Oceanography

In oceanography studies, the iron needed to fertilize infrequent plankton blooms in High Nutrient, Low Chlorophyll (HNLC) regions was assumed to come almost entirely from wind-blown dust.

That's not the case in the North Pacific, say Phoebe Lam and James Bishop of the Earth Sciences Division at the Department of Energy's Lawrence Berkeley National Laboratory

They report that the key source of iron in the Western North Pacific is not dust but the volcanic continental margins of the Kamchatka Peninsula and the Kuril Islands.


From a site at 47 degrees north latitude and 160 degrees east longitude in the Western North Pacific (marked X), iron and manganese found at depths of 100-200 meters originated hundreds of miles away, from the continental shelves of the Kamchatka Peninsula and Kuril Islands. Particulate and dissolved iron and manganese hydroxides came from the upper shelf, and, after further processing, more iron (now poor in manganese) came from deeper on the slopes.

A new modeling approach using sea ice motion data to follow parcels of ice backward in time at monthly intervals for up to 3 years while accumulating a history of the solar radiation and air temperature to which the ice was exposed offers new hope for increased accuracy in climate change models, say scientists with the U.S. Geological Survey and the Russian Academy of Sciences, Moscow. This is the only model based entirely on historical observations.

Using this new technique, the thickness of Arctic sea ice was estimated from 1982 to 2003. Results showed that average ice thickness and total ice volume fluctuated together during the early study period, peaking in the late 1980s and then declining until the mid-1990s. Thereafter, ice thickness slightly increased but the total volume of sea ice did not increase.

A team of scientists from Cardiff University’s School of Earth and Ocean Sciences and Amgueddfa Cymru - National Museum Wales travelled to Africa to find new evidence of climate change which helps explain some of the mystery surrounding the appearance of the Antarctic ice sheet.

Ice sheet formation in the Antarctic is one of the most important climatic shifts in Earth’s history. However, previous temperature records show no evidence of the oceans cooling at this time, but instead suggest they actually warmed, presenting a confusing picture of the climate system which has long been a mystery in palaeoclimatology.

The rise of oxygen and the oxidation of deep oceans between 635 and 551 million years ago had an impact on the increase and spread of the earliest complex life, including animals, according to a study in PNAS.

The atmosphere had almost no oxygen until 2.5 billion years ago and it was not until about 600 million years ago that the atmospheric oxygen level rose to a fraction of modern levels. Geologists and evolutionary biologists have speculated that the rise of the breathing gas and subsequent oxygenation of the deep oceans are intimately tied to the evolution of modern biological systems.

Scientists from Commonwealth Scientific and Industrial Research Organisation (CSIRO) and Woods Hole Oceanographic Institution (WHOI)aboard the research vessel Southern Surveyor returned home today with a collection of coral samples and photographs taken in the Southern Ocean at greater depths than ever before.

Using a remotely operated submersible vehicle the international research team captured images of life found on deep-sea pinnacles and valleys up to three kilometres beneath the Ocean’s surface.

During a three-week voyage, scientists from CSIRO’s Wealth from Oceans National Research Flagship and the US collaborated to retrieve examples of live and fossilised deep-ocean corals from a depth of 1650 metres near the Tasman Fracture Zone, south-east of Tasmania.

Ice loss in Antarctica increased by 75 percent in the last 10 years due to a speed-up in the flow of its glaciers and is now nearly as great as that observed in Greenland, according to a new, comprehensive study by UC Irvine and NASA scientists.

In a first-of-its-kind study, an international team led by Eric Rignot, professor of Earth system science at UCI and a scientist with NASA’s Jet Propulsion Laboratory, Pasadena, Calif., estimated changes in Antarctica’s ice mass between 1996 and 2006 and mapped patterns of ice loss on a glacier-by-glacier basis. They detected a sharp jump in Antarctica’s ice loss, from enough ice to raise global sea level by 0.3 millimeters (.01 inches) a year in 1996, to 0.5 millimeters (.02 inches) a year in 2006.

In an PLoS ONE article, Joan B. Company and colleagues at the Institut de Ciències del Mar (CSIC) in Spain describe a mechanism of interaction across ecosystems showing how a climate-driven phenomenon originated in shelf environments controls the biological processes of a deep-sea living resource.

The progressive depletion of world fisheries is one of the key socio-economical issues of the forthcoming century. However, amid this worrying scenario, Company’s study demonstrates how a climate-induced phenomenon occurring at a decadal time-scale, such as the formation of dense shelf waters and its subsequent downslope cascading can repeatedly reverse the general trend of overexploitation of a deep-sea living resource.

Increasing amounts of ice mass have been lost from West Antarctica and the Antarctic peninsula over the past ten years, according to research from the University of Bristol and published online this week in Nature Geoscience.

Meanwhile the ice mass in East Antarctica has been roughly stable, with neither loss nor accumulation over the past decade.

Professor Jonathan Bamber at the University of Bristol and colleagues estimated the flux of ice from the ice sheet into the ocean from satellite data that cover 85% of Antarctica's coastline, which they compared with simulations of snow accumulation over the same period, obtained using a regional climate model.

The last fish you ate probably came from the Bering Sea. At present, the Bering Sea provides roughly half the fish caught in U.S. waters each year and nearly a third caught worldwide.

While the basic dynamics of a 'greenhouse ocean' are not well understood, marine ecologists writing in Marine Ecology Progress Series expressed concern that, if their predictions are true, a warming ocean would lead to a much different ecology there.

“All the fish that ends up in McDonald’s, fish sandwiches — that’s all Bering Sea fish,” said USC marine ecologist Dave Hutchins.

A new study by University of Colorado at Boulder researchers indicates older, multi-year sea ice in the Arctic is giving way to younger, thinner ice, making it more susceptible to record summer sea-ice lows like the one that occurred in 2007.

The team used satellite data going back to 1982 to reconstruct past Arctic sea ice conditions, concluding there has been a nearly complete loss of the oldest, thickest ice and that 58 percent of the remaining perennial ice is thin and only 2-to-3 years old, said the lead study author, Research Professor James Maslanik of CU-Boulder's Colorado Center for Astrodynamics Research.