Dissolved oxygen level in world oceans declining

A new analysis of decades of data on oceans across the globe has revealed that the amount of dissolved oxygen contained in the water – an important measure of ocean health – has been declining for more than 20 years.

Researchers at Georgia Institute of Technology looked at a historic dataset of ocean information stretching back more than 50 years and searched for long term trends and patterns. They found that oxygen levels started dropping in the 1980s as ocean temperatures began to climb.

“The oxygen in oceans has dynamic properties, and its concentration can change with natural climate variability,” said Taka Ito, an associate professor in Georgia Tech’s School of Earth and Atmospheric Sciences who led the research. “The important aspect of our result is that the rate of global oxygen loss appears to be exceeding the level of nature’s random variability.”

The study, which was published April in Geophysical Research Letters, was sponsored by the National Science Foundation and the National Oceanic and Atmospheric Administration. The team included researchers from the National Center for Atmospheric Research, the University of Washington-Seattle, and Hokkaido University in Japan.

Falling oxygen levels in water have the potential to impact the habitat of marine organisms worldwide and in recent years led to more frequent “hypoxic events” that killed or displaced populations of fish, crabs and many other organisms.

Researchers have for years anticipated that rising water temperatures would affect the amount of oxygen in the oceans, since warmer water is capable of holding less dissolved gas than colder water. But the data showed that ocean oxygen was falling more rapidly than the corresponding rise in water temperature.

“The trend of oxygen falling is about two to three times faster than what we predicted from the decrease of solubility associated with the ocean warming,” Ito said. “This is most likely due to the changes in ocean circulation and mixing associated with the heating of the near-surface waters and melting of polar ice.”

The majority of the oxygen in the ocean is absorbed from the atmosphere at the surface or created by photosynthesizing phytoplankton. Ocean currents then mix that more highly oxygenated water with subsurface water. But rising ocean water temperatures near the surface have made it more buoyant and harder for the warmer surface waters to mix downward with the cooler subsurface waters. Melting polar ice has added more freshwater to the ocean surface – another factor that hampers the natural mixing and leads to increased ocean stratification.

“After the mid-2000s, this trend became apparent, consistent and statistically significant — beyond the envelope of year-to-year fluctuations,” Ito said. “The trends are particularly strong in the tropics, eastern margins of each basin and the subpolar North Pacific.”

In an earlier study, Ito and other researchers explored why oxygen depletion was more pronounced in tropical waters in the Pacific Ocean. They found that air pollution drifting from East Asia out over the world’s largest ocean contributed to oxygen levels falling in tropical waters thousands of miles away.

Once ocean currents carried the iron and nitrogen pollution to the tropics, photosynthesizing phytoplankton went into overdrive consuming the excess nutrients. But rather than increasing oxygen, the net result of the chain reaction was the depletion oxygen in subsurface water.

That, too, is likely a contributing factor in waters across the globe, Ito said.

— source rh.gatech.edu

Nuclear Plants Forced to Cut Output Due to Warm Weather

Sweden’s top nuclear power generators have been forced to cut output because of exceptionally warm weather in Scandinavia, and their output could be reduced for over a week, their operators said on Wednesday. Oskarshamn, part of Germany’s E.ON and Forsmark, operated by Swedish utility Vattenfall have both cut output because warm sea water temperatures are limiting their ability to cool down. For each degree above 23 decrees Celsius in the cooling water, each unit has to decrease power by 3 percent. If sea temperatures reach 26 degrees, block 3 has to be shut, while at 28 degrees, the other two have to be closed as well, a Vattenfall spokesman said. Sea temperatures are currently around 22-23 degrees, according to the Swedish weather service.

— source scientificamerican.com 2014

A crucial crack in an Antarctic ice sheet grew 11 miles in only 6 days

The widening rift in the Larsen C ice shelf in West Antarctica has reached a (relative, for ice) fever pitch in the past few months, stretching for more than 110 miles and gaping more than 1,000 feet across. In just the last couple of days, the crack grew another 11 miles and took a sharp right turn toward the sea. It now ends a mere eight miles from totally breaking through, according to observations from ice-monitoring mission Project Midas. Floating ice shelves like Larsen C hold back the flow of ice sheets and glaciers into the sea, meaning the entire West Antarctic Ice Sheet is about to get more unstable.

— source grist.org

Arctic stronghold of world’s seeds flooded after permafrost melts

It was designed as an impregnable deep-freeze to protect the world’s most precious seeds from any global disaster and ensure humanity’s food supply forever. But the Global Seed Vault, buried in a mountain deep inside the Arctic circle, has been breached after global warming produced extraordinary temperatures over the winter, sending meltwater gushing into the entrance tunnel.

soaring temperatures in the Arctic at the end of the world’s hottest ever recorded year led to melting and heavy rain, when light snow should have been falling. “It was not in our plans to think that the permafrost would not be there and that it would experience extreme weather like that,” said Hege Njaa Aschim, from the Norwegian government, which owns the vault.

— source theguardian.com

yes. we dont know nature completely. until all people are equal, do not play with nature. once we are all equal then its ok. Vault are not solution.