Local data shows State trend
From the October 2007 edition of Agriculture Today.
Localised analysis of weather station data has illustrated a distinct Statewide warming trend and changes to seasonal rainfall distribution across NSW.
The results have been presented at nine regional community forums, looking at the impacts of climate change.
NSW Department of Primary Industries (DPI) project officer, Michael Cashen, has presented weather station data dating as far back as 1957, demonstrating local impacts to participants, at forums at Muswellbrook, Narrabri, Tamworth, Buronga, Dubbo, Bega, Nowra, Broken Hill, and most recently Goulburn in late August.
"We wanted each audience to know how their own localities have been changing, as they framed up their opinions after attending the forums," Mr Cashen said.
Four more forums are planned in the next month. Mr Cashen said the DPI Climatology in Agriculture project group has been analysing historic trends in agricultural climatic indices across NSW.
The temperature analysis has involved a comparison with the standard 1961 to 1990 benchmark.
From the analysis, the climate group has assessed a number of potential impacts on agricultural production systems, and begun to explore management strategies to respond to future change.
In the case of livestock, one typical index analysis at Jerrys Plains (see graphs) included the number of days during summer when the animal heat stress index Temperature Humidity Index (THI) was exceeded.
"We know that once most British breeds cross the threshold of 78 (THI), production begins to decline as the animal reduces intake," Mr Cashen said.
"Animals try to cool themselves by panting, which in turn reduces the carbonate balance of the blood, increases acidification of tissues and rumen, and reduces intake, digestion rate and production.
"Panting also affects hormones and enzymes, reduces fertility, growth and production, increaseing metabolic disorders, cuts resistance to infection and at the extreme, increased mortalities."
"Another good example of our findings comes from the climatic index for horticulture Heat Degree Days (HDD) typical of the results for the State is that of Jerrys Plains," Mr Cashen said.
"It shows there has been a steady increase in the rate of accumulated heat units across NSW."
Implications for increased heat accumulation during the grape growing season for viticulture, for example, include earlier bud initiation, earlier fruit maturity (increases in sugars decreases in acids), decreased fruit size and yield, fruit quality issues (for example vine decline), potential reduced fruit set, longer growing season and increased water use.
The climate forums are funded under the NSW Government’s Community Action Grant program and staged in collaboration with Catchment Management Authorities.
The DPI has a one day accredited course titled ‘The farmers’ guide to managing climate risk’ for anyone who wants more on the latest climate change projections and variability for NSW.
Contact Michael Cashen, Paterson, (02) 4939 8953.
- Ron Aggs
