Investigate the impact of climate variability and change on agricultural production and evaluate strategies for adaptation and mitigation

What this dot point is asking

This elective asks you to investigate how climate variability (the year-to-year swings from droughts to floods) and longer-term climate change affect agricultural production, and to evaluate what producers do to adapt to those impacts and to mitigate their own emissions. NESA wants you to distinguish variability from change, to explain the production impacts mechanistically, and to judge adaptation and mitigation strategies for effectiveness and cost. Australia is one of the most climate-variable farming environments on Earth, so real local examples are essential.

The answer

Variability versus change

Climate variability is the natural swing between wet and dry years, driven for Australia largely by the El Nino Southern Oscillation, the Indian Ocean Dipole and the Southern Annular Mode. El Nino years tend to bring drought to eastern Australia, La Nina years bring wetter conditions and flooding. Climate change is the long-term shift on top of this variability: rising average temperatures, more frequent and intense heat, a drying trend in the southern cropping zones (especially the cool-season growing rainfall that grain crops depend on), and more extreme rainfall and fire weather. The two interact, so a drought in a warming climate is hotter and harder on crops and stock than the same drought decades ago.

Impacts on production

The impacts run through the whole farm system. In cropping, lower and less reliable growing-season rainfall reduces yields and shifts the viable cropping zone, while heat at flowering and grain fill cuts grain set and quality. In livestock, heat stress reduces feed intake, growth, conception and milk production, and drought collapses pasture, forcing destocking, expensive supplementary feeding, and welfare risk. More extreme events bring flood, bushfire and erosion. The economic impact is severe income volatility and rising risk, which strains farm finances and rural communities.

Adaptation strategies

Adaptation manages the impacts producers cannot avoid:

• Conservative and flexible stocking. Setting stocking rates to the long-term carrying capacity, keeping a feed and water reserve, and being ready to destock early protects pasture and finances through drought.
• Drought-tolerant and shorter-season species and varieties. Deep-rooted perennials such as lucerne, and shorter-season crop varieties, better match a drying, more variable climate.
• Water security. Investing in dams, efficient irrigation and soil-moisture monitoring stretches scarce water.
• Diversification and risk tools. Spreading enterprises, building cash reserves, using the Farm Management Deposit scheme, forward selling and multi-peril crop insurance smooth income across good and bad years.
• Infrastructure for heat. Shade, trees, water points and altered handling times reduce livestock heat stress.

Mitigation strategies

Mitigation reduces agriculture's own greenhouse emissions, which in Australia are dominated by methane from ruminant livestock and nitrous oxide from soils and fertiliser. Strategies include improving feed efficiency and animal productivity so emissions per kilogram of product fall, supplementing diets with methane-reducing additives (such as the seaweed Asparagopsis being commercialised in Australia), better fertiliser management to cut nitrous oxide, building soil carbon through pasture and stubble management, and replacing diesel and grid power with on-farm solar and bioenergy. Many producers pursue carbon farming, generating Australian Carbon Credit Units from soil-carbon or revegetation projects as a new income stream.

How to use this in the exam

Distinguish variability from change early, then explain impacts with a mechanism (heat stress reducing intake, drying reducing growing-season rainfall). Provide a balanced set of adaptation and mitigation strategies, label which is which, and evaluate each for cost and effectiveness using real Australian examples such as the millennium drought, carbon farming, or methane-reducing feed additives.