Post by L Roebuck on Sept 9, 2005 6:57:44 GMT -5
Stalagmites are biological rainfall records
Friday, 9 September 2005
Presenter: Genine Unsworth
www.abc.net.au/southwestwa/stories/s1457165.htm
Rainfall records going back thousands of years are waiting to be read in South West caves.
In 1911, a stalagmite began growing on a tourist boardwalk in Moondyne cave, Western Australia. That little growth had Dr Pauline Treble very excited. As a paleo-climate scientist, Dr Treble is interested in the weather records held in nature. At the time, she was working on her PHD and trying to establish whether or not stalagmites could be used to reconstruct weather patterns.
Because its age was known, Dr Treble was able to compare the stalagmite's geochemical markers with observational records for the period. "We were able to figure out which geochemical signals were recording the rainfall decreases that happened from about 1970 onwards."
The technique of reading weather history from stalagmites has been known since the 60s. "Stalagmites preserve trace elements as well as carbon and oxygen isotopes which come from the rain and the soil above the caves," explains Dr Treble. Different amounts are preserved in the stalagmite depending upon the amount of rainfall.
In the 1990s, technological advances allowed scientists to read minute changes in the geochemical record. A laser hooked up to a mass spectrometer reads what sort of trace elements are in the calcite. "The laser scans the surface and it shows how the geochemical trends have changed through time and that tells us how wet it was."
The Moondyne result was incredibly exciting, says Dr Treble, because it verified that they could go back in time. "The potential is the ability to read rainfall records for thousands of years back."
Dr Treble has just started a new phase of research in the west. Working with the Department of Conservation and Land Management, Dr Treble collected two stalagmites, one from Golgotha near Margaret River and the other from Yanchep Cave just north of Perth. "We're thinking that this will probably cover the last 1,000 years," she says.
The research will benefit those bodies concerned with water usage in the region, says Dr Treble. The Water Corporation, the Department of Environment, CSIRO and CALM all are contributing to her work. "What we are hoping to do is to reconstruct rainfall records for about the last 1,000 years in the region because what that will tell us is what the natural rainfall variability for the South West region."
The ultimate goal is to figure out whether the current dry period that started in the 70s, normal variability or is it something unusual. In other words, is the drier climate natural or it is a man made trend? The answer has implications for water use and sustainability for the decades to come.
"What is most fascinating to me is the massive archive of information that is contained in these formations that tell us about past climates."
Friday, 9 September 2005
Presenter: Genine Unsworth
www.abc.net.au/southwestwa/stories/s1457165.htm
Rainfall records going back thousands of years are waiting to be read in South West caves.
In 1911, a stalagmite began growing on a tourist boardwalk in Moondyne cave, Western Australia. That little growth had Dr Pauline Treble very excited. As a paleo-climate scientist, Dr Treble is interested in the weather records held in nature. At the time, she was working on her PHD and trying to establish whether or not stalagmites could be used to reconstruct weather patterns.
Because its age was known, Dr Treble was able to compare the stalagmite's geochemical markers with observational records for the period. "We were able to figure out which geochemical signals were recording the rainfall decreases that happened from about 1970 onwards."
The technique of reading weather history from stalagmites has been known since the 60s. "Stalagmites preserve trace elements as well as carbon and oxygen isotopes which come from the rain and the soil above the caves," explains Dr Treble. Different amounts are preserved in the stalagmite depending upon the amount of rainfall.
In the 1990s, technological advances allowed scientists to read minute changes in the geochemical record. A laser hooked up to a mass spectrometer reads what sort of trace elements are in the calcite. "The laser scans the surface and it shows how the geochemical trends have changed through time and that tells us how wet it was."
The Moondyne result was incredibly exciting, says Dr Treble, because it verified that they could go back in time. "The potential is the ability to read rainfall records for thousands of years back."
Dr Treble has just started a new phase of research in the west. Working with the Department of Conservation and Land Management, Dr Treble collected two stalagmites, one from Golgotha near Margaret River and the other from Yanchep Cave just north of Perth. "We're thinking that this will probably cover the last 1,000 years," she says.
The research will benefit those bodies concerned with water usage in the region, says Dr Treble. The Water Corporation, the Department of Environment, CSIRO and CALM all are contributing to her work. "What we are hoping to do is to reconstruct rainfall records for about the last 1,000 years in the region because what that will tell us is what the natural rainfall variability for the South West region."
The ultimate goal is to figure out whether the current dry period that started in the 70s, normal variability or is it something unusual. In other words, is the drier climate natural or it is a man made trend? The answer has implications for water use and sustainability for the decades to come.
"What is most fascinating to me is the massive archive of information that is contained in these formations that tell us about past climates."