Climate change threat to the ‘sand castle’ of farming

Neil Lyon, June 27, 2019

THE threat and uncertainty that climate change presents to Australian agriculture is an issue farmers should be taking very seriously, according to South Australian Research and Development Institute (SARDI) principal scientist in climate application, Peter Hayman.

Addressing the Australian Farm Institute’s (AFI) “Farming in a risky climate” conference in Brisbane, Dr Hayman urged farmers to acknowledge the uncertainty, draw from the scientific evidence and plan to mitigate the risk of a hotter, drier farming environment, particularly in southern Australia.

South Australian Research and Development Institute (SARDI) principal scientist in climate application, Peter Hayman, and Climate Change Authority chair and AFI director, Wendy Craik.

This is an edited transcript of Dr Hayman’s presentation to the AFI conference:

Solid science

We are changing the radiative properties of the atmosphere which is changing the temperature, and that is having implications for rainfall.

It is a mature science. What we are seeing in Australia is that, while there is year-to-year variability, the temperatures are rising.

The straightforward explanation is that we are changing the radiative properties of the atmosphere largely by burning fossil fuels.

Sand castle analogy

In trying to explain climate change, I use a simple analogy about “What destroyed the sand castle on the beach – was it a wave or the tide”?

In climate data we have both ‘waves’ and ‘tides’ – year-to-year variability and longer term trends.

A lot of farmers will say they believe it is ‘waves’ where they are seeing a lot of natural variability in the climate. Of course, there is year-to-year variability. There is also decadal variability we need to take into account.

But underlining all this is a strong ‘tide’ of rising temperatures.

Short-term simplicity

Simply looking at the current impact of climate change is like talking to a doctor about how you compare now without any discussion about the future.

If you are in your early 30s and are drinking and smoking, you might go to the doctor and they might say your health is slightly different to the health of the average 30-year-old. If you keep the habit of drinking and smoking you are going to be a very sad 50-year-old and you might not make 60 or 70.

In climate change, a lot of the discussion is about the warming to this stage being unequivocal without the discussion about the fact we are going into a future that goes between worrying and terrifying and the risk of very serious things happening.

Warmer world, drier southern Australia

A warmer world would be a wetter world, especially at the tropics and the poles.

The problem is there is a drying in the mid latitudes. So, what I say to farmers in South Australia is a warmer world is a wetter world, except where you chose to inherit a farm.

In recent decades there has been severe drying in the south of Australia. If you take out the 2010/11 La Nina and the 2016 La Nina, it is a very sad story. They are two wet years in a run of dry years since the Millennium drought.

Firm predictions for temperature, not so rainfall

The projections are clearer for temperature than they are for rainfall. There is a lot of decadal variability.

We would be surprised by a cool decade. We will get cool years, we will get cool days – and it is character building to have people tell you climate change isn’t happening because ‘today is cold’ – but we would be surprised with a cool decade.

However, we might get a wet decade in a drying trend.

Public debate

Be careful that media will sometimes interview the one scientist that is disagreeing and one that is agreeing, which gives a false sense of balance.

In public opinion, be also careful that some people are loud that they disagree with the climate science. But they are a significant minority.

Studies show that people who disagree think more people are with them than there are. And the people who agree with the consensus think there are fewer people with them than there are.

How can farmers deal with the uncertainty?

We are very confident that the climate is changing. We are also confident there is a lot of adaptive capacity.

Australian agriculture has a very vested interest in slowing the change and reducing the amount of change globally because we are possibly heading to a future where insurance, adaptive capacity and better crops are not going to help us.

In the short term, farmers need to acknowledge the uncertainty and talk about risk management and insurance.

Farmers need to build resilience, be careful about over-reliance on precise projections, prepare for a warmer, more variable and water-constrained future.

There is better and better information about short term weather and seasonal forecasting.

It is important to keep a watching brief on the drying in the south.

Are there some regions that won’t be sustainable for agricultural use?

There is a lot of confidence in the basic climate science. However, that doesn’t translate into exactly knowing what climate change will mean for you in your location.

There will be some areas that have new opportunities and some areas that will become really difficult for agriculture.

When we say we are not sure what is going to happen with rainfall, some of my farmer friends say that means the rainfall will stay the same. No it doesn’t. It just means we don’t know exactly what is going to happen.

What will the impact of climate change be on irrigated agriculture?

The exacerbating effect on runoff of a declining rainfall and a warmer world is quite worrying. There is likely to be less runoff.

Especially in the Murray Darling basin, there is the worry about the timing of rainfall decline. If we were to see decline in autumn rainfall that would be a concern.

The water aspect is worrying, especially when you ask irrigators how they will manage heat effects, their answer is ‘water’.

There are real issues as to how policy interacts with climate. It is a really important and vexed question.





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  1. Steven Hobbs, July 2, 2019

    Plants certainly will respond to higher CO2 concentrations and warmer tempertures, but trends I am observing and recording are a 21% decline in GSR rainfall, higher rainfall variability, and a longer frost season, typically 138 days long on average. Don’t overlook that warmer seasonal conditions will contribute to an increase in plant diseases (no cold season to supress or kill off pathogens) and there will also be a corresponding increase in pest insect populations… interesting and challenging times ahead!

  2. Peter Norris, July 2, 2019

    Peter and Steve,
    I am not so sure the future will be so dire. AgFACE trial work showed a 26% yield increase and around 30% improvement in water use efficiency for yield and biomass at Horsham due to elevated CO2 with Yitpi wheat. This will surely offset some of the lower rainfall.
    Response of wheat growth, grain yield and water use efficiency to elevated CO2 under a Free-Air CO2 Enrichment (FACE) experiment and modelling in a semi-arid environment.
    O’Leary, G.J. et al. Global Change Biology (2015) 21, 2670 – 2686, doi: 10.1111/gcb.12830.

    Also Elevated temperatures and CO2 improved yield of Corn 25% and Soybean by 31% .
    Sci Total Environ. 2019 May 20;666:405-413. doi: 10.1016/j.scitotenv.2019.02.149. Epub 2019 Feb 11.
    Elevated CO2 and temperature increase grain oil concentration but their impacts on grain yield differ between soybean and maize grown in a temperate region.
    Qiao Y1, Miao S2, Li Q2, Jin J3, Luo X2, Tang C4.

    Crop choice may also change to suit higher spring temperatures. Chickpea (on soils that suit) will tolerate higher temperatures.
    Something to consider.

  3. Stephen Powles, June 27, 2019

    This is an excellent article by Peter Hayman

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