Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Supervolcano eruption -- in Sumatra -- deforested India 73,000 years ago

25.11.2009
A new study provides "incontrovertible evidence" that the volcanic super-eruption of Toba on the island of Sumatra about 73,000 years ago deforested much of central India, some 3,000 miles from the epicenter, researchers report.

The volcano ejected an estimated 800 cubic kilometers of ash into the atmosphere, leaving a crater (now the world's largest volcanic lake) that is 100 kilometers long and 35 kilometers wide. Ash from the event has been found in India, the Indian Ocean, the Bay of Bengal and the South China Sea.

The bright ash reflected sunlight off the landscape, and volcanic sulfur aerosols impeded solar radiation for six years, initiating an "Instant Ice Age" that – according to evidence in ice cores taken in Greenland – lasted about 1,800 years.

During this instant ice age, temperatures dropped by as much as 16 degrees centigrade (28 degrees Fahrenheit), said University of Illinois anthropology professor Stanley Ambrose, a principal investigator on the new study with professor Martin A.J. Williams, of the University of Adelaide. Williams, who discovered a layer of Toba ash in central India in 1980, led the research.

The climactic effects of Toba have been a source of controversy for years, as is its impact on human populations.

In 1998, Ambrose proposed in the Journal of Human Evolution that the effects of the Toba eruption and the Ice Age that followed could explain the apparent bottleneck in human populations that geneticists believe occurred between 50,000 and 100,000 years ago. The lack of genetic diversity among humans alive today suggests that during this time period humans came very close to becoming extinct.

To address the limited evidence of the terrestrial effects of Toba, Ambrose and his colleagues pursued two lines of research: They analyzed pollen from a marine core in the Bay of Bengal that included a layer of ash from the Toba eruption, and they looked at carbon isotope ratios in fossil soil carbonates taken from directly above and below the Toba ash in three locations in central India.

Carbon isotopes reflect the type of vegetation that existed at a given locale and time. Heavily forested regions leave carbon isotope fingerprints that are distinct from those of grasses or grassy woodlands.

Both lines of evidence revealed a distinct change in the type of vegetation in India immediately after the Toba eruption, the researchers report. The pollen analysis indicated a shift to a "more open vegetation cover and reduced representation of ferns, particularly in the first 5 to 7 centimeters above the Toba ash," they wrote in the journal Palaeogeography, Palaeoclimatology, Palaeoecology. The change in vegetation and the loss of ferns, which grow best in humid conditions, they wrote, "would suggest significantly drier conditions in this region for at least one thousand years after the Toba eruption."

The dryness probably also indicates a drop in temperature, Ambrose said, "because when you turn down the temperature you also turn down the rainfall."

The carbon isotope analysis showed that forests covered central India when the eruption occurred, but wooded to open grassland predominated for at least 1,000 years after the eruption.

"This is unambiguous evidence that Toba caused deforestation in the tropics for a long time," Ambrose said. This disaster may have forced the ancestors of modern humans to adopt new cooperative strategies for survival that eventually permitted them to replace neandertals and other archaic human species, he said.

Editor's note: To reach Stanley Ambrose, call 217-244-3504; e-mail: ambrose@illinois.edu

Diana Yates | EurekAlert!
Further information:
http://www.illinois.edu

More articles from Earth Sciences:

nachricht Impacts of mass coral die-off on Indian Ocean reefs revealed
21.02.2017 | University of Exeter

nachricht How much biomass grows in the savannah?
16.02.2017 | Friedrich-Schiller-Universität Jena

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Impacts of mass coral die-off on Indian Ocean reefs revealed

21.02.2017 | Earth Sciences

Novel breast tomosynthesis technique reduces screening recall rate

21.02.2017 | Medical Engineering

Use your Voice – and Smart Homes will “LISTEN”

21.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>