Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

U. of Colorado study shows massive CO2 burps from ocean to atmosphere at end of last ice age

14.05.2007
A University of Colorado at Boulder-led research team tracing the origin of a large carbon dioxide increase in Earth's atmosphere at the end of the last ice age has detected two ancient "burps" that originated from the deepest parts of the oceans.

The new study indicated carbon that had built up in the oceans over millennia was released in two big pulses, one about 18,000 years ago and one 13,000 years ago, said Thomas Marchitto and Scott Lehman of CU-Boulder's Institute of Arctic and Alpine Research, who jointly led the study. While scientists had long known as much as 600 billion metric tons of carbon were released into the atmosphere after the last ice age, the new study is the first to clearly track CO2 from the deep ocean to the upper ocean and atmosphere and should help scientists better understand natural CO2 cycles and possible impacts of human-caused climate change.

"This is some of the clearest evidence yet that the enormous carbon release into the atmosphere during the last deglaciation was triggered by abrupt changes in deep ocean circulation," said Marchitto. Marchitto and Lehman are both faculty members in the CU-Boulder geological sciences department.

While much of the CO2 released by the oceans after the end of the last ice age about 19,000 years ago was taken up by the re-growth of forests in areas previously covered by ice sheets, enough remained in the atmosphere to pump up CO2 concentrations significantly, the authors said. Today, CO2 levels are higher than at any time in at least the past 650,000 years because of increased fossil fuel burning.

"The timing of the major CO2 release after the last ice age corresponds closely with deep-sea circulation changes caused by ice melting in the North Atlantic at that time," said Lehman. "So our study really underscores ongoing concerns about the ocean's capacity to take up fossil fuel CO2 in the future, since continued warming will almost certainly impact the mode and speed of ocean circulation."

The team analyzed sediment cores hauled from the Pacific Ocean seafloor at a depth of about 2,300 feet off the coast of Baja California using an isotopic "tracer," known as carbon 14, to track the escape of carbon from the deep sea through the upper ocean and into the atmosphere during the last 40,000 years. Extracted from the shells of tiny marine organisms known as foraminifera -- which contain chemical signatures of seawater dating back tens of thousands of years -- carbon 14 is the isotope most commonly used to radiocarbon date organic material like wood, bone and shell.

They found the carbon 14 "age" of the upper ocean water was basically constant over the past 40,000 years, except during the interval following the most recent ice age, when atmospheric CO2 increased dramatically. The study shows the carbon added to the upper ocean and atmosphere at the end of the last ice age was "very old," suggesting it had been stored in the deep ocean and isolated from the atmosphere for thousands of years, said Marchitto.

"Because carbon 14 works both as a 'tracer' and a 'clock,' we were able to show that the uptake and release of CO2 by the ocean in the past was intimately linked to how and how fast the ocean circulated," said Marchitto.

Humans have pumped an estimated 300 billion tons of carbon into the atmosphere since the Industrial Revolution, and the oceans have taken up about half of it, said Lehman.

"If the oceans were not such a large storage 'sink' for carbon, atmospheric CO2 increases in recent decades would be considerably higher," he said. "Since the uptake of CO2 on Earth's land surface is being offset almost entirely by the cutting and burning of forests, any decrease in the uptake of fossil fuel CO2 by the world's oceans could pose some very serious problems," Lehman said.

"When the ocean circulation system changes, it alters how carbon-rich deep water rises to the surface to release its carbon to the atmosphere," said Interim Director of INSTAAR Jim White, a climate scientist who was not involved in the study. "This is important not only for understanding why glacial times came and went in the past, but it is crucial information we need to understand how the oceans will respond to future climate change."

Studies by CU-Boulder and other institutions in the past several years have shown sharp declines in Arctic sea ice in recent decades and a loss in ice mass from Greenland, which some believe could combine to alter North Atlantic circulation and disrupt ocean circulation patterns worldwide.

Thomas Marchitto | EurekAlert!
Further information:
http://www.colorado.edu

More articles from Earth Sciences:

nachricht How much biomass grows in the savannah?
16.02.2017 | Friedrich-Schiller-Universität Jena

nachricht Canadian glaciers now major contributor to sea level change, UCI study shows
15.02.2017 | University of California - Irvine

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>