As it happened: BoM officially declares El Niño weather event; rift over treaty deepens among No campaigners

That’s where we’ll leave our live coverage of today’s events, thanks for joining us.

We’ll be back on deck with you tomorrow morning. Here’s what you need to know tonight.

• The Bureau of Meteorology urged people to prepare for extreme heat and bushfire this summer as it declared the onset of an El Nino and a positive Indian Ocean Dipole, two weather events that make Australia hotter and drier.
• The Australian National University in Canberra will ramp up its security after a young man faced court for allegedly stabbing two students and attacking two others with a frying pan.
• In its first budget since 2010, NSW Labor will deliver a $7.8 billion deficit this year before delivering a modest surplus of $844 million next financial year.
• Premier Daniel Andrews has sought to justify a possible tax on short-stay accommodation and Prime Minister Anthony Albanese said Airbnb is placing more stress on renters in his electorate.
• The Antarctic’s sea-ice has reached a record low and the consequences could be devastating, polar experts have warned.
• One of the aviation industry’s most senior economists told a Senate inquiry that Australia’s domestic airline competition has weakened substantially since COVID-19.
• The Reserve Bank Board considered raising interest rates by a quarter percentage point earlier this month due to the risk of inflation remaining too high for too long.

The Bureau of Meteorology has finally declared that an El Nino weather pattern is under way, increasing the likelihood of a hot and dry summer for Australia as global weather records tumble.

The declaration comes as cloudless skies over the continent, which are typical of El Nino conditions, have seen high temperatures develop inland and flow towards the east coast, where early spring heat records have been shattered.

The El Nino declaration follows those already made by the US Climate Prediction Centre, the United Nations World Meteorological organisation and the Japan Meteorological Agency.

The bureau’s criteria for declaring an El Nino includes measurements of sea surface temperature in parts of the Pacific Ocean and the direction and strength of trade winds.

The winds typically blow from east to west across the Pacific. During El Nino, the winds weaken, leading to less moisture in the air around Australia, reduced rainfall and higher temperatures.

Here’s what the bureau’s national manager of climate services, Dr Karl Braganza, said this afternoon:

It was an auspicious day for the Bureau of Meteorology to call an El Nino as Sydney sweltered through the equal-hottest September day on record.

“Sydney’s provisional maximum temperature of 34.6ºC on Tuesday was the city’s equal highest September temperature on record, matching the same value from September 26, 1965, said Weatherzone meteorologist Ben Domensino.

“On an average September day, Sydney would typically see maximum temperatures peaking around 20ºC.”

A large low-pressure system expanding across Australia caused a pool of hot air to spread across the continent, bringing record heat, Domensino said.

Bushfires are burning in many states as a result. An emergency warning has been issued for the popular Tasmanian holiday of Coles Bay this afternoon as an out of control bushfire burns towards the town and campers.

Returning to politics, Prime Minister Anthony Albanese has called for respectful debate after footage emerged of protesters calling Liberal senator Alex Antic a “racist dog” as he entered an event on Monday headlined by Coalition Indigenous Australians spokeswoman Jacinta Nampijinpa Price.

Antic posted footage on Twitter showing a small group of protesters yelling at him as he entered the No event in Adelaide.

Albanese said he “condemned nasty behaviour wherever it occurs”, while Opposition Leader Peter Dutton said the vision was disturbing.

Albanese added: “Of course some of the tone of the debate has been unfortunate. That’s the truth. What I would say to people is be respectful. I respect every Australian regardless of whether they’re going to vote Yes or whether they’re going to No.”

As well as declaring an El Nino event, the Bureau of Meteorology has announced the Indian Ocean Dipole (IOD) has switched to its positive phase.

The IOD has a similar drying effect on Australia to El Nino, especially across the continent’s south and east. The bureau said the weather pattern can have a particularly strong effect in reducing rainfall across Victoria.

The combination of the two rainfall-reducing, heat-summoning weather patterns will make summer hotter and drier.

“When these two things occur together, it can increase rainfall deficiencies over spring,” Dr Karl Braganza, the bureau’s national manager of climate services, said.

“We are already seeing extreme conditions in some parts of the continent. Today we’ve had catastrophic conditions on the south coast of NSW, just to underscore that risk.”