Heat shock ahead for global croppers

02 Feb, 2015 01:00 AM
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.

Gregor Heard

Gregor Heard

is the national grains writer for Fairfax Agricultural Media
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4/02/2015 8:20:27 AM

I would say with a well educated guess that Nico and Jeffito are one in the same person. What do you think Nico/Jeffito? Editor's note: Nico and Jeffito are not the same person.
4/02/2015 8:53:45 AM

nico, I know how science operates. However, I see nothing in the behaviour of the AGW 'faithful' that suggest they do.
4/02/2015 9:48:05 AM

GT, "anti climate change group" are those that do not accept any evidence that there is a climate change occurring and that there is a strong likelihood this is being induced by human activity
4/02/2015 10:31:28 AM

I would say your confused, Jeffito. They are two different groups. No one has ever suggested there is no climate change. 1/ A few cranks have suggested that climate change is human induced and is the end of the world . 2/ Most sensible and intelligent people know that the climate has always changed and its of natural origin and accept that any influence that humans have caused is so minor its not measurable and is beneficial anyway. I am in the second group. Which group are you in Jeffito?
4/02/2015 12:04:34 PM

Qlander, you once quoted the motto of the Royal Society. Apart from that, you have given no indication that you have any comprehension of science, climate or otherwise. However, you continue to produce slurs such as "the AGW faithful" which is simply insulting. Science is not a matter of faith.
Old Crow
4/02/2015 12:15:58 PM

That's a bit hypocritical isn't it, Nico. Aren't your "denialist" slurs also insulting?
Peter Williams
4/02/2015 1:56:49 PM

Yea well in my book, religion and global warming fall into the same category.....a philosophical debate about things which are yet to be proved. Most of us in Australia have grave reservations about both as you can see from the responses here.
4/02/2015 2:40:07 PM

Nico, you are nothing but a hypocrite firmly on the gravy train. You don't answer any of the simple questions put to you and continually think you are above anyone else with your putting down of anyone who may be smart enough to observe and question the crap that is dished out by your gods you continually bow to and defend. Your AGW garbage is only theories based on models and it takes many of them, and certainly not on actual observation. There is no such thing used any more by the AGW FAITHFUL. You say it's not belief system, then if that's the case you have nothing.
4/02/2015 6:00:50 PM

nico - exactly anyone who uses words like believe or trust know nothing of science. Science works on evidence and repeatable experiment, not belief and trust. That's for religion and politics.
5/02/2015 7:42:48 AM

Max, have a look at this website prepared by the (conservative) government of NSW. It lists the observed effects of global climate change. There are many other sources for this information, so I chose one close to home. Your idea that global warming is not being observed is simply factually wrong. And you don't seem to understand the function of mathematical modelling. See: http://climatechange.environment. nsw.gov.au/About-climate-change-i n-NSW/Evidence-of-climate-change/ Observed-global-climate-change
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