Climate and Greenhouse Basics
Climate risk, climate change, pricing carbon and carbon farming are now major political and social forces that impact on all industries, including dairy. It is important dairy farmers understand these issues in the context of their business.
Understanding climate risk, the climate change debate and how it affects individual dairy businesses requires some understanding of what drives climate and weather, predictions about future climate and the greenhouse gases the dairy industry emits.
Understanding weather and climate
The difference between weather and climate is simply time. Climate is what the weather is usually like (for example, summers are usually hot) and weather is at a particular place and time (for example, a hot day with a sudden thunderstorm). Climate change describes the changes in the long-term averages of daily weather.
Just as the weather changes from day-to-day, climate also changes. Global and regional climates are in a constant state of change on time-scales from months to millions of years.
The earth’s climate has seen periods of intense warmth and bitter cold. These historical changes in the climate were caused by natural processes, but there is increasing evidence that human activities have the potential to cause additional changes to the climate.
Natural causes of climate change include changes in the earth’s orbit, the sun’s activity and ocean currents, large volcanic eruptions and meteor impacts. Oceanic and solar influences have a mild to strong influence on year-to-year climate variability. Periods of warming and cooling in history can be attributed to these types of events.
Human activity is also contributing to longer-term climate variability, through increases in the concentrations of some greenhouse gases in the atmosphere. Since the industrial revolution there has been a steep rise in the concentration of greenhouse gases in the atmosphere.
Greenhouse gases include carbon dioxide, methane, nitrous oxide and water vapour. They capture the heat that is given off when the sun’s energy warms the surface of the earth. This direct human contribution to an increase in greenhouse gas concentrations is often referred to as the enhanced greenhouse effect. Contributing activities include burning of fossil fuels, deforestation, farming and landfill sites.
Weather and climate tools for farmers
There are a number of useful tools available to help farmers better understand and forecast weather and climate at a local level. A number of relevant sites/tools for dairy farmers have been provided below.
Dairy Australia is currently working on a collaborative project to develop improved seasonal forecasting tools for farmers. The Forewarned is Forearmed project is using farmer reference groups to analyse existing weather and seasonal forecasting tools and determine the best fit-for-purpose data that can help with on-farm decision making. The project will deliver outputs by June 2021 which will be made available on this page once finalised.
For information on seasonal outlooks and conditions, visit the Bureau of Meteorology Climate Outlooks.
Climate Kelpie is for Australian farmers and their advisors. It connects them to tools and information about climate to help them make decisions about their farm business.
Climatedogs are short animations used to explain key climate features that can effect rainfall in Victoria. There are currently five Climatedogs:
- Enso (outlines the tropical moist air in Equatorial Pacific Ocean – El Nino Southern)
- Indy (outlines the moisture from Indian Ocean)
- Sam (influences the intensity and frequency of cold fronts)
- Ridgy (influences high-pressure systems that can block rainfall)
- Eastie (influences deep low-pressure systems dominating annual rainfall in Gippsland)
Watch below the short animations for each of the climate dogs.
New South Wales has also developed some Climatedogs animations.
The Bureau of Meteorology's Water and the Land page provides links to agricultural services and forecasts for rainfall, temperature, wind and warnings.
Australian climate information
Australia’s climate has warmed by just over one degree Celsius since 1910, leading to an increase in the frequency of extreme heat events (CSIRO State of the Climate 2018). The warming trend occurs against a background of year-to-year climate variability, mostly associated with El Nino and La Nina in the tropical Pacific. Understanding of the climate influences across Australia is vital to down-scaling global climate change impacts for Australia and regions.
Regional climate change attribution studies have shown significant consistency between observed increases in Australian temperatures and those from climate models forced with increasing greenhouse gases.
Attributing observed regional rainfall changes is a more difficult task than attributing temperature changes. This is especially so in Australia, where intrinsic rainfall variability year-on-year and decade-to-decade timescales is large. However, literature to date seems to indicate that drying across Australia cannot be explained by natural variability alone. For example, warming reduces the temperature gradient between the equator and pole, reducing the energy available to mid-latitude weather systems.
Australian climate change projections show how Australia’s climate may change in the future, using up to 40 existing global climate models. The projections indicate that continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system (see figure below).
