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Heat wave odds stacked high
18th March, 2008
It’s official. Adelaide’s heat wave has been an extraordinary event likely to occur just once in 3000 years.
Atmospheric scientist, Dr Warwick Grace, is working with the South Australian Research and Development Institute (SARDI) Climate Applications Unit to gain a better understanding of heat waves in the Riverland and other wine growing regions of South Australia.
Dr Grace has developed what is believed to be the first heat wave occurrence model based on records from all over the State dating back more than 100 years, and statistics from the past 30 years collected at the SA Bureau of Meteorology Kent Town office.
“This heat wave is close to being off the scale. It is an extraordinary event with a .03% chance of occurring – the odds are about the same as tossing 12 coins and getting all heads or all tails,” said Dr Grace.
Dr Grace has modelled data for Adelaide, Nuriootpa, Loxton and the Coonawarra.
“Adelaide, with 15 days over 35 degrees, returns a one in 3000 year event, while Nuriootpa with 13 days over 35 degrees is a one in 1000 year event, Loxton with 15 days over 35 degrees is a one in 200 year event, and the Coonawarra with five days over 35 degrees is a one in 10 year event.”
SARDI Climate Applications Unit leader, Dr Peter Hayman, says Dr Grace’s work is very valuable in characterising the climate of different regions and the likelihood and duration of heat waves they might face in the current climate and future climates.
“In the past the emphasis has been on changes in average temperatures, characterising for example a whole summer as being warmer or cooler. This summer, based on average temperatures, will be rated as a cooler summer overall despite this extraordinary heat wave. So we have to consider these extreme events and better understand the weather patterns that cause them, and how we can manage them in the vineyard.”
The information will feed into projects funded by the Grape and Wine Research and Development Corporation and the Centre for Natural Resource Management to help growers manage risk in dealing with climate variability.
One project that will particularly benefit is looking at heat stress on vines to understand viticulture ‘thresh-holds’. Vines are being tested at critical growing periods in purpose built heat-stress tents to artificially increase canopy and bunch temperatures by up to 10 degrees above the norm.
Ultimately the SARDI team hopes to find a way to predict periods of high risk of heat stress, and in turn ensure minimal losses by identifying when growers must prepare – perhaps through canopy management or altering their irrigation regimes.
Further information: Dr Peter Hayman, South Australian Research and Development Institute (SARDI) on (08) 8303 9729 or 0401 996448 or SARDI Media Communications Heather Riddell 0417 851936.
Dr Warwick Grace, Grace Research Network, (08) 8277 6847
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