Latest news with #AntarcticSeaIce
Yahoo
01-07-2025
- Science
- Yahoo
Antarctic summer sea ice is at record lows. Here's how it will harm the planet
On her first dedicated scientific voyage to Antarctica in March, the Australian icebreaker RSV Nuyina found the area sea-ice free. Scientists were able to reach places never sampled before. Over the past four summers, Antarctic sea ice extent has hit new lows. I'm part of a large group of scientists who set out to explore the consequences of summer sea ice loss after the record lows of 2022 and 2023. Together we rounded up the latest publications, then gathered new evidence using satellites, computer modelling, and robotic ocean sampling devices. Today we can finally reveal what we found. It's bad news on many levels, because Antarctic sea ice is vital for the world's climate and ecosystems. But we need to get a grip on what's happening – and use this concerning data to prompt faster action on climate change. Our team used a huge range of approaches to study the consequences of sea ice loss. We used satellites to understand sea ice loss over summer, measuring everything from ice thickness and extent to the length of time each year when sea ice is absent. Satellite data was also used to calculate how much of the Antarctic coast was exposed to open ocean waves. We were then able to quantify the relationship between sea ice loss and iceberg calving. Data from free-drifting ocean robots was used to understand how sea ice loss affects the tiny plants that support the marine food web. Every other kind of available data was then harnessed to explore the full impact of sea ice changes on ecosystems. Voyage reports from international colleagues came in handy when studying how sea ice loss affected Antarctic resupply missions. We also used computer models to simulate the impact of dramatic summer sea ice loss on the ocean. In summary, our extensive research reveals four key consequences of summer sea ice loss in Antarctica. 1. Ocean warming is compounding Bright white sea ice reflects about 90% of the incoming energy from sunlight, while the darker ocean absorbs about 90%. So if there's less summer sea ice, the ocean absorbs much more heat. This means the ocean surface warms more in an extreme low sea ice year, such as 2016 – when everything changed. Until recently, the Southern Ocean would reset over winter. If there was a summer with low sea ice cover, the ocean would warm a bit. But over winter, the extra heat would shift into the atmosphere. That's not working anymore. We know this from measuring sea surface temperatures, but we have also confirmed this relationship using computer models. What's happening instead is when summer sea ice is very low, as in 2016, it triggers ocean warming that persists. It takes about three years for the system to fully recover. But recovery is becoming less and less likely, given warming is building from year to year. 2. More icebergs are forming Sea ice protects Antarctica's coast from ocean waves. On average, about a third of the continent's coastline is exposed over summer. But this is changing. In 2022 and 2023, more than half of the Antarctic coast was exposed. Our research shows more icebergs break away from Antarctic ice sheets in years with less sea ice. During an average summer, about 100 icebergs break away. Summers with low sea ice produce about twice as many icebergs. 3. Wildlife squeezed off the ice Many species of seals and penguins rely on sea ice, especially for breeding and moulting. Entire colonies of emperor penguins experienced 'catastrophic breeding failure' in 2022, when sea ice melted before chicks were ready to go to sea. After giving birth, crabeater seals need large, stable sea ice platforms for 2–3 weeks until their pups are weaned. The ice provides shelter and protection from predators. Less summer sea-ice cover makes large platforms harder to find. Many seal and penguin species also take refuge on the sea ice when moulting. These species must avoid the icy water while their new feathers or fur grows, or risk dying of hypothermia. 4. Logistical challenges at the end of the world Low summer sea ice makes it harder for people working in Antarctica. Shrinking summer sea ice will narrow the time window during which Antarctic bases can be resupplied over the ice. These bases may soon need to be resupplied from different locations, or using more difficult methods such as small boats. Anarctic sea ice began to change rapidly in 2015 and 2016. Since then it has remained well below the long-term average. The dataset we use relies on measurements from US Department of Defense satellites. Late last month, the department announced it would no longer provide this data to the scientific community. While this has since been delayed to July 31, significant uncertainty remains. One of the biggest challenges in climate science is gathering and maintaining consistent long-term datasets. Without these, we don't accurately know how much our climate is changing. Observing the entire Earth is hard enough when we all work together. It's going to be almost impossible if we don't share our data. Recent low sea ice summers present a scientific challenge. The system is currently changing faster than our scientific community can study it. But vanishing sea ice also presents a challenge to society. The only way to prevent even more drastic changes in the future is to rapidly transition away from fossil fuels and reach net zero emissions. This article is republished from The Conversation. It was written by: Edward Doddridge, University of Tasmania Read more: Invasive carp threaten the Great Lakes − and reveal a surprising twist in national politics The rising rate of type 2 diabetes in young New Zealanders is becoming a health crisis 'Completely unexpected': Antarctic sea ice may be in terminal decline due to rising Southern Ocean salinity Edward Doddridge receives funding from the Australian Research Council.
The Guardian
01-07-2025
- Science
- The Guardian
Tracking sea ice is ‘early warning system' for global heating - but US halt to data sharing will make it harder, scientists warn
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. Sign up for Guardian Australia's breaking news email 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. 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.' 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. Guardian Australia has requested comment from NSIDC and the US Department of Defence.