Australia is projected to experience (CSIRO 2018):
- Further increases in sea and air temperatures, with more hot days and marine heatwaves and fewer cool extremes
- Further sea level rise and ocean acidification
- Decreases in rainfall across southern Australia with more time in drought, but an increase in intense heavy rainfall throughout Australia
More detailed regional weather and climate information has been developed by the Bureau of Meteorology for all of the 56 regional catchments across Australia. These provide a summary of the latest climate information by catchment (2019) and are freely available on the Bureau of Meteorology website.
Global climate information
Climate has always been changeable. Ice ages occur every 100,000 years due to wobbles in the earth’s orbit plus positive feedbacks. For example, the delayed responses of greenhouse gases and ice sheets enhance the orbital effect on temperature by about 50%.
However, since the 1950s, many of the observed changes are unprecedented over decades to millennia. For example, northern hemisphere warmth of the last half century is likely the highest in the past 1,300 years. Increasing evidence demonstrates that warming of the global climate system is unequivocal (Intergovernmental Panel on Climate Change).
Concentrations of all the major long-lived greenhouse gases in the atmosphere continue to increase, with carbon dioxide (CO2) concentrations rising above 400 parts per million since 2016 and the CO2 equivalent (CO2-e) of all gases reaching 500 ppm for the first time in at least 800,000 years. Emissions from fossil fuels continue to increase and are the main contributor to the observed growth in atmospheric CO2.
The threat of climate change to existing ecosystems, supply chains, livelihoods and health are becoming more apparent. Bold action to address climate change is required at global scales across countries, borders and industries in order to meet global goals of keeping global warming levels below 1.5 degrees Celsius.
Most indicators of climate change continue to reflect trends consistent with global warming.
The Intergovernmental Panel on Climate Change (IPCC) consists of leading scientists from around the world who review and provide the best consensus judgement on climate change. The IPCC concludes that:
- Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system. Warming will continue to exhibit interannual-to-decadal variability and will not be regionally uniform.
- There will be more hot days and fewer cold days over most land areas. Heat waves will occur with higher frequency and duration. Occasional cold winter extremes will continue to occur.
- Changes in the global water cycle in response will not be uniform.
- Global ocean will continue to warm, affecting ocean circulation.
- Artic sea ice will continue to shrink and thin, so too will global glacier volume.
- Global mean sea level will continue to rise, but the rate is uncertain.
The latest series of peer-reviewed reports by the IPCC provide some insights into implications for Australia and wider agriculture industry, but are high level. Regular climate updates for Australia can be sought from the Bureau of Meteorology.
Implications for the dairy industry
While there is a growing consensus on the causes and likelihood of climate change, there is uncertainty about the level of impacts across the sector. Given that predictions are for a hotter, drier south and wetter north, the impacts will likely be complex and vary by region and business.
In 2016, Dairy Australia commissioned the CSIRO to analyse the climate change impacts on the Australian dairy industry and the eight dairy regions . The analysis showed that:
- Australia is already experiencing impacts from recent climate change. These are now evident in increasing stresses on water supply and agriculture, changed natural ecosystems and reduced seasonal snow cover.
- Ongoing vulnerability to extreme events demonstrated by substantial economic losses caused by droughts, floods, fire, tropical cyclones and hail.
- Some adaptation has already occurred in response to observed climate change. Examples come from sectors such as water, natural ecosystems, agriculture and coasts.
A warmer and drier climate poses challenges for the dairy industry in areas such as pasture growth, run-off into dams, viability of shade trees, managing feed, heat stress, pests, weeds, diseases and reproduction. More extreme daily rainfall increases risks for flooding, erosion, water-logging, infrastructure, supply chain and transport.
By 2030, a one to 6°C temperature rise above 1990 levels is expected. Inland areas will experience the greatest level of warming, with coastal areas slightly less affected. To give an indication of the scale of these temperature rises, a 1°C rise would make Melbourne like Wagga Wagga in New South Wales, a 3°C rise like that of Sydney and a 6°C rise like that just north of Roma in Queensland.
The repercussions for the dairy sector of an increasingly warming climate will be threefold:
- Continuing to adapt and respond to biophysical impacts of climate change
- Demonstrating to community, supply chain and government that the industry is part of the solution in reducing greenhouse gas emissions
- Integrating climate action with broader risk and environmental stewardship approaches.
The Climate Change and Dairy fact sheet provides more detail on this.
Climate change and dairy factsheet(16 July 2020)PDF, 750.07 KB