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 Atmospheric pressure impacts greenhouse gas emissions from leaky oil and gas wells
21.10.2019 | University of British Columbia

nachricht Strong storms generating earthquake-like seismic activity
16.10.2019 | Florida State University

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Solving the mystery of quantum light in thin layers

A very special kind of light is emitted by tungsten diselenide layers. The reason for this has been unclear. Now an explanation has been found at TU Wien (Vienna)

It is an exotic phenomenon that nobody was able to explain for years: when energy is supplied to a thin layer of the material tungsten diselenide, it begins to...

Im Focus: An ultrafast glimpse of the photochemistry of the atmosphere

Researchers at Ludwig-Maximilians-Universitaet (LMU) in Munich have explored the initial consequences of the interaction of light with molecules on the surface of nanoscopic aerosols.

The nanocosmos is constantly in motion. All natural processes are ultimately determined by the interplay between radiation and matter. Light strikes particles...

Im Focus: Shaping nanoparticles for improved quantum information technology

Particles that are mere nanometers in size are at the forefront of scientific research today. They come in many different shapes: rods, spheres, cubes, vesicles, S-shaped worms and even donut-like rings. What makes them worthy of scientific study is that, being so tiny, they exhibit quantum mechanical properties not possible with larger objects.

Researchers at the Center for Nanoscale Materials (CNM), a U.S. Department of Energy (DOE) Office of Science User Facility located at DOE's Argonne National...

Im Focus: Novel Material for Shipbuilding

A new research project at the TH Mittelhessen focusses on the development of a novel light weight design concept for leisure boats and yachts. Professor Stephan Marzi from the THM Institute of Mechanics and Materials collaborates with Krake Catamarane, which is a shipyard located in Apolda, Thuringia.

The project is set up in an international cooperation with Professor Anders Biel from Karlstad University in Sweden and the Swedish company Lamera from...

Im Focus: Controlling superconducting regions within an exotic metal

Superconductivity has fascinated scientists for many years since it offers the potential to revolutionize current technologies. Materials only become superconductors - meaning that electrons can travel in them with no resistance - at very low temperatures. These days, this unique zero resistance superconductivity is commonly found in a number of technologies, such as magnetic resonance imaging (MRI).

Future technologies, however, will harness the total synchrony of electronic behavior in superconductors - a property called the phase. There is currently a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International Symposium on Functional Materials for Electrolysis, Fuel Cells and Metal-Air Batteries

02.10.2019 | Event News

NEXUS 2020: Relationships Between Architecture and Mathematics

02.10.2019 | Event News

Optical Technologies: International Symposium „Future Optics“ in Hannover

19.09.2019 | Event News

 
Latest News

Fraunhofer LBF and BAM develop faster procedure for flame-retardant plastics

21.10.2019 | Materials Sciences

For EVs with higher range: Take greater advantage of the potential offered by lightweight construction materials

21.10.2019 | Materials Sciences

Benefit and risk: Meta-analysis draws a heterogeneous picture of drug-coated balloon angioplasty

21.10.2019 | Medical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>