Latest news with #Silvano
India Today
08-07-2025
- Science
- India Today
Antarctic water is dramatically getting saltier. It's not good news
A dramatic transformation is unfolding in the Southern Ocean, where scientists have discovered that surface waters around Antarctica are becoming saltier, despite a rapid and unprecedented decline in sea revelation, made possible by data from the European Space Agency's SMOS (Soil Moisture and Ocean Salinity) satellite, upends long-held assumptions about the region's response to climate change.A Surprising ReversalTraditionally, melting sea ice is expected to freshen ocean surface waters, as freshwater from the ice dilutes the salty sea. Monitoring the Southern Ocean is notoriously difficult. (Photo: Getty) advertisement However, since 2015, Antarctica has lost an area of sea ice comparable to Greenland, one of the most extensive environmental changes in recent of becoming fresher, the surface waters south of 50 S latitude have grown saltier, according to a research team led by the University of shift is 'deeply troubling,' said Dr. Alessandro Silvano, lead author of the study published in PNAS. 'Melting ice should freshen the ocean, not make it saltier. Yet SMOS satellite data reveal the opposite is occurring.'A Dangerous Feedback LoopThe increase in surface salinity is altering the ocean's cold, fresh water floats above warmer, saltier water, trapping heat in the ocean's depths and promoting sea ice formation. Accelerated global warming as less ice means more heat is absorbed by the ocean. (Photo: Getty) Now, saltier surface waters allow heat from below to rise more easily, melting sea ice from beneath and making it harder for new ice to has coincided with the unexpected return of the Maud Rise polynya—a vast area of open water in the Weddell Sea not seen since the 1970s—highlighting just how abnormal current conditions ConsequencesThe loss of Antarctic sea ice has far-reaching implications:Disrupted ocean currents and altered climate patterns global warming as less ice means more heat is absorbed by the ocean and released to the to Antarctic wildlife, including penguins, as vital habitats the Southern Ocean is notoriously difficult, but the integration of SMOS satellite data with in-situ measurements has enabled the creation of a comprehensive 15-year dataset. The loss of Antarctic sea ice has far-reaching implications. (Photo: Getty) This breakthrough, achieved through advanced algorithms developed by the University of Southampton and the Barcelona Expert Centre, is part of ESA's Science for Society Silvano warns, 'We might be closer to passing a tipping point than expected and have potentially entered a new state defined by persistent sea ice decline, sustained by a newly discovered feedback loop.'As Antarctica undergoes rapid, unexpected changes, continuous satellite and in-situ monitoring will be essential to understand and predict the consequences for our planet.- EndsTrending Reel
USA Today
02-07-2025
- Science
- USA Today
Scientists find a 'dangerous feedback loop' in sudden sea ice melt
Over the past few years, researchers have discovered dramatic and "unexpected" shifts in the Southern Ocean, with saltiness rising and sea ice in steep decline. It's about as remote as it gets, yet what happens in the Southern Ocean near Antarctica impacts all of us. And what's going on down there? Over the past few years, researchers have discovered dramatic and "unexpected" shifts in the Southern Ocean, with saltiness rising and sea ice in steep decline, according to a new study. It matters, researchers say, because losing Antarctic sea ice is a planetary problem: "If this salty, low-ice state continues, it could permanently reshape the Southern Ocean – and with it, the planet," said study lead author Alessandro Silvano of the University of Southampton in a statement. "The effects are already global: stronger storms, warmer oceans, and shrinking habitats for penguins and other iconic Antarctic wildlife," he said. Record low sea ice Since 2015, Antarctica has displayed record-low sea ice extent, according to the study, which appeared in the peer-reviewed journal Proceedings of the National Academy of Sciences. In fact, since 2015, Antarctica has lost sea ice equal to the size of Greenland – the largest environmental shift seen anywhere on Earth in the last few decades. The Southern Ocean is also getting saltier, and this unexpected change is making the problem worse. 'Saltier surface water allows deep ocean heat to rise more easily, melting sea ice from below," Silvano said. "It's a dangerous feedback loop: less ice leads to more heat, which leads to even less ice." What is sea ice? Sea ice is frozen ocean water that melts each summer, then refreezes each winter. Antarctic sea ice is typically at its smallest in late February or early March, toward the end of summer in the Southern Hemisphere. Sea ice loss – especially in the Arctic but also in the Antarctic – is one of the clearest signals of global warming, the National Climate Assessment reported in 2018. In addition to human-caused warming of the Earth's atmosphere and oceans, multiple factors – including the geography of Antarctica, the region's winds, as well as air and ocean temperatures – affect the ice around Antarctica. Maud Rise polynya opens up The dramatic loss of sea ice around Antarctica has occurred with the re-emergence of the Maud Rise polynya in the Weddell Sea – a huge hole in the sea ice nearly four times the size of Wales, which hadn't occurred since the 1970s, the study reports. A polynya is an area of open water surrounded by sea ice. 'The return of the Maud Rise polynya signals just how unusual the current conditions are," Silvano said. Penguins rely on sea ice In Antarctica, it's penguins that rely on sea ice. Due to the dramatic loss of sea ice there, several colonies of emperor penguins face "quasi-extinction" in the decades to come, a study released in 2023 reported. More: With hurricane season brewing, Pentagon stops sharing satellite weather data Satellite data will be cut off Alberto Naveira Garabato, co-author of the study from the University of Southampton, said, 'The new findings suggest that our current understanding may be insufficient to accurately predict future changes.' However, the U.S. Defense Department is cutting off weather forecasters from data gathered by its special satellites that can "see" through the clouds. "(The new study) makes the need for continuous satellite monitoring all the more pressing, so we can better understand the drivers of recent and future shifts in the ice-ocean system,' Garabato said.
