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Sea ice can be ‘early warning system' for global heating — but the US is halting data sharing
Sea ice can be ‘early warning system' for global heating — but the US is halting data sharing

National Observer

time15-07-2025

  • Science
  • National Observer

Sea ice can be ‘early warning system' for global heating — but the US is halting data sharing

This story was originally published by The Guardian and appears here as part of the Climate Desk collaboration Scientists analysing the cascading impacts of record low levels of Antarctic sea ice fear a loss of critical US government satellite data will make it harder to track the rapid changes taking place at both poles. Researchers around the globe were told last week the US Department of Defence will stop processing and providing the data, used in studies on the state of Arctic and Antarctic sea ice, at the end of this month. Tracking the state of sea ice is crucial for scientists to understand how global heating is affecting the planet. Sea ice reflects the sun's energy back out to space but, as long-term losses have been recorded, more of the planet's ocean is exposed to the sun's energy, causing more heating. The National Snow and Ice Data Center, based at the University of Colorado, maintains a Sea Ice Index used around the world to track in near real-time the extent of sea ice around the globe. In two updates in the past week, the centre said the US government's Department of Defence, which owns the satellites that contain onboard instruments used to track sea ice, would stop 'processing and delivering' the data on 31 July. The US Department of Defense's decision to halt sharing of critical sea ice data "couldn't come at a worse time," according to researchers. Climate scientists have been warning that Trump administration cuts have targeted climate functions across government, and there has been fears the sea ice data could be targeted. The news comes as new research, some of which relied on the data, found that record low amounts of sea ice around Antarctica in recent years had seen more icebergs splintering off the continent's ice shelves in a process scientists warned could push up global sea levels faster than current modelling has predicted. Dr Alex Fraser, a co-author of the research at the Australian Antarctic Program Partnership (AAPP), said NSIDC's sea ice data was 'our number one heart rate monitor' for the state of the planet's ice. 'It's our early warning system and tells us if the patient is about to flatline. We need this data and now [the scientific community] will be forced to put together a record from a different instrument. We won't have that continued context that we have had previously.' NSIDC has said it is working with alternative and higher-resolution instruments from a different satellite, but has warned that data may not be directly comparable with the current instruments. Fraser said: 'We are seeing records now year on year in Antarctica, so from that perspective this could not have come at a worse time.' Dr Walt Meier, a senior scientist at NSIDC, said there were other 'passive microwave instruments' that could keep the long-term record going, but he said differences with older sensors created a 'a challenge to make the long-term record consistent and there will be some degradation in the consistency of the long-term record.' 'I think we will end up with a robust and quality record that users can have confidence in,' Meier said, but said this would add to uncertainty to estimates of trends. Asked why the government was stopping the data, he said because 'everything is old and resources are limited, my guess is that it is not worth the time and effort to upgrade the systems for such old sensors, which may fail at any time.' The research, published in the journal PNAS Nexus, found a link between increasing numbers of icebergs calving from floating ice shelves and the loss of sea ice. While the loss of sea ice does not directly raise sea levels, the research said it exposed more ice shelves to wave action, causing them to break apart and release icebergs faster. Glaciologist Dr Sue Cook, also from AAPP, said 'like a cork in a bottle' those shelves help to slow down the advance of land-based ice that does raise sea levels if it breaks off into the ocean. She said the higher rates of iceberg calving seen in Antarctica were not accounted for in calculations of how quickly the ice sheet might break apart and contribute global sea levels. 'If we shift to this state where summer sea ice is very low but we continue using models based on previous periods, then we will definitely underestimate how quickly Antarctica will contribute to sea level rise,' she said. The study also outlined other knock-on effects from the record low sea ice levels in the Antarctic, including the loss of more seals and penguins if trends continued. As many as 7,000 emperor penguin chicks died in late 2022 after the early break-up of the stable ice they used for shelter while they grow their waterproof plumage. A US Navy spokesperson confirmed the data processing from its defence meteorological satellite program (DMSP) would stop on 31 July 'in accordance with Department of Defense policy.' DMSP is a joint program owned by the US Space Force, the spokesperson said, and was scheduled for discontinuation in September 2026. 'The Navy is discontinuing contributions to DMSP given the program no longer meets our information technology modernization requirements.'

