Australia is the world’s largest cotton producer, with an annual value of about $2.7 billion. While irrigation has doubled production, cotton yields are sensitive to climate change. Changes in moisture availability and temperature are known to impact on productivity.
Without on-farm adaptation, the continuing change in the climate and extreme weather will affect the industry’s yields.
Researchers at the Climate Systems Hub have applied their knowledge of how climate is likely to affect cotton growth to help identify the risks, challenges, and opportunities faced by the industry now and in the future.
Climate drivers affect cotton yield
Climatic drivers, such as the El Niño – Southern Oscillation (ENSO), Indian Ocean Dipole (IOD) and Southern Annular Mode (SAM), affect conditions across Australia, including temperature and rainfall. Climate models can help predict the occurrence of these drivers. The La Niña phase seems to be transitioning towards neutral with predictions now shifting towards an El Niño event in 2023.
The flooding over the last year on the east coast of New South Wales during 2021-22 highlights the weather extremes that can be linked to these large-scale climate drivers. Researchers at the Climate Systems Hub investigated the effect of climate on cotton yield and how climate drivers can be used to predict growing conditions.
Matching climate and cotton yield trends
Hub researchers analysed the impact of climate at three cotton dryland farms and two irrigated farms in east Australia (see Figure 1). Working with the cotton industry, researchers matched cotton yield data to rainfall and temperature data for the past 20 years. They examined the role of climate drivers, including ENSO, IOD, and SAM, and whether they increased or decreased cotton yields.
The study found that cotton yields at dryland farms were highest during average to high temperatures and average to heavy rainfall, decreasing during hot to extremely hot and dry conditions. However, irrigated farms were not as sensitive to high temperatures, achieving high yields when temperatures were average to extremely high. Dry weather and low to average rainfall reduced yields.
Researchers found a link between sea surface temperatures and favourable early growing seasons. As sea surface temperatures can be forecast up to three months in advance, they provide short-term forecasts of growing conditions and cotton yield. This timeframe is sufficient to allow farmers and crop managers to plan and implement adaptive strategies.
An eye to the future
Climate must be considered when planning and managing valuable inputs such as water and other inputs used in cotton crops.
Collaboration between climate researchers and industry is critical for communication among stakeholders on the ground and in the cotton supply chain, as well as determining effective adaptation strategies to support and enhance Australia’s billion-dollar cotton industry.
Benefits of the research
Understanding the links between climate drivers and crop yield helps to predict growing conditions and enables crop managers to adopt strategies to reduce vulnerabilities and build resilience to climate impacts.
This study also provides a framework to analyse historical cotton crop performance under various climatic conditions. It provides insights into extreme climatic variability and the limitations if climate is not considered or if rainfall alone is used as a proxy for seasonality.