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

jeffito
5/02/2015 9:18:39 AM

Qlander says "nico - exactly, (comma added) 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." Mainly correct. This is partly at least what I and (I presume) Nico have been saying. Observations/Facts/ Measurements, then hypothesis, then experiment, then data, then question, do the data support or otherwise the hypothesis? If No, another hypothesis. No room here for belief because it can lead to biased interpretation. Trust is another question altogether.
Brence
5/02/2015 10:13:25 AM

Peter William's comment draws attention to the fact that scientists can't prove anything . The scientific method involves the development of theories to explain things . These theories are subjected to further research that could lead to their being modified or discarded. Clearly scientists have looked at all of the data on global and solar factors relating to climate change in the last 150yr and developed a theory that involves AGH gases. Many posters here dispute this theory , That's fair enough but to be fair dinkum they must present an alternative theory with some facts and figures
Black Stump
5/02/2015 10:28:14 AM

Yes I have looked at the NSW Govt climate change website Nico and I must say its just a clone of IPCC policy. Its full of science fiction , half truths , total fabrications and outright false information. I am shocked at the deceit and I really wonder who is pulling the strings and what the political agenda is when they have to resort to such factually false information by Mike Bairds Govt. But his birthday is April 1st so perhaps its all a joke eh ?
Max
5/02/2015 10:53:16 AM

Nico, jeffito, Susan and any other AGW believers, you just don't get it do you. No one questions genuine science but if you have to use manipulated adjusted figures and then apply mathematical modelling of many varieties to achieve your preconceived outcomes, then you have major problems and to call that process scientific, then you have even bigger problems. I don't care if a conservative government, the IPCC, or whoever wants to go along with the scam, it doesn't make it legitimate and past predictions and outcomes have proven that time and time again.
Max
5/02/2015 11:12:37 AM

Brence, the other factual alternate has been presented time and again and that is that there has always been natural climate change and there always will be natural climate change and there is nothing you or any other human can do about it. That has been proven time and again with AGW prediction after AGW prediction continually being way short of the reality. The believers who can't accept and understand that, well, they are true believers.
nico
5/02/2015 11:14:26 AM

Max, and Stump: your excited assertions are no more than that. Assertions. You offer no evidence, no facts, no counter-arguments. Stump, the NSW govt web site refers to scientific papers. In your stream of abuse, you make no attempt to refute the evidence. Please provide facts and figures to back your assertions.
Qlander
5/02/2015 11:18:39 AM

When you report 2014 as being the warmest year on record. But you don't say that the result is still well with in the error bars and 'record' means less then a century. That's not science - that's politics. When you imply that any warming is proof that it's caused by human generated CO2. Even though you can't accurately account for the movement of all CO2 in the system - that's not science, that's politics. When you say that you can measure the average temperature of the planet to with in 100th of a degree, even though the instruments you use aren't that accurate.
Qlander
5/02/2015 11:25:32 AM

And the planet varies by up 50 degrees at any given time, and almost the same at any given place over the course of a year. That's not science, that's politics. When you a abandon all independent rational thought, and believe the people who behave this way, simple because they have a title that implies authority - that's religion.
jeffito
5/02/2015 11:51:18 AM

Max, you use that word "belief" again. As I said in an earlier post, it is not part of the scientific process or language. And the scientific process does all it can to avoid "preconceived outcomes". So you are wrong again in your understanding of science. Prediction is an important part of much science eg what will the weather be next week, how will the winds behave at the Northcliffe fire etc. Modelling is the scientific process of predicting the future. It is based on collected facts, figures, observations etc. Modelling does not produce exact matches to future events but they get refined.
Black Stump
5/02/2015 11:57:38 AM

And tell me Brence are we supposed to send the whole world's economy broke all on a theory? The facts and figures are there to see Brence if you choose to look, the CAGW theory belongs with the flat earth theory, the sky is falling theory, the end of the world tomorrow theory, little green men from mars theory, your theory is a load of closed minded, wildly exaggerated crap. And most intelligent people realised this many years ago.
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