April 24, 2024

What we know about Australia’s top 10 wild weather events from last year – from combinations of fires and floods to extreme rainfall caused by cyclones

Fire. Flood. Fire and flood together. Double storms. Unprecedented rains. Hot flashes. Climate change is making some of Australia’s weather conditions more extreme. In 2023, the country was hit by a wide range of particularly intense events, with impacts across the entire economy. The winter was the warmest since 1910, while we had the driest September since at least 1900.

We often see extreme weather as discrete events in the news. But it can be helpful to look at what’s happening throughout the year.

Today, more than 30 of Australia’s leading climate scientists released a report analyzing ten major climate events in 2023, from early fires to low snowpack and compound events.

Can we say to what extent climate change contributed to these events? Not yet. It usually takes several years of research before we can clearly say what role climate change plays. But the long-term trends are well established – more frequent and intense heatwaves across most of Australia, marine heatwave days that have more than doubled over the past century, and short, intense precipitation events that have intensified in some areas .

figure showing extreme weather conditions of 2023
2023 was the hottest year on record. See what the year was like in Australia.
ARC Center of Excellence for Climate Extremes

What happened in 2023?

January. Event #1: Record rainfall in the north (NT, WA, QLD)

The year began with above-average rainfall in northern Australia, influenced by the “triple dip” phase of La Niña.

Some parts of the country were already experiencing heavy rain even before Cyclone Ellie arrived. From late December 2022 to early January 2023, Ellie brought heavy rainfall to Western Australia, the Northern Territory and Queensland, resulting in a once-in-100-year flood of the Fitzroy River. Interestingly, Cyclone Ellie was only a “weak” Category 1 tropical cyclone. So why did it cause so much damage? In their analysis, climate scientists suggest that it was actually low wind speeds in the middle troposphere that allowed the system to stop and continue raining.

February March. Event 2: Extreme rainfall and food shortages (NT, QLD)

Climate scientists observed the same behavior from late February to early March 2023, when a persistent, slow-moving low pressure system known as a monsoon trough dumped widespread, heavy rain over the Northern Territory and northwest Queensland. The resulting floods cut off transport routes in the NT and led to food shortages.

June August. Event 3 and 4: Warmer winter, little snow (NSW)

After a wet start to the year, conditions became drier and hotter in southern and eastern Australia. New South Wales had the warmest winter on record, with daily highs more than 2°C above the long-term average.

The unusual heat and lack of precipitation resulted in the second worst snow season on record (the worst was in 2006).

figure showing very low 2023 snow levels in Australia
Snow levels in New South Wales and the Australian Capital Territory were well below long-term averages, shortening the ski season.
ARC Center of Excellence for Climate Extremes

September. Event 5: Record Heatwave (SA)

In September, South Australia faced a record heatwave. Temperatures reached 38°C in Ceduna. As warming continues, scientists suggest that unusual heat and heat waves during the cold season will become more frequent and intense.

September also saw El Niño and a positive Indian Ocean Dipole declared by the Bureau of Meteorology. When these two climate factors combine, we have a greater chance of a hot and dry Australia, especially during late winter and spring.



Read more: 2023’s extreme storms, heat and wildfires broke records – a scientist explains how global warming fuels climate disasters


October. Event 6, 7 and 8: Composite fire and flood event (VIC), composite wind and rain storms (TAS), exceptionally early fires (QLD)

Dry conditions gave rise to an unusually early fire season in Victoria and Queensland. In October, the Western Downs region of Queensland was hit hard. Dozens of homes and two lives were lost in the city of Tara.

In the same month, the Gippsland region of Victoria was hit by consecutive fires and floods, a phenomenon known as a compound event.

While it’s difficult to attribute these events to climate change, scientists say warm, dry winters make Australia more prone to early-season fires.

Also in October, a different composite event hit Tasmania in the form of successive low pressure systems. The first dumped a month’s worth of rain in a few days across much of the state, while the second brought strong winds. The rain from the first storm loosened the soil, making it easier to fell the trees.

Scientists say the combined effects were more severe than if just one of these events occurred without the other. These extreme events made up of wind and rain are expected to occur more frequently in regions such as the tropics as the climate continues to change.

November. Event 9: Crops destroyed by supercell storm (QLD)

In November, a supercell storm hit southeast Queensland, destroying A$50 million worth of crops and farm equipment. Initial research suggests that extreme winds and storm surges may become more likely due to climate change, but more work is needed.

hail storm on crops
The hail storm destroyed crops in Queensland’s Lockyer Valley, a large agricultural area.
Shutter

December. Event 10: Unprecedented flooding from Cyclone Jasper (QLD)

In mid-December, Tropical Cyclone Jasper made landfall as a Category 2 tropical cyclone in northern Queensland. The system weakened to a tropical low and then stalled at Cape York. The weather system’s northerly winds drew moist air from the Coral Sea, which collided with drier southeasterly winds. This caused persistent heavy rainfall in the region – up to 2 meters in some places. Watersheds flooded the entire region, causing widespread damage to roads, buildings and crops. Similar to former Tropical Cyclone Ellie, most of the damage occurred after landfall when the system stalled and dumped rain.

Climate change could make extreme weather even more extreme

It is generally easier to identify and understand the role of human-caused climate change in large-scale extreme events, especially extreme temperatures. So we can say that the exceptional warmth of the winter of 2023 was likely intensified by what we did to the climate system.

For smaller-scale extremes, it is often more difficult to determine the role of climate change, but there is some evidence that short, intense precipitation events are becoming even more intense as the world warms. Early season wildfires and low snow cover are consistent with what we expect in the context of global warming.

There is also a growing threat arising from the risk of compound events, where simultaneous or consecutive extreme events can amplify damage.

Australia’s intense weather events during 2023 are generally what we can expect to see as the world becomes increasingly hotter due to the heat-trapping greenhouse gases that humanity continues to emit.



Read more: Global warming could exceed 1.5°C by 2024 – here’s what that could look like


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