Growers respond to new era

Climate change models point to receding winter rainfall patterns for WA's southern half, in a future that would see declining growing season rainfall in some areas traded for more summer rain.

As part of the National Adaptation and Mitigation Initiative, climate change profiles were developed for nine locations across WA's grain growing region.

These profiles took weather data from as far back as 1939 to collate what kinds of changes those areas had already seen and then used climate change forecast models to extrapolate what might happen in the future.

Department of Agriculture and Food climatologist Ian Foster helped work on the profiles and said although they showed our climate was already changing, farmers had responded and were now growing more grain on less rain.

"What we've seen from the past and probably for the future is that season breaks may become a little later but still pretty variable from year to year," he said.

"But farmers have already responded by changing their sowing technology."

While most areas are set to experience a decline in growing season rainfall under climate change models, Dr Foster said there were subtle differences across the grainbelt.

"Spatially across the Wheatbelt is the south coast has been different from the west coast regions," he said.

"One reason why (the west coast) has experienced such a decline in rain and the south coast hasn't is because those areas get most of their rainfall with the north-westerlies ahead of a cold front.

"If the cold fronts are either weaker or less frequent, then you see it most strongly up and down the west coast and the South West corner.

"When you get to the south coast, when a cold front is approaching they get a much smaller proportion of rain in the north-westerlies ahead of the front and a much larger amount in the south-westerlies after it has gone through."

Dr Foster is quick to point out that the story of climate change isn't one of doom and gloom for the State's farmers.

He said the seasons of 2010-11 and 2011-12 were evidence that growers could minimise risk when they needed to and yet still capitalise on opportunity.

"In some of the regions the (predicted) potential yields went up for the future, more for the medium to high-rainfall zone," he said.

"The challenges that it was bringing up was for the low rainfall areas on heavier soils."

The good news for WA farmers is that since the 1970s yield increases have continued to occur despite a drying climate and farmers are already using technology to cope with seasonal variability.

"That's the question - where the next set of gains are going to come from," Dr Foster said.

"We are in one part of the world where the climate change models are consistent and that at least gives us some clear guidance that we need to still chase water use efficiencies.

"The idea (of these climate profiles) is just to raise people's awareness that those sort of seasons, if the drying continues, will become more common.

"That drives the thinking that if it then becomes more common, what do we need to do to adapt to this.

"Do we need to change technologies? One of the purposes of all these things is to encourage people to think how their doing their season management at present.

"Their systems and rules in place now, are they going to be sufficient for the future?"