Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The tropics play a more active role than was thought in controlling the Earth’s climate

12.10.2005


One million years ago a change in the tropics made the northern hemisphere ice masses expand



Researchers from the Universitat Autònoma de Barcelona and Durham University (UK) have discovered that a million years ago, global climate changes occurred due to changes in tropical circulation in the Pacific similar to those caused by El Niño today. Changes in atmospheric circulation caused variations in heat fluxes and moisture transport, triggering a large expansion of the polar ice sheets and a reorganisation of the Earth’s climate. The discovery, published in Geology, shows that local climate changes in the tropics can create more global climate changes, and emphasises the hypothesis that the tropics play a more active role than was thought in controlling the Earth’s climate.

The planet enters and leaves glacial periods approximately every 100,000 years. However, a million years ago these cycles lasted only 40,000 years. Scientists have reconstructed the chain of climatic events that brought about a change in the frequency of glacial periods and that occurred alongside changes in sea temperatures in the Pacific Ocean and alongside significant changes to tropical climates. The researchers have worked mainly with data obtained from the remains of marine organisms that have accumulated over time in the tropical Pacific. These fossil records show that approximately 1.2 million years ago, the difference in sea temperatures between the East and West Pacific began changing gradually over the course of 400,000 years. In the equatorial regions surrounding Central America, the sea cooled; while around Indonesia, sea temperatures barely changed. This caused changes in atmospheric circulation, creating what is now known as the Walker circulation.


According to the researchers, these changes to tropical atmospheric circulation caused a change in heat fluxes and moisture transport to the polar regions. This brought about an increase in snowfall, enabling the ice sheets, particularly in the northern hemisphere, to expand and change in the frequency of glacial periods from 40,000 to 100,000 years. Until now this expansion was thought to have been influenced only by the ice sheets themselves and by the ocean currents and the atmospheric circulation at high altitude in the northern hemisphere, as well as by CO2 levels in the atmosphere. "Our results show that local climatic changes in the tropics can produce global changes," stated Antoni Rosell of the UAB, one of the authors of the research. "We are seeing that the tropics play a more active role than was thought in controlling the Earth’s climate".

The two researchers, Antoni Rosell, a researcher of the Catalan Institute for Research and Advanced Studies (ICREA) for the UAB Institute of Environmental Science and Technology, and Erin L. McClymont, of Durham University (UK), currently at the University of Bristol, have published these results in Geology, the most important scientific journal in this field.

The uneven rhythm of the Earth’s cooling process

The Earth has been passing through a cooling period for several million years. The process is not one of gradual, continuous cooling, but rather one of sporadic stops and starts. Professor Rosell’s previous article, published in Nature, looked at one of these transitions. This transition was significant because it resulted in the cooling of large parts of the northern hemisphere, especially North America. The latest article looks at another one of these transitions, this time in the more recent past and on a global scale. This transition is very important in climatology, as it coincides with a change in the frequency of glacial periods, the reasons for which are not fully understood. Although it was a change in the North Pacific that caused the northern hemisphere permafrost 2.7 million years ago, in the more recent case 1 million years ago, the origin of the permafrost was at the tropics.

Octavi López Coronado | EurekAlert!
Further information:
http://www.uab.es

More articles from Earth Sciences:

nachricht Multi-year submarine-canyon study challenges textbook theories about turbidity currents
12.12.2017 | Monterey Bay Aquarium Research Institute

nachricht How do megacities impact coastal seas? Searching for evidence in Chinese marginal seas
11.12.2017 | Leibniz-Institut für Ostseeforschung Warnemünde

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

A whole-body approach to understanding chemosensory cells

13.12.2017 | Health and Medicine

Water without windows: Capturing water vapor inside an electron microscope

13.12.2017 | Physics and Astronomy

Cellular Self-Digestion Process Triggers Autoimmune Disease

13.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>