Navigation Links
New Nature study illuminates 55 million years of the carbon cycle and climate history
Date:8/30/2012

A study in the August 30 issue of Nature provides, in unprecedented detail, the history of a crucial indicator of the relationship between the carbon cycle and climate processes over the past 55 million years. Over this time period, when the Earth is known to have transitioned from "hothouse" to "icehouse" conditions, the oceans also experienced a dramatic shift in the carbonate compensation depth, or CCD. Defined as the depth below which carbonate minerals (such as calcite) dissolve completely, the CCD is known to fluctuate over time it shallows during warm periods, and deepens when ice age conditions prevail. Now, however, scientists have a detailed and quantifiable record of just how much the CCD has shifted during recent geological history.

The study, which relies on seafloor sediment cores collected during a pair of 2009 expeditions on board the JOIDES Resolution, demonstrates that 55 million years ago, the CCD of the Pacific Ocean sat at an average of about two miles (3.3-3.6 km) below the sea surface. As the Earth cooled, however, the CCD sank reaching its deepest point of almost three miles (4.8 km) between 13 and 11 million years ago. Today, the Pacific's CCD sits just less than three miles (4.5 km) deep, and is thought to be on the rise as a result of modern, human-induced climate change.

"Long-term change in CCD and changes in Earth's atmospheric carbon dioxide concentration both result from shifts in how carbon is cycled by earth processes," says study co-author Mitchell Lyle, a geoscientist at Texas A&M University who co-led the second of the two expeditions. "Adding geologic reserves of carbon into the oceans and atmosphere by burning coal or petroleum, for example causes oceans to become more acidic and causes the atmosphere and oceans to warm. This new CCD record is an important step toward understanding how the carbon system balances out over long time frames. "

The Pacific Ocean has remained the largest ocean on Earth for millions of years. Today, it covers one third of the planet's surface, and its biologically productive equatorial region plays a very important role in the global carbon cycle and long-term climate patterns. Over four months, the drilling vessel JOIDES Resolution operated by the U.S. Implementing Organization on behalf of the National Science Foundation (NSF) and the Integrated Ocean Drilling Program (IODP) drilled nearly four miles of core samples at eight different locations across the center of the Pacific basin.

"We often discuss global warming induced by man-made carbon dioxide. However, on geological timescales of millions of years, other processes determine the carbon cycle," says lead author Heiko Plike, a geoscientist at the University of Bremen who co-led the first expedition. Volcanoes are a major natural source of atmospheric carbon dioxide, while the weathering of carbonate rocks can remove the gas from the atmosphere. "The overall balance of these processes is reflected in the CCD," explains Plike.

In the Nature study, Plike, Lyle and their co-authors demonstrate that, in the equatorial Pacific, the CCD did not follow a one-way path to the depths as the planet cooled down. Rather, the data reveals five intervals in the "greenhouse" world (prior to 33 million years ago) during which the CCD fluctuated upwards and downwards in a range between 650 and 3,000 feet (200-900 m), and at least four more major excursions in the last 20 million years. "These events, which often mirror warming and cooling phases, persisted between 250,000 and one million years," Plike explains. They resulted from minor differences between how much calcium was added to the oceans by weathering versus how much carbon dioxide was added to the ocean-atmosphere system by volcanic eruptions. The cycling of carbon between the sea surface and deep ocean further complicated the situation.

"Understanding the processes that caused these CCD excursions will provide important new insights about how the carbon cycle and climate are linked," Lyle says. "And, they will help us better understand how and when the current spike in atmospheric carbon dioxide will eventually level out."


'/>"/>

Contact: Miyuki Otomo
miyukiotomo@iodp.org
81-367-013-189
Integrated Ocean Drilling Program Management International
Source:Eurekalert

Related biology news :

1. 15-year study: When it comes to creating wetlands, Mother Nature is in charge
2. Epigenetic signatures direct the repair potential of reprogrammed cells
3. Nature: Video reveals wave character of particles
4. 2012 ACMG Foundation/Signature Genomic Laboratories Travel Award winner announced
5. Stoneflies mapped across Ohio, with implications for water quality and nature conservation
6. Gene signature helps identify risk of relapse in lung cancer patients
7. Natures billion-year-old battery key to storing energy
8. Can natures beauty lift citizens from poverty?
9. Biosignatures distinguish between tuberculosis and sarcoidosis
10. Nature: Microscope looks into cells of living fish
11. Nature or nurture? It may depend on where you live
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:4/11/2017)... BEACH GARDENS, Fla. , April 11, 2017 ... identity management and secure authentication solutions, today announced ... contract by Intelligence Advanced Research Projects Activity (IARPA) ... for IARPA,s Thor program. "Innovation has ... onset and IARPA,s Thor program will allow us ...
(Date:4/11/2017)... -- NXT-ID, Inc. (NASDAQ:   NXTD ) ("NXT-ID" ... of independent Directors Mr. Robin D. Richards and ... furthering the company,s corporate governance and expertise. ... Gino Pereira , Chief Executive Officer ... guidance and benefiting from their considerable expertise as we move ...
(Date:4/5/2017)... YORK , April 5, 2017 Today ... is announcing that the server component of the HYPR ... known for providing the end-to-end security architecture that empowers ... HYPR has already secured over 15 million ... makers including manufacturers of connected home product suites and ...
Breaking Biology News(10 mins):
(Date:10/12/2017)... ... October 12, 2017 , ... ... Market with the addition of its newest module, US Hemostats & Sealants. , ... thrombin hemostats, absorbable hemostats, fibrin sealants, synthetic sealants and biologic sealants used in ...
(Date:10/11/2017)... , ... October 11, 2017 , ... ... gene in its endogenous context, enabling overexpression experiments and avoiding the use of ... small RNA guides is transformative for performing systematic gain-of-function studies. , This ...
(Date:10/11/2017)... , Oct. 11, 2017  VMS BioMarketing, a leading ... a nationwide oncology Clinical Nurse Educator (CNE) network, which will ... need for communication among health care professionals to enhance the ... nurses, office staff, and other health care professionals to help ... breast cancer. ...
(Date:10/11/2017)... Florida (PRWEB) , ... October 11, 2017 , ... ... Drug Administration (FDA) has granted orphan drug designation to SBT-100, its novel anti-STAT3 ... for the treatment of osteosarcoma. SBT-100 is able to cross the cell membrane ...
Breaking Biology Technology: