The Northern Agricultural Region (NAR) has a Mediterranean climate, with warm dry summers and cool wet winters. Average daily maximum temperatures along the coast over the 30 years between 1990 and 2019 were ~31°C in summer (January) and ~20°C in winter (July). Average daily maximum temperatures inland over the same period were ~36°C in summer (January) and ~18°C in winter (July). Annual rainfall of around 300-400 mm allows intensive agriculture throughout the majority of the region (BoM 2020). In the northeast, where annual rainfall is less than 250 mm, the economy is dominated by mining and pastoralism.
Winter rainfall is generally reliable, with ~60 mm difference from one year to the next (BoM 2019). Spring rainfall is also moderately reliable, particularly in the region’s south west, while summer and autumn rainfall is much less predictable across the region from year to year. The autumn break (defined as at least 25 mm of rainfall over three days, prior to the commencement of sowing) occurs towards the end of May in the south west of the region, early to mid-June through much of the central region and in mid-July in the east and north east.
While Western cultures tend to use a four season model (summer, autumn, winter, spring) for the yearly calendar, many Aboriginal communities use a six season model (Mamid 2020). These seasons are not defined by dates, rather by observable changes in nature such as temperature; winds; animal migration patterns, hibernation and breeding behaviour; the flowering of plants; rain; and food availability. The Noongar people of the south-west region of Western Australia are one example of a group who observe six seasons. The seasons are known as Birak (First Summer, approximately December-January), Bunuru (Second Summer, February-March), Djeran (Autumn, April-May), Makuru (Winter, June-July), Djilba (First Spring, August-September), and Kambarang (Second Spring, October-November).
The short-term – within and between – year variability of NAR weather patterns is due to naturally occurring internal and external factors driven by the changing seasons, regional topography, location and global climate processes. Global climate processes that affect the climate and weather of the NAR include the El Niño Southern Oscillation (ENSO) which broadly influences whether a given year is relatively wet or dry; the Indian Ocean Dipole which influences the timing and amount of spring rainfall; the Sub-Tropical Ridge which drives the Mediterranean-type climate of the NAR overall; the Southern Annular Mode which brings cold fronts bearing rain from the Antarctic in the winter and; the Madden-Julien Oscillation which predominantly influences summer weather (Climate Kelpie 2020).
The climate is also changing as a result of human activities such as burning fossil fuels for energy, large-scale land-clearing land and unsustainable commodity production and consumption practices (e.g. food waste, excess packaging; IPCC 2013). All of these activities release greenhouse gasses (GHGs) into the atmosphere and cause global warming along with related shifts in other aspects of the climate (DAWE 2020). Climate change is impacting our weather, natural resources, infrastructure and livelihoods now and will continue to do so in the long term. These impacts require management at multiple levels, including the regional and local level.
CSIRO and Bureau of Meteorology, Australia
The climate of the NAR has already been measurably altered by climate change. Click on the tabs below to see more information on climate-related changes that have already been observed in the NAR.
Mean temperatures have increased by 1.4°C since 1910 (CSIRO 2020) leading to an increase in the frequency of extreme heat events and heat waves (BoM 2018). In the last 30 years in the NAR (BoM 2019), the average number of hot days (maximum temperature > 38°C) per year on average has increased by almost 25%. The year 2019 was the hottest year on record (CSIRO 2020). The average annual number of moderate to severe heat stress days for livestock (temperature humidity index THI ≥ 80) has almost doubled. The region experienced an average of 60 days per year with a THI ≥ 80 between 1989–2018, compared to an average of 44 days per year between 1959–1988.
Researchers use general circulation models (also known as global climate models or GCMs) to predict how the climate is likely to change in the future based on different GHG emissions scenarios. Common scenarios include dramatically reduced emissions or moderately reduced emissions vs. a business-as-usual scenario).
Watch this CSIRO video to find out why GHG emissions are a major contributor to climate change and how different emission scenarios are used to take this into consideration when projecting future climate (embedded CSIRO Projecting future climate change video: https://youtu.be/ooPhtxt62Tk). When many models agree on the direction of change, there is said to be High Confidence that the projected change will occur.
CSIRO (2016) prepared future climate projections for clusters of Australia’s NRM regions, the results of which are summarised below. The Northern Agricultural Region is part of the Southern and South-Western Flatlands West (SSWFW) cluster, comprising NRM regions in southwest Western Australia covering the wheat, sheep and wine producing agricultural areas as well as the cities of Perth, Bunbury, and Geraldton.
Climate projections for the SSWFW are based on the outputs of 40 GCMs developed by Australian and international scientists. The projections are the most comprehensive ever released for Australia. For more information view the full report or visit the Climate Change in Australia website. For a summary of the findings, view the SSWFW webpage or see the table below. For the most up-to-date impacts and projections for Australia, see the State of the Climate Report 2020 (CSIRO 2020).
Temperatures will continue to increase in all seasons
Scientists have very high confidence that average, maximum and minimum temperatures will all continue to increase substantially in the future.
