Subscribe free to our newsletters via your
. Earth Science News .

The role of oceanic carbon reservoir over glacial cycles
by Staff Writers
Beijing, China (SPX) Apr 17, 2014

File image.

Glacial cycles at 104-yr time scale have been the focus of Quaternary paleoclimatology over the last century. In recent years with the emergence of continuous high-resolution records (ice cores, deep-sea sediments etc.) from the longer geological past, increasing evidence underscores the significance of long- duration processes at the time scale of 105-yr or more.

WANG Pinxian and colleagues from the State Key Laboratory of Marine Geology, Tongji University, reviewed long-term variations in the oceanic carbon reservoir and indicated their crucial role in major climate regime changes over Quaternary glacial cycles. This work, entitled "Long-term cycles in the carbon reservoir of the Quaternary ocean: a perspective from the South China Sea", was published in National Science Review. 2014, Vol 1(1): 120-144.

A puzzling question in Quaternary paleoclimatology is why the interglacials are different, even with similar orbital parameters? The recent findings in the South China Sea offer a new clue for its solution.

In well preserved deep-sea sediment sections recovered by Ocean Drilling Program Leg 184 of the South China Sea in 1999, three long-term cycles (~500 kyr) in Pleistocene carbon isotope (d13C) sequence have been found and demonstrated to be common in the global ocean. Because carbon has a residence time of 105-yr in the ocean, the long-term cycles are best represented by oceanic d13C.

Before the Pleistocene, the oceanic d13C sequences display a 400-kyr signal related to the long-eccentricity of orbital forcing, with carbon isotope maximum events (d13Cmax) occurring at the eccentricity minimum. The long eccentricity 400-kyr cycles of d13C can be hypothetically explained by changes in ratio between particulate and dissolved organic carbon (POC/DOC) in the ocean, depending on the monsoon-controlled nutrient supply. After 1.6 Ma, however, the 400-kyr cycle in d13C is obscured.

The d13C maxima are out of phase with the eccentricity signal, extending the periodicity to ~500-kyr(Fig.1). The paper explains that the ocean restructuring at 1.6 Ma marked by the isolation of a sluggish abyss under the Southern Ocean could have disturbed the long eccentricity rhythm in the oceanic carbon reservoir and extended the 400-kyr cyclicity of d13C.

Interestingly, long-term processes of 105-yr exist also in the hydrological (ice sheet changes) cycles. The last million-year period has experienced two major changes in the climate regime, namely the mid-Pleistocene transition (MPT, centered at 0.9 Ma) and mid-Brunhes event (MBE, at 0.4 Ma).

The MPT represents intensification and prolongation of the glacial /interglacial cycles from 41- to 100-kyr frequencies, while the MBE is considered as a critical period of transition to enhanced amplitudes of glacial/interglacial cycles. Thus, the South China Sea records reveal that long-term processes in ice-sheet and carbon cycles are connected.

As seen from Figure 2, the MPT and MBE were preluded by d13C max-III~1.0 Ma and d13Cmax-II ~0.5 Ma, respectively, and both the d13Cmax events were in turn prefaced by unusually warm interglacials in the Antarctic region. The causal link between these long-term processes remains unclear, but one of the crucial mechanisms could be the nutrient transfer from the Southern Ocean northward, which led to major changes in the biological pump of the global ocean.

The paper concludes that the long-term biogeochemical processes originating from the Southern Ocean must have played a crucial role in ice-sheet waxing and waning, and the major environmental events in the Quaternary comprise a continuing chain of events that remain a largely ignored aspect in climate studies.

Long-term cycles in the carbon reservoir of the Quaternary ocean: a perspective from the South China Sea


Related Links
Science China Press
Beyond the Ice Age

Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks DiggDigg RedditReddit GoogleGoogle

Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

New technology helps paleontologists see Ice-Age bee in intricate detail
Los Angeles (UPI) Apr 14, 2013
Scientists in California recently used CT scanning technology to capture remarkably detailed photos of an Ice Age bee, preserved in a nest of ancient leaves. The Megiachile gentiles specimen - a species of bee that's still alive today - was first excavated from Los Angeles' La Brea tar pits in the 1970s, but the fossil was too delicate to be investigated by hand. So it was set aside. ... read more

Malaysia vows to be transparent with 'black box' data

Solomons flood victims 'terrified' after quakes

Survey finds majority of Malaysians distrust govt on MH370

Mini-sub to dive again after aborting first MH370 search

Vanguard Space Technologies Antenna Reflectors on Amazonas Satellite Launch

Middle Eastern country orders more border radar

Headwall Extends Global Reach in Asia/Pac and Israel

A new twist for better steel

Mini-sub deploys to scour ocean depths in MH370 hunt

Uncharted depths provide reality check for MH370 hunt

Reef fish arrived in two waves

A small coral-eating worm may mean big trouble for reefs

Growth of Antarctic ice sheet triggered warming in the Southern Ocean during Miocene

New technology helps paleontologists see Ice-Age bee in intricate detail

Canada boycotts Arctic Council meeting in Moscow

La Brea Tar Pit fossil research shows climate change drove evolution of Ice Age predators

Climate: Farming emissions to rise 30% by 2050

Oyster aquaculture could significantly improve Potomac River estuary water quality

Danone says China recall weighs on first-quarter sales

GM crops under the microscope at international debate

Increase in activity at DRC's Nyamulagira volcano

Magnitude 7.5 quake strikes off Solomon Islands: USGS

Cyclone warning lifted on Australia's Barrier Reef coast

Death toll rises to 23 in Solomons floods

Obama to meet Djibouti President on May 5

Campaigning conservationist shot in DR Congo

US Marines headed to Chad park to fight poaching

Top Nigerian Islamic body accuses military over Muslim deaths

Researchers say Neanderthals were no strangers to good parenting

Evolution explains facial hair trends

New method confirms humans and Neandertals interbred

Indigenous societies' 'first contact' typically brings collapse, but rebounds are possible

The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.