This WA town just topped 50 degrees Celsius – a dangerous temperature that many Australians will have to get used to

While Australians are used to the summer heat, most of us only have to endure the occasional day of over 40 degrees Celsius.

On Thursday however, the temperature peaked at 50.7C in Onslow, a small town in Western Australia about 100km from Exmouth.

Remarkably, the city sits right next to the ocean, which usually provides cooling. By contrast, the notoriously hot town of Marble Bar only reached 49.6C this summer, despite its inland location.

If confirmed, Onslow’s temperature would equal Australia’s hottest on record at Oodnadatta, South Australia in January 1960. It would also mark only the fourth day above 50C for an Australian site since the beginning of reliable observations.

Unfortunately, this extreme heat is becoming more common as the world heats up. The number of days above 50C has doubled since the 1980s. These dangerous temperatures are now being recorded more often – not just in Australia, but in cities across Pakistan, India and the Persian Gulf. This poses real threats to the health of those who experience them.

Where does the heat come from?

Reaching such extreme temperatures requires a buildup of heat over several days.

Onslow temperatures have been near average since a few heat waves hit the Pilbara in the second half of December. So where does this unusual heat come from?

A weather map showing systems and fronts on a map of Australia
The January 13 weather map shows conditions half an hour before the 50.7°C record. The blue dotted line marks the trough that meets the coast near Onslow and helped bring in the warm air.(Provided: Bureau of Meteorology)

In short, burning desert. South to southeast winds blew very warm air from the upstate into Onslow. The wind was coming from an area that has received little to no rain since November, so the very hot air was also extremely dry.

The dry air allowed the sun to beat at full intensity preventing any cloud cover or thunderstorm formation. The result? The temperature rose and rose throughout the morning and into the early afternoon, and the temperature peaked at over 50°C just before 2:30 p.m. local time.

Aren’t we in a colder period of La Niña?

Australia’s climate is strongly tied to the conditions of the Pacific Ocean. Right now we are in a La Niña event where we have colder than normal ocean temperatures near the equator in the central and eastern Pacific.

La Niña is generally associated with cooler and wetter conditions. But its effects on the Australian weather are strongest in spring, when we had unusually wet and cool conditions in the east of the continent.

During the summer, the relationship between La Niña and Australian weather patterns generally weakens, with its strongest impacts normally confined to the northeast of the continent.

During La Niña we typically see fewer and less intense heat waves across much of eastern Australia, but the intensity of extreme heat in Western Australia is not much different between La Niña and El Nino.

The pattern of extreme heat in Western Australia and flooding in parts of Queensland is fairly typical of a La Niña summer, although temperatures above 50°C are extremely rare.

Flood waters crossing a country road
Recent flooding in Queensland is also typical of La Nina summers.(Provided: Susie Ross)

Climate change is driving up the temperature

Should these temperatures be a surprise? Unfortunately no. Australia has warmed by around 1.4°C since 1910, well above the global average of 1.1°C.

In northern Australia, average summer temperatures have not increased as much as in other parts of the country, as summers in the Top End have also become wetter. This corresponds to models of climate change.

When conditions are right in the Pilbara, however, the heat is significantly more extreme than before. Heat events in the region have become more frequent, more intense and longer lasting, just like in most other regions.

Most of us have chosen not to live in the warmer parts of Australia. So you might think you don’t have to worry about 50°C heat waves. But as the climate continues to warm, heatwave conditions are expected to become much more common and extreme across the continent.

In urban areas, roads and concrete absorb heat from the sun, raising peak temperatures by several degrees and creating dangerous conditions.

Even if we keep global warming below 2°C in line with the Paris Agreement, we can still expect to see our first 50°C days in Sydney and Melbourne in the years to come. In January 2020, Sydney’s western suburb of Penrith came very close, reaching 48.9C.

A seagull perches on a rock in Sydney Harbor in the foreground, with a heat haze over the city of Sydney visible in the background.
Sydney and Melbourne will experience 50C days in the coming years.(ABC News: Mary Lloyd)

As you know, it will be very difficult to achieve even keeping global warming below 2°C, given the need to urgently reduce greenhouse gas emissions over the next decade.

As things stand, global actions to reduce emissions suggest we are actually on track for a warming of around 2.7°C, which would have devastating consequences for life on Earth. .

We already know what we need to do to prevent this frightening future. The stronger the action to reduce greenhouse gas emissions globally – including by major carbon emitters like Australia – the less the world will warm and the less Australian heat extremes will will intensify. This is because the relationships between greenhouse gas emissions, global temperatures and Australian heat extremes are roughly linear.

You might think Aussies are good at surviving the heat. But the climate in which you were born no longer exists. Unfortunately, our farms, wildlife and suburbs will struggle to cope with the extreme heat predicted for decades to come.

Let’s work to make this 50C record an outlier – not the new normal.

Andrew King is a senior lecturer in climate science at the University of Melbourne. This piece first appeared on The Conversation.


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