Here’s what Australia faces if and when we pass 1.5C of warming by 2027

Australia faces ongoing Black Summer-level bushfire catastrophes, the decimation of coastal homes, and a dead Great Barrier Reef if the world becomes 1.5C hotter and stays there. And the first time we’ve ever surpassed this tipping point is likely to take place in the next four years.

A damning report from the World Meteorological Organization (WMO) has forecast a 66% chance of the world recording an average temperature increase of 1.5C hotter than in pre-industrial years, a probability WMO said has surged from 10% in 2021 and nearly zero in 2015.

A potent combination of El Niño — La Niña’s hotter, dryer brother — and climate change is to blame, according to the latest global Annual to Decadal Climate Update, which also warned there is a 98% likelihood of at least one year between now and 2027 being the hottest on record.

Dr Kimberley Reid is an atmospheric scientist from the ARC Centre of Excellence for Climate Extremes at Monash University. She told Crikey exceeding 1.5C on an ongoing basis is something climate scientists agree will occur as soon as the 2030s without drastic human intervention.

If we do not act fast, Reid told Crikey, Australia can expect several catastrophes of biblical proportion — and they may all happen at once.

Homes on the coast could fall into the sea

A 2022 study found that global temperatures 1C above pre-industrial levels — a point the world has already passed — would be enough to gradually collapse the West Antarctic ice sheet, something that would eventually cause the sea level to rise by four metres.

But some of the country’s most expensive beachside homes are already feeling the effects of coastal erosion, Reid said, where the land beneath a property is lashed by king tides during east coast lows that can cause partial or entire collapse.

“There are quite a few places, not just coasts, as we saw last year with all the flooding, where it’s very risky to be building houses because of the extreme weather events,” Reid said.

Adelaide’s West Beach, Glenelg, Henley and Brighton, as well as parts of the Gold Coast and Sydney’s northern beaches, are already working to secure homes at risk — but about 87% of Australians live within 50 kilometres of the nearest shoreline and could be displaced by a rising sea level.

Reid said it’s not just rising sea temperatures that put coasts at risk — ocean storms and tropical cyclones from warming weather will grow “very intense, and such intense storms can cause a lot of coastal erosion in a very short period of time”.

Cyclones typically occur in the NT and far north Queensland, Reid explained, because you need ocean temperatures above 26C for them to form. “But as temperatures warm, that magical number would shift further south,” she said, bringing cyclones to Brisbane and as far as NSW.

Black Summer bushfires could happen again. And again

The 2019-20 bushfire season scorched more than 24 million hectares of land, killed 33 people, and led to the deaths of 450 from smoke inhalation, increasing the stratospheric temperature above Australia by 3C, one study suggested.

A repeat of Black Summer is Reid’s “biggest concern”, and the chances rise significantly in a year when the global temperature surpasses 1.5C transpires. It’s a tipping point, she said, because it’s hard to come back from.

“As these extreme events occur more often, the recovery time decreases. And there’s a point where you just can’t recover properly, because it’s too many extreme events.”

Reid said three back-to-back La Niñas, where the temperatures have been cooler and average rainfall has been higher, have seen vegetation growth in eastern Australia grow abundantly.

“If we do get such a hot global year of 1.5C, which brings a hot, dry period over Australia, that vegetation will dry out and become kindling for bushfires. We may see another Black Summer bushfire season.”

The Great Barrier Reef would die

The natural wonder, which is about the size of Germany, has been hit with five mass-bleaching events in recent history (1998, 2002, 2016, 2017 and 2020) because of rising ocean temperatures driven by human emissions of greenhouse gases.

The reef has actually benefited from a relatively mild La Niña summer, according to the Reef Snapshot: Summer 2022-23, a joint report by the Great Barrier Reef Marine Park Authority, the Australian Institute of Marine Science and CSIRO.

It found while sea temperatures in spring were the hottest on record, summer sea temperatures were slightly above average at most, leading to some bleaching in the northern, central and southern regions. But, crucially, “no mass coral bleaching”, it said.

Coral can recover from mild bleaching, but if the temperature is too hot for too long, it dies.

Australia would enter a health crisis

The human cost of such calamities would be wide-ranging, said Dr Annabelle Workman, a climate scientist at the Melbourne Climate Futures, Melbourne Law School and Melbourne School of Population and Global Health.

“These types of events, and climate change more broadly, can impact human health in different ways, including physically — through illnesses like heat stress and dehydration,” Workman told Crikey.

“But also mentally — including eco-anxiety, pre-traumatic stress and post-traumatic stress. Further, there are likely to be impacts on outdoor workers in some parts of Australia in a warmer world.”

Not only that, Reid said, but longer, meaner droughts place livestock and crops at risk, which already grow on the driest continent on earth.

Dairy cows are one of the most susceptible livestock species to heat stress, affected by increased temperatures as low as 23C, while one of Australia’s most abundant crops — golden wheat, the key ingredient in bread — would become scarce.