Climate change impacts on agriculture

Likely impacts of climate change on agriculture

Changes to carbon dioxide, temperature, rainfall and wind conditions are expected to cause a range of local impacts as described below.

The enterprises and regions most at risk will be:

• Those already stressed – economically or biophysically (e.g. as a result of land degradation, soil salinity or loss of biodiversity).
  
• Those at the edge of their climatic range or tolerance.
  
• Those where large and long-lived investments are being made — for example, dedicated irrigation systems, slow growing cultivars, and processing facilities.

Following are some likely impacts on agriculture.

Temperature impacts

• Changes to crop yields and pasture growth, depending on the optimum temperature ranges for growth of each species or variety.
  
• Reduced protein content for some grain crops, as a result of heatwaves.
  
• Increased heat stress in livestock, resulting in reduced milk production, reduced meat production and quality, and increased mortality.
  
• Increased frequency, speed and intensity of wildfires (more lightning strikes and longer dry spells are likely to contribute to increased frequency of fires).
  
• Cool climate growing areas become unproductive for some traditional crops, such as cherries and cool climate wine grapes.
  
• Warmer, moister conditions can result in the entry or proliferation of some weeds, pests and diseases (especially fungal infections).
  
• New crop or stock opportunities in areas previously considered too cool (e.g. warm climate fruits).
  
• Extended or changed (e.g. earlier) growing seasons, possibly leading to opportunities to enter markets by supplying produce earlier than do current suppliers.
  

• Reduced vernalisation² of fruit crops, due to increased minimum temperatures or less chilling.

Rainfall/water supply impacts

• Reduced crop yields, when the negative impacts of reduced available moisture in the soil and atmosphere exceed the positive impacts of increased carbon dioxide concentration in the atmosphere.
  
• Large regional differences in the impacts on crop yields — there is a high chance of decreases in productivity and value for wheat in Western Australia, but high chances of increases in Emerald (Qld) and Wagga Wagga (NSW) (10).
  
• Flow-on effects from changes in crop yields and crop prices for livestock industries, for which bought-in grains and other fodder is a major input cost.
  
• Reduced pasture growth as a result of decreased winter and spring rainfall in southern Australia could significantly constrain animal production, under current farming systems (11).
  
• Greater demands on water resources, due to decreased supply and possibly increased demand.
  Increased soil salinity and reduction in the area of productive agricultural land due to greater reliance on irrigation.
  
• Increased erosion potential with heavy rainfall events.

Extreme events

• Multiple impacts associated with more frequent, longer, and hotter droughts.
  
• Crop/pasture and property damage associated with strong winds, flooding, hail and storms (and possibly loss of livestock and decreased livestock production).

Coastal impacts

• Increased salinity of water in estuaries due to sea level rise.
  
• Possible reduction in the amount of water suitable for irrigation.
  
• Possible reduction in area of land suitable for agriculture.

Goyder’s line

Using likely scenarios of climate change derived from multiple climate models and emissions scenarios, Howden and Hayman examined the probability of shifts in Goyder’s line in South Australia, concluding there was a small probability of the line shifting north, but a larger probability of it shifting south, increasing pressure on marginal cropping zones (21).

Ecosystem impacts

The productive ranges of native South Australian species of plants and animals are likely to change significantly, with a tendency towards shifts southerly and towards higher, cooler ground. Cleared land is likely to provide an obstacle to many species attempting to adopt these changes.

Trade impacts

As climate change is a global phenomenon, costs and benefits will impact upon other regions, including Australia’s overseas agricultural competitors. In some situations that could threaten current South Australian advantages and marketing opportunities.

North America is expected to enjoy warmer conditions, leading to increased productivity and increased competition (supply) in international markets such as those for wheat and barley. Changes in temperature will alter animal husbandry requirements in Europe, allowing animals to be housed indoors for shorter periods, or not at all, substantially reducing production costs. Changes in pest and disease incidence, and severity of infestations, in crop and animal enterprises of Australia’s trading competitors are also likely to occur.

Vulnerability

Vulnerability is a function of exposure to climate factors, sensitivity to change and capacity to adapt to that change. Systems that are highly exposed, sensitive and less able to adapt are vulnerable. This is illustrated in figure 14 below. Adaptation strategies therefore involve the identification of sectors/systems/regions vulnerable to change and an examination of the scope to increase the coping capacity of those systems — their resilience — which in turn will decrease that vulnerability. Prioritisation will also depend on identifying vulnerable systems or regions whose failure or reduction is likely to carry the most significant consequences. (15)

Figure 14: Vulnerability to climate change depends on our ‘exposure’, our ‘sensitivity’ and our ‘adaptive capacity’ (15).

Websites for more information:

Further information on global projections of changes in temperature, precipitation, average annual water runoff, water stress and crop yields can be found at:

Australian Greenhouse Office
www.greenhouse.gov.au/agriculture

South Australian Government   
www.climatechange.sa.gov.au

2006 CSIRO Report: Climate Change under enhanced greenhouse conditions
http://www.climatechange.sa.gov.au/PDFs/SA_CMAR_report_High%20resolution.pdf

2 Vernalisation refers to a plant’s requirement for a period of cold temperature (or chilling) to initiate flowering.

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