Latest news with #seaice
Yahoo
14 hours ago
- Science
- Yahoo
NASA satellite sees sea ice crack apart in Canada
When you buy through links on our articles, Future and its syndication partners may earn a commission. NASA satellites looked down on huge cracks forming in sea ice in Canada's far north. The Amundsen Gulf is named after Roald Amundsen, a Norwegian explorer who, in the early 1900s, embarked on a voyage into the Northwest Passage, a winding narrow passage through the Canadian Arctic Archipelago. Amundsen was hoping to use the Northern Passage as a shortcut, reducing travel time, according to NASA's Earth Observatory. After facing several hazards, his ship and crew successfully emerged from the passage, becoming the first people to successfully navigate the dangerous terrain. Amundsen's ship, called the Gjøa, was only crewed by six men, all of whom helped conduct meteorological observations while sailing. The Amundsen Gulf lies in the Northwest Territories of Canada. While Roald Amundsen and his crew paved the way for other ships to navigate the Northern Passage, the route still poses dangers for ships due to the shifting sea ice. Seasonal changes can cause sea ice to melt and break apart, drifting in the cold arctic waters. While this in itself may not be necessarily dangerous, if the sea ice accumulates enough, it can create "choke points" that block ships from sailing through. In this image, taken by the MODIS (Moderate Resolution Imaging Spectroradiometer) on NASA's Terra satellite, much of the sea ice is still "fastened" to the coastline, but other chunks have migrated into the Beaufort Sea. This ice break up will continue for several months as warmer temperatures and wind help to crack apart the thick arctic ice. The cycle usually begins in March 2025, according to NASA's Earth Observatory You can read more about sea ice levels in the arctic as satellites like Terra and other continue to observe Earth's many beautiful structures.
RNZ News
28-05-2025
- Health
- RNZ News
Antarctica's sea ice is changing, and so is a vital part of the marine food web that lives within it
By Jacqui Stuart and Natalie Robinson* of Adélie penguins on sea ice in the Gerlach inlet next to the Mario Zucchellis station, the Italian base in Terra Nova Bay, in the Antarctic. Photo: Liv Cornellisen Antarctica is the world's great cooling unit. This vital part of Earth's climate system is largely powered by the annual freeze and melt of millions of square kilometres of sea ice around the continent. Our research shows changes to this annual freeze cycle in McMurdo Sound can lead to shifts in the diversity of algal communities that live within the sea ice. At the start of the southern winter, as sea water begins to freeze, it expels salt and forms heavy and very cold brine. This sinks to the seafloor, ultimately forming what's known as Antarctic Bottom Water. This is then pumped out to the rest of the world through several major oceanic currents. Historically, this cycle meant that Antarctica effectively doubled in size and the continent was surrounded by an enormous apron of sea ice at the peak of winter. But the changing climate is shifting this annual cycle. Major ocean currents transport cold Antarctic Bottom Water out to the rest of the world. Photo: The Conversation / Jacqui Stuart, VUW, CC BY-NC-ND For the past decade, Antarctic sea ice has been in decline. It hasn't been a steady trend, but each year since 2016 less sea ice has formed compared to historic averages. Antarctica's annual maximum sea ice extent in September 2023 was the lowest on record, with approximately 1.75 million square kilometres less sea ice than normal - an area equivalent to about 6.5 times the land area of Aotearoa. Change happening at the continental scale is usually well documented and publicised. However, smaller, more local changes are also occurring in places such as McMurdo Sound, the home of Aotearoa New Zealand's only Antarctic outpost. For four of the last seven years, unseasonable winter southerly storms have been associated with significant delays in the timing of sea-ice formation within McMurdo Sound. Where measurements were taken during these "unusual" years, the sea ice that formed later was thinner (1.5 metres compared to 2.5 metres) and had less snow cover (about 5 centimetres versus 15-30 centimetres) compared to the same locations during "typical" years. Antonia Radlwimmer (left) and Chris Pooley preparing a sea ice core for transport to the University of Otago Physics Antarctic Ice Lab. Photo: Inga Smith Another type of ice, known as "platelet ice", also appears to be affected by the later formation of sea ice. A layer of platelet ice extends into the ocean below the sea ice in some regions around Antarctica, including McMurdo Sound. It is a fragile lattice structure made up of loosely consolidated plate-shaped ice crystals, creating an upside-down reef-like structure. The resulting protective environment is a hot spot for primary productivity - microscopic algae that support the base of the marine food web. When sea ice forms later, the platelet ice doesn't have as much time to accumulate beneath and can be metres thinner than beneath older ice (down to about 1 metre from more than 3 metres). Why should we care about sea ice? Because, it isn't just a frozen, lifeless sheet expanding out from the continent, broken by the odd silhouette of a seal or a gathering of penguins on the top. Beneath the desolate surface, where ice meets water, green meadows of microalgae can spread out as far as the eye can see. Microalgae are single-cell, plant-like organisms that use sunlight to create energy. Similar to land-based meadows, they provide food for many other creatures. In winter, when other sources of food can be scarce, this sea-ice superstore plays a crucial role in feeding other inhabitants of McMurdo Sound. The frozen expanse of McMurdo Sound. Photo: Claire Concannon / RNZ Our research indicates that when the sea ice forms later, microalgal communities living within the ice are also different. In later-forming sea ice, these vital communities are less diverse and dominated by fewer species. Some species usually abundant in earlier-forming sea ice are absent or in low numbers when the sea ice forms later. Interestingly, though, it appears the quantity of microalgae in later-forming ice conditions is similar to "typical" ice. However, instead of being spread out through almost three metres depth of the platelet layer, they are crammed into a metre-thick habitat instead. These microscopic snacks are diverse in shape, size and the roles they play in the ecosystem. It can help to think of microalgal communities as the produce section in the supermarket. Each type has preferred growing conditions and different nutritional values, producing varied quantities of important resources such as proteins, carbohydrates and fatty acids. Imagine, one winter the weather is different and all that grows are cabbages and sweet peas. These won't provide you with all the nutrients you need. This mirrors the problem when there is less diversity at the base of the food web. As the microalgal communities shift in the ways our research has observed, the quantity and quality of resources they provide are likely to change, too. These early signals matter. They foreshadow wider ecological impacts, especially, if Antarctic sea ice continues to thin, retreat or form later each year. We need more research to establish the nuances of these changes and the extent of their impact. But it is worth remembering that what happens at the base of the food web in Antarctica doesn't necessarily stay there. These changes could ripple through ecosystems further afield with the potential to affect key fisheries in the Southern Ocean. By paying close attention now, we have a chance to understand and adapt, to ensure ecosystems stay resilient in a changing world. *Jacqui Stuart is a Postdoctoral Researcher in Marine Ecology, Te Herenga Waka - Victoria University of Wellington; Natalie Robinson is a Marine Physicist, National Institute of Water and Atmospheric Research (NIWA). This article was first published by The Conversation .
