Climate change in Australia
Climate change has been a critical issue in Australia since the beginning of the 21st century. Australia is becoming hotter and more prone to extreme heat, bushfires, droughts, floods, and longer fire seasons because of climate change. Climate issues include wildfires, heatwaves, cyclones, rising sea levels, and erosion.[2][3][4]
Since the beginning of the 20th century, Australia has experienced an increase of over 1.4 °C in average annual temperatures,[5] with warming occurring at twice the rate over the past 50 years compared with the previous 50 years.[6] Recent climate events such as extremely high temperatures and widespread drought have focused government and public attention on the effects of climate change in Australia.[7] Rainfall in southwestern Australia has decreased by 10–20% since the 1970s, while southeastern Australia has also experienced a moderate decline since the 1990s. Rainfall is expected to become heavier and more infrequent, as well as more common in summer rather than in winter. Australia's annual average temperatures are projected to increase 0.4–2.0 °C above 1990 levels by the year 2030, and 1–6 °C by 2070. Average precipitation in the southwest and southeast Australia is projected to decline during this time, while regions such as the northwest may experience increases in rainfall.
Climate change is affecting the continent's environment and ecosystems. Australia is vulnerable to the effects of global warming projected for the next 50 to 100 years because of its extensive arid and semi-arid areas, and already warm climate, high annual rainfall variability. The continent's high fire risk increases this susceptibility to changes in temperature and climate. Meanwhile, Australia's coastlines will experience erosion and inundation from an estimated 8–88 cm increase in global sea level. Australia's unique ecosystems such as the Great Barrier Reef and many animal species are also at risk.
Climate change also has diverse implications for Australia's economy, agriculture and public health.[8] Projected impacts include more severe floods, droughts, and cyclones.[9] Furthermore, Australia's population is highly concentrated in coastal areas at risk from rising sea levels, and existing pressures on water supply will be exacerbated. The exposure of Indigenous Australians to climate change impacts is exacerbated by existing socio-economic disadvantages which are linked to colonial and post-colonial marginalisation.[2] The communities most affected by climate changes are those in the North where Aboriginal and Torres Strait Islander people make up 30% of the population.[10] Aboriginal and Torres Strait Islander communities located in the coastal north are the most disadvantaged due to social and economic issues and their reliance on traditional land for food, culture, and health. This has raised the question for many community members in these areas, "Should we stay or move away?"[10]
Australia is also a contributor to climate change, with its greenhouse gas emissions per capita above the world average. The country is highly reliant on coal and other fossil fuels, although renewable energy coverage is increasing.[11] National mitigation efforts include a commitment to achieving net zero emissions by 2050 under the Paris Agreement, although Australia has repeatedly ranked poorly in the Climate Change Performance Index and other international rankings for its climate targets and implementation. Adaptation can be performed at national and local levels[12] and was identified as a priority for Australia in the 2007 Garnaut Review.
Climate change has been a divisive or politicised issue in Australian politics since the 2000s, contributing to successive governments implementing and repealing mitigation policies such as carbon pricing. Some Australian media outlets have promoted climate misinformation. The issue has sparked protests in support of climate change policies, including some of the largest demonstrations in Australia's history.
Historical aspects[edit]
Pre-instrumental climate change[edit]
Paleoclimatic records indicate that during glacial maxima Australia was extremely arid,[232] with plant pollen fossils showing deserts as far as northern Tasmania and a vast area of less than 12% vegetation cover over all of South Australia and adjacent regions of other states. Forest cover was largely limited to sheltered areas of the east coast and the extreme southwest of Western Australia.
During these glacial maxima the climate was also much colder and windier than today.[233] Minimum temperatures in winter in the centre of the continent were as much as 9 °C (48 °F) lower than they are today. Hydrological evidence for dryness during glacial maxima can also be seen at major lakes in Victoria's Western District, which dried up between around 20,000 and 15,000 years ago and re-filled from around 12,000 years ago.[234]
During the early Holocene, there is evidence from Lake Frome in South Australia and Lake Woods near Tennant Creek that the climate between 8,000 and 9,500 years ago and again from 7,000 to 4,200 years ago was considerably wetter than over the period of instrumental recording since about 1885.[235] The research that gave these records also suggested that the rainfall flooding Frome was certainly summer-dominant rainfall because of pollen counts from grass species. Other sources[236] suggest that the Southern Oscillation may have been weaker during the early Holocene and rainfall over northern Australia less variable as well as higher. The onset of modern conditions with periodic wet season failure is dated at around 4,000 years before the present.
In southern Victoria, there is evidence for generally wet conditions except for a much drier spell between about 3,000 and 2,100 years before the present,[237] when it is believed Lake Corangamite fell to levels well below those observed between European settlement and the 1990s. After this dry period, Western District lakes returned to their previous levels fairly quickly and by 1800 they were at their highest levels in the forty thousand years of record available.
Elsewhere, data for most of the Holocene are deficient, largely because methods used elsewhere to determine past climates (like tree-ring data) cannot be used in Australia owing to the character of its soils and climate. Recently, however, coral cores have been used to examine rainfall over those areas of Queensland draining into the Great Barrier Reef.[238] The results do not provide conclusive evidence of man-made climate change, but do suggest the following: