The sky in Sydney is an eerie yellowish-orange as smoke and dust blown eastward from drought-fueled wildfires smothered the sunlight. Australians are choking on the foul air and their eyes are watering. It’s served as a reminder that something is amiss Down Under this spring.

Officials advised the ill, very young and elderly to limit their exposure to the air, as for a time, the air quality in Australia’s largest city was about as poor as some of the most polluted cities worldwide, including Delhi and Zhengzhou, China.

The bush fires that have been plaguing Australia for the past few weeks continue to rage, with the possibility that some fires in New South Wales could merge into megafires.

In addition, record heat has gripped much of the country this week, with numerous monthly temperature records falling, including in Melbourne, where the high reached 105.6 degrees (40.9 Celsius) on Thursday, tying a record that dates back to 1894, according to the Bureau of Meteorology.

While fire weather warnings have been downgraded slightly for Friday, local time, Thursday featured “catastrophic” fire danger — the highest threat level — in the state of Victoria, along with dangerous conditions in South Australia, New South Wales and Queensland.

Fires burning in New South Wales covered Sydney and other areas of the state’s eastern coast in a stifling blanket of hazardous smoke. Tiny particles in the smoke, known as particulate matter 2.5, can enter the lungs and aggravate asthma and other chronic health conditions, as well as raise the risks for other illnesses.

The extreme heat has been relentless. On Wednesday, for example, temperatures in a portion of every mainland Australian state and the Northern Territory hit at least 104 degrees (40 Celsius). While not unheard of, this is nevertheless unusual, particularly for this time of year.

What’s especially worrisome to public officials and residents throughout the most fire-prone areas is that Australia typically sees its peak fire activity during the summer, rather than the spring. The heat and code red fire danger in Victoria on Thursday were more akin to the “worst conditions you’d see in February or March,” according to Victoria’s emergency services minister Lisa Neville.

“This shows us what the risks will be in summer around Victoria, so we still have a long way to go to be ready,” she said, according to the Guardian newspaper.

The record heat this week has toppled November records in South Australia, too. Nullarbor, for example, hit 116 degrees (46.6 Celsius). The heat even spread to Tasmania, which typically has more moderate temperatures because of cooler winds from the surrounding ocean. Hobart, for example, tied its record for the hottest November day on Thursday, the Bureau of Meteorology reported.

Satellite image showing smoke and thermal anomalies (red dots) from Australian bush fires on Nov. 20, 2019. (NASA)

A large area of South Australia was more than 29 degrees (16 Celsius) above average for this time of year, the BOM found. In other words, the heat experienced this week was more typical of February in the Land Down Under, which, given drought conditions in many areas, is worrisome for the long fire season ahead.

The size of the fires that are still burning is difficult to fathom. Two fires west of Port Macquarie in New South Wales have each burned more than 250,000 acres. In total, the state of New South Wales has seen at least 2,471,053 acres go up in smoke, the majority of it burning in sparsely populated areas.

More than 600 homes have been destroyed by bush fires so far this season in New South Wales, according to the Rural Fire Service, and six people have been killed so far.

Climate change as a threat multiplier

Research shows that human-caused climate change is playing a role in amplifying the fire risk and ratcheting up the heat across large parts of Australia. Wildfires are worsening with climate change because heat and drought make the landscape more flammable. Months of rainfall deficits have left Australia parched; January through October 2019 was the second-warmest and second-driest such period on record.

Because of the combination of drought and heat, fires are burning in ecosystems that typically don’t see bush fires, according to an interview Science Magazine published with David Bowman, a fire ecologist and director of the Fire Center at the University of Tasmania in Hobart.

“We’re seeing recurrent fires in tall, wet eucalypt forests, which normally only burn very rarely. A swamp dried out near Port Macquarie, and organic sediments in the ground caught on fire,” Bowman said. “When you drop the water table, the soil is so rich in organic matter it will burn. We’ve seen swamps burning all around.”

Smoke haze hangs over the Sydney Opera House as a water taxi passes by on Thursday. (Rick Rycroft/AP)

“This is teaching us what can be true under a climate changed world. The numbers, scale, and diversity of the fires is going to reframe our understanding of bushfire in Australia. This is a major event which will have huge intellectual and policy legacies.”

According to a comprehensive 2015 federal climate report, the ongoing bush fires are burning in areas of Australia that are likely to see an uptick in the average forest fire danger index and the number of days with severe fire danger. The study pinned these trends on human-caused climate change, in large part because a warming climate dries out vegetation faster, worsening drought impacts.

Long-term climate trends in Australia show sharp warming and an increase in extreme heat events. Last summer was the country’s hottest on record, and the BOM found climate change exacerbated extreme heat events as well as droughts during the year. Overall, Australia’s average annual temperature has increased by 1.8 degrees since 1910, the BOM found, and a 2018 report by the agency said: “There has been a long-term increase in extreme fire weather, and in the length of the fire season, across large parts of Australia.”