[Aqualist] Media Release: Snowy Mountains much colder and drier at end of the last Ice Age

[Simon Haberle]

Media release from recent AAA Conference at Jindabyne, NSW
(see http://www.australianarchaeologicalassociation.com.au/media/index.html)

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Snowy Mountains much colder and drier at end of the last Ice Age

  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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Professor Chappell s comments were made during his keynote speech at the 
25th 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.

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.

Contacts:
John Chappell, (02) 6125 8113
Tim Winkler, ANU Marketing and Communications (02) 6125 5001
Jane Morrison, AAA Conference Media Officer (02) 6294 0146 Mobile 0414 279 571
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