Cropping

Is climate variability really on the rise?

Neil Lyon, September 18, 2017

AUSTRALIA’s climate has always been variable and the level of climate variability is neither increasing nor decreasing in most parts of Australia, according to soil scientist and environmental analyst, David Freebairn.

David Freebairn

Dr Freebairn, who runs climate workshops for farmers and led the project to develop the CliMate app, says the contention that there is an increase in climate variability – which is often cited as the cause of a plateauing in wheat yield gains (see Grain Central story) – is not supported in the data he draws from climate analysis.

“I have checked out the proposition that climate is either changing or getting more variable and, in short, this rarely appears the case, except in parts of Western Australia which are getting drier,” he said.

“If you want to find variability you can. I can find trends sometimes. If I go to Western Australia it has definitely been getting drier over the last century. But that’s about it.

“If you look at different periods, sometimes it gets wetter, sometimes it gets drier. By picking your period you can get whatever answer you want.”

Dr Freebairn points to site-specific analysis from the CliMate app, such as the example in Figure 1 from Narrabri in north-west NSW, that covers a century of weather records.

Figure 1: Total rainfall, Narrabri Airport, 1900-present. (Source: Australian CliMate)

“Over the last 100 years, rain and/or temperature are highly variable, but rarely is there useful data showing a better or worse signal – it’s just plain variable,” he said.

“I won’t get into an argument that wheat yields are not increasing as fast as we might hope, except to say that growers are getting better at growing it with better agronomy.

“If the breeders keep diseases at bay, maybe they are doing a grand job to allow the better agronomy to express itself – which it is.”

Dr Freebairn said the area-specific climate analysis within CliMate allowed producers to do their own assessment of climate variability at their location.

Website: www.climateapp.net.au

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David Freebairn was principal soil scientist with the Department of Natural Resources and Mines (Queensland) for 31 years (1976 – 2007); a consultant to the GRDC (2004 – 2011); principal environmental scientist with Natural Solutions (2007 – 2014); and is currently an independent soil scientist and environmental analyst.

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