Northern Australia could have dangerously high heat most days of the year by 2100, study finds

Tropical regions, including northern Australia, could experience dangerously high heat levels most days of the year by 2100, while southern regions of Australia could experience heat waves deaths every year new research suggests.

The study published in the journal Communications Earth & Environment suggests that even if the world abides by the Paris agreement to limit global warming to 2°C, exposure to dangerous heat “will likely increase by 50 to 100% in most of the tropics.

The research, co-authored by researchers from Harvard University and the University of Washington, used the US National Weather Service’s Heat Index, which classifies ‘dangerous’ heat as above 39C (103°F) due to increased likelihood of heat cramps or heat exhaustion.

The study found that without major emission reductions, previously rare deadly heat waves will become annual occurrences in mid-latitudes – temperate regions between 30 and 60 degrees north and south of the equator.

In Australia, mid-latitudes are south of a line drawn midway between Geraldton and Perth in Western Australia to Bourke in New South Wales, according to the Bureau of Meteorology.

“The health consequences of regularly very high temperatures, especially for the elderly, the poor, and outdoor workers, would be profound and would require a baseline shift to extreme heat hazards,” the researchers found.

Dr Andrew King, a lecturer in climate science at the University of Melbourne, who was not involved in the study, said: ‘When you look to exceed previous high temperatures, you are more likely to do so. do earlier in tropical areas. than in other regions of the world.

“It’s also dangerous if you have heat combined with very humid conditions,” King said. “Our bodies sweat to cool themselves through evaporative cooling, and when it’s hot and humid, we just can’t really do that.”

“Part of the problem is that the countries most at risk in the tropics tend to be poorer countries…they have to adapt to a problem that they didn’t really cause in the first place.”

King said precautions that could be taken to limit the health effects of high heat included better forecasting of extreme heat episodes, planning to ensure people were well hydrated and discouraging individuals from working at outside on the most dangerous days.

The study highlighted the need to prioritize “reducing greenhouse gas emissions and reaching net zero as quickly as possible”, he said.

It comes as another paper, published in Scientific Reports, revealed that the 2019-2020 bushfires resulted in the greatest warming of the stratosphere – the second layer of Earth’s atmosphere – in more than 30 years.

Millions of tonnes of smoke aerosols were injected high into the atmosphere by Australia’s black summer bushfires. British researchers have found that the smoke temporarily warms the lower stratosphere and extends the life of the 2020 ozone hole, which develops each spring in the southern hemisphere.

The stratospheric temperature rose by 0.7°C from November 2019 to March 2020 – the biggest increase since the eruption of Mount Pinatubo in the Philippines in 1991.

“It is likely that future climate change will increase the frequency and intensity of wildfires, increasing the likelihood of more frequent stratospheric events. [smoke] upcoming events,” the researchers found.

Director of the Center for Atmospheric Chemistry at the University of Wollongong, Professor Clare Murphy, who was not involved in the research, said: ‘When you put aerosols in the atmosphere they both scatter light from the sun, but they can also absorb heat. The type of aerosols you get from the fires are more of the black carbon type absorbers.

“Fundamentally, climate change has been driven by atmospheric composition… There are feedback loops back and forth with ozone depletion and with global warming.”

Northern Australia could have dangerously high heat most days of the year by 2100, study finds

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