Is climate variability really increasing?

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 the soil scientist and environmental analyst, David Freebairn.

Dr Freebairn, who runs climate workshops for farmers and led the CliMate app development project, says there is an increase in climate variability – which is often cited as the cause of a capping wheat yield gains (see Grain Central story) – is not supported by the data it derives from climate analysis.

“I have checked the proposition that the climate is changing or becoming more variable and, in short, this rarely seems to be the case except in parts of Western Australia which are becoming increasingly drier,” he said. declared.

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

“If you look at different times, sometimes it’s wetter, sometimes it’s drier. By choosing your rules, you can get the answer you want.

Dr Freebairn points to the site-specific analysis of the CliMate app, like the example in Figure 1 from Narrabri in northwest New South Wales, which covers a century of weather records.

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

“Rain and / or temperature over the past 100 years has been very variable, but there is rarely any meaningful data showing a better or worse signal – it’s just variable,” he said.

“I won’t go into the argument that wheat yields aren’t increasing as fast as you might hope, except to say that producers are improving to grow it with better agronomy.

“If breeders keep disease at bay, maybe they’re doing a great job of allowing the best agronomy to express itself, which it is. “

Dr Freebairn said area-specific climate analysis within CliMate has allowed growers to make their own assessment of climate variability at their location.

Website: www.climateapp.net.au

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

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