Daily Mail
08-05-2025
- Science
- Daily Mail
Scientists hope to halt climate change by REFREEZING the Arctic - here's how it could work
When it comes to curbing climate change, scientists will try almost anything. And experts at the University of Cambridge are no exception – as they have been given funding to see if global warming could be slowed by refreezing the Arctic. A team will explore whether the Arctic's rapidly diminishing sea ice could be artificially thickened by pumping seawater onto the surface in winter. If successful, it could reduce summer melt and slow regional warming, they said. For years, scientists have sounded the alarm over the Arctic's rapidly-shrinking sea ice cover. Many expect the region to be ice-free in the summer in the 2030s, even if sharp cuts to emissions are made immediately. Some researchers say the only way to stop this from happening is to artificially thicken the ice – which polar wildlife and Inuit communities depend on. But how, exactly, would it work? Sea ice forms naturally by water freezing on the bottom of existing ice which floats on the ocean's surface. As the ice grows it becomes a thicker insulating layer between the cold Arctic air above the ice and the water below, so the rate of freezing slows down. Any snow on the ice's surface also acts as an insulator, further slowing the rate of new ice growth. One technique that Cambridge's Centre for Climate Repair is looking into is called surface thickening. This aims to increase the sea ice thickness directly when there is no snow by pumping seawater onto the surface, so it is directly exposed to the cool atmosphere and thickens the ice from above. Another method can be used when there is snow on the surface of the ice. It involves filling the voids of air within snow with seawater – eventually turning the snow into solid ice which then leads to more natural freezing at the ice's base. Field trials are set to begin in Canada this year in collaboration with Real Ice, whose mission is to 'preserve and restore Arctic Sea Ice'. Last year the company said tests have validated the idea, with a pilot borehole thickening the ice shelf by 50 centimetres compared with a control site between January and May. Crucially, the results show that the technique triggered 25 cm of natural ice growth on the underside of the ice shelf. The method was first proposed by Steven Desch at Arizona State University and his colleagues in 2016. They estimated that deploying ice thickening over 10 per cent of the Arctic could more than reverse recent ice loss in the region. 'Our objective is to demonstrate that ice thickening can be effective in preserving and restoring Arctic sea ice,' Andrea Ceccolini, from Real Ice, previously told New Scientist. 'Every action we can take to make the ice last longer during the summer will give us extra weeks of solar radiation reflection back to space, which is less energy absorbed by the planet.' The scheme is one of 21 geo-engineering projects that will receive a total of £57 million in UK taxpayer money to assess a range of controversial techniques to curb the effects of global warming. The funding comes from the government's Advanced Research and Invention Agency (Aria). WHY DO POLAR BEARS NEED ICE TO SURVIVE? Loss of ice due to climate change has a direct impact on the ability of polar bears to feed and survive. The bears need platforms of ice to reach their prey of ringed and bearded seals. Some sea ice lies over more productive hunting areas than others. Arctic sea ice shrinks during the summer as it gets warmer, then forms again in the long winter. How much it shrinks is where global warming kicks in, scientists say. The more the sea ice shrinks in the summer, the thinner the ice is overall, because the ice is weaker first-year ice. But the Arctic has been warming twice as fast as the rest of the world. In some seasons, it has warmed three times faster than the rest of the globe, said University of Alaska at Fairbanks scientist John Walsh. In the summertime, polar bears go out on the ice to hunt and eat, feasting and putting on weight to sustain them through the winter. They prefer areas that are more than half covered with ice because it´s the most productive hunting and feeding grounds. From late fall until spring, mothers with new cubs den in snowdrifts on land or on pack ice. They emerge from their dens, with the new cubs, in the spring to hunt seals from floating sea ice. Simply put, if there isn't enough sea ice, seals can't haul out on the ice and polar bears can't continue to hunt. In recent years the sea ice has retreated so far offshore that the bears have been forced to drift on the ice into deep waters - sometimes nearly a mile deep - that are devoid of their prey.
