Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists study ocean to understand global cooling

07.01.2005


The depth in the ocean where calcium carbonate dissolves at a faster rate than it is deposited is called the calcite compensation depth (CCD). At present this depth is approximately 4,500 meters (14,700 feet) with some variation between and within ocean basins. Because the CCD is linked to ocean acidity, which is, in turn, linked to atmospheric carbon dioxide concentrations and, hence, to global climate, it is important for scientists to understand the impact of possible changes in its depth.

In the current issue of Nature, URI Graduate School of Oceanography (GSO) visiting scientist Helen Coxall describes how the deepening of the CCD in the Pacific Ocean correlated to global cooling approximately 34 million years ago, when the first significant permanent ice sheets appeared on Antarctica. Other members of the scientific team include Paul Wilson, Southampton Oceanography Center, UK, Heiko Pälike and Jan Backman, University of Stockholm, Sweden, and Caroline H. Lear, Rutgers University, New Jersey.

"This event 34 million years ago marks the transition from a warm ’greenhouse’ climate state, when atmospheric carbon dioxide levels were naturally high and there was no or very little ice at the poles, to the cold glaciated climate state of the modern world that was characterized by lower carbon dioxide," said Coxall. "It is therefore equivalent to global warming in reverse. The results of our study are crucial to the understanding of how climate change works, especially how rapidly major changes in ice-sheet growth and sea level rise and fall occur under altered conditions of atmospheric carbon dioxide."



Coxall and her colleagues analyzed sediment records and found that the deepening of the CCD was more rapid than previously documented and occurred in two jumps of about 40,000 years each, in step with the onset of Antarctic ice-sheet growth. The 40,000-year interval was separated by a plateau of 200,000 years.

The glaciation began after the Earth entered a cooler phase during an interval when the Earth’s orbit of the Sun favored cool summers. The researchers’ observations suggest that it was the prolonged absence of warm summers, inhibiting summer snow melt, not the occurrence of cool winters favoring accumulation, that was important for establishing the first major ice sheets on Antarctica. Although the pattern of Earth’s orbital configuration was the ultimate trigger for creating conditions that led to ice-sheet growth, a natural long-term decrease in atmospheric carbon dioxide levels, which promoted global cooling, was responsible for increasing Earth’s sensitivity to this factor.

In addition, analysis of the data indicates that along with the growth of the Antarctic ice sheet, glaciation in the Northern Hemisphere must also have been taking place.

Lisa Cugini | EurekAlert!
Further information:
http://www.gso.uri.edu

More articles from Ecology, The Environment and Conservation:

nachricht Scientists produce a new roadmap for guiding development & conservation in the Amazon
09.12.2016 | Wildlife Conservation Society

nachricht Successful calculation of human and natural influence on cloud formation
04.11.2016 | Goethe-Universität Frankfurt am Main

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

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

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>