In the near future (2030), annual average temperatures across all emissions scenarios are expected to increase by a further 0.5 to 1.2°C above the 1986-2005 climate. Towards the end of the century (2090), temperatures are projected to be 2.6 to 4.2°C warmer than they are now on average under a high emissions scenario, and 1.1 to 2.1°C warmer under intermediate emissions scenarios.
Hot days will be hotter and more frequent and there will be less frost
Scientists have very high confidence that the number and frequency of hot days, the temperatures reached on hot days, and the intensity and duration of heat waves will all continue to increase substantially in the future.
In the near future (2030), extreme temperatures across all emissions scenarios are expected to increase at a similar rate to average temperature, i.e. 0.5 to 1.2°C above the 1986-2005 climate by 2030 and a further 1.1 to 4.2°C by 2090.
Scientists additionally have high confidence that the number and frequency of frost days (with minimum temperatures under 2°C) will decrease across the region in the future.
Crop and livestock farms in the Northern Agricultural Region will be adversely affected by climate change (Kingwell & Payne 2015). Climate change will give rise to an increased number of adverse seasonal conditions and result in poorer production and reduced profitability over time. Projected increases in extreme events such as droughts and floods could also trigger increases in insect outbreaks and weed prevalence as the climate becomes more inhospitable for native vegetation and the competitive advantage of weeds increases.
Broadacre crop and pasture production may also decline in drier, warmer northern and eastern areas. The amount of water available for horticulture and other agricultural activities will be affected by reduced surface water flows into farm dams and aquifers (DPIRD 2020). Livestock welfare risks may increase if higher temperatures reduce the availability of feed and increase heat stress prevalence. Higher temperatures can also affect livestock productivity by reducing reproductive rates, growth rates and milk production (DPIRD 2020). While water erosion and salinisation are likely to reduce due to declining rainfall, wind erosion may increase in regions where declining rainfall limits groundcover.
Climate change mitigation consists of actions taken to reduce the magnitude or rate of global warming and its related effects. Generally, mitigation involves reducing greenhouse gas emissions related to human activities such as transport, agricultural and industrial production, and energy use. The use of fossil fuels for energy accounts for about 70% of GHG emissions and the primary challenge for mitigation is the replacement of coal, gas, and oil energy production with clean and renewable energy sources. Mitigation also involves new more efficient technologies and making older equipment more energy efficient. In addition changing land management practices and consumer behaviour to use fewer resources and release fewer emissions will also be important in achieving mitigation.
With a relatively high standard of living, low use of public transport, and dependence on coal for power, Australia has one of the world’s highest per capita emissions (16.8 tonnes of CO2 equivalent per person in 2018). Only oil-rich nations such as Bahrain, Kuwait, Qatar, and Saudi Arabia have meaningfully higher per capita carbon footprints (EU Report 2019). Australia’s land-clearing rates also contribute to emissions and are also among the highest in the world. Australia is the only developed nation to feature in a 2018 WWF list of deforestation hotspots.
In 2007, Australia ratified the Kyoto Protocol, an international treaty committing states to reduce GHG emissions, and introduced carbon pricing requiring large businesses to purchase emissions permits in 2012. Unfortunately the policy and legislation was later repealed. Australia signed up to a second commitment period of the Kyoto Protocol (2012-2020), and adopted the Paris agreement in 2016 (another international agreement to reduce GHG emissions), committing to reduce emissions by 26-28% below 2005 levels by 2030. Achieving this target will involve reducing per capita emissions by half, and economy-wide emissions by two-thirds via changes in the energy mix with increases in the use of renewables (wind, solar). To achieve these targets will also require increases in energy efficiency, reducing land clearing, and promoting reforestation and land management programs.
Aboriginal and Torres Strait Islander people in Australia are especially vulnerable to the impacts of climate change (Bowles 2015). The impacts of climate change must be urgently mitigated to support Indigenous Australians to maintain their connection to Country. Mitigation strategies relevant to the NAR include*:
*Lists are indicative not exhaustive
The bulk of Australia’s greenhouse gas emissions reduction efforts are likely to come from the energy sector through improved efficiency and renewable energy (Renewable Energy Targets).
The land sector can also contribute to reducing Australia’s greenhouse gas emissions through changed farming and forestry practices.
Climate change adaptation consists of actions taken as part of a process of adjusting to the actual or expected impacts of climate change. These changes include increases in the frequency or severity of weather-related disasters. These actions and adjustments are intended to avoid or minimise harms and exploit beneficial opportunities arising from climate change. Even if greenhouse gas emissions are reduced or stabilised soon, global warming and its effects will last many years and the need for adaptation is now unavoidable (IPCC 2013).
Adaptation actions can be incremental. The central aim is to maintain the current system in the face of changing conditions or transforming through actions that change the fundamental attributes of a system in response to climate change and its impacts. The need for adaptation varies from place to place, depending on the type and scale of climate impacts on a region and how sensitive the social, economic, and environmental systems in the region are to the impacts of climate change. Adaptation actions often focus on “no regrets” measures that also provide complementary biodiversity, soil health, social, or water benefits. Building healthy landscapes and communities by alleviating pressures such as poverty, land degradation and invasive species builds local environments that are more resilient to climate change.