Straits Times
01-07-2025
- Science
- Straits Times
Near Antarctica, saltier seas mean less ice but more heat: Study
Increases in salinity in seawater near the surface could help explain some of the decrease in Antarctic sea ice that have been observed over the past decade. PHOTO: BRITISH ANTARTIC SURVEY Some of the water around Antarctica has been getting saltier. And that has affected the amount of sea ice at the bottom of the planet. A study published on June 30 in the Proceedings of the National Academy of Sciences found that increases in salinity in seawater near the surface could help explain some of the decrease in Antarctic sea ice that have been observed over the past decade, reversing a previous period of growth. 'The impact of Antarctic ice is massive in terms of sea-level rise, in terms of global warming, and therefore, in terms of extremes,' said Alessandro Silvano, a senior scientist at the University of Southampton studying the Southern Ocean and lead author of the study. The findings mean 'we are entering a new system, a new world', he said. Each year, the sea ice floating atop the Earth's polar oceans melts in the summer and refreezes in the winter, acting as a mirror that bounces the sun's heat back into space. Since the late 1970s, as global temperatures ratcheted upward, sea ice in the Arctic has been swiftly declining. But in the Antarctic sea ice continued to grow into the 2010s. The study used data from satellites to track changes by using a brightness measurement that subtly correlates to salt content. But because the signal is small and easily drowned out by other factors, Dr Silvano said, it wasn't possible to analyse them effectively until recent advances in algorithms. When Dr Silvano and his co-authors first noticed the rising salinity, they doubted the signal was real, suspecting an error in the satellite data. But as physical measurements from ocean instruments began to confirm the trend, they realised the signal was accurate. 'Because melting ice should freshen the ocean, we thought that we should have seen freshening, right?' Dr Silvano said, adding that climate change is also increasing precipitation and runoff from melting glaciers in the Antarctic, which should mean more fresh water coming into the ocean's surface. 'Instead, we saw increasing salinity.' As the salt content increases, the density of the water changes, drawing warmer water – typically stashed deep under the surface – upward. Hotter water causes the ice floating on it to melt, and prevents it from growing back in the winter as much as it used to. Because less sea ice means less fresh water balancing out the salinity and warmth, it's a feedback loop that threatens greater warming, he said. Sharon Stammerjohn, a senior research associate at the University of Colorado Boulder's Institute of Arctic and Alpine Research, who was not involved in the research, described the paper as a sort of missing link for the potential drivers of Antarctic sea-ice changes. 'We have been struggling for about the last decade to try to figure out why Antarctic sea ice had such a rapid decline and continues to decline,' she said. Typically, Dr Stammerjohn said, the ocean acts as a bank of planetary heat. Because fresher water is less dense, it acts as a lid, holding back the salt and trapping heat deep below the surface. Rising salinity means the layers of the ocean are mixing more, and letting more heat escape to the surface. 'Up until 2015 we kind of kept a lid on that,' she said. Cecilia Bitz, a professor of climate science at the University of Washington, said observations of the Antarctic's complex dynamics and vast, hard-to-access landscape remained sparse until about 10 years ago. Then, improvements in satellite data along with a growing fleet of autonomous buoys with sensors, known as Argo floats, which provided some of the data used in Dr Silvano's study, began to fill in the gaps. Recently, the Department of Defense announced it would be no longer be providing some of the satellite data that researchers use to monitor changes in sea ice. According to an announcement Monday, the data will become unavailable after July 31. 'This not only affects polar researchers who rely on this for Antarctic sea ice and Arctic sea ice, but another sensor on there is key for hurricane forecasting,' Dr Stammerjohn said. While the details of how the scientific community might adapt when this program is canceled are unclear, she said, there are other satellite products, including ones maintained by the European Space Agency and the Japan Aerospace Exploration Agency, that may be able to fill the gap. NYTIMES Find out more about climate change and how it could affect you on the ST microsite here.
