Heat shock ahead for global croppers

02 Feb, 2015 01:00 AM
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103
 
Temperatures could rise a whopping 4.2 degrees on average by 2090

AN international report has made a sobering finding, with computer models showing global wheat production could fall six per cent for every one degree of temperature rise.

The study, published online in Nature Climate Change, found that not only would production fall, but volatility would increase.

The rate of decreases in productivity is a massive concern for Australian producers, given a joint release from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the Bureau of Meteorology (BoM) last week showed temperatures could rise up to 1.2 degrees on average in southern Australia from the average from 1986-2005.

The BoM/CSIRO study showed temperatures could rise a whopping 4.2 degrees on average by 2090 under a high emissions scenario and also forecast lower rainfall in key cropping zones in southern and eastern Australia, especially in winter and spring, the critical seasons for winter crop production.

However, contributor to the Nature Climate Change study on wheat production, Garry O’Leary of the Victorian Department of Economic Development, Jobs, Transport and Resources (DEDJTR) said the study was based on no adaptation to a changing climate.

"This study is concerned solely with rising temperatures, we have just used standard varieties and have not factored in the impact of rising carbon dioxide levels," Dr O’Leary said.

The work involved comparing 30 simulation crop models against field experiments where crops were grown at mean temperatures ranging from 15 to 32 degrees.

CSIRO and BoM researchers say their study, which makes use of 40 different global models, shows warming patterns will continue after an increase in average temperatures of 0.9 degrees since 1910.

"There is very high confidence that hot days will become more frequent and hotter", CSIRO principal research scientist, Kevin Hennessy said.

Rainfall declines will be first felt in southern mainland Australia before the area with lower rainfall increase across subtropical regions after 2030.

Mr Hennessy said the agriculture sector would need to prepare for the changes predicted in the report.

"This research has been strongly aligned with the needs of Australia's natural resources sector", Mr Hennessy said.

"Other researchers are using this information to assess potential impacts and management options."

And in worrying news for growers, Dr O’Leary said many crop production modelling products had not adequately factored in the damage done by high temperatures.

"The wheat yield declines due to temperature increases were likely to be larger than previously thought and are likely to begin taking effect earlier than expected with only small temperature increases having an impact," he said.

Tim McClelland, the co-ordinator for forecasting tool Yield Prophet with Birchip Cropping Group (BCG) said there were a number of ongoing challenges with forecasting tools.

"We’ve factored in increased temperatures and the impact it has on the crop in terms of earlier flowering, but modelling systems inherently overestimate the yield slightly."

Mr McClelland said the tool could also make allowances for different cultivars and maturity dates.

"We have eight different categories in terms of variety choice and that is factored into our modelling."

He said with Yield Prophet, challenges now included creating a system for new crops and better accounting for mineralised fertiliser.

Dr O’Leary said Australia, with large tracts of near-arid cropland, could be especially hard hit by rising temperatures.

However, he said adaptation of new practices could help.

"Drought and heat tolerant varieties will be the holy grail for breeders, and there is also a lot of work to be done to extreme events at sensitive stages of a crop’s development, such as heat or frost at flowering."

In terms of in-crop yield monitoring, Dr O’Leary said that the Australian models performed well but not in all tests and no single model of all the 30 was shown to be superior.

Australian models used included the Agricultural Production Systems Simulator (APSIM) and other experimental forms of that system.

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FarmOnline
Gregor Heard

Gregor Heard

is the national grains writer for Fairfax Agricultural Media
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READER COMMENTS

Bigfoot
3/02/2015 6:43:00 AM

Strong disbelief in the observable facts reminds me of denialism, Jeffito. And you're in denial. I am also fascinated by your denialism of real science and your crude comment, how low can you go, Jeffito?
jeffito
3/02/2015 7:43:33 AM

Simply asked the question. No mention of politics or religion made. So cool it.
jeffito
3/02/2015 7:46:07 AM

Great cartoon here neighbours. https://www.flickr.com/photos/mon kchips/4254681996/
nico
3/02/2015 8:24:08 AM

Rose, there's not much "debate" here. There's ill-informed yapping. The real debate, and it is robust, is taking place in the pages of the scientific journals.These are open to anyone who takes the trouble to read, and to distinguish between ideological rubbish and objective rational science. Science functions by being questioned and challenged, but this is not done by ignorant assertion. Science is also independent of belief. Jeffito's speculation is interesting.
Old Crow
3/02/2015 8:45:33 AM

Don't try to back out of it jeffito , you tried to make the connection between religion and CAGW skeptics . Why would you even bring it up ? A bad move by you , don't you think Jeffito ?
Qlander
3/02/2015 8:49:47 AM

Jeffito brings religion to the debate simply because, to him it's a religious debate.
nextonice
3/02/2015 9:19:43 AM

Not all science is based on real facts. Historically climate changes every season, every month, week and day. Science does not have enough global statistical data based on fact to conclude the predictions they have modelled. The predictions so far have been dismal but the climate warmest zealots believe in AGW. Agriculture will flourish and our future of food production in the world will be safe. The scientist could work harder by curing cancer and other terrible disease blights on humans.
Makka
3/02/2015 9:56:35 AM

IF the weather is becoming more extreme, I believe that the most successful crops will be perennial pastures and livestock! Comments?
fridgimus
3/02/2015 9:59:24 AM

There is undeniably a connection, old crow.
jp
3/02/2015 10:23:34 AM

Meanwhile... as the wrath of the rising oceans and the fires of the warming planet punish the non-believing infidels for not paying the carbon tax, the High Priest of the believers, the mighty Al Gore, and his celebrity disciples live lives of tranquillity, in CO2 spewing mansions big enough to accommodate entire villages in luxurious opulence...
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