Hot and wet and here to stay
From grazier to grape grower the climate is changing what we grow.
Professor Wayne Meyer was watching the weather when the millennium drought ended and he noticed something new was happening. A rain event from Indonesia swept down from the northwest of the continent and into South Australia in the summer of 2011. His weather station monitored what happened – it rained and rained, in what the carefully spoken professor calls “a significant event”. And then it happened again and again – the past summer saw what once would have been called unseasonably strong January falls. In fact, in three of the last five years there was good summer rain.
“It’s the direct result of climate change,” Professor Meyer says.
“Ocean temperatures are warming and the climate projections show more intense summer rain and lower falls in winter and spring,” he says.
This is good news for the pastoral regions of the state, the University of Adelaide resource management scientist says. More summer falls will mean better ground cover as seasonal grass species revel in the rain, here and into northern Victoria and south western New South Wales. So much so that Professor Meyer says what is occurring is a world-changing event, literally.
The Mallee took six months to respond to the 2011 summer rains but when it did it accompanied the huge growth of inland grasslands, which sucked a massive amount of CO2 out of the atmosphere, he explains.
“It actually caused a small blip in the planet’s CO2 signature. A change in vegetation cover in inland Australia rates on a world scale,” Professor Meyer adds.
But not everybody wins with wet summers. The state’s agriculture and horticulture crops require rain in winter and spring; grapes and cherries, for example don’t cope with hot and wet summers.
Growers need to work out how to adapt, Professor Meyer says.
That we must all learn how to adapt is a theme throughout his work. For decades he has watched the weather, and how we interact with it and the change to the landscape. This in turn shapes what we can grow, sustainably and otherwise.
“If we are hard-nosed about it, agriculture as it is practised now isn’t sustainable. Our rate of soil loss exceeds soil formation and we use more energy than we capture,” he warns.
Over three decades Professor Meyer has built, maintained and analysed models that make his case.
With a PhD in agronomy from the University’s renowned Waite Research Institute he has observed and analysed irrigation and evaporation, salinity and sustainability in the US and Africa, but mainly in the Murray-Darling basin and across other parts of South Australia.
Professor Meyer has taught and researched at the University of Adelaide since 2007, when he took up the inaugural chair of natural resource science. He now has two major research projects underway.
One is the Ozflux micrometeorological monitoring station, just outside Renmark, which continually measures exchanges of water vapour, carbon dioxide, and energy between the terrestrial ecosystem and atmosphere. This facility plugs into a national, and in turn, global network and provided the data that showed the planetary impact of the Mallee and grassland vegetation growth following the 2011 rains.
His other project is the Landscape Futures Programme which incorporates landform and soil, land and water use, climate and crops to assess the impact of agriculture and changed vegetation. Built over 30 years, it can model the impacts of what communities want from their environments and what is possible by cooperating, rather than trying to conquer, the landscape. “We can present options for the future and show how we get there,” Professor Meyer says.
So how are we doing? For the River Murray the core issue remains: “the resource is finite and if you want to maintain the river system there is only so much water you can take out. There is still too much water extracted to keep the river and floodplain in good condition,” he says.
But things are on the mend as research helps change community thinking. “The Murray isn’t out of the woods but since rehabilitation started in the ‘70s it’s been a great revamp,” Professor Meyer adds that putting a price on water has certainly helped, by making people aware of its value. “We got through the last drought because of water trading.”
And our grasp of groundcover has also made a difference. “There’s been a revolution in agriculture in the last couple of decades. Conservation agriculture, with minimum tillage, can have a huge impact on protecting soils,” he says.
Professor Meyer contrasts the great federation drought and the recent, and far less damaging millennium dry. “We had a lot less stock, a lot less rabbits and far more cover on the land, which is the most important thing you can do.”
He adds that farmers can adapt to summers with more bursts of extreme heat by using shading, but only if they can grow sufficiently profitable crops to cover the high capital cost.
But understanding that we must adapt to the environment, instead of trying to bend it to our needs isn’t universal. Professor Meyer says he still sees farmers cultivating land for weed control and destroying any vegetation cover. “People are still working land which is pre-disposed to blow.”
And old problems that are no longer as apparent are dormant, not defeated. Such as dry land salinity in irrigation areas. “When we get the inevitable wet period of seven or eight years it will reappear. Water evaporates but salt stays and all water includes salt,” he says.
Which is what makes his modelling so important. It can show the outcomes of all sorts of scenarios: “Now instead of asking what people want from the landscape we can ask what they want to experience. It is a way of finding out what people really value,” Professor Meyer says.
As his data demonstrates: when the climate changes, adaption is everything.
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