Australia’s climate is the backdrop against which our landscapes and seascapes, our ecosystems and biodiversity, and our society and economy have all developed. The nature of our soils, vegetation, species, ecosystems, air and urban environments all depend on the Australian climate. Australia’s climate is naturally variable across seasons, years and decades. Much of this variability is driven by broader influences in the global climate system driven by ocean and atmospheric changes and cycles, such as the El Niño–Southern Oscillation, and associated El Niño and La Niña events. Australia’s climate, along with the global climate, is changing as a result of human-induced climate change (see Climate change and extreme events). Climate change is also having a high impact on the variability of our climate. We are already experiencing increased temperatures, changed rainfall patterns, increased extreme bushfire weather, and changed frequency and severity of extreme events such as heatwaves. These changes are having a profound effect on all aspects of our environment (see Landscape and seascapes, Ecosystems, Biodiversity, and Human society and wellbeing). The Australian climate has warmed by a mean of 1.4 °C on land and 1.1 °C in the oceans since consistent national records began (see Climate shifts). Some parts of Australia are warming faster than others, but almost all areas are warming in all seasons. Our warmest year on record was 2019, with temperatures 1.5 °C above the average for the standard 1961−90 reference period. The decade from 2011 to 2020 was Australia’s warmest on record, and every individual year from 2013 to 2020 ranks in the top 10 warmest on record nationally. Temperature is a fundamental driver of all biological processes, and rapid changes in temperature (as observed across Australia) present a stress to most ecosystems. They may result in changes to species’ ranges (both expansions and contractions), changes to growth and reproduction rates, or mass mortality events. For example, across the Great Barrier Reef, the first-ever consecutive years of mass coral bleaching, in 2016 and 2017, were followed by an additional bleaching event in 2020, all of which occurred during periods of abnormally high sea surface temperatures. There have also been substantial changes in many other parts of the climate system, including rainfall. Rainfall has decreased in south-eastern and south-western Australia since 1970, and increased in north-western Australia, with indications of shorter but more intense rainfall events (BOM 2021a). Declines in water availability strongly influence the distribution of plants and animals, and the health of terrestrial and aquatic ecosystems. Low rainfall and high evaporation rates are having a profound effect on river systems. Since 2016, many water storages have fallen below 10%, with acute impacts in the Murray–Darling Basin (BOM 2021a), including large-scale fish deaths in 2019. Sea level rises along much of Australia’s coastline continued to be above the global average of 3–3.5 millimetres per year, and the low-lying Torres Strait islands are highly vulnerable (see Other climate-related changes) (Green et al. 2010, Suppiah et al. 2011, TSRA 2014, Rainbird 2016). Although Australia is no stranger to extreme events such as tropical cyclones, hailstorms, blizzards, flooding rains, storm surges, heatwaves and bushfires, climate change is affecting the frequency, intensity and distribution of these events, and even creating new forms of environmental impact – for example, fires that increase lightning strikes from the firestorms they create, and smoke-induced oceanic phytoplankton blooms (see Extreme events). Assessment Climate and extreme events Assessments of state are poor Assessments of trend are deteriorating Legend How was this assessment made Share on Twitter Share on Facebook Share on Linkedin Share this link Assessment Climate 2021 Australia’s lands and seas are warming, and much of the south has experienced reduced winter rainfall and severe drought in recent years. Rainfall is increasing in the north-west. Sea levels continue to rise faster than the global average and threaten coastal communities. Assessments of state are poor Assessments of trend are deteriorating Related to United Nations Sustainable Development Goal targets 11.5, 13.2, 15.3 Assessment Extreme events 2021 The impacts of climate-related extreme events on the Australian environment are mixed, with heatwaves having a negative impact on land and in the oceans, but floods and bushfires having a mixture of negative and positive impacts depending on location and context. The combined impacts of all extreme events are increasing as they change in frequency, intensity, duration and distribution. Assessments of state range from poor to good Assessments of trend range from deteriorating to stable Related to United Nations Sustainable Development Goal target 15.3
Assessments of state are poor Assessments of trend are deteriorating Legend How was this assessment made Share on Twitter Share on Facebook Share on Linkedin Share this link Assessment Climate 2021 Australia’s lands and seas are warming, and much of the south has experienced reduced winter rainfall and severe drought in recent years. Rainfall is increasing in the north-west. Sea levels continue to rise faster than the global average and threaten coastal communities. Assessments of state are poor Assessments of trend are deteriorating Related to United Nations Sustainable Development Goal targets 11.5, 13.2, 15.3 Assessment Extreme events 2021 The impacts of climate-related extreme events on the Australian environment are mixed, with heatwaves having a negative impact on land and in the oceans, but floods and bushfires having a mixture of negative and positive impacts depending on location and context. The combined impacts of all extreme events are increasing as they change in frequency, intensity, duration and distribution. Assessments of state range from poor to good Assessments of trend range from deteriorating to stable Related to United Nations Sustainable Development Goal target 15.3