[ASC-media] Media release: revealing past climates
jcamedia at starclass.com.au
Sat Aug 21 08:10:19 EST 2004
NATIONAL SCIENCE WEEK 2004 MEDIA RELEASE
August 21, 2004
COSMIC RAYS & NUCLEAR SCIENCE: UNLOCKING THE SECRETS OF PAST CLIMATES
The hi-tech skills of Australian nuclear scientists are coming to the aid of climate researchers wanting to know how quickly climates changed in the past.
Among key questions being tackled are: when did the great glaciers of the last ice age disappear from Tasmania and New Zealand and how long did it take? Does the Antarctic ice sheet look the same today as it did a million years ago?
Dr David Fink of the Australian Nuclear Science and Technology Organisation (ANSTO) says that one of the key questions for Australians is whether natural climate variability in the past behaved the same in the southern hemisphere as in the north.
"Up till now, most of the research has been in the northern hemisphere, so we know a lot more about climate change in the north than we do in the south. Our new research is revealing real differences," he says.
Advances in scientific technique now allow scientists to use radiocarbon dating and rare radioactive isotopes of beryllium, aluminium and chlorine found in sediments, corals, ice cores and rocks as indicators of climate change.
"These very rare natural radio-isotopes act like tiny nuclear clocks that gives us a telltale signals about how and when the climate changed in the past. In some cases this can be linked to archaeological finds to give us insights into the reasons why human populations moved in prehistoric times or why ancient kingdoms fell.
"These isotopes occur naturally by the process of cosmic rays passing through the atmosphere. Radiocarbon dating is now revealing ocean and atmospheric conditions from corals in the Indian ocean and trees from Tasmania or ancient air trapped in bubbles in ice cores. Some of these cosmic rays also bombard exposed rocks on the earth's surface, so now we can do the same dating trick with other special radioisotopes. This new technique is called exposure age dating.
Dr Fink says that the world-class ANTARES Accelerator Mass Spectrometry Facility at ANSTO gives his team a uniquely powerful tool for measuring the minute concentrations - sometimes only a few thousand million rare atoms - of these cosmogenic 'clocks'.
The team is using the technique to measure the ebb and flow of alpine glacier systems over the past 100,000 years in Tasmania, New Zealand, Irian Jaya and Antarctica.
"We have also used exposure dating on Antarctic mountain peaks, and we found a surprising amount of change in the Antarctic ice sheet over the past two million years," he says.
Dr Fink says that this precise dating of climate variation in the southern hemisphere has been seized on by environmentalists, and by archaeologists who have been puzzled and intrigued by human movement in Asia and the Pacific region.
Dr Fink's work is part of an ANSTO project called CcASH - Cosmogenic Climate Archives of the Southern Hemisphere.
Dr Fink is one of more than 160 eminent Australian scientists available for interview about their work and science in general during National Science Week. For details visit: www.scienceweek.info.au
To contact Dr David Fink: phone 02-9717 3048 or 0425 306 194 (mobile)
For information on National Science Week:
Telephone: 02 6205 0281
Mobile: 0407 781 891
Facsimile:02 6207 0072
E-mail:scienceweek at orac.net.au
For more events in National Science Week 2004, please visit:
National Science Week is supported by the Commonwealth Government Department of Education Science and Training (DEST) and the Department of Industry Tourism and Resources (DITR).
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