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Climate: Robotic gliders probe secrets of Southern Ocean

Detailed measurements to help pinpoint rate of ice shelf melt

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Melting Antarctica ice shelves are raising global sea level. bberwyn photo.

Staff Report

FRISCO — The Southern Ocean, surrounding Antarctica, is mostly separated from the rest of the world’s oceans by a sharp temperature boundary and swift currents. But the border between the different masses of water is regularly blurred by giant swirls of water that may be transporting warmer water to the edge of the frozen continent.

Knowing how that process works could help scientists understand how fast Antarctic ice shelves will melt and raise global sea level, according to Caltech scientists who used robotic gliders to track the movement of water in the region. Continue reading

Climate: Southern Ocean layering could lead to big Antarctica meltdown along with surge in sea level rise

‘The big question is whether the ice sheet will react to these changing ocean conditions as rapidly as it did 14,000 years ago’

The ice fields of Antarctica

The ice fields of Antarctica. bberwyn photo.

Staff Report

FRISCO — A stratification of the ocean around Antarctica could lead to more rapid melting of ice sheets, triggering a sudden surge in sea level rise. That last time that happened was well before the global warming era, about 14,000 years ago, but scientists are now seeing signs of a similar pattern.

A new study found that in the past, when ocean temperatures around Antarctica became more layered, with a warm layer of water below a cold surface layer,  ice sheets and glaciers melted much faster than when the cool and warm layers mixed more easily. This defined layering of temperatures is exactly what is happening now around the Antarctic.

“The reason for the layering is that global warming in parts of Antarctica is causing land-based ice to melt, adding massive amounts of freshwater to the ocean surface,” said ARC Centre of Excellence for Climate System Science researcher Prof Matthew England, an author of the paper, published in Nature Communications.

Continue reading

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How does the Southern Ocean regulate global climate?

Major research project to examine carbon cycling, circulation dynamics

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A new research project will help explain how the Southern Ocean helps regulate the global climate. bberwyn photo.

Staff Report

FRISCO — Even though it’s eparated from the rest of the world’s oceans by a strong circulation of currents and a distinct temperature gradient, the Southern Ocean is known to be a key driver of global climate and carbon cycles.

Climate researchers and oceanographers may soon know a lot more about the enigmatic ocean as they deploy hundreds of robotic floats deployed around Antarctica in a six-year, $21 million research project aimed at understanding ocean dynamics, chemistry and carbon cycling. The new instruments will increase the flow of Southern Ocean data 30-fold. Continue reading

Climate: Does the Southern Ocean hold the ice age key?

Abysmal waters play huge role in global carbon cycles

The water in the Antarctic Sound can be smooth as glass, and sometimes look thick and oily, probably because it's so cold. Click on the photo to learn about some of the environmental issues in Antarctica.

The water in the Antarctic Sound can be smooth as glass. bberwyn photo.

By Summit Voice

FRISCO — The remote Southern Ocean, encircling Antarctica, may be a key driver of the carbon cycle, inhaling and exhaling enough carbon to help shift the global climate in and out of ice ages.

For decades, scientists have been trying to figure out what exactly, along with the known wobbles in Earth’s journey around the sun, may cause the huge shifts that lead to vast ice sheets covering many of the planet’s land masses. Continue reading

Scientist find source of mysterious Southern Ocean sound

New data could help minke whale conservation efforts

A group of Antarctic minke whales. Photo courtesy Ari S. Friedlaender, Oregon State University

A group of Antarctic minke whales, which have been identified as the source of a mysterious sound in the Southern Ocean. Photo courtesy Ari S. Friedlaender, Oregon State University.

Staff Report

FRISCO — If you’ve ever heard mysterious sounds that you can’t identify, you’re not alone. For decades, researchers have tried to trace the source of a unique rhythmic sound in the remote Southern Ocean that’s often been recorded, but never definitively pinpointed — until now.

This week, scientists with NOAA’s Northeast Fisheries Science Center said the sound is generated by the Antarctic Minke whale, the smallest of the “great whales” or rorquals, a group that includes the blue whale, Bryde’s whale, and humpback, fin, and sei whales. Rorqual whales are relatively streamlined in appearance, have pointed heads and, with the exception of humpback whales, small pointed fins. Continue reading

Climate: Freshwater cap around Antarctica inhibiting natural upwelling of warmer water

Findings may help explain recent expansion of Antarctic sea ice

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Study shows impacts of increased precipitation over Southern Ocean. bberwyn photo.

Staff Report

FRISCO — Enhanced rainfall over the Southern Ocean may be blocking the release of relatively warm waters from the depths, researchers said this week in a study published in Nature Climate Change.

The research shows that salinity at the surface of the Southern Ocean has steadily decreased since the 1950s. This lid of fresh water on top of the ocean prevents mixing with the warm waters underneath. As a result, the deep ocean heat has been unable to get out and melt back the wintertime Antarctic ice pack. Continue reading

Unraveling the secrets of ocean waves

Satellite tracking helps researcher develop a formula to predict swell decay

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Surfers catch an evening wave at Half Moon Bay, Cailifornia, bberwyn photo.

By Summit Voice

FRISCO — Surfers have long tracked swells across thousands of miles of open ocean to try and predict when the best waves might hit their local beach, and new research by an Australian National University professor may help fine-tune those forecasts.

“Ocean cargo shipping, offshore oil and gas production, and even recreational activities such as surfing, are all dependent on wave action,” said Ian Young, vice-chancellor of ANU. “It is therefore critical that we are able to predict swell.”

Young, who is affiliated with the Research School of Earth Sciences, was interested in determining the rate at which ocean swells decay as they travel across the ocean, so he tracked them with orbiting satellites. The results showed that the decay of the swell depends on how steep the wave actually is.

“Steep waves decay very quickly. However, typical swell is not very steep and can travel across oceanic basins with only a relatively small loss of energy,” he said.

Over 200 individual cases were tracked, making this study the first to provide such comprehensive data of this decay.

“What we were able to do is track the swell from the satellite as it moved from the south to the north, some 1,400 kilometres. We only chose cases where there was no wind so that we could be confident that all we were measuring was the swell decay … We can take these results and put them into a mathematical formula that can be put straight into computer models used by national weather bureaus

“This will increase our ability to better predict wave action. As 70 per cent of the world’s oceans are dominated by swell, it’s extremely important to be able to predict them accurately,” he said.

It is estimated that 75 per cent of waves across the world are not actually generated by local winds. Instead, they are driven by distant storms which propagate as swell.

“For most of the Indian, Pacific and South Atlantic oceans, it is actually the weather in the Southern Ocean thousands of kilometres away that dominates the wave conditions … The Southern Ocean is dominated by big low pressure systems that move across it year round. These systems generate waves that then grow and can travel tens of thousands of kilometres from where they were actually formed, to crash on a beach in Australia.”

Professor Young’s research is published in the Journal of Physical Oceanography.

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