Trump cuts satellite data on Antarctic sea ice just as it's needed most
Trump cuts satellite data on Antarctic sea ice just as it's needed most

Sydney Morning Herald

time01-07-2025

  • Science
  • Sydney Morning Herald

Trump cuts satellite data on Antarctic sea ice just as it's needed most

The US decision is part of what has been widely described as an assault on climate science by the Trump administration. It also affects other work by NASA and the National Oceanic and Atmospheric Association, including hurricane forecasting, as reported by The Guardian US. This masthead sent questions to the US embassy in Australia and the Pentagon, but did not receive a response by deadline. One important dataset under threat is the Sea Ice Index, which has continuous readings back to the late 1970s. It shows that until about 2015, sea ice was around average, or even a bit above average, but since 2016 it has been consistently low. Doddridge said the satellites were past their mission life but remained operational, suggesting the data would still exist but not be shared for scientific work, forcing scientists to use sources with less reliability and continuity such as Japanese or Chinese satellites. 'We won't lose complete access to sea ice data,' Doddridge said. 'What we will lose is a long-term record of well-calibrated, interoperable satellite sensors. What that means is that we won't be able to compare future extremes with past extremes anywhere near as accurately.' The impacts of extremely low sea ice in Antarctica The PNAS Nexus paper canvasses a wide range of impacts from extremely low sea ice, from ecological harm to feedback loops for global warming. Emperor penguins needed landfast sea ice for breeding platforms, Doddridge said, while Adelie penguins relied on sea ice to stay dry while they underwent a 'catastrophic moult', in which they replace all their feathers over a few weeks and temporarily lose their waterproofing. Crabeater seals give birth to their pups on large ice floes and need to stay with them for the two to three weeks between birth and weaning, but are vulnerable to predators such as leopard seals if the ice floes become smaller or harder to find. The paper also raises the spectre that low sea ice could affect the population of Antarctic krill, small crustaceans that are a main food source for a number of whale species, and which need sea ice in the larval stage. Loading Perhaps the biggest impact of low sea ice is the feedback effect it could have on the destruction of the ice shelf – the part of the ice sheet of compacted snow that sits on the ocean rather than over rock – through iceberg formation or melting, and the corresponding effect on sea level rises. Dr Sue Cook, a glaciologist and co-author on the PNAS Nexus paper, said sea ice suppressed ocean swells and waves close to the ice shelf. If the ice shelf was directly exposed to swell, it would start to bend and crack and might disintegrate into icebergs that then disperse out into the open ocean, Cook said. 'In the 15-year record that we looked at, the years with the least summer sea ice produced more than twice as many icebergs as the years with the most summer sea ice,' Cook said. 'This link between iceberg production and sea ice presence isn't something that we include in any of our ice sheet models at the moment, and that means that we might be underpredicting how quickly the Antarctic margin will retreat as sea ice dwindles around the continent.' She added that most models were based on 15 to 20 years of data, which included long periods of good sea ice coverage. 'If we shift to this state where summer sea ice is very low, but we continue using models based on the previous period, then we will definitely underestimate how quickly Antarctica will contribute to sea level rise,' she said. Dr Will Hobbs, a sea ice scientist with AAPP and co-author of the paper, said one of the most important roles of sea ice was the albedo effect, in which it essentially acts as a sunshade in summer. This works because snow-covered ice reflects about 90 per cent of the sunlight back into space, whereas the darker water of the open ocean absorbs 90 per cent of the sunlight, and warms accordingly. Hobbs said that historically in the Southern Ocean, the system always resets in the midwinter, but the researchers found that in a year of extremely low ice, such as 2016, it would affect the next summer and take about three years to fully recover. Hobbs said statistical analysis using reconstructions of the last century suggested there was a 0.1 per cent chance that the low sea ice trend was part of natural variability.

