Ecologists and oceanographers are attempting to predict the future impacts of climate change by reconstructing the past behavior of Arctic climate and ocean circulation.
In a November special issue of the journal Ecology, a group of scientists report that if current patterns of change in the Arctic and North Atlantic Oceans continue, alterations of ocean circulation could occur on a global scale, with potentially dramatic implications for the world's climate and biosphere.
"This research presents a compelling example of how climate change has altered marine ecosystems," said David Garrison, director of the National Science Foundation (NSF)'s Biological Oceanography Program, which funded the research. "It illustrates the value of basic research in understanding the underlying mechanisms and consequences of rapid climate change."
Charles Greene of Cornell University and colleagues reconstructed the patterns of climate change in the Arctic from the Paleocene epoch to the present.
Over these 65 million years, the Earth has undergone several major warming and cooling episodes, which were largely mitigated by the expansion and contraction of sea ice in the Arctic.
"When the Arctic cools and ice sheets and sea ice expand, the increased ice cover increases albedo, or reflectance of the sun's rays by the ice," says Greene, the lead author on the paper. "When more of the sun is reflected rather than absorbed, this leads to global cooling."
Likewise, when ice sheets and sea ice contract and expose the darker-colored land or ocean underneath, heat is absorbed, accelerating climate warming.
Currently, the Earth is in the midst of an interglacial period, characterized by retracted ice sheets and warmer temperatures.
In the past three decades, changes in Arctic climate and ice cover have led to several reorganizations of northern ocean circulation patterns.
Since 1989, a species of plankton native to the Pacific Ocean has been colonizing the North Atlantic Ocean, a feat that hasn't occurred in more than 800 thousand years. These plankton were carried across the Arctic Ocean by Pacific waters that made their way to the North Atlantic.
"When Arctic climate changes, waters in the Arctic can go from storing large quantities of freshwater to exporting that freshwater to the North Atlantic in large pulses, referred to as great salinity anomalies," Greene explains. "These GSAs flow southward, disrupting the ocean's circulation patterns and altering the temperature stratification observed in marine ecosystems."
In the continental shelf waters of the Northwest Atlantic, the arrival of a GSA during the early 1990s led to a major ecosystem reorganization, or regime shift. Some ocean ecosystems in the Northwest Atlantic saw major drops in salinity, increased stratification, an explosion of some marine invertebrate populations and a collapse of cod stocks.
"The changes in shelf ecosystems between the 1980s and 1990s were remarkable," says Greene. "Now we have a much better idea about the role climate had in this regime shift."
The changes observed in recent decades are only the tip of the iceberg. Previous interglacial periods have ended when the global ocean's deep circulation slowed in response to reductions in the formation of North Atlantic Deep Water, or NADW, a large, deep mass of highly saline water in the North Atlantic.
At these tipping points in the Earth's history, NADW formation was disrupted by pulses of freshwater entering the North Atlantic. The slowing of the global ocean's deep circulation results in less heat being transported to higher latitudes, accelerating ice formation and advancing the Earth into glacial conditions.
Recent modeling studies show that NADW formation will likely be resilient to freshwater pulses from the Arctic during the 21st century, according to the authors.
Continued exposure to such freshwater forcing, however, could disrupt global ocean circulation during the next century and lead to very abrupt changes in climate, similar to those that occurred at the onset of the last ice age.
"If the Earth's deep ocean circulation were to be shut down, many of the atmospheric, glacial and oceanic processes that have been stable in recent times would change, and the change would likely be abrupt," says Greene.
"While the ecosystem consequences of gradual changes in the ocean are somewhat predictable, all bets are off after such abrupt changes occur."
More than 20 dead in Russian nuclear sub accident
by Vera Negdanova VLADIVOSTOK, Russia (AFP) --
At least 20 people were killed and 22 injured in an accident on a Russian nuclear submarine in the Sea of Japan, the navy said Sunday, the worst such incident since the 2000 Kursk disaster.
The nuclear reactor that powers the submarine was not damaged in the accident and background radiation levels in the vicinity of the accident in a Russian naval testing zone were "normal," a naval spokesman said.
"During sea trials of a nuclear-powered submarine of the Pacific Fleet the firefighting system went off unsanctioned, killing over 20 people, including servicemen and workers," said Captain Igor Dygalo, the navy's spokesman.
The submarine was undergoing sea trials and the state RIA Novosti news agency said the tests were in preparation for planned delivery of the submarine to India. This however was not confirmed by officials.
The victims included both servicemen and shipyard workers aboard the submarine for the sea trials, Dygalo said. Officials said the dead comprised six sailors and 14 civilians.
The injured were evacuated from the stricken submarine aboard an accompanying ship and were taken to a hospital on shore where they were being treated, Pacific Fleet hospital officials said.
