[ASC-media] Media Release: Global Warming Contributes to Australia ¹ s Worst Drought

Control Publications science at control.com.au
Mon Mar 24 12:03:50 EST 2003

Monday 24 March 2003

For immediate release

Global Warming Contributes to Australia¹s Worst Drought

During 2002, Australia experienced its worst drought since reliable records
began in 1910. The average rainfall over the whole of Australia for the 9
months of March­November 2002 was the lowest ever during this period.

³This drought has had a more severe impact than any other drought since at
least 1950, because the temperatures in 2002 have also been significantly
higher than in other drought years,² write Prof David Karoly, Dr James
Risbey, Dr Anna Reynolds and Dr Karl Braganza in the April edition of
Australasian Science, published today.

³The 2002 drought temperatures are extraordinary when compared with the four
other major droughts since 1950Š Average maximum temperatures for 2002 were
more than 1.0ºC higher than these other droughts.

³While a 1°C rise in average temperature may appear to be a relatively small
increase, it can have a major impact on the severity of drought. Higher
temperatures lead to higher evaporation of water from the soil, plants,
lakes and rivers. Higher evaporation rates, in turn, make it difficult to
sow crops, place existing crops under stress, and result in even more water
being taken from rivers and reservoirs. This places additional stress on
water supplies and has a detrimental impact on agricultural productivity and
the health of vegetation.²

While seasonal rainfall in Australia is influenced by a number of climate
processes, temperature does not naturally vary as much. ³For the 2002
drought, the record high maximum temperatures are so large that they are
unlikely to be explained by natural variability in response to processes
such as El Niño. They do, however, fit with changes expected due to global

In 2001 Prof Karoly, a former Monash University academic now based at the
University of Oklahoma¹s School of Meteorology, was a lead author of a
report by the Intergovernmental Panel on Climate Change (IPCC) concluding
that ³most of the observed (global) warming over the last 50 years is likely
to have been due to the increase in greenhouse gas concentrations².

³Australia¹s average surface temperature increased by more than 0.7ºC
between 1950 and 2001,² Prof Karoly writes in Australasian Science.

Please cite AUSTRALASIAN SCIENCE MAGAZINE as the source of this story.

Dr James Risbey can be contacted on (03) 9905 4461.
For copies of the article call the Editor, Guy Nolch, on (03) 9500 0015 or
visit www.control.com.au

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