Trump cuts satellite data on Antarctic sea ice just as it's needed most
Trump cuts satellite data on Antarctic sea ice just as it's needed most

The Age

time01-07-2025

  • Science
  • The Age

Trump cuts satellite data on Antarctic sea ice just as it's needed most

The US decision is part of what has been widely described as an assault on climate science by the Trump administration. It also affects other work by NASA and the National Oceanic and Atmospheric Association, including hurricane forecasting, as reported by The Guardian US. This masthead sent questions to the US embassy in Australia and the Pentagon, but did not receive a response by deadline. One important dataset under threat is the Sea Ice Index, which has continuous readings back to the late 1970s. It shows that until about 2015, sea ice was around average, or even a bit above average, but since 2016 it has been consistently low. Doddridge said the satellites were past their mission life but remained operational, suggesting the data would still exist but not be shared for scientific work, forcing scientists to use sources with less reliability and continuity such as Japanese or Chinese satellites. 'We won't lose complete access to sea ice data,' Doddridge said. 'What we will lose is a long-term record of well-calibrated, interoperable satellite sensors. What that means is that we won't be able to compare future extremes with past extremes anywhere near as accurately.' The impacts of extremely low sea ice in Antarctica The PNAS Nexus paper canvasses a wide range of impacts from extremely low sea ice, from ecological harm to feedback loops for global warming. Emperor penguins needed landfast sea ice for breeding platforms, Doddridge said, while Adelie penguins relied on sea ice to stay dry while they underwent a 'catastrophic moult', in which they replace all their feathers over a few weeks and temporarily lose their waterproofing. Crabeater seals give birth to their pups on large ice floes and need to stay with them for the two to three weeks between birth and weaning, but are vulnerable to predators such as leopard seals if the ice floes become smaller or harder to find. The paper also raises the spectre that low sea ice could affect the population of Antarctic krill, small crustaceans that are a main food source for a number of whale species, and which need sea ice in the larval stage. Loading Perhaps the biggest impact of low sea ice is the feedback effect it could have on the destruction of the ice shelf – the part of the ice sheet of compacted snow that sits on the ocean rather than over rock – through iceberg formation or melting, and the corresponding effect on sea level rises. Dr Sue Cook, a glaciologist and co-author on the PNAS Nexus paper, said sea ice suppressed ocean swells and waves close to the ice shelf. If the ice shelf was directly exposed to swell, it would start to bend and crack and might disintegrate into icebergs that then disperse out into the open ocean, Cook said. 'In the 15-year record that we looked at, the years with the least summer sea ice produced more than twice as many icebergs as the years with the most summer sea ice,' Cook said. 'This link between iceberg production and sea ice presence isn't something that we include in any of our ice sheet models at the moment, and that means that we might be underpredicting how quickly the Antarctic margin will retreat as sea ice dwindles around the continent.' She added that most models were based on 15 to 20 years of data, which included long periods of good sea ice coverage. 'If we shift to this state where summer sea ice is very low, but we continue using models based on the previous period, then we will definitely underestimate how quickly Antarctica will contribute to sea level rise,' she said. Dr Will Hobbs, a sea ice scientist with AAPP and co-author of the paper, said one of the most important roles of sea ice was the albedo effect, in which it essentially acts as a sunshade in summer. This works because snow-covered ice reflects about 90 per cent of the sunlight back into space, whereas the darker water of the open ocean absorbs 90 per cent of the sunlight, and warms accordingly. Hobbs said that historically in the Southern Ocean, the system always resets in the midwinter, but the researchers found that in a year of extremely low ice, such as 2016, it would affect the next summer and take about three years to fully recover. Hobbs said statistical analysis using reconstructions of the last century suggested there was a 0.1 per cent chance that the low sea ice trend was part of natural variability.

Threats to NOAA-funded snow and ice data products alarm polar scientists
Threats to NOAA-funded snow and ice data products alarm polar scientists

E&E News

time07-05-2025

  • Science
  • E&E News

Threats to NOAA-funded snow and ice data products alarm polar scientists

An assortment of NOAA-funded snow and ice data products — considered crucial by many scientists for polar research — are at risk of breaking, degrading or going dark as the Trump administration seeks to cut the agency's budget and staff. NOAA's National Centers for Environmental Information (NCEI) decommissioned the products as of Monday, meaning they'll no longer fund the high-level maintenance that keeps the datasets up and running. That's according to a Tuesday announcement from the National Snow and Ice Data Center (NSIDC), a polar research institute that's part of the NOAA-funded Cooperative Institute for Research in Environmental Sciences in Colorado. NSIDC houses the decommissioned snow and ice products, which include datasets on global sea ice extent, snow cover and at least 130,000 glaciers around the world. Some of them, like the Sea Ice Index, contain satellite data extending back to the 1970s. Advertisement The data products won't disappear, according to NSIDC's director, Mark Serreze. And they'll still be updated with new information. But they won't be maintained at the same levels as before.

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