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<font size=2>Media release from recent AAA Conference at Jindabyne, NSW
<br>
(see
http://www.australianarchaeologicalassociation.com.au/media/index.html)<br><br>
___________________________________________________________________________________<br>
</font><div align="center"><font size=4><b>Snowy Mountains much colder
and drier at end of the last Ice Age<br><br>
</font></div>
Recent scientific studies have discovered that temperatures in the
Snowy Mountains about 20 000 years ago were 8 to 9 degrees colder
and conditions in Australia were also probably drier than today in most
parts of Australia.<br><br>
</b>According to Professor John Chappell of the Australian National
University s Research School of Earth Sciences, scientists previously
believed that the temperature in Australia at the end of the last Ice Age
was around 5 degrees colder than it is today.<br><br>
Until recently we summarised the Australian situation as being about 5
degrees and somewhat drier for a few thousand years. New evidence
indicates that we underestimated the change , Professor Chappell
said.<br><br>
Ice sheets on the northern continents were at their maximum extent 20 000
years ago the Last Glacial Maximum (LGM) and conditions were colder and
drier than today. This poses the question of how humans adapted in order
to live through these harsher conditions. To begin to consider this, we
must first estimate how much harsher conditions were then, compared with
today. <br><br>
The northern ice sheets we now know to have been close to their maximum
size from about 28 000 to 18 000 years ago an interval of about 10 000
years. Recent studies of glacial and ice-related landforms in the Snowy
Mountains and Tasmania indicate that temperatures in the LGM in
south-eastern Australia were 8 to 9 degrees colder than today. These
discoveries have prompted a re-evaluation of the LGM and the conditions
that preceded it.<br><br>
There is little doubt that arid conditions extended across much of the
Australian interior at the LGM. Dune fields then covered about 60 per
cent of the continent, and were more mobile, and appear to have
been active in areas now used for agriculture, particularly in
Western Australia. The duration of the period of maximum aridity is not
well established and may have been no longer than a few thousand years to
judge from windblown dust found in sediments in the Tasman Sea.<br><br>
Similarly, the most intensely cold episode, which led to maximum aridity,
also extended for little more than a few thousand years, from about 24
000 years to 19 000 years ago.<br><br>
However, to characterise the LGM simply as having been arid and very much
colder gives a false impression. Climate is more than a matter of
rainfall or temperature: evaporation, groundwater and surface runoff
affect the landscape, together with its vegetation and fauna.<br><br>
Also, paradoxically, there was more water in localised parts of the
Australian landscape at the end of the last Ice Age than there is today.
For example, Lake George near Canberra, which is now dry, was 12 metres
deep and larger than it has ever been since Europeans arrived in the area
in the 1800s.<br><br>
The context of human activity about 20 000 years ago in Australia was not
only much colder, it was also very different in other ways. It was a land
of even greater contrasts than it is today. The great desert tracts may
have been even harsher than now, but the alternation of floods and
droughts that bedevils our climate today, appears not to have been as
extreme as it is today. Human subsistence in wetland, riverine and
better-watered upland areas may have been more dependable then as the
climate was less variable, even though it was much colder.<br><br>
The LGM was but the last in a procession of dramatic climate changes that
affected the entire world throughout the last few million years. It is
salutary to observe that human impacts on the biota, measured in terms of
extinctions and land degradation, exceed the effects of the climatic
impacts, throughout this long history of repeated changes. <br><br>
Professor Chappell s comments were made during his keynote speech at the
25<sup>th</sup> annual conference of the Australian Archaeology
Association held at Jindabyne from 3 to 7 December 2003. The first
conference of the association was held at Kioloa, New South Wales in
1978.<br><br>
More than 200 delegates from Australia and overseas attended the
conference at Perisher Blue s Station Resort just out of Jindabyne.
During their stay many delegates took the opportunity to visit the
Kosciuszko National Park to view significant Aboriginal and geological
sites in the area.<br><br>
Contacts: <br>
John Chappell, (02) 6125 8113<br>
Tim Winkler, ANU Marketing and Communications (02) 6125 5001<br>
Jane Morrison, AAA Conference Media Officer (02) 6294 0146 Mobile 0414
279 571<br>
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