What factors put Australia on the red line of Climate Extremes?

Rising temperatures are fueling widespread environmental degradation in Australia and an intensification of natural disasters, a government report on climate change said.

Red line of Climate Extremes

The State of the Climate report indicated that global warming is melting Australia's mountainous areas and contributing to ocean acidification and rising sea levels.

In a 27-page report, the Australian government assesses the alarming damage to the environment due to global warming. The increase in average temperatures in Australia of 1.47°C since 1910 has brought multiple consequences from unprecedented fires in 2019-2020 to devastating floods in Sydney or a rise in sea level.

"Climate change hits our country hard. We have seen an increase in temperatures and extreme weather events with heat waves. In the south of the country, we are seeing a reduction in precipitation. Snowfall is on the decline. And we are seeing an increase in ocean temperatures which affects fishing off the south-east coasts," Ailie Gallant, a climatologist at the University of Melbourne said.

“The magnitude of the changes shows that cleaning up our energy use is an urgent priority,” she said.
Environment Minister Tanya Plibersek called it a "sobering" reading. “For our environment, for our communities, this report reinforces the urgent need for climate action,” she said.

Warming of oceans

Australia has experienced a series of extreme events in recent years that experts link to rising global temperatures: from devastating floods in Sydney to the terrible fires of the southern "black summer" of 2019 and 2020, to four episodes of bleaching of the Great Coral barrier.

“These changes are occurring at an increasing rate,” the report states. "In the past decade there have been unprecedented extremes that have led to natural disasters aggravated by man-made climate change," the text states.

“The warming of the oceans, together with the increasing frequency, intensity and duration of marine heat waves, pose a significant threat to the long-term health and resilience of coral reef ecosystems,” underline the authors of the report ' State of the Climate 2022'.

One of the most spectacular and disturbing effects of the alteration of the marine ecosystem by climate change is the massive bleaching of the Great Barrier Reef which extends over 2,300 kilometres along the Australian coast. Four such phenomena have been recorded in recent years: in 2016, 2017, 2020 and 2020.

"Mass bleaching is a stress response in corals that occurs primarily due to elevated ocean temperatures. Recovery is possible, but mortality may occur if heat stress is too severe or prolonged," the report authors warn.

Sea temperature effects

Adriana Humanes, an ecologist at the University of Newcastle, who has carried out scientific research on the Great Barrier Reef in Australia, details the mechanism that leads to the bleaching of the coral reef: "Corals are animals that live in symbiosis with algae that they live in its tissue. These microalgae give the animal its colour. 

Currently, the temperature in which they find themselves is very close to the maximum limit that they can tolerate. Then any minimal increase in sea temperature affects them and the algae come out of the coral tissue. The coral cannot live more than a month or so without these algae. If the temperatures during these heat waves stay too high, they usually fail to reabsorb these algae and they die and look white.”

Key points

• Australia's climate has warmed by an average of 1.47 ± 0.24 °C since national records began in 1910.

• Sea surface temperatures have increased by an average of 1.05°C since 1900. This has led to an increase in the frequency of extreme heat events over land and sea.

• There has been about a 15 per cent decrease in rainfall from April to October in South West Australia since 1970. In the same region, May to July rainfall has seen the largest decline, about 19 per cent, since 1970.

• In south-eastern Australia, there has been a decrease of about 10 per cent in rainfall from April to October since the late 1990s.

• There has been a decline in the flow of current on most meters in Australia since 1975.

• Rainfall and water flow have increased in parts of northern Australia since the 1970s.

• There has been an increase in extreme fire weather and a longer fire season in much of the country since the 1950s.

• There has been a decrease in the number of tropical cyclones observed in the Australian region.

• Snow depth, snow cover, and the number of snow days have decreased in alpine regions since the late 1950s.

• The oceans around Australia are acidifying and have warmed by more than 1°C since 1900, contributing to longer and more frequent marine heat waves.

• Sea levels are rising in Australia, including more frequent extremes that increase the risk of flooding and damage to coastal infrastructure and communities.

What is coming?

• Continuous increase in air temperature, more extremes of heat and fewer extremes of cold.

• Continued decrease, on average, in cool season rainfall in many regions of southern and eastern Australia, likely to lead to more dry weather, but with continued climate variability leading to short-lived heavy rain events duration on a range of time scales.

• Continued increase in the number of hazardous weather days for fires and a longer fire season for southern and eastern Australia.

• Further sea level rise and continued warming and acidification of the oceans around Australia.

• Increasing and longer-lasting marine heatwaves will affect marine environments such as kelp forests and increase the likelihood of more frequent and severe bleaching events on Australia's coral reefs, including the Great Barrier Reef and Ningaloo Reef.

• Fewer tropical cyclones, but a greater proportion are expected to be high intensity, with large variations from year to year.

• Reduction in average snow depth in alpine regions, but with variations from year to year.

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