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 Stagnation in the South Pacific Explains Natural CO2 Fluctuations
23.02.2018 | Carl von Ossietzky-Universität Oldenburg

nachricht First evidence of surprising ocean warming around Galápagos corals
22.02.2018 | University of Arizona

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Attoseconds break into atomic interior

A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.

In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...

Im Focus: Good vibrations feel the force

A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.

By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Basque researchers turn light upside down

23.02.2018 | Physics and Astronomy

Finnish research group discovers a new immune system regulator

23.02.2018 | Health and Medicine

Attoseconds break into atomic interior

23.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>