Agriculture and Food Supply

The forces that shape our climate are also critical to farm productivity

The National Farmers’ Federation has suggested that climate change is possibly the biggest risk facing Australian farmers over the coming century

Temperature: An increase in average temperature can affect:

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  engthen the growing season in regions with a relatively cool spring and fall;

• adversely affect crops in regions where summer heat already limits production;

• increase soil evaporation rates

• increase the chances of severe droughts.

• reduce productivity

Rainfall, floods and severe storms: Changes in rainfall can affect:

• soil erosion rates and soil moisture

• crop yields

• tropical cyclones, droughts and flooding rains impact on food production and supply

• wildfires cause loss of fodder, animals, and farm infrastructure (sheds, fences, machinery)

• hail causes significant crop losses

• the increased risk and rates of salinization http://www.epa.gov/climatechange/effects/agriculture.html

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Food and Fiber

• 60% of Australia is used for commercial agriculture (Pestana, 1993).

• 2% is used for broad acre and intensive crop production

• 4% is sown to pastures

• 50% of the gross value of farm production is cropping,

• 25% of the gross value of farm production is meat production

• 25% of the gross value of farm production are livestock products such as wool and milk

• a 10% reduction in rainfall would counter the effect of a doubled CO₂ concentration.

• a 20% reduction in rainfall at doubled CO₂ is likely to reduce pasture productivity by about 15% and live-weight gain in cattle by 12% Howden et al. (1999d)

How will agriculture adapt to a shifting climate?

The agriculture sector is vulnerable to the potential impacts of climate change including:

• a reduction in annual average rainfall over much of the Australian continent

• increases in mean annual temperature and atmospheric carbon dioxide concentrations

• increased frequency of extreme weather events such as flooding and drought

• altered distribution and survival of pests and weeds, which are likely to have a significant impact on agricultural production in some regions

• increased risk of heat stress for intensively housed animals

• Warmer temperatures may also increase the distribution of weeds, pests and diseases

the likely impacts on different types of agriculture.

http://www.greenhouse.gov.au/agriculture/impacts.html

Heat Stress in Corn – poor kernel formation A9b_s1_2

Examples of climatic sensitivities in agriculture

Annual cropping

The grains industry, Australia’s largest crop based industry, is sensitive to the timing of frosts, sowing

rains and rain in spring. In addition, cumulative temperature impacts may be important, as well as

increases in wind speed.

Dairy cattle

The dairy industry is vulnerable to climate change, especially because of the sensitivity of dairy

cattle to heat stress (high temperature coupled with high humidity).

Sheep and beef cattle

The timing and seasonal patterns of rainfall are important for pasture based livestock industries.

The extensive beef production industry has learned to cope with regionally variable rainfall; it is

more adaptable than many rural industries. For the sheep industry, cold events (wind, rain, and low

temperature in combination) are a common risk for recently shorn and new born animals.

Horticulture

Hail storms and frosts are major climatic risks for the fruit industry.

For apples and pears, the timing of rainfall is important; in dry conditions the availability of irrigation water is crucial. Higher night temperatures can be a problem for some late harvested varieties of fruit.

Viticulture

For the viticulture industry, the timing of rainfall is critical. Late summer rainfall can lead to splitting,

ringing, disease exposure and rot. Generally wet summer conditions can lead to fungal and bacterial

infection from the soil. Frosts at bud burst and fl owering can also devastate yields.

Source: Steffen and Sims (2006).

World's Most Important Crops Hit
By Global Warming Effects http://www.countercurrents.org/cc-connor230307.htm 23 March, 2007

• warming over the past two decades has already had real effects on global food supply Rising temperatures between 1981 and 2002 caused aloss in production of wheat, corn and barley that amounted in effect to some 40 million tons a year - equivalent to annual losses of some £2.6bn.

• six of the most widely grown crops in the world - wheat, rice, maize, soybeans, barley and sorghum. Production of these crops accounts for more than 40 per cent of the land in the world used for crops, 55 per cent of the non-meat calories in food and more than 70 per cent of animal feed

• cereal crops are suffering from lower yields during a time when agricultural technology, including the use of chemical fertilisers and pesticides, has became more intensive. the observed fall in cereal yields could be clearly linked with increased temperatures between 1980 and 2002 - around the world during a period when average temperatures rose by about 0.7C although the rise was even higher in certain crop-growing regions of the world. David Lobell of America's Lawrence Livermore National Laboratory in California,

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