People in the NAR have been responding to climate variability and change for thousands of years. The 10,000-year-old oral histories of Aboriginal Australians tell of a time when sea-levels were rising (between 7,000 and ~20,000 years ago according to the scientific record), and how people responded (Nunn 2018). In more recent times, farming communities have coped with the naturally variable and often extreme climate by adjusting sowing times or adopting new water-saving techniques. These knowledge systems and coping strategies are extremely important for responses to climate change and, in the case of Aboriginal Australians are rooted in a deep familiarity with the local environment, learned over many generations. Always incorporate traditional knowledge into vulnerability assessments and adaptation planning. In some cases, traditional coping strategies may not be sufficient to adapt to new conditions outside the range of those previously experienced, but transformative adaptation actions must still recognise and respect that traditional knowledge.
Successfully adapting to climate change requires activities to be undertaken across various land tenures and industries, by a broad cross-section of the community. Adaptation strategies relevant to the NAR include*:
*Lists are indicative not exhaustive
The agriculture sector will face reduced water availability and potentially longer spells of warmer and drier conditions, including the possibility of more frequent and more intense droughts (DPIRD 2020).
Changes in temperature and rainfall as a result of climate change will mean that the local environment of many native species will be different in the future. Many species will need to adapt to these changes, move to a new environment in which they can survive, or risk becoming extinct.
A flexible strategy focused on maintaining large populations of native species, securing ecosystem health, and promoting connection between areas of native vegetation across the landscape has the best chance of helping native species to adapt to a changing climate (DAWE 2013).
Current patterns of settlement and land use in many coastal areas will become increasingly unsustainable due to sea-level rise and changes in waves, winds and extreme events (DAWE 2009; CoastAdapt 2017).
Invasive species are likely to cause more harm as the climate changes. Many invasive species are generalists and highly adaptable, able to tolerate or take advantage of change and disturbance and thrive over a wide range of climatic conditions.
A warmer, drier climate may disadvantage native species while being tolerable or even preferable for harmful invasive species and weeds (Invasive Species Council 2009). One of the best ways to assist nature to adapt to inevitable climate change is to reduce the threat of invasive species through control and management.
Reductions in rainfall and increases in temperature mean that continued adjustment and management (supply and demand) of increasingly scarce water resources will be required.
Revegetate riverbanks and estuarine environments to limit soil erosion and sedimentation and improve water quality
Climate Kelpie connects Australian farmers and their advisors to tools and information about climate to help make better decisions about farm business. For information on the climate processes that influence rainfall in Australia: http://www.climatekelpie.com.au/index.php/climatedogs/. For a monthly national temperature and rainfall forecast http://www.climatekelpie.com.au/index.php/forecast/. For links to a variety of decision-support tools for farmers http://www.climatekelpie.com.au/index.php/decision-support-tools/
For three-month seasonal climate outlooks for WA, sign up for DPIRD’s Seasonal Climate Outlook newsletter https://www.agric.wa.gov.au/newsletters/sco which is published monthly and provides a weather outlook for the South West Land Division which includes much of the NAR.
This fifth, biennial State of the Climate report draws on the latest monitoring, science and projection information to describe variability and changes in Australia’s climate. Observations and climate modelling paint a consistent picture of ongoing, long term climate change interacting with underlying natural variability. http://www.bom.gov.au/state-of-the-climate/. The Bureau of Meteorology also has a very useful interactive climate change trends and extremes tracker http://www.bom.gov.au/climate/change/#tabs=Tracker&tracker=timeseries
CSIRO’s Climate Change in Australia website provides a wealth of information on climate change projections, impacts, and adaptation options, and includes a regional climate change explorer tool presenting detailed climate change projections for Australia’s NRM regions. The Northern Agricultural Region is located within the southern and southwest flatlands (west) cluster.
CSIRO’s AdaptNRM website provides NRM groups with information, tools, and resources to support regional climate adaptation planning. Modules include adaptation planning, weeds and climate change, and implications of climate change for biodiversity.
CSIRO and BoM’s State of the Climate 2020 report presents the latest climate research, encompassing observations, analyses and projections to describe year-to-year variability and longer-term changes in Australia’s climate. The report is a synthesis of climate change science in Australia and includes new information about Australia’s climate of the past, present and future.
For information on the national Emissions Reduction Fund, Emissions and Energy Reporting System, and Renewable Energy Targets, visit the Clean Energy Regulator’s website. For more information on Carbon Farming, visit the Carbon Famers of Australia website.
The state government’s Climate Change Strategy, Adapting to our Changing Climate, outlines the climate change challenges we face and establishes a high-level strategic framework for climate change adaptation in the sectors of Water, Energy, Agriculture, Forestry & Fisheries, Infrastructure, Community Development, and Ecosystem Management.
Climate Interactive provides a set of interactive, easy-to-use, and scientifically rigorous simulation games for using in workshops to play out various climate change scenarios and identify what works for addressing some of the biggest global climate change challenges.
Many useful reports on the physical science basis of climate change as well as mitigation and adaptation options can be found on the homepage of the United Nations’ Intergovernmental Panel on Climate Change.