Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Geologists Create 5-Million-Year Climate Record

10.04.2006


Brown University geologists have created the longest continuous record of ocean surface temperatures, dating back 5 million years. The record shows slow, steady cooling in the eastern equatorial Pacific, a finding that challenges the notion that the Ice Ages alone sparked a global cooling trend. Results are published in Science.

Using chemical clues mined from ocean mud, Brown University researchers have generated the longest continuous record of ocean temperatures on Earth.

The 5-million-year record is a history of temperatures in the eastern equatorial Pacific, or EEP, located off the coast of South America. The area is an anomaly – a huge swath of cool water in the tropics – that plays an important role in global climate. In the EEP, trade winds pull nutrient-rich cold water to the surface, which makes for fertile fisheries off the coasts of Peru, Chile and Ecuador. The interplay of wind and water can also fuel El Niño events, a large-scale warming in the EEP that slows the upwelling of cold water and forces changes in weather, such as droughts or floods, far from the tropical Pacific.



In the EEP, the Brown geology team found that surface temperatures were 27° C 5 million years ago. Surface temperatures are 23° C today. In between, they found a pattern of steady cooling – roughly one degree Celsius every million years.

This finding, published in Science, contradicts the long-standing notion that rapid glacier growth in the high northern latitudes about 3 million years ago alone set off dramatic cooling of the global climate. The finding shows instead that glaciation was part of a long-term cooling trend.

The climate record suggests that ocean regions near Antarctica were the main driver of EEP cooling by continuously pumping cold water into the area. This finding was bolstered by additional evidence that glacial cycles affected the tropical Pacific long before the advent of large ice sheets in the Northern Hemisphere.

“The Southern Hemisphere, not the Northern Hemisphere, more likely had a stronger effect on temperature and productivity in the eastern Pacific,” said Kira Lawrence, a graduate student in the Department of Geological Sciences and the lead author of the Science paper. “We may need to refocus where we look to understand the evolution of climate over the past 5 million years.”

Lawrence, post-doctoral research fellow Zhonghui Liu, and Professor Tim Herbert used sediment cores pulled from hundreds of meters below the surface of the Pacific by a ship operated by the Ocean Drilling Program, an international research organization. Moving down the cores, collecting small samples of gray mud, scientists can go back in time. The end result: Thousands of glass vials filled with climate history.

But how do you extract history from mud? The answer was found in tiny marine fossils.

To date the sediments, the geologists analyzed fossils and traces of oxygen trapped in the shells of microscopic ocean organisms. To get temperatures, the Brown team looked to algae, infinitesimal surface-dwellers that produce fatty compounds called alkenones. Algae crank out two kinds of alkenones depending on the surrounding water temperature. When water is cooler, algae make more of one kind. When water is warmer, they produce more of another. By carefully measuring the amount of these alkenones in each sample, researchers were able to calculate past surface temperatures.

The resulting 5-million-year timeline might have a practical use. Scientists trying to predict future climate change may use the data in computer simulations that model natural climate variability as well as predict the impact of accelerated warming due to greenhouse gas emissions.

Herbert said the work has other implications for understanding climate change.

“Results from the past prove that it is possible for the EEP to exist in a kind of permanent El Niño state, which would have immense climate and biological repercussions if it were to happen again under global warming,” Herbert said. “The geological evidence also suggests that to predict warming in the EEP, the key ocean region to monitor is near Antarctica.”

The National Science Foundation and the Geological Society of America funded the work.

Wendy Lawton | EurekAlert!
Further information:
http://www.brown.edu

More articles from Earth Sciences:

nachricht New studies increase confidence in NASA's measure of Earth's temperature
24.05.2019 | NASA/Goddard Space Flight Center

nachricht New Measurement Device: Carbon Dioxide As Geothermometer
21.05.2019 | Universität Heidelberg

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: New studies increase confidence in NASA's measure of Earth's temperature

A new assessment of NASA's record of global temperatures revealed that the agency's estimate of Earth's long-term temperature rise in recent decades is accurate to within less than a tenth of a degree Fahrenheit, providing confidence that past and future research is correctly capturing rising surface temperatures.

The most complete assessment ever of statistical uncertainty within the GISS Surface Temperature Analysis (GISTEMP) data product shows that the annual values...

Im Focus: The geometry of an electron determined for the first time

Physicists at the University of Basel are able to show for the first time how a single electron looks in an artificial atom. A newly developed method enables them to show the probability of an electron being present in a space. This allows improved control of electron spins, which could serve as the smallest information unit in a future quantum computer. The experiments were published in Physical Review Letters and the related theory in Physical Review B.

The spin of an electron is a promising candidate for use as the smallest information unit (qubit) of a quantum computer. Controlling and switching this spin or...

Im Focus: Self-repairing batteries

UTokyo engineers develop a way to create high-capacity long-life batteries

Engineers at the University of Tokyo continually pioneer new ways to improve battery technology. Professor Atsuo Yamada and his team recently developed a...

Im Focus: Quantum Cloud Computing with Self-Check

With a quantum coprocessor in the cloud, physicists from Innsbruck, Austria, open the door to the simulation of previously unsolvable problems in chemistry, materials research or high-energy physics. The research groups led by Rainer Blatt and Peter Zoller report in the journal Nature how they simulated particle physics phenomena on 20 quantum bits and how the quantum simulator self-verified the result for the first time.

Many scientists are currently working on investigating how quantum advantage can be exploited on hardware already available today. Three years ago, physicists...

Im Focus: Accelerating quantum technologies with materials processing at the atomic scale

'Quantum technologies' utilise the unique phenomena of quantum superposition and entanglement to encode and process information, with potentially profound benefits to a wide range of information technologies from communications to sensing and computing.

However a major challenge in developing these technologies is that the quantum phenomena are very fragile, and only a handful of physical systems have been...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

 
Latest News

On Mars, sands shift to a different drum

24.05.2019 | Physics and Astronomy

Piedmont Atlanta first in Georgia to offer new minimally invasive treatment for emphysema

24.05.2019 | Medical Engineering

Chemical juggling with three particles

24.05.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>