Oceanography

Are they landing marks for aliens? Craters from World War II bombs? The first pictures, which appeared in 2008 after being taken by a tourist, showed some strange circular formations in the shallow waters off the famous white cliffs of chalk on the island Møn in Denmark. And then they disappeared. In 2011, the circles came back, and this time there were so many that they made it into media stories. Since those first images appeared, people have searched for an explanation.  Researchers from the University of Southern Denmark and University of Copenhagen say the mystery is solved.…

A group of researchers say they have established a new biomarker for how stressed polar bears are about climate change.     Last year, a team reported that fluctuations in climate and ice cover are closely related to stress among polar bears in East Greenland as indicated by levels of the stress hormone cortisol in hair samples. The team is hopeful this type of analysis will be beneficial once others learn that it can now be done with much greater reliability. "Nobody else has done this so far," says Jerrold Meyer of the University of Massachusetts Amherst, who calls himself a…

Near the center of Antarctica, measurements from CryoSat - which exists to make comprehensive measurements of the polar regions in an unusually high-inclination orbit and latitudes of 88° north and south -  have detected an unusual pattern in the ice sheet’s elevation.  CryoSat carries a radar altimeter that can ‘see’ through clouds and in the dark, providing continuous measurements over areas like central Antarctica that are prone to bad weather and long periods of darkness.  The radar measures the surface height variation of ice by timing the interval between the…

Marine cyanobacteria are tiny ocean plants that produce oxygen and make organic carbon using sunlight and CO2, and so they are primary engines of Earth's biogeochemical and nutrient cycles. They nourish other organisms through the provision of oxygen and with their own body mass, which forms the base of the ocean food chain. Researchers have discovered a new benefit of these tiny cells: Cyanobacteria continually produce and release vesicles, spherical packages containing carbon and other nutrients that can serve as food parcels for marine organisms. The vesicles also contain DNA, likely…

Pine Island Glacier is one of the biggest routes for ice to flow from Antarctica into the sea and the floating ice shelf at the glacier's tip has been melting and thinning for the past four decades, causing the glacier to speed up and discharge more ice. It's been a key factor in estimates for sea level rise in a warming world but it turns out that the ice shelf melting depends on the local wind direction, which is tied to tropical changes associated with El Nino. The Pine Island ice shelf seems to have thinned nearly continuously, though observations only began in the 1970s. Earlier studies…

An international team of scientists predicts that seafloor dwelling marine life will decline by up to 38 percent in the North Atlantic and over five percent globally over the next century, due to global warming. The changes will be driven by a reduction in the plants and animals that live at the surface of the oceans that feed deep-sea communities. As a result, ecosystem services such as fishing will be threatened.  Even the most remote deep-sea ecosystems are not safe from the impacts of climate change, their numerical model found. In the study, led by the National Oceanography Centre…

A new aquifer in the Greenland Ice Sheet holds liquid water all year long in the otherwise perpetually frozen winter landscape. And it's big - 27,000 square miles.  The reservoir is a "perennial firn aquifer" because water persists within the firn; layers of snow and ice that don't melt for at least one season. Researchers believe it figures significantly in understanding the contribution of snowmelt and ice melt to sea levels.  The Greenland Ice Sheet is vast, covering roughly the same area as the states of California, Nevada, Arizona, New Mexico, Colorado and Utah combined. The…

There has been a snowfall decrease in Canada's subarctic regions and that has led to worrisome desiccation of the regions' lakes - this has happened in the past also, of course, but it was less noticeable.  Researchers came to this conclusion after studying 70 lakes near Old Crow, Yukon, and Churchill, Manitoba. Most of the lakes studied are less than one metre deep. According to the analysis, more than half of those located on relatively flat terrain and surrounded by scrubby vegetation show signs of desiccation. The problem stems chiefly from a decline in meltwater; for instance, from…

Basic ocean conditions such as current directions and water temperature play a huge role in determining the behavior of young migrating salmon as they move from rivers and hit ocean waters for the first time -  and how the fish fare during their first few weeks in the ocean has a profound impact on species' ability to survive into adulthood. After their birth in fresh water, salmon migrate to the ocean, where they must quickly adapt to an environment unlike anything they've experienced before – deep water full of new predators, with strong currents and competition from all sides. The…

Climate understanding of the past is based primarily on ice cores.  By studying information about Earth's climate and greenhouse gases  in past, scientists can understand better how temperature responds to changes in greenhouse-gas concentrations in the atmosphere and make better predictions about how climate will change in the future.  Researcher have now identified regions in Antarctica they say could store information from as far back as 1.5 million years, almost twice as old as the oldest ice core drilled to date.  "Ice cores contain little air bubbles and, thus,…