Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists Confirm Historic Massive Flood in Climate Change

01.03.2006


Scientists from NASA and Columbia University, New York, have used computer modeling to successfully reproduce an abrupt climate change that took place 8,200 years ago. At that time, the beginning of the current warm period, climate changes were caused by a massive flood of freshwater into the North Atlantic Ocean.



This work is the first to consistently recreate the event by computer modeling, and the first time that the model results have been confirmed by comparison to the climate record, which includes such things as ice core and tree ring data.

"We only have one example of how the climate reacts to changes, the past," said Gavin A. Schmidt, a NASA Goddard Institute for Space Studies (GISS), New York, researcher and co-author on the study. "If we’re going to accurately simulate the Earth’s future, we need to be able to replicate past events. This was a real test of the model’s skill."


The study was led by Allegra LeGrande, a graduate student in the department of Earth and Environmental Sciences at Columbia University. The results appeared in the journal "Proceedings of the National Academy of Sciences" (PNAS) in Jan. 2006.

The group used an atmosphere-ocean coupled climate computer model known as "GISS Model E-R" to simulate the climate impact of a massive freshwater flood into the North Atlantic that happened about 8,200 years ago after the end of the last Ice Age. Retreating glaciers opened a route for two ancient meltwater lakes, known as Agassiz and Ojibway, to suddenly and catastrophically drain from the middle of the North American continent.

At approximately the same time, climate records show that the Earth experienced its last abrupt climate shift. Scientists believe that the massive freshwater pulse interfered with the ocean’s overturning circulation, which distributes heat around the globe. According to the record of what are known as "climate proxies", average air temperatures apparently fell as much as several degrees in some areas of the Northern Hemisphere.

Climate researchers use these proxies, chemical signals locked in minerals and ice bubbles as well as pollen and other biological indicators, as indirect measures of temperature and precipitation patterns in the distant past. Because GISS Model E-R incorporates the response of these proxies in its output, the authors of the PNAS study were able to compare their results directly to the historical record.

The researchers prodded their model with a freshwater flow equal to between 25 and 50 times the flow of the Amazon River in 12 model runs that took more than a year to complete. Although the simulations largely agreed with records from North Atlantic sediment cores and Greenland ice cores, the team’s results showed that the flood had much milder effects around the globe than many people thought.

According to the model, temperatures in the North Atlantic and Greenland showed the largest decrease, with slightly less cooling over parts of North America and Europe. The rest of the northern hemisphere, however, showed very little effect, and temperatures in the southern hemisphere remained largely unchanged. Moreover, ocean circulation, which initially dropped by half after simulated flood, appeared to rebound within 50 to 150 years.

"The flood we looked at was even larger than anything that could happen today," said LeGrande. "Still, it’s important for us to study because the real thing occurred during a period when conditions were not that much different from the present day."

The GISS climate model is also being used for the latest simulations by the Intergovernmental Panel on Climate Change (IPCC) to simulate the Earth’s present and future climate. "Hopefully, successful simulations of the past such as this will increase confidence in the validity of model projections," said Schmidt.

The study was funded by NASA, National Defense Science and Engineering Graduate Fellowship, and the National Science Foundation.

Rob Gutro | EurekAlert!
Further information:
http://www.nasa.gov/vision/earth/lookingatearth/abrupt_change.html
http://www.nasa.gov

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 >>>