The submarine itself returned to the port of Bolshoi Kamen, site of a large refitting shipyard near Vladivostok, where the bodies of the dead were offloaded and sent to nearby morgues, a spokesman for the shipyard said.
A source with the Pacific Fleet's hospital in Vladivostok told AFP that the injured people evacuated from the submarine aboard a destroyer were suffering various degrees of poisoning.
Other sources, who requested anonymity, said an additional 20 people with less serious poisoning were being treated aboard another ship, the Sayany, which was escorting the submarine.
The accident occurred Saturday and Dygalo said President Dmitry Medvedev had been briefed on the situation by Defence Minister Anatoly Serdyukov and had ordered a "full and meticulous" investigation.
Dygalo did not identify the submarine involved and did not explain how the accidental activation of the ship's fire extinguishing system resulted in the casualties.
However, a source in the Amur shipyard administration named the submarine as the K-152 Nerpa, a nuclear-powered submarine of the Project 971 Shchuka-B type, or Akula-class by NATO classification, the RIA Novosti news agency reported.
In October officials from the Amur shipyard reported the launch of sea trials for the 8,140-tonne Nerpa, which was put into production in 1991.
The Nerpa was due to be leased to the Indian navy, with New Delhi reportedly paying two billion dollars for the lease of two Akula-class submarines, with an option of buying them when the lease runs out.
Federal investigators meanwhile on Sunday opened a criminal probe into the accident, Interfax news agency reported.
Dygalo told AFP that the submarine itself was not damaged and there was no radiation leakage from the vessel's reactor.
"I announce with full authority that the submarine's reactor compartment is functioning normally and that background radiation aboard the submarine is normal," Dygalo said.
A total of 208 people were aboard the submarine, but of those only 81 were servicemen while the others were naval technicians and specialists.
The toll of dead and injured made the weekend accident the worst involving a Russian submarine since the 2000 Kursk disaster, when 118 crewmen died when their nuclear submarine sank after an onboard explosion in the Barents Sea.
The Kremlin was harshly criticised at home and abroad for its sluggish and secretive response to the Kursk disaster, but seemed to be moving quickly to avoid a repetition this time.
Dygalo said Medvedev had ordered the defence ministry to provide "all possible aid and support to the victims' families."
Fire suppression systems on submarines may rely on chemical liquids. It was unclear however how the accidental activation of the system on the Russian sub resulted in the deaths and injuries.
In addition to the Kursk disaster in August 2000, Russia has seen a string of accidents and mishaps with its naval submarines.
Nine sailors died aboard a K-159 submarine when it sank in the Barents Sea in August 2003 while being towed to port for decommissioning. Only one seaman survived that incident.
In 2005, a mini-submarine of the Pacific Fleet got snared underwater in a fishing net, requiring the help of a British rescue team that arrived many hours later as its oxygen supplies were dwindling.
Thursday, November 6th, 2008
FR8 Venture was hit by huge waves killing two crewmembers working on deck in 2006.
A report by the Marine Accident Investigation Branch (MAIB) concerning the 2006 death of two sailors around Pentland Firth claims the ship’s master should have never left the safe harbor of Scapa Flow and should have delayed the sailing.
Ravindra Shrirang Bagal, 31, and Harjivan Bhikhabhal Kharva, 39, had been working on the deck of the tanker when they were hit by massive waves. The UK Coast Guard said the weather conditions were ‘horrendous’ and there were strong winds, heavy seas and huge swells. The two men were hit by massive waves and died of their injuries. A third crewmember was airlifted to the hospital where he eventually recovered.
The investigation identified safety issues, which included: The two large waves that came over the bow were not under any circumstances considered normal and waves this size should have been expected in the prevailing weather conditions. The master should have delayed the sailing.
Leaving the shelter of Scapa Flow before the foredecks were secured was the duty of the master. The crew should have been clear of the foredeck of the ship because there was little margin for error. The company should have had effective safety measures in place with an effective plan of action.
FR8 Shipmanagement PTE of Singapore reviewed all recommendations and has now set policy for all its ships. Navig8 Ship Management Pte, Ltd. is a shipping company. It controls a fleet of product tankers primarily for the oil products sector. The company trades a time-charter fleet; owns and invests in tonnage; manages vessels for third parties and for its own account; and acts as a cargo broker for oil traders; and trades in the freight derivatives market. Its products and services include ship owning, ship chartering, commercial management, technical management, cargo chartering, and risk management.
The company was founded in 2003 as FR8 Shipmanagment Pte, Ltd. and later changed its name to Navig8 Ship Management Pte, Ltd. in 2007. The company is based in Singapore, Singapore. It has offices in London and Mumbai, as well as in Singapore and the United States.
To read the MAIB Investigation report, click HERE