoveries, such as human footprints in New Mexico dating back some 23,000 years, suggest that humans were on the continent much earlier. These early Americans likely migrated from Beringia along the Pacific coastline. Beringia is a land bridge between Asia and North America that appeared during the last ice age maximum when ice sheets trapped large amounts of water and caused sea levels to drop.

Now, in a study presented at the American Geophysical Union Annual Meeting (AGU23) in San Francisco on Friday, December 15th, paleoclimate reconstructions of the Pacific Northwest show that sea ice has grown even further south than humans. This suggests that it may have been a means of transportation.

Coastal migration theory

The idea that early Americans may have traveled along the Pacific coast is not new. People may have been south of the giant ice sheet that once covered much of the continent by at least 16,000 years ago. Given that ice-free corridors would not open for thousands of years before these early arrivals, scientists proposed that people instead migrated along a “kelp highway.” Along this path, early Americans slowly made their way down to North America by ship. Abundant supplies found in coastal waters.

Archaeologists have discovered evidence of coastal settlements in western Canada dating back 14,000 years. But in 2020, researchers noted that freshwater from melting glaciers at the time may have created strong currents, making it difficult for people to travel along the coast.

Sea ice in Nunavut, Canada. Credit: Grid-Arendel CC-BY-NC-SA

An icy highway crossing a dangerous sea

To get a more complete picture of ocean conditions during key periods of human migration, Summer Pretorius and colleagues at the U.S. Geological Survey examined climate proxies in marine sediments along the coast. Most of the data came from small fossilized plankton. Its abundance and chemistry help scientists reconstruct ocean temperatures, salinity, and sea ice cover.

Praetorius’ presentation is part of a session at AGU23 on the climate history and geology of Beringia and the North Pacific during the Pleistocene. This year, his week-long conference brought together 24,000 of his experts from all areas of earth and space sciences in San Francisco and 3,000 online participants.

Using climate models, Praetorius’ team found that at the height of the Last Glacial Maximum, about 20,000 years ago, ocean currents were more than twice as strong as they are today due to glacial winds and falling sea levels. Pretorius said it would have been very difficult to travel by boat in these conditions, although it was not impossible to row.

However, records show that much of the region had winter sea ice until about 15,000 years ago. As a cold-adapted people, “they may have been using the sea ice as a foothold instead of having to row against this terrible glacial current,” Pretorius said.

Sea ice as a migration path

People in the Arctic now travel along the sea ice on dog sleds and snowmobiles. Pretorius said early Americans may also have used the “sea ice highway” to travel and hunt marine mammals, slowly making their way into North America in the process. Climate data suggest that conditions along the coastal route may have been favorable for migration between 24,500 and 22,000 years ago and between 16,400 and 14,800 years ago, possibly due to the presence of winter sea ice.

Integration of old and new theories

It’s difficult to prove that people used sea ice for travel, given that most ruins are underwater, but the idea is that without land bridges or easy ocean travel, humans It provides a new framework for understanding how it arrived in North America.

And the Sea Ice Highway is not mutually exclusive with other human movements beyond it, Pretorius said. The researchers’ model shows that by 14,000 years ago, the Alaska Current had calmed down, making it easier for people to travel by boat along the coast.

“There’s nothing wrong with it,” she said. “We are always amazed by the ingenuity of ancient humans.”

Source: scitechdaily.com