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 Climate satellite: Tracking methane with robust laser technology
22.06.2017 | Fraunhofer-Gesellschaft

nachricht How reliable are shells as climate archives?
21.06.2017 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>